Chapter 12
Pages of History
(A). Part of Taurus-Littrow Valley seen from Station 8. A few features are identified in (B) for scale.
(B). The author at the rear geopallet of the LRV parked on a southwest-facing slope of the Sculptured Hills at Station 8 during EVA-3. This station marks the easternmost extent of exploration of the valley of Taurus-Littrow by Apollo 17. The westernmost extent was at Station 2 (~11.3 km distant) at the southeast end of the Nansen moat, visited the previous day on EVA-2. In the photo, Station 2 is just next to the white spot (see bright, haloed crater in Fig. 11.23↑) to the left of the vertical arrow under “Sta. 2”. The downward curving part of the line under the arrow marking Sta. 2, a lobe of the Lee-Lincoln Scarp, is the Hole-in-the-Wall ramp that provided access to the base of the South Massif. The continuation of the scarp is indicated to the right of the Sta. 2 arrow to beyond the edge of the photo. The LM marked at left is ~3.8 km away. The span of the rims of craters Cochise and Shakespeare (both ~600 m across) are marked for reference. Cochise extends beyond the left edge of the photo. An enlarged view of this labeled image in a separate window is available here. (cropped from NASA photo AS17-146-22387).
Day 8 – Third Extravehicular Activity (EVA-3)
Apollo 17’s third and final day of exploration can be interpreted to have provided evidence of events occurring within a few tens of millions of years of the birth of the Moon and its parent Solar System, as well as documentation on four of the major, basin-forming impacts that occurred within the first billion years of Solar System history. One sample, troctolite 76535, like its related sample dunite 72415, accumulated from minerals formed hundreds of kilometers deep within the lunar magma ocean only to be moved upward through gravitational overturn of the upper mantle beneath and triggered by an extremely large basin excavation, the Procellarum impact, brought them to the surface. Samples of coarse-grained, igneous rocks, norites 77215 and 78235, indicate that the Procellarum basin, the oldest and largest of lunar basins, formed ~4.34 billion years ago and was responsible for overturn of the mantle cumulates beneath it as well as the pressure-release generation of noritic and other magmas of the Mg-suite of lunar rocks (see Chapter 13).
Samples of impact melt-breccias from Stations 6 and 7 document the relative and absolute ages of three of those large basins— Crisium, Serenitatis and Imbrium. Other samples relate to the subsequent reheating and partial remelting of the solidified magma ocean to produce surface eruptions of pre-mare lithoclastic (mixed gas and rock fragments) crustal debris, Taurus-Littrow mare basalts, and pyroclastic ashes, the latter derived from both upper and lower mantle sources.
Regolith samples collected at Stations 1 and 6-9 appear to correlate with regolith ejecta deposits in the deep drill core obtained on EVA-1 and help to define the source craters for those deposits.
EVA-3 Wake Up and Preparation[1]
The Texas Aggie “War Hymn”, awoke us as we began our third and final day of lunar exploration. I had a feeling that Flight Director Gerry Griffin, an enthusiastic Texas Aggie, was responsible for this choice of wakeup music.
After a long pause, Cernan said, “I want you (Fullerton) to say it first….”
“Hello there, Challenger,” Fullerton finally replied. “The Gold Team Flight Director picked out the morning selection, and he said that if you can find some maroon dirt, today, instead of orange, you’ll probably get a lot more cooperation out of him.” The many other Texas Aggies in Mission Control probably gave great encouragement as well as loud “huzzahs” to this music selection. Coincidentally, orange is the school color of the Aggies’ principle sports rival, the University of Texas; but, strangely enough, it also is one of my college’s (Caltech) colors.
“I figured the Gold Team might do that. You know, I’ve woke up to a lot of pleasant thoughts, but never to an Aggie before. …Hey, Gordo, don’t forget I’m a Boilermaker [from Purdue].”
“Roger…”
“I feel like one (the drink called a Boilermaker = a shot glass of whiskey followed immediately by a glass of beer) right now. …Tell the Gold Team Flight Director we’ll find just about anything he wants today.”
“Okay; I’ll do that,” Fullerton replied. “The Challenger looks as good as ever. No problems at all through the night.”
“That’s outstanding. How’s America?”
“It’s in the same shape. Just clicking along. Ron’s been up for a few hours now and really gathering up the data.”
“Outstanding, Gordo…”
“Challenger, the name of the game today is to stay with the EVA prep timeline. We’re not going to talk much to you, except to bug you a little and stay on your back to keep with the timeline, if at all possible. We’d like to get out on time. Over.”
“Okay, Gordo. That’s been our motive all along, and we will stay with it. As of right now, we’re one hour behind. Is that correct?”
“That’s affirmative. Although, if you stay on the normal timeline, that’s fine with us. We don’t need to gain any, but we just don’t want to lose any from where we’re starting now.”
“Yeah. Understand. Understand…”
“How did you sleep, Geno?” I asked while rolling up my hammock.
Yawning with an open mike, Cernan then said to me, “Good. How are you this morning?”
“Great! Can you believe it, but my forearms are not sore from all that fatigue, yesterday.”
“Houston, Challenger,” I called after I had checked the Caution and Warning lights, cabin pressure, and all the quantity and pressure indicators for oxygen and propellants. We already had rolled up the hammocks and sleeping bags and begun to dig into breakfast.
“Go ahead, Challenger…”
“Okay, Gordy,” I replied and continued by saying, “Crew Status report is good, in case you hadn’t noticed. We haven’t kept an itemized accounting of the food. …[There] weren’t enough blanks on the [Checklist] paper to do that. But we have ate, …[rather] have eaten, pardon me, we have eaten just about everything in the various meals. I guess the shrimp was the only thing we didn’t really eat. And we’ve been drinking a lot of water and all the juices and tea and stuff, so I think we’re in pretty good shape there. Commander had a Seconal last night, and he slept 3 good and 3 intermittent hours. LMP had no medication and had 6 good hours of sleep. If you’ve got some lift-off time data, well, I’ll copy it.” Actually, during each rest period, I would sleep for about two hours or so, wake up, scan the Caution and Warning lights, make sure all the normal sounds sounded normal, and then go back to sleep.
“That’s affirm,” Fullerton answered and began a slow read of emergency lift-off times for the next six orbits (“revs”) or about 12 hours. This would take us through EVA-3. “Okay; start with Rev 38. Time is 162:22:52. Rev 39 is 164:21:24; 166:19:55; 168:18:27; 170:16:59; 172:15:31. That should have been rev 43 (the last one), and read back starting with rev 38.”
I gave him a rapid read-back and then asked, “And what is our present rev?”
“That’s a good question. Let’s see here, …we’re working on rev 37. …Ron just went by you about ten minutes ago on rev 37.”
“Gordy,” Cernan interjected, “we’re pressing on [with breakfast], but if you’ve got any good words, like news and what have you, while we are, we’d appreciate it.”
For this pre EVA-3 breakfast, Cernan enjoyed spiced oat cereal and a cereal bar, sausage patties, irradiated ham, six apricot cereal cubes, fruit cocktail and pears, and four cheese cracker cubes. His beverages were cocoa, tea and lemonade. I had almost the same choices except for substituting six pieces of gingerbread for the apricot cereal cubes, peaches for the fruit cocktail, and pineapple-grapefruit drink for lemonade and cocoa.
“Okay,” Fullerton, after a pause, responded to Cernan’s request for news. “There hasn’t been a lot of news, but I’ll read you what we’ve got. Former President Truman is still holding on. His heartbeat, breathing, and temperature all became unstable yesterday, but then he improved again. A Methodist minister in Kansas City said, ‘He’s a rugged guy who’s hanging in there, and he’s going to make it.’
“The headlines were full of reports of the find of orange dirt and the rest of your adventures yesterday. Internationally, the U.S. and North Vietnam held intensified secret peace talks, and Henry Kissinger prepared to return to Washington, probably this afternoon, I understand, after a final session with Le Duc Tho. The French press said a compromise was in the works on the withdrawal of North Vietnamese troops from the South.
“The Houston Rockets (basketball team) lost to Buffalo up in Buffalo last night, but the hockey team, the Aeros, took a 6 to 4 win over the Alberta Oilers. Really, that’s about it on the news, except maybe for the weather, which finally broke. A cold front cleared out the drizzly rain last night, and for the first time since you’ve launched – that I can remember anyway – we’ve been able to look up and see the Moon, directly. It’s a pretty sight as always. That’s not much of a report, but that’s about all we have. Over.”
“Okay; thank you,” Cernan said. “What’s the date today?”
“It’s Wednesday – let’s see – Wednesday, the 13th of December. … Right now, it’s about 1:35 in the afternoon (Central Standard Time).”
“Okay; just took a quick peek up there [through the overhead window]. I can’t really see too much of the North American continent. South America looks pretty good. And it might be my eyeballs rather than the clouds up there, but it looks like most of the clouds are up into the north-central part of the southeastern United States.”
“I have a satellite picture here, and that’s about the way it looks.”
“Well, it’s sunny and pleasant in the valley of Taurus-Littrow. …And, Gordo, what is our Sun [elevation] angle going out today?”
“I’ll get you an answer on that. …Couple of questions: first of all, the Surgeon would like Biomed Right.” As Cernan continued talking to Fullerton, the Surgeon would have to wait to see my heartbeat and respiration data, as I was not yet on the communications loop. I had been on “watch” all during the rest period and had decided to go off-line for a while. Near the end of Chapter 11 is a photograph of the Rover that I took from my window (AS17-140-21354). It and the crop from it, shows both the Rover and its equipment and repaired fender as well as how extensively our activity around the Challenger has disturbed the regolith. Clearly, future bases and settlements on the Moon will require stabilizing or covering areas subjected to long-term foot or transport disturbance.
Fig. 12.1. View of the Rover from Challenger’s LMP window prior to the beginning of EVA-3 showing its equipment and the repaired fender. The image also shows the disturbance of the regolith surface by our activity around the Challenger. See also Fig. 11.151↑ in Chapter 11 for the wider area window pan, and Fig. 11.152↑ for the enlarged crop which shows the Rover details. (NASA Photo AS17-140-21354).
“And they (the Flight Surgeons) were wondering how your hands feel this morning?”
“Hands are in good shape, Gordo. No problem,” Cernan quickly replied. No one on the Moon would have said anything that would have kept him from a third EVA unless it was extraordinarily serious. Cernan’s hands did not look good with blisters and rawness showing on the knuckles. His fingernails, like mine, showed the effects of damage to the quick caused by scrapping against the inside of our gloves. My nails did not ache, but if I hit them on something hard, a sharp pain resulted. As our hands had no EVA cooling like the rest of our bodies, I am sure that the thin nylon liners I used adsorbed perspiration so that my knuckles did not rub as firmly against the rubber bladder as did Cernan’s. Fluid shift from our legs in one-sixth gravity also may have caused some swelling in our fingers, causing more serious rubbing in Cernan’s case.
“Okay; that sounds good. …Sun [angle] is getting up there; about 33 degrees now…” The recorded consumption of cooling water during the three EVAs does not show that Sun angle made an attributable difference in heat load: 1.572, 1.339, and 1.566 pounds per hour for Cernan while mine were 1.508, 1.326, and 1.589.
As we continued to eat breakfast, I said, “Guess we should do the PLSS oxygen top off while things are quiet.”
“Okay, lets do yours first and then we can put it back on the floor.”
Having been through this twice before, we proceeded to do the topoff without much comment, while at the same time continued to eat.
“Okay; we’ll go Biomed Left and both PLSSs have been topped off,” Cernan reported. He meant Biomed Right.
In addition to topping off the PLSS oxygen, we also installed the food sticks and drink bags in the two suits in preparation for putting them on for EVA-3. Mission Control had monitored yesterday’s replenishment of cooling water and, from the quantity used and our visual checks, apparently felt confident that the tanks were full.
“Gene, I’m looking at what broke on my Hasselblad sample bag holder, and I think that I need some good tape to hold it together.”
“The duct tape is still out on the Rover.”
“Yeah, I know, but I probably can use the tape that binds the food bags together, what do you think? It is thinner than duct tape and seems pretty sticky.”
“Sounds like a plan.”
“I am surprised that the ground has not made a suggestion or two. They must have forgotten the problem.”
“Gordy, the LMP isn’t hooked up [to Comm and Biomed] right now. He will be shortly, so stand by on the Biomed.”
“Okay. …Say I have a few words on the Command Module trajectory that might be of interest, although it doesn’t affect your procedures any…”
“Go ahead.”
“Okay. The command module orbit somehow is missing all the mascons. And it’s not degrading into a circular (orbit) like we thought it would. It’s just staying where it was, about a 70 by 50 [nm apolune and perilune].”
[By measuring slight variations in the velocity (Doppler tracking) of the pre-Apollo Lunar Orbiter spacecraft, lunar scientists discovered the existence of roughly circular mass concentrations (“mascons”) in the lunar crust that are hundreds of kilometers in diameter.[2] The more recent GRAIL mission has provided more precise definition of the distribution of mass in the lunar crust. [3] (See Chapter 13).
It had been expected that the net effect of America’s interaction with lunar gravitational perturbations would cause its orbit to become more circular during our three-day stay on the surface (37+ orbits). Evans’ orbital tracks since he put America into the 70 by 50 nm orbit instead had taken him outside of major mascons, resulting in exposure to a more average gravitational field than anticipated. The lunar gravitational model used by FIDO in Mission Control also could not take into account any farside anomalies that we now know are significant. Future lunar missions will have a far more detailed gravity model with which to work.
Gaining gravitational information about the farside constituted one of many reasons I tried to convince NASA management that Apollo 17 should land in the farside basin, Tsiolkovsky. To do this would require adding the capability to communicate with and track spacecraft over the farside. I first suggested a farside landing after the Apollo 13 mission as the culmination of a proposed site selection strategy that would revitalize public and scientific interest in Apollo. That plan consisted of Apollo 14 repeating the Apollo 13 objective to land at Fra Mauro, followed by Apollo 15 landing at Tycho, Apollo 16 landing in the north with access to permanent shadow, Apollo 17 touching down in the Orientale basin, and, finally, taking the then still scheduled Apollo 18 to the farside basin, Tsiolkovsky. Although certainly doable with Apollo-era technology, this post-Apollo 13 plan did not attract much interest in increasingly conservative NASA management circles.
Soon after being assigned to Apollo 17, I again suggested that Tsiolkovsky be considered as a landing site, backing up that proposal, with the help of the “Lunar Mafia” (see Chapter 2), with significant preliminary analysis on how to do it. NASA management again found the idea unattractive. Finally, the Director of the Manned Space Craft Center, Chris Kraft, stopped me in the hall of Building 1 one day and told me to forget the idea, and I gave up the effort. Although I often lobbied hard for an idea, particularly those vetted through the “Lunar Mafia”, I knew how to follow a direct order to “stop.”
Later, Cernan attributed management’s reluctance to consider Tsiolkovsky as a landing site to cost (probably ~$100 million add-on to a ~$500 million mission, in 1972 dollars), possible delay (not likely, as we had about 14 months to prepare), and risk.[4] With farside communications, and a front side backup site, the risk would be no greater than any other Apollo mission. Cernan states[5], however, “I was involved in discussions at the level of Chris Kraft and George Low and it quickly became obvious that it (farside landing) wasn’t going to happen. Jack used to go on crusades like this and get other people involved and go into the details of how to do it and what it was going to cost. And that was good. But Jack used to have the habit of pushing people and pushing people without knowing – politically or diplomatically – when to quit. And, finally, Chris got fed up.” Cernan had it right about Kraft’s reaction to my proposal, although at the time, Cernan never mentioned to me that he had discussions on this subject with either Low or Kraft. Neither Low nor Kraft mentions such a conversation in their diary[6] or book[7], respectively, nor does Cernan cover the point in his published personal story.[8]
Cernan also leaves out of his comments, although Tom Stafford may never have told him, that one of my “crusades” resulted in their Apollo 10 mission determining where Apollo 11, the first landing on the Moon, would occur (see Chapter 2). My aim for Apollo 17, on the other hand, was to add public excitement and potentially great new discoveries to the country’s final Apollo mission with the hope that it would help keep the Moon as part of our space future. What I did not realize at the time was that management probably had tired of Apollo and may have felt that they had dodged the bullet of losing a crew in space. To these engineers, Space Shuttle development had become more exciting than continued lunar exploration, the results of which held little interest to them. In this psychological environment, Tsiolkovsky was a basin too far for Apollo 17. In the final analysis, it turned out that flying the Shuttle would have far more proven risk that Apollo missions to the Moon.]
“So what we’re planning on,” Fullerton continued, “is an extra little maneuver about one hour prior to the normal plane change [prior to your ascent and rendezvous], which will lower the Command Module altitude at the plane change node to 60 [miles]. This will be about an 11-feet-per-second RCS (Reaction Control System) burn. And then Ron will do the plane change at the normal time, but it’ll be a little bigger than we had planned. I think the last hack was about 365 feet per second for [the] plane change [using the SPS (Service Propulsion System)].” This need for an orbital plane change resulted from the Moon rotating beneath America’s orbit while we were on the surface.
“And we’ve checked the consumables,” Fullerton continued. “That puts the RCS right on the pre-flight line (plan). He’s (Evans) been running about 4 or 5 percent above it (less than forecasted). That will use up that [excess fuel] pad there, put him back to nominal on RCS. And on the SPS, that puts you right down on the CSM rescue redline; so, really no problem— in good shape, consumable-wise. Over.” The “rescue redline” consisted of the propellant needed to rescue the Challenger in the event of a major under burn of the Ascent Engine and the use of almost all of Challenger’s RCS propellant just to get into a lower, temporarily stable orbit for rendezvous.
“Okay. Sounds like a good rendezvous posture,” Cernan agreed.
[A number of contingencies had to be considered in determining what fuel would be required for rendezvous. Normally, the more maneuverable and much less massive LM Ascent Stage would be the active spacecraft during rendezvous, but Evans in the CSM could do that job by several computer assisted or manual means so long as the LM reached an orbit that would be stable for a sufficient number of revolutions of the Moon. The LM also could perform the docking procedures, if necessary for some reason, although usually these would be done by the CSM. In addition, a number of equipment failure possibilities existed related to either the LM or the CSM that would require leaving the lunar surface prematurely. Getting into orbit would provide more time to consider various options to deal with a deteriorating situation than we would have if we remained on the lunar surface. Such a situation might relate to leaks of propellant or consumables, power system deterioration, a major suit problem, or sickness to name a few possibilities. Basically, more options existed to deal with problems if the two spacecraft were in orbit or joined together than if we stayed apart.
The situation for missions to Mars will be very different, I believe. Landing aborts will be to the surface rather than back into orbit, as it would seem unlikely that, having gone to the time and expense to go to Mars, the abort plan would be to come home without landing and exploring. Also, it may be that it will be desirable to have two landers and two landing crews both for redundancy and for the nominal potential of two landings on each mission. Alternatively, all the crew might land each time, leaving the return to Earth spacecraft in orbit and managed remotely from Earth. These considerations will require significant new engineering design and operational considerations for Mars missions over those used for Apollo, all of which can be evaluated during a return to the Moon program.]
As we continued to eat and drink and work through the EVA PREP Checklist, I said, “Good decision on not going back to Shorty. Sampling the North Massif boulders to compare with Station 2 and the possibility that Van Serg will be another Shorty-like crater must have been on their minds.”
“Yeah. Makes sense.”
“I hope that fender fix holds up for another long traverse.”
“It should,” Cernan assured me. “I really cranked down on those clamps.”
“Let me have the water gun for a drink,” I requested. “I am not sure one water bag full (about one liter or 32 ounces) is going to be enough today with that higher Sun. Now that I have my condom stretched, I should be able to pee okay.”
“Good idea. Here you go.”
“That ALSEP Gravimeter is a pain in the butt,” I continued. “Sounds like they have a problem within the instrument’s mechanisms. Deployment certainly looks to be okay. I still wonder if we couldn’t bias the tilt a little with some soil and make it right.”
“That’s their call. You made the suggestion. …Let me have the water gun, now.”
“Your hands going to be okay?” I asked. Having a partner without full use of his grip seemed like something I should know. At the time, I also did not know how badly Cernan had hurt his leg (Achilles tendon) in our pre-launch softball game with our mission support people at the Cape, or that he had a prostate infection to boot.[9] One would think that this is information that a partner on a high-risk lunar mission would have shared with his LMP. Had Chris Kraft been fully aware of the seriousness of his condition and the cover-up, on top of the cover-up of the cause of Cernan’s helicopter crash[10], I probably would have flown to the Moon with John Young, the Backup Commander. Note that Jack Sweigert had replaced Ken Mattingly just before launch of Apollo 13 because Ken had just possibly been exposed to measles. On the other hand, Cernan’s prostate infection apparently had been properly treated and one-sixth gravity eased the strain on his tendon so, obviously, no great harm had come of either issue, so far.
“I’ll be all right. I’ll put plenty of salve on them.”
Getting back to the upcoming EVA, I said, “I think we probably should assume that we have a pretty good representation of samples of the subfloor gabbros, now, from around here and from Stations 1 and 5. Mainly, at Stations 6 and 7, we should look for significant variations from what we have seen so far at Station 2. Anyway, I am anxious to get to those big boulders at the base of the Massif.”
“Sounds like a good plan,” Cernan agreed.
After about thirty minutes of this casual conversation and after finishing our breakfasts, I called, “Okay, Houston. You got any updates to the EVA cuff checklists?”
“No, I don’t think there is, Jack. Although I do have a write-in for the Lunar Surface Checklist, and one that you really don’t need to write in on the prep card. Over.”
“Go ahead.”
“Okay. [Go to] Page 5-10 on the Lunar Surface Checklist. The reason for this change is to prevent cabin pressure from increasing. It got up to 5.7 yesterday. And it will also prevent Water Sep spin down like happened yesterday, if you happen to have the return hose blocked against the wall outlet there. The change is to write in on the upper left corner of 5-10, just prior to ‘SUIT ISOL VALVE ACTUATOR OVERRIDE – SUIT DISCONNECT.’ Write in ‘PRESSURE REG’S A AND B TO EGRESS.’ And then down five lines, where it says ‘CABIN GAS RETURN [VALVE] – EGRESS’, change it to ‘CABIN GAS RETURN (VALVE) – AUTO, VERIFY.’ Over.” This change would deactivate and seat the cabin O2 regulators and let the cabin suit circuit regulate cabin pressure. Normally, we would have put the Pressure Regulators to EGRESS just before depressurization of the cabin, but the small leak through Reg B in its EGRESS position required the change in procedure.
“Okay, Gordy. At the top of the page, “REG(ULATOR)’S A AND B to EGRESS,” and then five lines down, ‘CABIN GAS RETURN (VALVE), AUTO, VERIFY.’”
“That’s right. And the only other change I have has to do with matching – just like yesterday – matching the purge valves to the OPSs to maximize the OPS capability. And we can just call you when you get to that point. Or if you want to write it down, you need 211 and Geno needs 208.”
“We’ve got that.”
“Okay. That’s all…”
“Okay, Gordy,” I eventually said, to verify the EVA-3 plan. “I guess we play the Cuff Checklist just as planned, with the exception of the bag numbers which have changed… the collection bag (SCB) numbers. …I have more or less repaired the sample bag holder on my camera. It’s taped on there (to the camera) pretty well with good tape – believe it or not – off the food bags. I don’t know that we have any other outstanding hardware problems.”
“I think in terms of sampling,” I continued, “Gene and I will try to shift the emphasis in the [dark] mantle area to fragments that are different from the gabbros (coarse-grained basalt) that we’ve sampled fairly well, [and,] I think, up to now, that presumably are subfloor materials. You might pass that word on and see if they (the Field Geology Team) agree with us.”
“Okay, Jack,” Parker came on to acknowledge my plan. “We copy that. …And, Jack, if you guys are at a convenient place to sit and listen while you’re doing some of your stuff, let me read up the planning for EVA-3 and the summary of what we think we have so far.”
“Go ahead.”
“I’ll read here from this thing just verbatim. It says, ‘EVA-3 continues to follow essentially the nominal pre-mission plan. Main objectives continue to be the North Massif – (Station 6/7) – Sculptured Hills (Station 8), and Van Serg Crater (Station 9). In view of the extensive observations of the dark mantle and plains subfloor unit on EVA-1 and [on EVA] 2 – particularly, therefore, Station 5 (Camelot) – the relative priority of Station 10 is reduced, so that Station 10 becomes a flexible station, who’s time allotment is a reserve, possibly providing more time at the earlier stations, if desired. However, mantle and block sampling at Station 10 are still important objectives.’ Walk-back constraints are not nearly as tight as they were yesterday, guys, and so we can be more flexible in reshuffling station times, if we need. We probably won’t be coming up against oxygen walk-backs like we did at Station 4 (Shorty). ‘Close-out time at the LM has been increased by 20 minutes to make the close-out less rushed and to allow for potential ALSEP troubleshooting. It is currently planned to take this time from Station 6/7. But if 6/7 requires more time when we get there, we can borrow it from one of the other stations;’ I guess, in particular, Station 10, probably.’
“The initial activity, …remember, we’re going to have to take explosive package 5 with us, and we’ll stick it under the LMP seat, and I’ll remind you in real-time when we get down on the ground on that one. And [EP] number 5 – the 3 pounder – will be deployed at Station 10, and again I’ll remind you about that in real-time, so you don’t have to bother to write it in on your checklist.
“Planned traverse proceeds as normal. We’re expecting to spend about an hour and twenty minutes at Station(s) 6 and 7; and the suggestion is that we may end up wanting to spend that totally at the split boulder at Station 6. But, of course, the option still exists to visit more than one place and sample other boulders if it seems feasible and attractive and desirable.’ They’re suggesting additional 500-millimeter photographs, especially if it seems that we can use those to document tracks and sources of the sampled boulders; for instance, at Station(s) 6 and 7.’
“We are continuing to hold the nominal 47 minutes at Station 8 – that is, 8A – and we still think that’s as good a place as any to sample the Sculptured Hills. Station 9 is still a nominal 30 minutes, but in view of the [apparent] similarities to Station 4, we’re anticipating a possible desirability to remove time from Station 10 to enlarge Station 9, but that will have to be a real-time decision, based upon what we find at Station 9.
“Station 10 continues nominal. We’re still interested in sampling the blocks and also interested in trenching to try and see if we can say something about the dark mantle/light area relationship and, perhaps, [we will do] the nominal coring. We’re going to deploy EP-5 there; and, other than that, they (the original and new plans) are basically the same. If we have the time during that closeout, …and you’ll note we have enlarged the closeout [time], somewhat, at the LM, based on our experience the last two nights, particularly for dusting. But also, if time permits, in that time we might try and use up the extra double core, if there is one, in the dark mantle near the LM or do some trenching near the LM. But that’s only if time permits at the very end, depending upon how the consumables run out.
“They want to call attention to two particular things here. One, since you guys really haven’t gotten any very big rocks so far, they’re recommending, they say here, and I quote: ‘The value of large individual samples has been demonstrated. We recommend that several football-sized samples of a uniform igneous rock be collected at Station 9 or 10.’ I’ll pass that on as [to] that. ‘Another point of interest is the 1- to 20-millimeter size section of the regolith, the dark mantle, the lithology. Then, any observations or collections you can make pertinent to that would be of interest in trying to determine the relationship of the dark mantle to the subfloor units – the gabbro – underneath.’
“Two short questions which I’ll ask, which I hope you can answer in just a very few words. One of them is a yes-and-no answer. One, they can’t find the geophone photos specifically called out in the transcript. There is apparently a little bit of garble at that point, and the people in the Backroom will be very happy if you could say once and for all, Jack, that, yes, you did get the geophone photos. Over.”
“Yes.”
“Roger. And the second one concerns the 1/4-pound charge which we deployed on the way in last night. Two questions on that: It appears to us from your voice transcript – we weren’t fast enough on it at the time – that that [charge] may be deployed closer to the ALSEP than the one you deployed on the way out. And we’d like an impression on that. And, number 2, you mentioned that you placed it in a depression. We’d like some feeling for that depression in terms of how much of a danger that bomb, …[rather], ‘charge’ might play to the ALSEP, when it goes off. If it’s in a depression of any sort, that’s probably pretty well protecting the ALSEP. Any comment on those two questions? Over.”
“Well, [on] the second one (question),” I responded, “it’s not in a major depression. But it is maybe [in] a…little dish, maybe a third of a meter deep. I imagine it will help [deflect debris] a little bit. That’s why we picked it. Just a second…”
“Gene, do you understand what they want to know about that charge placement?”
“I guess they are not sure how close to the ALSEP it ended up.”
“[Bob,] I’m not sure we understand your first (second) question very much.”
“Okay. We have a feeling that when you…”
“Bob, don’t you have the mileages?” Cernan interrupted.
“Roger. But there’s again some confusion on that.”
“Can’t you pinpoint that [deployment]?”
“Yeah, and those mileages also seem to indicate that [8 is closer to the ALSEP]. …We had that callout; remember, you drove back by and you said you saw the flag [on EP-4, deployed at the start of the outbound drive], and then you said you actually saw the charge itself first. And it was some time after that you said you deployed the [second] charge. And we have the opinion from both that and the [reported] mileage that you probably deployed the second charge closer to the ALSEP than the first one. Do you have any sort of a feel for that?”
“Ah, yeah; I remember saying that,” Cernan said, skeptically. “But that’s when I did a big 360 [degree turn] – and Jack was out of film – and I just lined up to take that picture with the LM in the background. And when I said, ‘Hey, I saw the charge first,’ I was really… Don’t take that comment too strong as far as the position of it. Bob, we’re looking for them (the flags) out there now, as a matter of fact. We can’t see them from here.” I had taken the 10× Leitz monocular out, but could not immediately pick up the flags on the charges in question. I wonder now if they would have wanted me to move an activated charge, assuming that their concerns were valid.
“Okay. We’ll let it go at that. And that’s all the questions and comments we have on today’s traverse. We’ll have a few real-time things on the surface, which I won’t bother you with [now] – a possible fix to the Surface Electrical Properties [experiment’s loose dust cover] and a possible trip back to the [ALSEP’s] Surface Gravimeter, which is still having its problems – but I’ll talk with you guys in real-time on those when you get on the surface, rather than bothering you with them now.
“Hey, Bob. How far should that last charge be from the ALSEP?” asked Cernan.
“They want it about 300 to 400 meters… And, Gene, you gave 0.2 for range (to the SEP transmitter) when you got back to the LM. And I guess the question would be: Did you ever go through zero on the way back to the LM? If you were at 0.2, and we think 092 was the bearing, then the LM is right where it (the Rover) thought it (the LM) was, and we were just a little confused by our distances. They don’t quite hold together.”
“No, I don’t think I ever went through zero, because I initiated at the SEP. …And, nah, I didn’t go through zero. …I’m positive.”
“We copy that. Okay. We’ll work on that.”
“This is something to think about,” interjected Cernan. “It’s not that far out there. You know if there is any question about that thing damaging the ALSEP… It’s just hard for us to recall how close they were. And we sort of thought you had them pinpointed for us. But, if you want it 3 to 400 meters, you might think about a late drive out there, just to make sure [it is not too close to the] ALSEP.” Now Cernan had my attention because I did not want to lose more exploration time dealing with the ALSEP nor did I think it would be a good idea to move an activated charge.
“No. We thought about that. We don’t want to do that. No, we don’t want to do that. So we’ll take care of it. Don’t worry about it now. That’s all we have. Press on with the PREP.”
“Hey, Bob; this is Jack. I can see the charge with the binocular (actually a Leitz monocular). It’s out almost behind a rock that’s between us (it) and the LM, but I can see it.” Laughing, I realized I misspoke. “I mean, a rock between it and the LM. I can’t give you any idea, though, how far it is.” This probably was EP-8. Post-mission analysis of our photographs placed this charge about 300 m from the Challenger and EP-4 was about 410 m. This, in turn, put EP-8 about 140 m and EP-4 about 225 m west of the ALSEP.[11] Although closer to the ALSEP than desired, all charges were later exploded without any noticeable effects to the other ALSEP experiments.
“Hey, Bob. Let me say again, I think we ought to emphasize the exotic looking fragments on the dark mantle.” During the rest period, I had thought about what we might have missed sampling during EVAs 1 and 2 and wanted to add my field perspective to the thinking in the Science Backroom. “And we ought to try to make sure that we look at a variety of rocks from the North Massif. I think we saw the major rock types on the South Massif yesterday, but we really didn’t spend a lot of time ranging along the front there to verify that completely.”
[Although we sampled three different boulders at the base of the South Massif (Station 2), I didn’t have an opportunity to wander along among the other boulders to see which might be most representative of the Massif as a whole. Two other sources of rough statistical data on this will come from the rake sample fragments from the slope debris, 72535-59, and the variety of rock samples I picked up from the avalanche deposit at Station 3, 73215-19, 35, 55 and 75. In combination, these samples and the three boulders (total of 20) should give an approximate measure of the proportion of various rock types exposed on the slopes of the South Massif (Chapter 13).]
“The other comment [is] on the 1- to 20-millimeter size fraction [of the dark mantle]. There isn’t an awful lot of that [fraction] in the dark mantle. That’s one of the striking things about it. In that size range there just isn’t very much except chips of what appear to be – [based on] a comparable albedo, anyway, – of the subfloor gabbro. …But we’ll keep our eyes open.” Although I had not yet correlated the black ash at Shorty Crater with the dark mantle, this observation related to the post-mission analysis showing that 5-15% of the dark mantle consisted of such very fine volcanic (pyroclastic) ash like we sampled at Shorty Crater.
“I’ll talk with the [Science] Backroom about Stations 6 and 7. We’ll get with you on that when you get there. And press on.”
“Houston, Challenger,” I called after a few minutes. “I was Biomed Right there for about 10 minutes, in case you’re curious.”
After getting a thumbs-up from the Flight Surgeon, Parker answered, “Okay, Jack. And it looked good…”
“Okay, Bob,” Cernan stated, after using the monocular for several minutes. “I’ve got them (charges) [in view], and the last one we deployed (EP-8), which I think is the easternmost one, is definitely further out than the first one we deployed (EP-4). And, you know, to judge distance is awful hard, but looking at Jack’s geophones, …I got to give you at least 300 meters, Bob.”
“Okay, Geno,” replied Fullerton. “Bob’s in the Backroom. I’m sure they’re listening, and we got that.”
“Yeah, I’ve got both of them with the monocular now. And the second one (EP-8) – the last one we deployed – is quite a bit farther out than the first one (EP-4).”
“Okay. I think that’s what they want to hear…”
“Gordo, I guess it’s half again or maybe even twice as far away as the first one we deployed. So we’re going to forget it.” Not that it would make any difference later, but Cernan had reversed the location of the two charges as well as misjudged the distances – easy to do without good identifiable references. As mentioned above, the Field Geology Team located the exact positions from the photographs we took at the time of deployment.
“Okay, Geno. That sounds good…”
“And, Gordo, I’m going off the air also here for about 10 minutes. It’ll speed things up a little bit.”
“Okay. Fine.”
At this point, we transitioned from the Lunar Surface Checklist to the EVA PREP Cuecard and began to repeat the preparations for an EVA that we had performed the day before, prior to EVA-2. This time, however, we did not have to worry about building a replacement fender for the Rover. The batteries looked good to LM TELEMU, when I cycled them through their telemetry, and the OPS oxygen pressures had not changed. In one of the required reports, Cernan noted that his Personal Radiation Dosimeter read 17043 and that mine was 24138. There was a brief problem with communications when I apparently hit the yaw control knob of the Steerable Antenna with the corner of the PLSS, but I was able to clear that up, quickly.
Our transmissions indicated that we both had rested relative to how we sounded after EVA-2. I may have slept better than Cernan, but we were ready for a big day of work. The communications and PLSS oxygen checks went well as did the revised configuration of Challenger’s Environmental Control System in preparation for depressurization. After taking big drinks of water, we donned our helmets, LEVAs, and gloves and went through the suit pressure integrity checks without a hitch. My visor movement remained stiff, but it looked like I could move it if I applied enough force.
When putting on my gloves, I said, “Okay, right glove’s locked and verified. …Okay, and the wrist cover on there is on. Gauntlet’s down. [Wrist] mirror’s very dirty. Boy, do I need a shave,” I added with a laugh when I saw my face in this mirror.
As we began to put on our gloves, I said, “Almost tempted to take those cover gloves off today.” The cover gloves are fingerless and protect the standard suit gloves from wear in the palm area. They added to the difficulty in gripping tools, however. Because we noticed that the cover gloves themselves had suffered considerable damage, both of us left them on for the first two EVAs so as not to risk unacceptable damage to the primary glove.
“I might take a look at that, too,” Cernan replied. “I hate to argue with success, but I need that dexterity today. …Bob, I don’t know if you caught it yesterday, [but] a little interesting facet of the whole EVA-2 exercise was the fact that I’ve already worn…the RTV off the [hammer handle]. …Not all of it, but right through to bare metal on the hammer sometime in the previous 2 days. No problem; it just interests me.” RTV stands for Room Temperature Vulcanizing silicone rubber that enhanced the gripping surface of the hammer. Problems experienced by Young and Duke on Apollo 16 had caused it to be added to our hammer. Obviously, when exposed to highly abrasive dust, the RTV did not wear well under heavy use, as took place during EVA-2 sampling and core tube emplacement.
[Overall, the Apollo A7LB space suits, largely assembled by the seamstresses at International Latex Corporation (ILC) in Dover, Delaware, held up surprisingly well in the face of the demands placed on them during ALSEP deployment and exploration. By cleaning and plugging inlet and exit ports when not in use, we did everything we could to limit dust on bearings and connectors, but this could not be close to perfect, given the amount of dust actually brought into the cabin after each EVA. On the other hand, the extraordinary motivation and dedication of contractor and NASA personnel led to almost everything produced and tested for Apollo performing better than ever anticipated. As I said after Apollo 17, “It makes a lot of difference if people believe what they are doing is the most important thing they’re going to do in their lives, and they don’t want to be responsible for screwing it up.”[12]]
As we began the integrity check of our suits, using oxygen from our PLSSs, Cernan asked, “Coming up?”
“Yep. …About 3.5 [psi] now.”
“Yeah, me too. …Okay, let me know when you are up.”
“I think I’m up; I’m 3.8.”
“Okay, let’s see if we can’t get the [PLSS O2 turned off]. Want me to get yours? I can.”
“I got it.” We both had become more dexterous in working our RCU switches than during the preparations for EVA-1.
“Okay, mine’s OFF.”
“Mine’s OFF.” I confirmed.
“MARK it. We wanted decay for one minute.”
“Okay, I started at 3.83 [psi].”
“Okay. That’s about exactly where I was. …Another 45 seconds to go.”
“Okay.”
“So far, it looks as tight as it was yesterday. …Another 30 seconds.”
“Maybe lunar dust is a good sealant,” I suggested in jest. Actually, the only signs of dust abrasion I ever saw on the suit bearings were the circumferential scratches on the glove and neck rings. Absent any radial scratches, dust would have little effect on suit integrity.
“CDR [at] 3.82 to 2.70.”
“2.70? 3.70,” I said, hopefully.
“3.70,” corrected Cernan.
“Understand. 3.70” acknowledged Parker.
“Okay, LMP was [3.]83 to 70.”
“Okay, Jack. You can get your O2 on.”
“It’s on.”
“Okay. Can you move to the left – a little bit to your left? I got to get in front here.” Facing Cernan, I needed to move as much toward the right rear of the crew area of the cabin as I could so that he could reach the latch on the front hatch.”
“Okay, you’re GO from here,” Parker reported. You could imagine Flight Director Gerry Griffin calling out the name of each of the Flight Controller consoles that would be watching the EVA and Challenger, followed by each lead Controller shouting, “GO, Flight!”
“Okay, let me turn this [cue card] over.”
We heard Parker but did not specifically say so, so he asked, “Seventeen, you copy ‘GO’?”
Still concentrating on reaching the hatch latch, Cernan said, “Okay, stand by. …Okay, Heck of a time to have to turn the Checklist over. Okay, we’ve got a GO for depress. On [Circuit Breaker Panel) 16, CABIN REPRESS – OPEN, and [then] CABIN REPRESS VALVE – CLOSED.
“Okay,” I said and began to rotate counter clockwise 180 degrees so I could get to Panel 16.”
“You need to get the breaker OPEN and the valve CLOSED.”
“Okay, stand by. Can you give me a little room to [rotate].”
“Let me [see]. …Okay. How’s that?”
Okay. …Okay, REPRESS [circuit breaker] is OPEN.”
“Okay. Now, why don’t you face the wall over there, and move in as close [to it as you can], and I’ll get the OVERHEAD VALVE.”
“Wait a minute, I’ve got to close the [CABIN] REPRESS VALVE. You got it all right, …Okay, it’s CLOSED, and I’ll get where I was yesterday [so you can reach the hatch].”
“Okay.”
“How’s that?” I asked, as I faced forward and pressed as close to the forward right side of the cabin as possible.
“We’ll find out in a minute. …I’ve got to get my PLSS [against you so I can use my right arm.]”
“Can you get it?”
“Well, [not yet]…”
“Okay, wait a minute,” I said. “I can turn with my back to the wall and you might have a little more [room]…”
“Well, I think…I feel like I’m hooked on something. Wait. I can’t turn either way. Stay where you are. …There. Okay. …Okay, the safety [pin on the overhead valve is pulled]. …Oh, boy, I’m glad I’m not an inch shorter. Okay, coming down, Jack. You ready?”
“Go ahead, to 3.5 [psi].” Still facing forward, I could monitor the cabin pressure gage.
“Okay, it’s (the overhead valve) OPEN.”
“Okay, 4.5 – 4 – Stand by. MARK.”
“[Valve to] AUTO.”
“Okay, [cabin is] at 3.5.”
“Can you read the checklist?”
“Okay, I can,” I answered. “Okay. ‘OPEN [then] AUTO [at] 3.5 [psi]’. Cuff checklist. …Ah…[that is, ‘Verify] Cuff Gauge does not drop below 4.6.’ It hasn’t.” This constituted another check on suit integrity.
“Mine’s (his suit pressure) good,” Cernan said.
“[You] Have to put your [left] hand down. I can’t read it (the Cue Card).” Cernan had used his left arm to brace against the AOT mount below which we put the Cue Card.
“Okay.”
“Cabin is holding at 3.5. And [Challenger’s] suit circuit is locked up at 4.5 and PGA is decaying [but] greater than 4.5.” I said, reading ahead and paraphrasing the Cue Card’s next instructions. “[It’s] 4.6. Okay. Okay, Bob, I’m starting my watch.” EVA-3 had begun.
EVA-3 Begins
“We’re GO,” confirmed Parker.
“Okay. You can go to OPEN [on the Overhead Dump Valve].”
“Okay, it’s OPEN,” Cernan declared.”
“Okay, and [suit] pressure is going up [as expected]. And the next step is, when you can, OPEN the Forward Hatch.”
“Okay, my suit’s relieving,” he reported.
“[Cabin pressure is] down to almost 1.5 now. …One psi…”
“Okay, my [suit] relief valve just seated at 5.3. Okay, where are we?”
“We’re at point five [psi].”
“I guess the next thing is to open the hatch, huh?”
“Yup…”
“I’ve got to get down out of 5 [psi suit pressure], too, here, before I can turn too well and open the hatch. I’m going to let it come down a little bit this time so I don’t get down there unnecessarily.” The difference between 5.3 psi and 3.7 psi, the normal suit pressure, made a tremendous difference in mobility. We literally had to metabolize the oxygen pressure down, converting it to CO2 that was extracted by the LiOH filters in the PLSS.
“Yeah. It’s (the cabin pressure) got a ways to go yet. …About point three now. …Point two…”
“I’ve got a tone,” Cernan said, “and it’s [a] water tone. Okay, I’m going to go after that hatch. …Can you slip to the right as far as you can?” Again I faced him with the PLSS backed against the right side of the cabin.
“[You] got it.” Looking out my window, I saw debris leave the hatch.
“Got to hold it [open] until the pressure decreases.”
“All sorts of junk going out there – ice…” With the right flow patterns, opening a hatch might remove some of the dust from under the floor.
“Okay, now. Okay. It’s partially open.”
“Okay, get your [sublimator feed]water [ON] if you can,” I told him.
“Okay, Jack,” interrupted Parker. “We’d like you to close REG(ULATOR) A, please.”
“Oh, close REG A, huh?” The LM TELEMU guys in Mission Control had new concerns relative to the slow leak we found after EVA-2. Closing REG A, rather than leaving it in EGRESS, would take it out of the active ECS loop.
“That’s affirm.”
“Okay, stand by. That’s not an easy task,” I declared as I needed to turn 180 degrees with Cernan still in the cabin. “REG A is CLOSED. …Gene, can you get my [PLSS feed]water?”
“Yeah…”
“Did you get in there (in the switch guard on the RCU)?”
“Okay, it’s OPEN.
“Okay. LMP’s water is OPEN. You got yours?”
“Yeah, I got mine.”
“Excuse me,” I said after an involuntary burp.
“Well, let’s see,” Cernan said, looking at the Cue Card for a final time.
“Okay, you got it (the hatch) open,” I noted, “so I need to turn around. [Lets] see if I can back in and out of the way of the door.”
“Say, Bob. What did you see in REG A?” asked Cernan.
“Stand by, Gene. We’re seeing high suit pressures, stand by.”
“High suit pressure?” I queried, incredulously, as that made no sense. Parker meant to say “high ‘suit-loop’ pressure.”
“Challenger – Gene – you’re GO to go out, and once you get out, maybe Jack can turn around and work on those [valves] a bit better. We’re seeing, I guess, the suit-loop’s a little high in pressure.”
“Okay, I’m looking at about 4.7 [psi] on the suit loop right now,” Cernan reported. “Okay, Jack, [here I go].” Cernan will turn and face aft and then start to move his feet behind him and out the hatch.
“There you go. …[I’ll watch your PLSS against the instruments.] …Okay, turn…”
As he bent and pushed his legs out the hatch, Cernan asked, “…What does it look like to you?”
“Well, you’re doing great; keep down. Just a little [PLSS] hang-up on the DISKEY.”
“I gotta get my arm down there.”
“You need to go to your left a little to clear the Purse and your harness. There we go.” The Purse hung from the panel in front of Cernan’s CDR position.
“Jack, you see this? This is one of those cards that [the support crew left us].”
“Yeah, I saw that, Gene.”
“I’ll put it right there.”
“Can you come forward just a little?”
“Forward?”
“That [PLSS harness] clip got away. Come towards [the bulkhead] in the cabin just a little. …There.”
“Okay?”
“Wait a minute. …Okay. I got it. …Okay, you’re in good shape.”
“Okay. …I’m on the porch. Whoo! I’m still at 4.3!”
“Okay, [Bob,] what do you want [me to do]?” I asked as I moved the hatch partially closed and faced the ECS valve panel. “What can I do for you, Bob?”
“Standby Jack. We’ll get a word to you in one minute.” I had expected that LM TELEMU would have been ready by this time.
“Okay, Jack, in the [meantime]…
“Well, I guess I ought to wait. …Get my L. E. C. (Lunar Equipment Conveyor) ready for you.”
“Okay. And everything looks normal on me, right now,” Cernan reported. “Wait ‘til I get pressure down a little bit… Everything’s normal, except a part of my nose itches I can’t get to.”
“I’ll give you the Jett Bag anyway, Geno, while they’re thinking.” With that, I kicked the Jettison Bag, with a day’s worth of trash, out the hatch to where Cernan could grab it.
“I guess that’s part of R&D (Research and Development)… Oh, yes, the Jett Bag. Santa Claus’s bag again.”
“Okay, Jack,” Parker finally called. “We’d like to have you stay in just a minute or so longer. We’re trying to keep track here of the suit circuit pressure and see if it stabilizes or starts to drop. The one REG[ULATOR] has just has been intermittently leaking. We still haven’t isolated it. And we think we’ve got it shut off, but we’re still watching it. So bear with us just a minute or so.”
“I’m bearing, Bob,” I replied, but I was not happy. “Time is relentless” on a mission, as Dick Gordon reminded me during Backup Crew training for Apollo 15. I now was using up my PLSS consumables. “I thought you isolated it (the REGULATOR problem) last night. …Okay, [Gene,] let me give you the ETB.”
“Yeah. …Give me that, and I’ll be on my way, working on the TGE. …Okay, got it (the ETB).” Cernan’s initial tasks outside are to start a Traverse Gravimeter reading and install an unused LCRU battery, previously placed under his Rover seat.
“Okay, Jack,” Parker called again, “and how about taking the SUIT CIRCUIT RELIEF valve, cycle it just to OPEN and then back to AUTO…” LM TELEMU was seeing a lower than normal pressure in the suit loop.
“Okay, Bob, stand by. …SUIT CIRCUIT RELIEF [valve] going OPEN, then AUTO. …That’s done.” This action would reset and test the auto-off function of this valve in case it was not seating properly, allowing suit circuit oxygen to leak into the now depressurized cabin.
“Okay, we’ll watch it for a minute here and let you know.”
“Okay, Bob. I’m going down the ladder.” Cernan, at least, was getting started outside. I still had to verify circuit breaker positions, turn Challenger’s tape recorder OFF, set VOX Sensitivity to MAX, turn off the Utility Floodlights, and turn on the 16mm sequence camera in my window. As yet, not much actual EVA time had been lost to this trouble-shooting by Mission Control.
“Yup, still there, Jack…? ‘Godspeed the crew of Apollo 17.’”
“Good.”
“Amen there, Gene,” added Parker. “Amen,.”
“Okay, Bob, I’m on the [foot]pad. And it’s about 4:30 (on) a Wednesday afternoon, as I step out on to the plains of Taurus-Littrow. Beautiful valley. The first thing I’ll do is I’ll turn the TGE ON, and I’ll give you a reading. …And I’m very much interested in my Rover battery [temperature].”
“And, Jack, you’re GO for exit and looks like we’ve got it (the Suit Circuit pressure anomaly) taken care of.” Apparently, cycling the valve had stopped the leak and the suit circuit pressure remained stable during this short monitoring period.
“Okay, and I’m checking the circuit breakers…”
“It’s (the TGE) ON and [I’m pushing] READ,” Cernan reported from near the footpad. “…Bob, it reads 222, 262, 207; 222, 262, 207. …Okay, get the visor down, Geno. Get the visor down. …Holy Smoley. Think it’d be better to leave it up. Beautiful out here today, Bob! We can look to the east for a change – a little bit, anyway, [because of] the higher Sun angle. …Okay, I’ll get the LCRU battery changed out.”
“Okay. And as you walk by there, if you walk by in the right side of the Rover, how about giving us a SEP temperature readout, please…
“SEP temperature is 103 degrees…, and the mirror is still clean.” This was a significant improvement over the 112 degrees he read at the end of EVA-2. “Well, let’s see if I can change this little baby (the LCRU battery), now. Supposed to be simple. …Bob, we have no use for the old battery, right?”
That’s affirm.” If this were at some future lunar base or settlement, the answer would be, “Put it into inventory, log it in, and save it.” Everything taken to the Moon has value and might be useful at some later time.
“Okay. I’m on the porch and the hatch is closed,” I notified everyone after the usual struggle to work the PLSS under the DSKY. As will be discovered after EVA-3, the interruption for trouble-shooting may have caused me to miss a step in the checklist that would have turned off the LM tape recorder. Anyway, I left it on.
“Oh! Don’t bump into that,” ordered Cernan.
“Are you talking to me or you?” I asked.
“I’m talking to me.”
“Okay, that sounds familiar,” I acknowledged as we both did that a lot, “and [everything] looks familiar – the ‘old plains’.”
“The valley of the Taurus-Littrow,” Cernan replied.
“Want me to get your [PLSS] antenna?”
‘Yes, let me get that [for you, too].”
“I’ll come over there (by the Rover),” I told him.
“I’ll get the TV on. I’ve already got the battery changed.”
After checking that the high gain antenna still pointed at the Earth, Cernan looked at his Cuff Checklist and said, “Okay, ‘Verify (LCRU) Mode 3’; I am in Mode 3; LCRU Blankets are open 100 percent, Battery Covers: I’m closing the Battery [Covers]. …Let me close it (the covers). Yeah, you can come and get my antenna.”
“Wait a minute. Let me set this (ETB) down. …Okay, stay there,” I added as Cernan turned away from me.
“I was just trying to [get in a better position for you].”
“Okay. …Okay, your antenna’s up. Wait a minute. [I need to] snap the snap. …Didn’t mean to do that (hit his LEVA as I bent over).”
“That’s all right,” Cernan said with a chuckle. “I can’t get close enough to you. There you are. …Lean a little more. …Antenna’s up. Let me get the snap.”
“And, 17, if you guys are interested, your shadows will be 8 feet long tonight.” Parker should have waited to give us this information until I had made an estimate on my own. Knowing my shadow was 8 feet probably would bias my estimate.
“How many meters is that, Bob?” I asked, pulling Parker’s chain as we had been talking in meters most of the time.”
“I’ll draw it out,” Cernan said, joining in the fun. “I’ll step it out for ya. You can measure it.” We both laughed at the idea of measuring anything while in the pressure suits.
Back to business, I said, “Well, I don’t know. …Should I take my gloves off? I mean my cover gloves.”
“Why don’t you leave them on for a while,” suggested Cernan, “and see where we’re going. See what the boulder field looks like up there [at Station 6].”
“Well, I know what it’s going to look like,” meaning we had seen one boulder field already at the base of the South Massif (Station 2). Station 6 at the base of the North Massif probably would be much the same.
“No, you don’t.” Cernan was getting technical on me.
“The point is: my hands will be much better off without them.” I hoped to reduce my hand and forearm fatigue on this, our last excursion on the Moon.
“Take them off, then. …Okay, Battery Covers are ‘CLOSED AND TIGHT’. High-gain is already oriented. Oh, they’ve even got TV, I guess.”
“That’s affirm.” Parker has moved to the correct “yes” response. Someone may have said something to him about his overuse of “roger”— that only means, “I understand”.
Parker continued. “And, Geno, when you push the Rover circuit breakers in, how about giving us a battery temperature reading on the Rover bats.” By the Checklist, Cernan had already pushed in the four Rover circuit breakers.
“[I’ll] tell them what my batteries are reading if I can.”
“Well, let me see if I can do something else while I’m waiting for you to finish there…”
“No, I’m done, Jack…”
“I’ll get the old SEP receiver.” I went behind the Rover to the SEP.
“Well, Bob,” Cernan responded, “battery 1 is 95 degrees and battery 2 is reading zero. So we got a gauge failure. In fact, its not reading zero; it’s off scale low.
“Okay, copy that. That’s a real cool-down, isn’t it?” Parker said, trying to be funny. “Okay, Jack, if you’re going to worry about the SEP, standby and don’t do the SEP until after you worry with the ETB, and we’ll get to you on that. When you get the ETB to the (CDR) seat, I’ll talk to you about it.” Parker has fallen behind us in the Checklist.
“Okay, 102 is the [SEP] temperature.” This was a drop of 10 degrees since the end of EVA-2. As the automatic cutoff temperature is 108ºF, we should get some SEP data on the way to Station 6.
“Okay, Bob…MARK.” Cernan had returned to the LSG to start a reading. …MARK gravimeter; it’s flashing. …Okay, we’ll take the Big Bag. I hope we can keep it on [the gate]…”
“Did you say [the Big Bag]?” I asked, having forgotten this item was on Cernan’s Cuff Checklist.
“Okay. A couple of things on that, Geno,” Parker broke in. “You might try tapping the thing (the Bag latch) to see if that loosens the dust. There’s also the hook business on the inside of the pallet that you could hook it (the Big Bag) on. Caution: if you open the Pallet, be careful not to knock the clamps off the fender. But you can also reach over the pallet to put the Big Bag on.” The Geo Gate attaches to the Pallet and, normally, we would not open the latter.
“Okay, Bob. I brushed it and tapped it (the Bag latch) yesterday. I’m not sure we’re going to have much luck with them.”
“Okay; copy that. You might want to put the Big Bag on the inside of the pallet there, if you can’t operate them (the latches).”
“Okay, Mag Kilo goes on the 500; is that correct?” I was emptying the ETB at the Rover.
“That’s affirm.”
“Okay, I’ve got Mags Mary and Franny and Nancy… and Donna …and Bobbie and…Karen.” Well rested, I was back to using female names. The extra film magazines went under Cernan’s seat, and the traverse maps for EVA-3 and my camera with black and white film went on my seat, temporarily. I needed the color film Hasselblad for a final panorama from about ten meters in front of Challenger.
“Jack, I’m also going to keep this (the dustbrush) in there [under my seat], …because it’s too hard to get [it out of its clips on the LCRU]. We’ll find a place for that in there.”
“Well, …okay.” My hesitation reflected concern about added dust where we kept the film magazines.
“It’s just too hard to get off the front end,” he explained. “Okay, let’s see. ‘Big Bag to gate; dustbrush to…’ [the seat]. Let me get that Big Bag on the inside of the gate if I can. Inside the gate or the pallet, Bob?”
“Inside the pallet. My fault there,” Parker responded.
“That (Checklist) says the ‘pallet’,” I interjected, pointing to my Cuff Checklist. The Checklist actually says “Big Bag to gate”, so I may have been kidding Parker.
“Yeah.”
“And if you open the pallet,” continued Parker, “be careful of the [fender] clamp. Probably, if it’s feasible, we suggest you reach across in front of the pallet – reach across the pallet to do it (hook the Big Bag) instead of opening it because of the clamps on the fender.” The pallet hinge is on the right rear corner of the Rover and, if opened too much, it might hit the inside clamp on the replacement fender.
“It’s not feasible. …It’s not feasible to do that. I got to open it (the pallet), plus our [pallet locking] hook is over center (unhooked). Let me get something to work on that with. …You know, Bob, how that pallet locking hook can be out of the little C-shaped release in there? It is [out of the release].”
“Oh, boy.” Parker exclaimed.
“I noticed that yesterday.”
Parker turned his attention back to me. “Jack. When you get done with the ETB, then you might save the gray tape (duct tape) out. We’re going to use a little bit of that on the SEP when you get done.”
“When are you going to do that? …What am I supposed to do, stand [around]? …Well…”
“We’ll turn both [SEP receiver] switches ON when you’re out at the SEP transmitter.”
“Well, the tape is in the CDR’s seat, and it’ll still be there,” I replied, a little put out that someone had forgotten where we had left the tape.
“No, we’d like to take the tape from the CDR’s seat and use it on the SEP, right now.”
“Okay. …You want me to do it or Gene to do it?” Cernan still was working at the back of the Rover.
“Why don’t you do it since the tape is there. No, let’s let Gene do it. Doesn’t really matter. Whoever wants to.”
“Okay, we’ll get it,” Cernan comments. “…Okay, Bob, the Big Bag is on the inside of the pallet. …This is the thing (a rod on the pallet) that’s in the way, Jack. …Get rid of this thing. We don’t need it anyway. …Okay, opening and closing of the pallet didn’t interfere at all with those [clamps on the] fenders.”
“These (pallet latches) aren’t clamped now,” I tell Cernan. “Here’s your [gray] tape.”
“Okay. The Big Bag is on the inside (of the pallet), though.”
“Yeah, but it’s also in the way [of latching the pallet]. …Okay, I got it [latched].”
“Sure is. Wait a minute. Wait a minute. Don’t close it (the gate),” he requests.
“Want me to get out of the way?”
“I’ll open it. See? It drags over that locking device,” Cernan pointed out as I worked to make sure the pallet was latched. …Okay, let me just see what we got to do here [on the Checklist]. Okay. ‘Big Bag, dust brush… SCB-7 to gate, mount 20-bag dispenser on Commander’s camera, 20-bag dispenser to the LMP, core cap dispenser to the gate’.”
“Okay. And, Jack, are you going out to take the pan now?” Parker asks.
“Well, as soon as I finish up here [with the pallet and gate], I’ll do that.” Meanwhile, Cernan takes the traverse maps from my seat and mounts them on the Rover console.
“And after you take the pan,” Parker added, “we’d like you to retrieve the Cosmic Ray Experiment. They’re expecting a little solar storm, and before the ‘rain’ gets on the cosmic ray experiment, they’d like to retrieve it. We’ll leave it in the ETB during the traverse.” I hoped that it would be just a “little solar storm,” or we were in trouble.
“Okay, …after the pan. All right?”
“Roger. It will just be a nominal retrieval.
“Okay, the gate’s locked.”
“…and we’ll put it (Cosmic Ray Experiment) in the ETB. Copied the gate.”
I moved to a spot in front of Challenger and started a color panorama that shows the appearance of the regolith, the Rover, our jettison bags, the MESA, ladder, and other items around Challenger at the start of EVA-3 (AS17-140-21359-80). Aligned, light-colored spots on the northeast facing slopes of the South Massif, in the first and last images of this panorama, have an apparent plunge about 20º to the northwest in contrast to the similar, southeastward plunge of similar lineaments on the southwest-facing slope of the North Massif. This contrast suggests a significant difference between the internal orientations of ejecta deposits within the two Taurus-Littrow massifs.
Although the images are moderately streaked due to having been taken looking up-sun, panorama frames AS17-140-21370 and 21371 provide good full frontal views of the Challenger, including Quad I and the MESA, hatch and ladder, Quad IV and the LRV stowage location, and two Jettison bags and one MESA pallet we had previously discarded.
Fig. 12.2. Two of my pan frames taken at the start of EVA-3. The lens flare, solar glare and streaks in the sky have been removed in combining the photos to facilitate a better view of the front of Challenger. Directly behind and to the left of the LM, is the reltively low, unnamed mountainous area we called the “hump” (Fig. 12.3) described in Chapter 8 (see Fig. 8.35↑). Behind and to the right of the LM is a group of low hills ~12 km distant and ~270 m high. The East Massif is just off the right edge of the photo (Fig. 12.4 below). For a larger scale view of this image in a separate window, click here. (Combination of NASA photos AS-17-21370, -21371).
Fig. 12.3. The ground track of the flight trajectory of Challenger into the valley of Taurus-Littrow. The tip of the red arrowhead is pointing close to the landing site. At the east end of the valley, Challenger flew over a mountainous area labeled the “hump” where Delta-H between the PNGS calculated model altitude of Challenger and the landing radar actual altitude differed as was expected. The “hump” is ~19 km from the LM and is ~1300 m high, a little more than half the altitude of the East Massif. (Base photo NASA AS17-M-0595).
Fig. 12.4. Partial panorama to the right of Fig. 12.2 showing the full expanse of the East Massif, ~16.8 km distant. The massif peaks at ~2076 m. Note the boulders on the slope just right of the peak as well as the layering further right. The tracks in the center and upper right of the pan are those of Cernan going to and from Poppie Crater at the start of EVA-1 (see Fig. 8.44↑). For a larger scale view of this image in a separate window, click here. (Combination of NASA Photos AS17-140-2173 and 140-2175.)
Panorama frames AS17-140-21373-75, enlarged, show the subdued cliff and slope structure in the west-facing slopes of the East Massif, possibly related to an internal layered structure within a relatively coherent Mg-Suite pluton that years later I inferred to constitute Imbrium ejecta that formed the Sculptured Hills and associated physiographic features with compositional indications (M3 data) of Mg-suite rock mineralogy (see Chapter 13).[13]
“Okay. …SCB-7… 20-bag dispenser goes on my camera when it gets back [from Jack’s pan]. ‘Short can under the LMP’s seat’. Okay. Jack, I’ll just go ahead and mount some of these bags on your camera while I’m here.”
“Okay. Thank you…”
“Okay. And, Gene, if you got time there with the camera… when you get done with the camera… how about getting some gray tape and we’ll put you to work on SEP for about a minute.” Parker should have known better; nothing just takes a minute during an EVA.
“The SEP receiver?”
“That’s affirm. …And if you get…”
“Stand by. Let me finish with SCB-7 here.” Then, he reached under my seat for the core-cap dispenser that he plans to mount on the gate for easy access, later.
“Okay. And did you get Jack’s camera fixed last night? I didn’t hear.”
“Yeah, we did.”
Cernan returns from the gate to my seat, saying, “Okay, there is already one [core-cap dispenser] on the gate. Leave that one there. Okay, ‘SCB-7 to gate; 20-bag dispenser on commander’s camera’. We’ll do it when he gets back [with the camera]; ‘20 bags on the LMP’s camera; core cap dispenser to gate’. There’s one there (on the gate), there’s one [back] under the [LMP’s] seat. Short can’s under the LMP’s seat. …Okay,” looking at the next page of the Checklist, “I got to put that cap dispenser on him; I got to give him a rammer [and] a hammer. Hey, Bob, what bag do you want on the LMP? Do we have [SCB-]8 here?” SCBs became mixed up on EVA-2.
“Stand by,” Parker said. “I think 8 went in [the cabin after EVA-2]. Either 4 or 6. No, excuse me; either 5 or 4.” SCB-6 also had been filled on EVA-2 and stowed in the cabin. Parker does not seem to be relying on the EVA guys for this information, but, instead, is relying on his memory or notes.
“Okay. We’ll put either 4 or 5 on there. Okay. I’ll have to wait until he gets back.” I had finished the panorama and gone to get the Sun and Shade halves of the Cosmic Ray Experiment. 45.5 hours ago, early in EVA-1, I had deployed the Sun half on the back landing strut and the Shade half on the outside of Quad IV.
“What do you want me to do now…?” Cernan mused. “Or let me give you TGE reading and get that out of the way… and then I’ll work on your SEP…” Cernan goes quickly to the TGE by Challenger’s ladder. “Okay. 670, 027, 001; that’s 670, 027, 001.” He then takes the TGE to its mounting position on the back of the Rover. “Fender wrinkled up in the Sun a little bit last night,” he noted.
“Okay, MARK it. The Cosmic Ray [Experiment] is terminated!” I announced, dramatically, as I closed the cover on each detector slide. “And, Bob, I took two 5-foot stereo pairs of the [Cosmic Ray] configuration.” (AS17-140 -21381-84).
Fig. 12.5. Down-sun view of the Cosmic Ray Experiment hanging on the sun side landing strut. A larger view of the experiment face in a separate window is available here. (NASA Photo AS17-140-21382).
“Copy. And we’ll stick it in the ETB and just hang it there [by the ladder].”
“Yep. And in case you’re wondering, and so you don’t confuse it (the Experiment) with a rock, it’s in [sample] Bag 106.” I used the MESA as a table while working with the deactivated Cosmic Ray Experiment.
[The Cosmic Ray Experiment recorded energetic heavy nucleons at energies greater than one million electron volts.[14] According to Leonard Fisk, a prominent solar physicist at the University of Michigan, the data that came from this Experiment[15] and from solar wind “window shades” deployed on earlier missions still represents the best information available on the composition of the solar wind during a period that lacked any pronounced activity on the Sun.[16]]
“Okay. What do you want done to the SEP?”
“Take some grey tape over to the receiver, Gene. And with reference to the fact that there is some Velcro missing on the front there, which hold the covers down, we’d like to tape the two covers together in the middle there – you know, where the two sides [of the cover] overlap in the middle of the box. Tape those two together. A short piece about an inch long should do it if they are clean.”
“Well, I doubt if the tape will stick because it doesn’t (stick) on dust, but I might be able to go over it with one piece to clean it and another piece to tape it.” Cernan is rightly questioning this approach. Duct tape just does not work on dusty surfaces.
“Okay. And the question beyond that: is there Velcro to hold one of those flaps down or not?”
“No.”
“Okay, so the Velcro is missing from both flaps, I take it.”
“Yes.”
Recalling what I had reported the day before, I interjected, “Bob, what happened was that the tape (adhesive) that held the lower Velcro on there (the cover) apparently came loose, and it stuck to the upper Velcro.”
“Okay. I understand that. In that case, we’d like to take a piece of [gray] tape and tape the cover down to keep it closed when it’s supposed to be closed. The feeling is that if the cover flaps [are] partly open, you may get specular reflection off the inside of the Mylar down onto the mirrors causing it to heat up during the drive when it’s supposed to be closed.”
“Okay, we’ll give it a try,” Cernan said.
“Okay; thank you. …And, Jack, if you’re done, you might go rescue EP number 5 from the (LM) footpad, and we’ll put it under the LMP’s seat.”
“Well, there are a lot of other things under there. Okay. I’ll ‘rescue’ it; we’ll see where the best place to put it is.”
“Hey, I got bags on your…I got bags on your camera, Geno.”
“Okay; thank you…”
“Okay, we’re going to put those two bags (SCBs) on the rear there on our PLSSs?” I asked him, rhetorically.
“The one under the LMP’s seat will go on the CDR,” Parker says, helpfully. “It’s the one with all the stuff in it.
“Yeah, I got core tubes in [SCB-]7 here, Jack. We’ll put either one of those [other SCBs on you].”
“Okay. So I can put the charge (EP-5) under my seat.”
“That’s affirm, I think, Jack,” Parker confirmed, partially, “once you get SCB-7 out of there.”
“Yep.”
“I feel like a kid stuck in taffy,” Cernan commented as he worked with grey tape for the SEP.”
“Sure is strange not to see some fine-grained rocks out here,” I observed. “Seen a couple, but certainly not very many. …That rock that you picked up at random [near Shorty, for example].” This observation relates to the paucity of examples of chilled, very fine-grained or glassy rock normally found at the tops of young basaltic lava flows on Earth and also anticipated to have been present originally on the Moon. Over billions of years, these flow tops would have been largely incorporated in the impact-generated regolith.
I then noticed Fendell had the TV camera pointed upwards. “What are you doing up there?” Then, I realized he was looking at Earth. “Okay.” In the future, the operator of any remotely controlled EVA TV camera should be integrated into the EVA operations rather than being able to point the camera at whatever strikes the operator’s personal interests.
“Bob, that’ll hold it (SEP cover) down. I hope it solves the problem.”
“And so does Dr. Strangelove.” Referring to the title character in the Stanley Kubrick 1964 film, this was Parker’s nickname for Canadian scientist, Dr. David Strangway, an active Co-Investigator for the SEP.
“Well, probably not any more than we would like to see it solved,” replied Cernan as he removed his right cover glove.
“Bob…,” I began. “Nothing. …Gene, your bag’s going to have two lowers and one upper [drive tubes]…”
“Did you re-sort things there, Jack?” interrupted Parker.
“What’s that?”
“Did you re-sort things in SCB-7? I was told…”
“Bag 7’s got… Bob, I… Go ahead.” Even the second and a half Earth-Moon-Earth communications delay bit us here.
“Okay. Our understanding was there were two uppers and one lower in bag 7, and two lowers under the LMP seat. Did you re-sort things there?”
“How do you want them?” The lower drive tubes had a re-enforced bit so they could be used for a single core.
“It doesn’t matter to us. I just wanted to make sure that we know what you are [doing] so we don’t let you get away too far [from the Rover] with two uppers and a lower. Two lowers and an upper is certainly better than two uppers and a lower. As long as we know what it is.”
“Okay. It’s two lowers and an upper,” as I first told Cernan.
Listening to this exchange, Cernan said, “Man, I’m confused. …Okay. When you’re ready, I’ll configure you.” Abbott and Costello would have had a field day with this dialog! (Their most famous comedy routine: baseball, is not unlike this upper-lower exchange!).
“Okay, here,” I commanded, “let me get this on you first since I got [it in hand]. …And I’m going to ask you to turn around 180 degrees because you’re up on a hill. I’ll never be able to do it (attach an SCB).”
“How’s that? I’m down in a hole now.”
“That’s beautiful. …Okay, just a minute. Can’t get this (hook) fixed.” …[I’m the] Tallest man on the Moon right now,” I joked. “…Okay, that’s done.”
“Okay?”
“Just a second. Let me close the [SCB] cover. …Not a very good cover. Okay.”
We both went over to the gate on the Rover, and Cernan said, “Okay, Bob, I’m going to put SCB-4 on Jack…”
“Say again there, Gene. SCB-6? [I mean] SCB-4; copy.”
“SCB-4 will go on Jack. Okay, Jack, I got to get these PLSS straps, too. Did you get mine? …The harness release straps?”
‘Oh, no. Let’s do that. I saw them as you got out, and then I forgot about them.”
“Yeah. Okay, yours is on over here. [This is] probably a better time to do them, anyway, rather than when we go out [of the LM]. Okay, let me get the bag (SCB). I’ll get the other one (strap) when I configure your other side. …Okay, you’re on. Okay, want to get my PLSS straps? Then I’ll be cleaned up, and then I finish your other side…”
“Let me get the other one,” I said after fixing one side of his PLSS. …Warmer out here today. …Heat treatment on the hands. …Okay, [you’re good].” As all the equipment we would be adding to the SCBs on our PLSSs was on the Rover back gate, we did all of this preparation out of sight of the front-mounted TV camera.
“Okay, stay right where you are,” Cernan ordered, “so I can get this [core tube rammer for your SCB]. …Okay. Now come over here [to my seat], and I’ll get you a core-cap dispenser, which I left here.”…Referring to his Cuff Checklist, he reviewed our preparation for the day. “Okay, you got SCB-4; you got the cap[s]; you got the rammer; I’ll take the hammer. You got the…that’s all you need. TGE is on the LRV. Okay, what charge you got there, Jack?”
“[EP-]5’s under my seat.”
“Five, okay. You got 5 there; we got [EPs] 2 and 3 on the [back of the] Rover; LCRU blankets are open 100 percent; battery covers are closed. I want to [check the battery cover.] Push that battery cover over there down just to make sure it goes down.”
“The [red] warning flag is up,” I warned him and Mission Control. This meant that the temperature of one of the batteries had gone above 125ºF. However, we had been given a new limit of 140ºF the day before. The flag also would pop up if a drive motor reached 400ºF, but clearly this was not the case at this point. Pushing the flag down reset it in case the other battery or a drive motor exceeded its temperature limits.
“Yep. It’s probably that [battery]. Already [hot], huh? Push it (the battery cover) on down over there.”
“Rover warning was up,” I repeated, thinking he had not heard me the first time.
“Get one [corner] right there.”
“It’s (the battery cover) down,” I verified.
“I’ll take a look at that gauge again, but the gauge on the high battery looked like it may have failed.” Looking at his Checklist again, Cernan read, “ ‘…LCRU blankets are open, battery covers are closed and pushed closed, dust LCRU…’ “
“I’m going to the SEP [transmitter]” I declared.
“Wait a minute before you do,” requested Cernan. “You got a second? Just come over here by the left front wheel [and we’ll get some pictures.] I know you got a second. Just a little bit closer to the left front wheel – towards me. Ah; that’s good, anywhere in there. …Wait a minute.” (See Fig. 12.6)
Fig. 12.6. “Tourist” photograph of the author prior to beginning exploration during EVA-3. Note the following: the LRV rock sampler attached to a yo-yo tether at my left waist; the cuff checklist on my left arm; watch above the cuff checklist; sample bags attached to the Hasselblad camera and camera mounted on the RCU; wrist-mirror on my right wrist (black band) — the intrepid field geologist ready to go! Note also the reflection of the Earth in my visor (see enlargement below). Also, the high-gain antenna (HGA) on the Rover is pointed to the Earth. (NASA Photo AS17-140-21386).
Crop from AS17-140-21386 showing my visor with the reflections of the photographer and the Earth above the South Massif.
“Can you do that likewise [of me]? Or can you hold it with that other camera [on your RCU]? It’s [my color camera] already set at 30 [feet focus].”
“Okay.”
“And you might want to take a couple…” This was a good call on Cernan’s part, as we got several “tourist shots” of ourselves with the Rover. These images (AS17-140-21388 to 21391) provide excellent views of how much the original lunar surface has been disturbed by our activities. This will be an issue that will need to be addressed in the case of lunar bases and settlements where repeated foot and vehicle traffic will need a stabilized surface.
Fig. 12.7. One of the corresponding “tourist” shots I took of Cernan after he took the ones of me. Note that the Hasselblad camera is not now attached to his RCU. I am using it to take this photo. (NASA photo AS17-140-21389).
Operations at the SEP Transmitter
“Seventeen, Houston. We think somebody lost their comm. Jack, it’s probably Gene going to O [from AR on the Mode switch]…” I was skiing my way to the SEP transmitter when this call came in.
“You read us, Bob?” I asked.”
“Roger. Read you now.”
“Bob, do you read Gene?” I heard Cernan calling Parker over our direct link, so he probably hit his Mode Switch out of AR over to A rather than to O (OFF).
“Reading you, Jack. I haven’t heard Gene yet.”
“Well, Gene’s calling you.”
“You read me?” Parker called again.”
“How do you read me, Bob?” Cernan asked after putting the Mode Switch back to AR.
“Okay, read you now,” answered Parker.”
“Okay, I didn’t do anything. I just jiggled my Mode switch here. …Okay,” he then said, referring to his Cuff Checklist, “We got 2 and 3 on the EP’s [on the gate] plus one (EP-5) under Jack’s seat. LCRU blankets are opened 100 percent; battery covers are closed; dustbrush – I’ve got [under my seat]; TGE – I’ve got; [film] mags and polarization filter is taken care of; and I’m ready to traverse [on the Rover] to the SEP.”
“Roger. We understand TV [will be] stowed and you’ve taken care of in the comm. And you might give us a Rover readout either now or when you get to the SEP.”
“Okay; we’ll see which is convenient.”
“Yeah. SEP [site] is probably more convenient while you’re sitting there waiting for the Nav to warm up or initialize – waiting for us to give you the reading.”
“Okay, [I’m] taking your TV. …Mode switch is 1.”
“Hey, Bob, are you watching LMP?” I inquired.
“Not any more he (Fendell) isn’t,” Cernan replied. “I took the TV [from them].”
“Okay.” I had hoped to get some more footage of my skiing technique so that it could be quantitatively compared with other modes of foot travel.”
“Bob, you still read?” asked Cernan.
“Roger. Read you loud and clear. We aren’t watching the LMP.” Parker had lapsed back to using “roger” to mean “yes” or “affirmative”.
“Okay, I just wondered because I just took the TV. I just want to make sure we got comm here.” Cernan was recalling the communication’s problem at the end EVA-2 when LM TELEMU had a configuration problem after Cernan switched to Mode 1.
“Yeah, we’re reading you in Mode 1.”
“And, for your information, we’ve both got our cover gloves off. …Okay, that’s (circuit breaker) in, that’s in, that’s in. Should have dusted my [Rover Startup] Checklist (decal) on the Rover. I can’t read [it] down there [on the console].”
“Bob, the old tape fix on the SEP [solar panels is] still working,” I reported (AS17-141-21510 and 21511), noting that only the ends of the gray duct tape, where my fingers had transferred some dust to the adhesive, had not adhered to the back of the panels. “Both mirrors (panels) have a little angular displacement, but not more than 5 degrees.”
Fig. 12.8. The SEP transmitter that I set up on EVA-2 seen from the backside. The tape ends mentioned in text are shown in the enlargement in Fig. 12.9. (NASA photo AS17-141-21511).
Fig. 12.9. Crop from Fig. 12.8 showing the backside details of the solar panels. The tape edges which are curling downwards because of lack of adhesion caused by lunar dust from my fingers are marked by the 4 black arrows. The hinges on the topside are of different sizes. The left one is smaller, allowing the leftmost panel to fold over the middle panel; and the right one is larger to allow the rightmost panel to fold over on top of the other two when the instrument was stowed. One of the antenna cables is marked under the lower right panel.
“Sounds like that’s the least of the SEP’s problems, but we have hope…” The stereo pair of photographs I took, in addition to documenting the status of the SEP transmitter, further illustrates the lack of penetration of footprints on fresh surfaces versus the deep penetration on previously disturbed surfaces.
Fig. 12.10. The stereo photo pair of the SEP transmitter displayed as a 3D anaglyph. (Derived from NASA photos AS17-141-21510, -21511; courtesy of the Editor).
Fig. 12.11. A partial pan documenting the SEP site and distance to the LM with Cernan in the Rover pointing north before he turned west to initialize the NAV system. The slightly darker regolith on this side of the LRV pointing in the same direction was made by the LRV tracks on EVA-2 in which the north-directed antenna cables were emplaced. A higher resolution view in a separate window is available here. (Derived from NASA photos AS17-141-21514 and 141-21512).
“Okay, you’re going to be over there, huh?” I said to Cernan as he stopped the Rover close to the SEP transmitter and pointed west with the Rover alignment gnomon shadow on zero. This position set the Rover up for a re-initialization of the Navigation system. “[Then,] I’ll go over here…”
“I don’t believe this,” Cernan said, looking at the roll indication with the Rover parked on nearly level ground.
“What’s the problem?” I reacted.
“Oh, nothing. That roll indicator isn’t worth a ding-dong. [It] says I’m rolled 10 degrees… Okay, Roll [estimated at] zero, pitch is zero; heading is 291; distance (from LM), 001; range, 000; amps hours are 90 and 85; volts are 65 (and) 65; Sun shaft device, by the way, is [on] zero.” “Batteries are 100 and off-scale low, and motors are all off-scale low…”
“Okay, and, Gene,” Parker responded, “we’d like to torque [the heading indicator] to two-eight-seven. Two-eight-seven.” This indicated only a four-degree drift in the heading indication since the start of EVA-2. Not bad for a simple single gyro system.
“Okay; in work. Let’s see, 287. That’s the heading from Cross City [VORTAC] to Tyndall [Air Force Base]. Okay, 27, 28; 287 right on the money.” Cernan referred to the heading for one leg of our frequent flights from Houston to Patrick AFB near the Kennedy Space Center.
“Bob, 45 Yankee (70290 and 70295) is a sample from near the SEP.…” I had taken the Rover sampler with me this time in case I had time to collect a sample or two.
[Post-mission analysis[17] indicated that the sample broke in two in the bag, becoming designated 70290 and 70295. Investigators described 70295 as a “weakly lithified (coherent) polymict (multi-rock type) breccia (fragmental rock).” This regolith breccia contains about 56% matrix, at least 10% agglutinates, about 12% basalt mineral clasts, and about 7% orange and black ash. Its intermediate Is/FeO maturity index is 43.[18]]
“Boy, I tell you, Jack,” Cernan alerted me. “That [transmission of yours] was all cut out.”
“Oh, well. I got the sample anyway.”
“We copied 45 Yankee near the SEP,” Parker acknowledged. “That’s all we have. If you give us a frame count when you get done, and give us an approximate location for the Rover, at least crosswise from the Y (Parker meant the “+” point where the four SEP antennae came together.), we’d appreciate it. …And we also need SEP receiver power and DSEA both ON. And we’d like the [SEP receiver] cover taped down when you get done, Jack…”
“Okay, Jack, keep me honest on those reels.” Cernan initialized the navigation west of the SEP transmitter, pointed west. He now had to turn around and drive to the transmitter and turn north for the SEP calibration run along an antenna. He had to maneuver into a position within 5 m of the north antenna arm and about 10 m from the transmitter. Before making the turn to the north, he will be driving into the Sun, making it very difficult to see. The “reels” he refers to constitute those that had contained the antenna cables and that we left at the end of each antenna as reference markers.
“Okay, you’re okay now,” I told him. “Let me get over on the [west] reel.”
“I don’t see [the antenna]…”
“See me?” I asked him, standing at the western antenna line near the transmitter. “Come on. You’re good.”
“Oh, there’s the SEP. Wait. Did I miss this other reel?”
“Yeah. There’s the [antenna]. …I’m on the antenna,” I repeated.
“What about the one coming west?”
“That’s what I [am standing on],” I replied. “No, you’re okay on the one [going] west. You’re way away from it.”
“Okay. Going to look back…”
“You want to…head towards the SEP. You’re okay.” Cernan just did not want to follow my guidance, for some reason.
“Oh, I see it (SEP transmitter) now,” he said, having raised up and twisted as much as possible to the right. “Okay.”
“Head towards it and then make your turn [to the north].”
“I see it. I’ll go over to it.”
“Matter of fact, turn on these tracks,” I suggested as he approached the tracks he made in laying out the orthogonal antenna array.
“Yeah. I’m in good shape. I see it (SEP transmitter). I see it.”
“Bob, that 45 Yankee [sample] (70290 and 70295) was a fine-grained basalt, I think. One of the few around here. That’s why I picked it up.”
Fig. 12.12. Sample 70295 that I picked up near the SEP transmitter. The shiny, dark impact glass and a number of embedded light colored fragments are clearly visible on this side of the sample (NASA photo S73-17192).
[70295 turned out to be a dark, largely fine-grained breccia rather than the fine-grained basalt for which I had hoped. A partial coating of shiny, dark impact glass may have caused my mistaken identification; however, in my haste, I failed to see the many light-colored fragments contained in the rock or possibly thought they were plagioclase crystals. Although we eventually collected a few fine-grained basalt samples, representing the rapidly cooled tops of lava flows, such flow top textures are not plentiful in Taurus-Littrow. The explanation for this may be that, in the 3.7 billion years since the last flows occurred on the surface of the subfloor, the relatively thin, chilled upper surface had been largely destroyed by regolith formation driven by micro- and macro-meteorite impacts. This initially limited volume of fine-grained basalt would be further diluted by ejecta from the numerous large craters around us that excavated coarse-grained subfloor gabbro from more slowly cooled zones at depth within the solidified flows.]
“Okay, [are] you stopped?” I asked Cernan.
“I’m stopped and I’m ready to go. …I’m 2 meters to the west of the north line,” Cernan reported more loudly to Parker. Both of us tended to talk louder to Mission Control than to each other. Earth is farther away than your crewmate so, naturally, you subconsciously felt it necessary to talk louder. At least that may be one explanation for our behavior. “And I guess I’m certainly within 5 meters of the transmitter.”
“Yep. You’re in good shape,” I agreed. As he prepared to drive along the north antenna arm for SEP calibration, Cernan zeroed-out the Rover’s distance and range counters. At the same time, I took several photographs of the calibration initial set-up relative to the SEP transmitter.
[Looking back toward Challenger as I took the photographs, I could see how disturbed regolith near the SEP transmitter had the same albedo and grayness as the near-by surface; whereas closer to the Challenger, disturbed regolith looks significantly darker than the surface (AS17-141-21512-17; see partial pan in Fig. 12.11↑). This gives a good illustration of how the Descent Engine effluents had winnowed away the darker regolith fines (mostly nano-phase iron-rich agglutinates) at the surface from the coarser and lighter gray regolith fragments that remained.]
“Okay, we’ll get that [exact Rover position] in the photos,” stated Parker. “And Gene, how’s the low-gain [antenna] oriented?”
“It’s oriented 355 and my (Rover) heading is 352.” The landing site specific bias on its pointing indicator allowed us to set the low-gain antenna to the Rover’s heading so that it actually would be pointed toward the Earth.
Standing behind the Rover, I asked Parker, rhetorically, “Okay, you want the (SEP) receiver ON…and [covers] taped down again, huh?”
“Roger. Both the receiver and the recorder ON – both switches ON – and then tape the cover down.”
“Okay, good luck. …I don’t know if that tape is going to hold. Okay, ON and ON. …Okay, it’s taped down more or less… And then I guess I’m supposed to get on [the Rover], huh?”
“Okay, Bob, Nav Reset is now OFF and I’m all zeroed up,” reported Cernan, as I jumped up and sideways into my seat.
Traverse to Station 6
“Okay. Copy that. And we’re ready for you guys to roll.”
“Okay, what’s the first range and bearing to the Rover sample, past Jones [Crater]?” Cernan asked, reviewing the next page of the Cuff Checklists, outlining tasks for the first part of the traverse to Station 6.
“Okay, it (the location) will be 185 (bearing) and 1.5 on the range.” This location comes from Mission Control’s estimate that the SEP transmitter lies 200 m east of the Challenger. Post-mission analysis showed that it was actually about 260 m east, but not a significant difference given the limited accuracy of the Rover navigation system.
“Okay, 185 and 1.5. 185 and one-and-a-half. Okay…”
“Excuse me, Gene,” I said as I flailed away trying to get seated and hitting the hand controller in the process.
“No problem…”
“Well, shoot …I’ve forgotten how [to get on].”
“Boy, that Challenger looks pretty from here, you know it.”
“Yep. …Okay, I’m on. …Did I want a [seismic] charge? No.”
“Nope,” agreed Cernan.
“No charge, Jack; no charge,” Parker interjected, unnecessarily.
“Okay. Got it. Got it,” I replied.
“Okay. 185 and 1.5 and I’m going to head on about 012,” Cernan declared. “We ought to go right through Jones.”
“Okay, and, Gene, remember,” Parker said, “the driving [needs to be] fairly slow – or fairly well controlled – the first 300 meters, and a “MARK” at the end of the antenna.”
“Watch that, Jack, watch that antenna lead …Uh-oh.” Cernan had wandered close to the antenna on my right and thought he had run over it.
“Keep going,” I advised.”
“[What does it] look like to you?”
“Okay so far; keep going. …Okay, let’s do that again…” He had put a big zigzag in what should have been a straight line for the calibration.”
“Yep. But a little different [this time].” Cernan said, somewhat chagrined at his lack of driving finesse. “I’ll pick up that same spot, I can see right where I was…” He turned left 360 degrees and went back to where we had started.
“Give us another MARK when you start up on that side,” Parker requested.
“Okay. We’ll give you a hack, Bob…”
“Okay,” I said hesitantly, “Ahh… You’re a little [close to the antenna, again]…”
“Yeah, I’m right on the track,” Cernan insisted. “Same tracks exactly.”
“Well, okay.”
“That’s exactly [right on]. I just came right over. Okay, we’re starting Bob. MARK it. …We can’t go too far in this heading. We’ve got a big hole up here. …Like a big one! …Wonder if that’s Rudolph?”
Fig. 12.13. The EVA-3 route. The small Rudolph Crater is below the ‘R’; Poppie Crater near the LM (at the end of the orange segment pointing to ‘P’) is to the right of ‘P’; and the location of the SEP transmitter is above ‘S’. ‘H’ is Henry Crater; ‘Sh’ denotes Shakespeare Crater; and ‘Co’ marks Cochise Crater. The lettering for Station 6 is partly overlapped by that for Station 7. The LRV numbers denote brief stops where I leaned out and picked up a rock sample while still seated. A wider scale version in a separate window is available by clicking here. (Base map, lettering (except white), and orange track from the LROC Apollo 17 Featured Site).
“Well, let’s see,” I said, looking at the photomap, “this is east. …Looks awful [familiar]. …It’s a double crater but it’s much bigger than I thought Rudolph would be.”
“No, if you’re where you think you are, you’re east of Rudolph quite a ways,” Parker speculated.
“Gee, I think you ought to know where we are by now, Bob.”
“Maybe that’s Lewis and Clark [Craters].” (‘L’ and ‘C’ on the enlarged Fig. 12.13).
“After you give me a MARK there [at the end of the antenna], I’ll talk to you about it.”
“I’m sorry, Bob,” Cernan apologized. “I guess you didn’t hear it. We’re passed the end of the antenna and we’re headed northeast.” Parker “didn’t hear it” because we didn’t say it. “That [omission] screw you up?”
“Did you give me a MARK when you started or a mark when you passed the antenna?”
“I gave you a MARK when I started and it took about 20 seconds to get to the end. …Is that good enough or do you want me to go back?”
“No. No. Press on. And, Jack, if you look at your contour map there, we think you (the Challenger) are located right now at approximately where the P in SEP is, just below the P in ‘Poppie’. In which case you’re probably driving through that little crater that’s just to the northeast there.” This location for the landing corresponds very closely to the final post-mission analysis, confirmed by photographs from the Lunar Reconnaissance Orbiter in 2010. The “little crater” to which Parker refers actually is a subdued old crater about 200 m in diameter (Fig. 12.13, crater in the bend of the orange track above ‘S’).
“Okay.”
“That’s (the crater) probably the one you came upon,” added Parker.
“Not very little, though,” Cernan commented.
“Okay, Bob. Boy, I wish I could see a little bit better…” I finally had a chance to get back into the geology along the traverse route. Photographs AS17-141-21519 to 21563 show a good, traceable sequence of features along this part of the traverse, including the apparently very dark boulder on the lower slopes of the North Massif (AS17-141-21533). “The major boulders [near our path] still look like the pyroxene gabbro (basalt). The surface texture has not changed. There is a granule population [on the surface], now that I look at it more closely with (at) the shadows [they cast]. But I have a feeling that most of those are… They look like they’re just very small clods. That should show up in some of the bulk samples we’ve taken. But, it is remarkable to me…[to see] the small number of fine-grain rocks. There’s one at about halfway between the SEP and the LM that I’d like to pick up, it’s a fairly good-sized one. Maybe we can get it when we get back. It looks like fine-grained basalt. I may have sampled one in 45 Yankee, there.”
Fig. 12.14. Near the beginning of our trek to Station 6. In the distance, the left arrow marks the dark boulder. The arrow at right marks the boulder at Station 6, our first destination on this EVA. The tilt in the image is due to the front wheel on my side passing through a small crater. See details of the two boulders in the next figure. (NASA photo AS17-141-21533).
Fig. 12.15. Detail of the area between the dark boulder and the Station 6 split boulder cropped from the previous photo.
Fig. 12.16. I took a photo of the dark boulder from the LM window after EVA-1 with the 500 mm Hasselblad camera. It shows a number of other boulders. Also see Fig. 11.149b↑ et seq. at the end of the previous chapter for a view of this boulder and its track with respect to the pan of the North Massif. The track made by the boulder indicates that the boulder wobbled from side to side as it rolled down the slope.(NASA photo AS17-144-21991).
“Well, I tell you,” Cernan said, “It’s not exactly the greatest place to navigate through.”
‘I think you ought to bear left, don’t you?” I suggested as he had taken a large eastward arc along the east rim of the old crater.
“Yeah. That’s where I’m going here. I just want to get across this [crater and] around these boulders.”
“There’s a crater we’re just passing,” I noted, “at 207/0.4, about 20 meters in diameter, with the pyroxene gabbro blocks on the rim – a few of them. It’s not an exceptionally blocky rim crater, but we are in an area where the block population is up to about 5 percent [coverage], in contrast to most of the area we traversed yesterday.”
“I tell you, going is a little bit rough; there’s a population of blocks, as Jack said, and an awful lot of small craters.”
“Yeah, I was just going to add that the frequency of craters in the 10 meter size range is quite a bit higher than we were used to yesterday… Oops, there’s one,” I added as the LRV bounced more than usual (see tilt of Fig. 12.14↑).
“Yep.”
“Snuck up on you,” I kidded. “And they all – although not exceptionally blocky rims – they all have a slightly, maybe 2 or 3 or 5 percent more blocks in their walls and on their rim than does the normal terrain.”
[This portion of our traverse toward the North Massif was partly through an area later referred to as the Crater Cluster in which Station 1 also was located (Fig. 12.17). Because of the higher abundance of blocks in this area, it is likely that the Crater Cluster was formed by high velocity secondary ejecta from an impact hundreds if not thousands of kilometers distant, although a family of meteors would have created a similar effect. A slightly different spectral signature in M3 images of the Crater Cluster area relatively to its surroundings indicates an admixture of material of a slightly different composition, favoring a secondary ejecta origin or excavation of mineral concentrations in the underlying basalt flow, as most of the material in a family of very high velocity meteors would have vaporized (see Endnote [13]). Preliminary examination of compositional data from both Kaguya’s Multi-Band imager and M3 suggests that the impacts may have distributed olivine and pyroxene-poor, plagioclase-rich material in and around the Crater Cluster, consistent with fractional crystallization and chemical differentiation trends seen in the Station 1 basalt rake samples (71500) (See Chapter 13).
A significantly greater contrast, related to the Crater Cluster’s rock abundance and regolith textures in the upper ~1 m of the regolith, appears in the processed, 12.6 cm wavelength Mini-RF 1 (radar) image in Figure 12.17. Of particular interest in this Mini-RF image are (1) the apparent abundance of rocks in and around the Crater Cluster explored at Station 1 on EVA-1, consistent with my reported observations in that area; (2) the apparent abundance of rocks in the light mantle avalanche, contrary to my reported observations, and which actually may relate to an induration of the fine debris in the upper portions of a fluidized avalanche deposit; and (3) the apparent absence of rocks in the dark fissures of probable pyroclastic ash that cross the Sculptured Hills and the one fissure of ash that diagonally crosses the slope of the North Massif (see Chapter 13).]
Fig. 12.17. View of Taurus-Littrow Valley from the Mini-RF instrument on the Lunar Reconnaissance Orbiter (LRO). Mini-RF data is processed to create a view known as a m-chi (m-Χ) deconvolution of the signal that uses multiple products derived from the data to illustrate variations in surface properties such as surface texture and rock populations within the upper meter of the regolith. Areas in blue (B) indicate few rock fragments larger than the wavelength of the radar signal (12.6 cm) within the upper meter and a relatively smooth surface, while surfaces that are red (R) or yellow are rougher or have more fragments larger than 12.6 cm at the surface or within the upper 1 meter of the regolith. The Crater Cluster area is outlined by the dashed curve; Camelot Crater is denoted by ‘C’; and Henry, by ‘H’. (Map generated by David Hollibaugh-Baker and Noah Petro (NASA/GSFC/JHU-APL)).
I continued, “Still no obvious structure within the dark mantling material itself.” As noted in Chapters 10 and 11, the volcanic ash that defined the dark mantle’s dark appearance on pre-mission images has had 3.5 billion years to be mixed into the regolith, so any “structure” related to ash eruptions would have long since disappeared. On the other hand, my recent studies of the 3 m deep drill core obtained at the ALSEP site (Chaper 10) indicate that the dark mantle is largely comprised of superposed regolith units ejected from the 200-600 m diameter impact craters on the valley floor. At this point, however, the implications of the discoveries at Shorty Crater (Station 4) and the deep drill core remained unknown.
“Bob, you said 185/1.5?” Cernan inquired of Parker.
“That’s affirm.”
“What do you want? …[Oh,] for the Rover [sample]?” I asked,
“Yeah, for a sample.”
“Oh, they changed it on us.” I had been concentrating on getting on the Rover when Cernan and Parker discussed the bearing and range for the sample. Our Cuff Checklist has the Rover sample at 192/1.6, based on Challenger’s planned landing point. “Okay. Still seeing the little pit-bottom craters with the glass in them. I’ve forgotten the acronym already, Bob, I’m sorry.” This was a kidding reference to Parker’s EVA-2 invention of GLPBC as the acronym for “glass-lined, pit-bottom craters”. “And you asked me for an LMP frame count a while back, and I believe it was 5. That was at the SEP.
“That was after the SEP photos, right?”
“That’s affirm. …Negative,” I corrected myself. “That was before the SEP photos. …Okay, Bob, looking up at the North Massif, we see the scattered, strewn field of boulders that generally seem to start, more or less, from a line of large boulders, which might indicate some structure. And those lines are roughly horizontal across the face that we’re looking at. The boulder tracks are irregular in shape, obviously [trending] downhill, but you’ll see in the pictures that they are…curved in places. But they’re all – [all] that I see – tend to be aggregates of little craters where the boulder was obviously tumbling and bouncing a little bit, …We’re out in (a) population of fragments now in the immediate area, at… Is that [bearing] 188?”
“188/0.9,” Cernan replied.
“[The fragment population is] generally about 1 percent between craters. But at the crater rims, it’s up to about 5 percent.”
[Fragments on the rims of craters that did not penetrate the regolith into coherent hard rock below would be mostly regolith breccias, that is, “instant rock” formed by impact compaction of local regolith, rather than much less friable crystalline basalt fragments derived from underlying lava flows. With far more EVA time than available to us, or some remote means of distinguishing regolith breccias from coherent bedrock fragments, the first appearance of bedrock fragments relative to the depth of craters would provide a measure of the thickness of local regolith. Regolith breccias on the rims of impact craters indicate relatively recent impacts as these friable fragments disintegrate quickly under continuous erosion by macro- and micro-meteor impacts. This will be discussed further in relation to the regolith breccias sampled at Van Serg Crater, Station 9. There, by comparison with the lack of such breccias at Shorty Crater (Station 4, Chapter 11), the presence of rim accumulations of regolith breccias indicates an impact significantly less than 3 million years old, the age of the Shorty impact, and probably less than one million years.]
“Copy that, Jack. And how far down the North Massif is the line of boulders?”
“Oh, there are several of them (linear boulder sources), Bob. What I’m talking about is about 100-meter-long lines where the boulder trains initiate (begin). And there’s one [source that] looks like [it is] about halfway, maybe two-thirds of the way down, in perspective. [There’s] another one that’s probably about halfway [down]. They’re just sort of scattered around on the Massif. …I think we’re getting close to [Jones Crater]. Well, we couldn’t be,” I added, after glancing at our photomap.
“I’ve got to move over here a little,” Cernan said, while he turned slightly toward the east.
“That must be Jones,” I speculated, looking at a line of three craters I had designated by that name.
“Where are you looking?”
“Off to the right,” I replied.
“Yeah, our heading that they’re [giving us is] sending us down here. …It really should put us to west of Jones. So that’s about right. …A lot of static in the background today.”
“Yeah, I think we are talking to you guys through the LM [comm] right now,” Parker explained. “And how about a speed reading?”
“Okay. We’re at 12 clicks and we’re full bore. …187/1.1.”
“Bob, I wish I could give you more on that structure in there (the North Massif), but I think those lines of boulder sources are about all we can see right now. [We] talked about the lineaments [on the Massif slopes] yesterday and they’re not nearly as obvious today in the higher Sun. Looking up Wessex Cleft, even with the Sun in the flat area there, it looks darker than the North Massif side. But again, the Sun angle may be fooling us, but I recall it was darker on the [overhead] photos.”
“The old man wrinkled face on the…”
“Sculptured Hills,” I said, helpfully, as Cernan searched for the right feature name.
“…Sculptured Hills, though, is evident as soon as you come (view) out of the Wessex Cleft [on to the southwest facing slope].”
“Yeah,” I agreed. “And they look like there are boulders up on the side of the Sculptured Hills; except that they aren’t nearly as big as those on the [slope of the] North Massif. The areas [on the Sculptured Hills], where the boulder source is, look like they’re made up of boulders no bigger than a meter, maybe; whereas, the North Massif boulders are up to several meters. Those boulder sources all seem to be up within a [upper] third of the height of the Sculptured Hills, just east of the Wessex Cleft…”
[This obvious difference in the size of the largest boulders between the North Massif and the Sculptured Hills constitutes strong evidence that the materials of the two features are structurally distinct as well as compositionally distinct as shown by M3 spectral data (see Endnote [13]).]
“Here [on the North Massif] is a boulder track that crossed the slope. See that, Geno?”
“Yeah. Yeah. I sure do now!”
“It looks like it goes, rather than perpendicular (90 degrees) to the contours, it probably is crossing them in a fairly straight line on an angle of 60 degrees, maybe.”
“[Plunging] Back to the east.”
“Yeah, to the east,” I agreed. ‘That one may be fairly near [the Station 6 boulder]…” Indeed, this is the track made by the large boulder we soon would investigate at Station 6. We had reached a point about two kilometers from the base of the Massif with Station 6 being about half a kilometer farther to the right or east.
“Jack, see that big boulder with that big track? It looks like it’s an elongated, rolled-up boulder. Look at that.” Cernan is referring to a group of boulders that appear significantly darker than others we had in view (AS17-141-21543). Images received from the Lunar Reconnaissance Orbiter, however, suggest that the dark character probably was the result of an overhang that created a long shadow under the boulder during our three-day stay in Taurus-Littrow.
“Yes, it does. Looks like it may be broken now.”
Fig. 12.18. The dark boulder is on the slope left of center; Station 6 boulder, at right arrow. We have stopped briefly at LRV-9, the sample site for 76120. (see Fig. 12.13↑) (NASA photo AS17-141-21544).
“Okay. Here we are: 1.5 and 185.”
“Okay, is this a Rover sample?”
“A Rover sample,” Cernan confirmed. “Tell me where you want it.”
“[Do you] see that little pit right over there about 30 feet ahead?” I asked him.
“Yeah, I think so.”
“Okay, I’ve got two pictures there [of the approach to the sample area]….” (AS17-141-21542 and 21543)
“How’s that?” Cernan came to a stop almost exactly where I had suggested.
Fig. 12.19. Cernan’s photo at the same stop. The dark boulder and track are between the HGA post and pointing handle. Station 6 is marked by the right arrow. Note the few wall boulders on the unnamed crater ahead. (NASA photo AS17-140-21392).
“That’s great. …Okay, this is a soil sample…,” I commented, as I reached down and to my right as far as possible.
“Hey, Geno,” I called to attract his attention after he took the locator photograph. I needed him to take the Dixie Cup off the sampler and twist it closed.
“Okay, and I just took a locator, …and CDR is on frame 41.”
“Got it (the sample bag)?”
“Ah, not yet… Got it now. Bag 46 Yankee (76120-24). …Your [accessory staff] bag open?”
“Yup.”
“Okay, it’s in,” he reported.
[Post-mission analysis of 76121 has been limited to measuring regolith maturity. With an intermediate to high maturity, 76121 ranks as one of the more mature basaltic regolith samples we collected, having an Is/FeO ratio of 71 versus regolith from the dark mantle with ratios around 55 and regolith from the bases of the Massifs and Sculptured Hills that have ratios of 80-93.[19] As discussed in Chapter 13, the presence of more than a few percent of ilmenite in the regolith appears to significantly slow the rate of maturation.[20]]
“We ought to tape that lead (strap) down,” I commented, “if we can remember it [at the] next stop. It’s in the way of [getting to the SCB]. …It’s sticking up.” The “lead” referred to here is a strap of Velcro hanging off the low-gain antenna staff.
“Okay, I’ll get it [then]. That thing came off that piece of Velcro. I’ll get it when I get back.”
“Okay. And LMP’s frame count…is three-five.
“Okay, Bob, I’d like a bearing and range [to Station 6].”
“Okay. Bearing and range for the large block, just beyond… Let’s see. …It’s just beyond (north-northeast of) the crater Henry. The large block there near the break of the slope, which is our next aiming point. The bearing and range there is 188 and 2.8.”
“188 and 2.8. Roger.” From our present position, this meant that we would need to drive north along the west rim of the ~600 m diameter crater I named Henry to reach the base of the Massif and then turn northeast and cross up the slope of the Massif to reach Station 6 (Fig. 12.20↓).
“And, Jack, what do you see,” Parker went on, apparently reading from a note from the Science Back Room, “in the way of boulders coming down the base of the Sculptured Hills, in terms of sampling opportunities at Station 8 and in terms of any boulder tracks that might lead down to boulders that might just possibly be accessible at Station 8?” I guess I had not been clear in my earlier mention of boulders only being visible on the higher reaches of the Sculptured Hills above Wessex Cleft.
“Watch it, Gene!” I exclaimed, as a crater appeared that surprised both of us. “Boulder tracks are not obvious on Sculptured Hills at all. It looks like there are fragments over there that would have had their sources higher up the slope. I think we can get boulders there. …We’ll have to get a little closer, Bob.”
“We’ll find out in a couple of hours.”
“Yeah, I will give you a reading on that before long. I wouldn’t eliminate Station 8 for the world – or the Moon – whatever’s available today.”
“Bob? What did you say? 188 [and] 2 point something?” Cernan asked.
“2.8.”
“Okay, thank you. See that big boulder, Jack, with those tracks? …That’s [a] funny looking boulder.”
“It looks like it may have stopped rolling,” I responded, “because it broke up. …Looks broken to me now.”
“Boy, they’ve got the low-gain right on ‘em. But, I tell you, we still got static.”
“I don’t have any, Gene. You may [have to hit your squelch wheel]”
“Well, I sure do (have static).”
“I don’t like the sound (shock) of your bounces,” I told him, suggesting that he might be hitting some of the small craters too hard. “Okay, you’ve got yourself in some holes here. …You’ve never… I’ve read you all along, though, so there’s no problem [with your transmissions]. Okay, there’s a big crater [off to the east]. I haven’t recognized Jones yet…” Apparently, we had driven to the east of the line of craters I called “Jones”. It would have been difficult for me to see them with my view to the left obscured by Cernan and the high-gain antenna. “Looks like you’re getting up on the rim of Henry here.”
“Well…” Cernan was not sure. “No, Henry should be to… I should be well west of Henry, I think. I wouldn’t be surprised if Henry isn’t right over that little rise on the right.”
“Bob, the surface structure hasn’t changed, [that is, the] texture [hasn’t changed]. We’re on a little bit of a rise in here now and still about 1 percent of the surface [are fragments]…” (AS17-141-21544 to 21550).
Fig. 12.20. The dark boulder, Turning Point Rock, Stations 6,7 Boulders (marked by black arrows from left to right, respectively), and Henry Crater. Turning Point Rock marks the spot where we turned to the right and began the climb uphill across the slope to the Station 6 boulder (see details in Fig. 12.21). (NASA photo AS17-141-21550).
Fig. 12.21. An enlargement from Fig. 12.20 showing the main features more clearly. We are skirting around the west rim of Henry Crater to get to Turning Point Rock (TPR).
“Here’s Henry right there, Jack.”
“There’s Henry! …I thought you were close to Henry.” Photograph AS17-141-21550 (Fig. 12.20) includes what will be called “Turning Point Rock” as well as the boulders at Stations 6 and 7.
[The track leading to the Station 6 boulder is clearly visible in this image; however, as will be noted below, the older track leading to the Station 7 boulder, later identified from a Lunar Reconnaissance Camera Orbiter image, is not visible. Although Henry Crater is visible in this photograph, the subdued character of the terrain illustrates the difficulty we had, from our near surface perspective, identifying specific crater landmarks, even large craters. Henry actually appears to be the topographically younger of the three, ~600 m diameter craters in this part of the valley; however, the absence of rim boulders and the presence of some patches of wall boulders indicate that Henry may be older than Horatio and, of course, also older than Camelot,
Henry, Cochise and Shakespeare, lie in an concave arc across the valley’s entrance to Wessex Cleft. Shakespeare, with no rim boulders or wall boulders visible in LROC images appears to be the older of the three, all of which appear to be topographically older than the ~500 million year age of Camelot (see Endnote [13]), based on comparisons of the presence, absence or degree of boulder concentrations on their rims or walls. These relative ages, that is, Camelot, Horatio, Henry, Cochise and Shakespeare from younger to older, are discussed in Chapter 13 with respect to probable sources of regolith ejecta layers in the deep drill core obtained at the ALSEP site. There, rough absolute ages are calculated for all these craters by summing the length of apparent regolith exposure ages, using the ~500 Myr topographic diffusion age of Camelot as control.]
“Okay, how about a range and bearing.
“188/1.8.”
“And we’re just southwest of Henry,” I added. “On the rim. Old Prince Henry, the Navigator!” (1394-1460 A.D., House of Aviz; sponsor and patron of Portuguese exploration; introduced the ‘Age of Discovery’).
“Watch that foot,” Cernan said as a wheel entered a small crater.
“It’s called a wheel, I think,” I kidded him when I finally figured out what he meant by “foot”. “And Henry looks much like Horatio did. [It] has boulders on its inner wall [but] not as many. They look light colored: a light-albedo, gabbroic appearance. There may be some right down there, though, that are fine grained; they look a little greyer.”
“Jack, there’s our target. …That’s one (boulder) right down there on [the] break in slope.”
“See the one we’ve got over [there] has a boulder track. That’s the one that crossed slope.”
“Yeah, if we could get up [there]…”
“Can we get up there?” I asked, as the slope looked more formidable than our pre-mission photographs suggested.
“It’s awful high (steep). We’ll see.”
“That’s the one. That’s Station 6, and that [boulder ahead] was [is] the…the turning boulder,” I declared.
“Yeah, that’s it.”
“The one right there…”
“Station 6 – we can probably get up there,” concluded Cernan.
“I think we can; it doesn’t look too bad. …The break in slope, right now, doesn’t show anything obvious, except that’s where the boulders start.” This break in slope that concentrated the boulders amounted to a change of about five degrees, apparently enough to stop the momentum of many rolling and bouncing boulders.
“Okay, we hope that’s fairly obvious,” Parker said, possibly concerned we might be asking too much of the Rover.
“And on up the hill (Henry’s rim) you have… But as I was saying, Henry just looks like a somewhat more mantled Horatio… [This dialog is] getting to be ridiculous,” I said with a laugh, seeing humor in the use of person names for craters.
“Say, Bob, I’m navigating – headed northwest now – to get around the western rim of Henry.” At about 600 m in diameter, Henry continued to appear to be an older version of Camelot Crater.
“And on that west rim, we’ve got about 10 percent boulder cover,” I added.
‘Okay. And a reminder, Jack,” Parker said, “to keep taking your Rover photos.”
“Yes, sir! And by ‘boulder’, I generally mean ‘fragment’, Bob, in this case. When I say 10 percent, I’m looking at stuff greater than about a centimeter in diameter. …I’ll try to say ‘fragment’ from now on and be more precise. …Okay. Here’s a little area where there’s [large blocks]. …This is the one part of the rim of Henry I see that has fairly large fragments, or boulders, on them up to 2 or 3 meters. But, again, they all appear to be buried. There are very few – except (in addition to) small ones – sitting out on the surface.”
“And, you know, the fragment population out here only goes out maybe 200 meters [from the rim crest], I expect.”
Fig. 12.22. We are working our way west of Henry. The line of boulders ahead is just before the 50-m crater in the rim of Henry. Locke Crater is further north of this rim crater, better seen in Fig. 12.23 below. (NASA photo AS17-141-21556).
“Okay. Now this [particular] concentration of boulders (we are driving past) is because of [ejecta from] a 50-meter crater in the rim of Henry.” Photographs AS17-141-21555-56 show the boulder field I described and its contrast with the surrounding area of low boulder concentration (Fig. 12.22). Ejected bedrock boulders stay within about a crater diameter of the impact point, whereas LROC images indicate that overlying regolith, in the one-sixth gravity environment, travels many crater diameters from that point. The regolith ejecta zones in the deep drill core 70001/9 (Chapter 13) also indicate that this phenomenon constitutes a major factor in regolith accumulation and redistribution.
“Okay, that sounds like Locke [Crater],” speculated Parker, prematurely.
“No. Locke, I can see [out ahead],” I replied. Locke, at about 100 m diameter, would be about twice the size of the crater on Henry’s rim that we were approaching (AS17-141-21556, Fig. 12.22).
“Take a picture in here, Jack.”
Fig. 12.23. We are approaching Locke Crater just beyond the boulders to the right of the map holder blocking most of the view. Turning Point Rock can be seen on the slope to the left of the rightmost fiducial cross. We will turn northeast and drive between Locke and Henry, which is off camera to the right. (NASA photo AS17-141-21557).
“I’m getting the picture.” AS17-141-21557 as compared with AS17-141-21558 (Fig. 12.24↓) shows that there are concentrations of boulders beneath the relatively much lower boulder content of the surface regolith in the area that would have constituted the ejecta blanket of Henry.
“Okay, that’s not [Locke]. …Locke’s right ahead of us,” asserted Cernan.
“This is one (not Locke) about 50 meters [in diameter] right on the rim crest of Henry, the due-west rim. Now Locke is just ahead of us. It also has boulders in its walls but has relatively few on the rim. …Characteristic of Henry, Locke, and Horatio is [that there is] essentially no change in the average frequency of boulders on the rim. The increase comes in the wall.”
[This striking difference between the boulder concentration on the rims and on the walls of these older craters strongly suggests that regolith formation on the rims has been nearly complete on Henry Crater. In contrast, the down-hill movement of new regolith toward the bottom of the craters continuously exposes fresh blocks in the walls until the slope lessens to the point where this movement does not keep up with new regolith formation on the wall slope This observation is consistent with the analysis of Camelot Crater suggesting that rim boulders on those craters where they are present actually are exposed wall rocks (Chapter 13) and that Henry formed before Camelot and probably before Horatio, where abundant boulders exist on Horatio’s walls. The general aging sequence of multi-hundred meter diameter craters in the valley appears to be roughly as follows: 1) concentration of ejected boulders on the ejecta blanket and rim with boulders and bedrock on the walls, 2) disappearance of ejected boulders on the ejecta blanket and rim with regolith development on the walls, 3) exposure of in situ wall rock at the rim with boulder streams on walls, 4) gradual incorporation of exposed wall rock and boulder streams into regolith with migration downward into increasingly shallow crater, and 5) disappearance of most boulders on walls as crater wall slopes lessen. As noted above, relative ages of craters become very important when interpreting the deposition ages of regolith ejecta zones in the deep drill core obtained at the ALSEP site (Chapter 13).]
“We’re at 184/2.3. We’re just about between Henry and…”
“Locke,” I filled in.
“Locke. Yeah; right between them.”
Fig. 12.24. We are driving northeast between Locke to the left and Henry to our right. Ahead, the Station 6 boulder is visible on the slope marked by the left arrow, and the smaller Station 7 boulder marked by the right arrow (see Fig. 12.24a for further details about Sta. 7). We will soon turn north again to head for Turning Point Rock. (See map in Fig. 12.25). Part of the Sculptured Hills is seen at right. The dip in terrain preceding it is the Wessex Cleft. (Base photo, NASA photo AS17-141-21558).
Fig. 12.24a. Location of the Station 7 boulder and the 3 boulders labeled a,b,c at right are described further in Fig. 12.71↓.
Fig. 12.25. A portion of our route past Henry and Locke. The 50-m rim crater on Henry’s rim is marked by the white arrow. (The route is approximate. For example, between Locke and Henry, it should be directed more to the NE before turning north; and at the top it should be on the north side of ‘LRV-10’, which is at Turning Point Rock). A larger view of the area can be seen in a separate window here. (Base map, lettering (except white), and orange track from the LROC Apollo 17 Featured Site).
“Okay. I copy that. And you guys are heading for that big boulder, which must be just dead ahead of you there, about half a kilometer.” Parker refers to a boulder, where we will turn northeast, about 400m north of Locke. It would be a good reference for the navigation system as it is visible on the pre-mission photographs.
“Well, Gene’s sort of headed for Station 6 now.”
“I’m going to take a tour around that boulder and give them a fix on it.”
“Okay. Go ahead,” I agreed.
“Yeah, and that would be a good mark to give us a range and bearing on, since it’s a pretty discrete point.”
“Yeah, we are,” Cernan said.
“Bob, the boulder concentrations in the wall of Henry have their upslope start at about, oh, I would guess an average of 30 meters down from the rim crest. The rim crest of Henry is not very well defined, but it’s there. And from that [first] initiation of boulders, they stream down the slope to the break-in-slope down at the floor.
“Still no obvious change in the dark mantle, as we’re just to the east of Locke now. …There’s a 30-meter crater, fairly subdued but still quite deep…[that is, a] subdued rim. Again, it looks as if it were mantled; [and it] has no significant increase in blocks on its rim. That crater, in any other place, would have been a very blocky-rim crater. It’s maybe 30 meters [across] by 5 meters deep…” It may be that the combined thickness of the dark mantle regolith and regolith talus at the base of the North Massif is thick enough to keep a crater of this size from reaching bedrock.
Man, that is a big rock up there!” I exclaimed, looking at the boulder at Station 6.” Then I continued, “Turning Point Rock is a split rock; [it] has [what] looks like a northwest-southeast overhang, with another block just this side of it – just to the south of that overhang. It’s a pyramid shape in cross section – [I mean] triangular shape in cross section – and it looks like it is pretty well fractured, although not pervasively like the rock at Shorty was [fractured].”
Fig. 12.26. We have turned to the north again heading for Turning Point Rock in the near distance beyond the two craters. At upper left is a closer view of the dark boulder, its down slope tracks partly visible. No tracks can be seen for Turning Point Rock, however. (NASA photo AS17-141-21560).
Fig. 12.27. A closer view of Turning Point Rock, but no down slope tracks are visible. The dark boulder is just at the left edge of the photo. Its tracks are a little more visible. (NASA photo AS17-141-21562).
“Okay, Jack, I know I can get up to Station 6.”
“Yeah.”
“I can drive up there.”
“Yeah,” I agreed again. “Now, Bob, Station 6 rock – one of them – is from that boulder track that runs obliquely across the contours.”
“Okay. I copy that, Jack. Sounds like good news.”
“And the pictures ought to pin down at least the [upper] end of the boulder track pretty well.”
“Boy, this is a big rock, Jack. Whew.”
“As I saw it, the [Station 6] boulder track started about halfway up the slope of the North Massif. …That [Turning Point Rock] is a big rock, [also].”
Turning Point Rock
“We’re at Turning Point Rock,” reported Cernan. And it looks like it’s… I don’t know if it’s mantled on top, but it’s certainly filleted. There’s a lot of the dark mantle up and on some of the shallower slopes of the boulder. And it’s on a little mound itself, as if much of it might be covered up.”
“Yup,” I replied, but realized that the rock may have mounded regolith in front of it when it came to rest. “Okay. It looks like a breccia from here.”
“Can you get a sample of it right here?” Cernan asked me. “You see these little chips?”
“Yeah, I probably can.”
“Okay, Bob. I’m 3 meters from Turning Point Rock on the east side, and I’m reading 186 and 2.8…”Ahh! [Need to run] that over.”
“Okay. Can you drive up [on the mound]?”
“Yep.”
“…[Go] to the… right there,” I directed. “Let’s see… No, I can get them. The thing is, I don’t know what it is [I’m sampling].”
“Well, but it’s part of these fragments around here, …I guess Turning Point Rock is …1, 2, 3, 4, 5, 6… Six meters high anyway,” Cernan counted, making a visual estimate of the height. (Post-mission measurement showed it to be about 7 m high.). “It’s a, …well, I’d say it’s a very rough, sub-rounded type of rock. By the face… Let me get this [sample bag], Jack. Okay.”
“There are two fragments in that sample.”
“47 Yankee (76130-37),” Cernan read off the Rover sample bag.
“Plus some dirt. And it’s (the sample location) about 4 meters from Turning Point Rock on the north side.”
Fig. 12.28. The 6 cm long breccia sample 76135 (left) and basalt sample 76136 (right) picked up at LRV-10 on the north side of Turning Point Rock (see Fig. 12.30↓). Note several vesicles and zap pits in both samples. See indented text below for further discussion. (NASA photos S73-15401 (left) and S73-15685 (right)).
[Post-mission examination divided this sample into regolith, (76130-34), a poikilitic (small crystals inside large crystals) vesicular impact melt-breccia (76135), and an ilmenite-olivine basalt fragment (76136). The basalt’s composition resembles that of Type A basalt 71055 obtained near Steno Crater (Station 1). The maturity of the regolith portion of this sample (76131) is intermediate to high with a maturity index of 70, somewhat higher than most regolith from the slopes of the massifs, suggesting relatively slow introduction of younger slope regolith from above.
No track on the slope of the North Massif leading to Turning Point Rock can be identified in photographs taken on our approach (AS17-141-21560-63 and AS17-140-21395); however, the concentration of boulders down-slope from Turning Point Rock may have broken off the main boulder when it came to rest and, along with the boulders up-slope from the main boulder, may indicate the direction from which it rolled (see AS17-141-21562, 64, 67 and 68 and AS17-140-21394, 96 and 97). Preliminary examination of the detailed patterns in the regolith on the North Massif, as shown by various LROC images, strongly suggests that a source crop for Turning Point Rock might be identified as has been done for the Stations 6 and 7 boulders. A comparison of the impact melt-breccia 76135, that may have come from Turning Point Rock, with Station 6 sample 76215 suggests that both Turning Point Rock and the Station 6 boulder came from the Crisium ejecta blanket, identified as the lower stratigraphic unit in the North Massif (see Chapter 13).]
“And presume you got some good photos of the rock,” Parker stated.
“Yeah, I got a couple,” I replied. “I hope they’re good.”
“Well, I’ll tell you what I’m going to do here, real quick.”
“And my locator is…56.”
“I’m going to do a… Jack, let me spin around this little crater here to the left.”
“Bob, it’s (Turning Point Rock) very coarsely vesicular; but, at first glance, it did not look like the pyroxene gabbro – although that rock (another rock nearby) does. It looks like it might be fragmental, although I’m suspicious that I’m looking at zap pits.”
“Oh, yeah,” I exclaimed as I observed more large vesicles during Cernan’s turn around Turning Point Rock. [I’m] getting them (black & white photographs). I got them. [Gene,] take one (a color picture). That’s a nice view [at that Sun angle]. Although neither of our photographs (AS17-141-21568 and AS17-140-21397) illustrates the large vesicles I reported, we would later examine them up close at Station 6. This further suggests that Turning Point Rock may be stratigraphically related to the Boulder at Station 6.
“Man, we’re on a little rise looking at this boulder [from the north]. That’s incredible. …Okay. We’re on the roll, Bob.”
“Bob, my guess is, right now, is that Turning Point Rock is a big piece of subfloor gabbro.”
Fig. 12.29. My photo of Turning Point Rock, showing Henry Crater behind it; and in the distance, the LM. The latter can be found by following the partial fiducial cross above Bear Mt. down below the mountain to the oblong whitish area. Also see Fig. 12.30 for an enlargment pointing to the location of the LM. (NASA photo AS17-141-21568).
Fig. 12.30. Cernan’s similar photo. Here the LM location is indicated by the inset enlargment from the same image. By comparing the right side behind Turning Point Rock in Fig. 12.29 and the left side in Fig. 12.30, the size of Henry Crater is apparent. Note the Rover tracks between Turning Point Rock and the smaller boulder on the slope under the HGA pointing handle. LRV-10, the spot where I picked up the samples shown in Fig. 12.28↑, is along the track between those boulders. (NASA photo AS17-140-21397).
[Even from a few meters distance, I could see that Turning Point Rock had large, smooth walled holes exposed at its surface. Although post-mission examination of Boulder 2 at Station 2 disclosed that it was very finely vesicular, we had not seen large vesicles in boulders studied at the base of the South Massif. I had not yet realized that impact breccias produced by partial impact melting of pre-existing breccias could be coarsely vesicular, similar to some subfloor gabbros we had sampled. This led to the thought that Turning Point Rock might be a coarsely vesicular example of subfloor gabbro. Photographs (AS17-141-21567-68 and AS17-140-21396-98), however, show a very rough and knobby surface, similar to portions of the Boulder at Station 6, suggesting that Turning Point Rock might be impact-generated melt-breccia rather than the more massive appearing subfloor gabbro.
AS17-140-21397 and AS17-141-21567, combined, give a good view of the inner wall of Henry Crater, showing that the east wall has large concentrations of boulders while the west wall, in contrast, is smooth (Figs. 12.29, 12.30 above). With an absence of rim boulders comparable to Camelot these relationships make the relative age of Henry about the same as Horatio or, as discussed above, possibly somewhat older.]
“Okay. I gather you changed your opinion.”
“What looked like fragments,” I replied, is (are) just big spalls where the zap pits have cleaned off the rock.” Another point I should have noticed is that Turning Point Rock, at about 7 m high, constitutes a boulder far larger than any subfloor gabbro boulder we had seen. Station 6 observations soon would add more perspective to this discussion.
“Okay. I copy that. And, guys, you might be happy to know that we think we’ve finally found the LM, because we were calling that for 188 and 2.8 [bearing and range], and you got there at 186 and 2.8.”
Approaching the Station 6 Split-Boulder
“That’s not bad,” replied Cernan. “…It’s (the Station 6 boulder) the split one up there, Jack. I’ve had my eye on it. …Get some more pictures [as we approach] (AS17-140-21399 and AS17-141-21569). …There’s some big boulders down here. Got it.”
Fig. 12.31. Driving upslope approaching the Station 6 boulder(s), which are the two boulders seen side-by-side (actually 5 in the group) beyond the larger foreground boulder in front of them. (NASA photo AS17-141-21569).
Fig. 12.32. Cernan’s photo as we neared the large foreground boulder with the Station 6 split boulders behind. We have been on a gradual cross-slope rise of ~2°-3° since leaving Turning Point Rock. Fig. 12.46↓ of the LRV parked at Station 6 shows this slope more clearly. The ground is steeper near the Station 6 boulder, the direct downslope to the left of the parked Rover being ~20º. (NASA photo AS17-140-21399).
“I sort of lost track of Station 6,” I admitted, having been concentrating on Turning Point Rock rather than Cernan’s driving.
“Nah. I got it. I’ve had my eye on that boulder. You can’t see the track from here. …I’ll bet you can. I can see it now. We’ll see it. We’ll be looking right up it; looking right up the old boulder track. …Man, I tell you, this navigating through here is not [easy]…”
“We’re in a region where, really, the general fragment population is no different [than the valley regolith],” I said, getting back to observation duties. “We’re up off the break in slope, although you wouldn’t notice it [except by a change in altitude, Fig. 12.31↑]… But we are [passed the break in slope] quite a ways. But the fragment population is not much different than out on the plains. The big difference is that there are these scattered blocks that are from a meter to probably 10 meters… no, 5 meters in diameter. Hard to say, maybe 8 [meters].” These boulders are shown in AS17-141-21570-74 along with the two major portions of the split boulder at Station 6.
Fig. 12.33. These next 3 photos show the boulder field and craters that Cernan had to avoid as we approached the Station 6 boulder group here located to the right of the large boulder next to the HGA handle. The Sculptured Hills dominate the background. (NASA photo AS17-141-21570).
Fig. 12.34. In this closer view, the Station 6 split boulders are in the center right of the photo. The terrain looks deceptively level although, as noted in Fig. 12.32, our driving direction cross-slope is only ~2°-3°. Note the large boulder and its shadow on the wall of a crater at right. The first pan I will make is located on the lip of a crater ca. 10 m to the left of the leftmost larger boulder of the split group (see planimetric map in Fig. 12.37↓, pan21). (NASA photo AS17-141-21572).
Fig. 12.35. The Station 6 boulder group is next to the HGA handle at left. The crater at right in front of the large boulder is ~20 m across. (NASA photo AS17-141-21574).
Fig. 12.36. An overhead view from the LROC QuickMap of our traverse from Turning Point Rock at lower left to the Station 6 boulders at upper right. Note a portion of the tumbling track made by the intact boulder before it hit its final resting place and fractured into several blocks. The largish crater near the center of the photo and between TPR and Station 6 is ~33 m across. It can also be seen in Fig. 12.20↑ to the right of the largest fiducial cross. The crater below the Station 6 boulders, also seen in Fig. 12.21↑ to the lower right of the boulders, is the same one noted in Fig. 12.35 (readers can access the QuickMap view by clicking here).
“See that track coming down?” Cernan asked me. “We’ll be looking right up that [boulder] track.”
“Yeah, yeah, you got it. I didn’t realize you were that far upslope,” I replied with a laugh. We attacked the ~20° slope by driving diagonally across-contours rather than head-on. This, of course, meant that I was leaning out over the right frame of the Rover.
“Yeah, we’re way upslope!”
“Yeah. You did it.”
“Not very uncomfortable for me on this side,” Cernan joked with a laugh, knowing I sat on the awkward, downhill side of the Rover. “How do you feel?”
“Oh, I feel fine. I just…” Then I looked to my right and said, “Until I looked down here and saw the slope we’re on.”
“Yeah, I know it.”
“And I can’t see any obvious change in albedo, like we could see with the light mantle yesterday…” The light mantle contact with the dark mantle had formed only about 75-100 million years ago, whereas the contact of the North Massif slope with the dark mantle had about 3.7 billion years to homogenize with subfloor basaltic regolith through constant impact reworking and down slope movement of debris. This made the albedo difference across the contact discernable only from a significant distance.
“You got a [crater coming up]…” I warned as we approached the boulder at Station 6. “Don’t… There you got her: a nice, nice place [to park]. Oh, oh, you don’t want to go over that way?” indicating an area to our left, near the boulder.
“I can make it. I want to park right…”
“And, Seventeen,” Parker called, “you want to park at a heading of 107; we’re going to open the battery covers and let them cool at this station. So a heading of 107.” The battery covers opened facing the back of the Rover, so this easterly heading would cause them to shade the batteries thermal radiator, exposing it to the extreme cold of deep space (4º Kelvin).
“107, huh?” answered Cernan. “Okay. I’ll get it up here…”
“Hey, that’s going to be moderately level right there (on the west side of the boulder).” Rather than being “level,” this parking orientation actually would tilt the Rover parallel to the ~20º slope we had been crossing.
“Yeah.”
“Trouble is,” I observed, “they’re (Mission Control) looking into the shady side of the block [with the TV].”
“Well, if I park on the other side, they won’t be able to [cool the batteries]. I can go right upslope a little bit.”
“That’s all right. We can work in there (the shadow). No, that’s all right.” Not anticipating what awaited me on the other side of the boulder, I naively thought that the boulder would be relatively uniform, as we had seen at Station 2 the day before, and that back-scattered sunlight from the regolith surface would be adequate for examination of the shadowed rock face in the detail I desired.
“Yeah, I can’t go up there [past the second, steeper break in slope]. Let me just [park here]. …This is going to have to be good. I can’t go up there.” This second break in slope went from about 20 degrees to about 26 degrees. Finding a spot to park higher up would have taken a lot of maneuvering and time.
“Yeah, I think you’re all right,” I agreed.
“That’s not very level, but…”
“Oh, not too [bad]. Not too hard [to work around]. Watch that turn…”
“That’s not very level,” stated Cernan, “but we’re not going to get much more level than that.
“No, that’s good.” I was impatient to get off the Rover and look at the boulder.
“Let me [see]. They wanted 107 [heading]. That’s the best I can do. That’s not very level for the gravimeter, but…let me see if I can get comm.” Because of our elevation and a clear line-of-sight to Challenger, TELEMU in Mission Control had probably been picking up our transmissions through the Challenger’s antenna.
Station 6 – The North Massif
Fig. 12.37. Plan view sketch map of Station 6, [21] showing the numbering scheme referred to in the text for the five blocks constituting the Boulder at Station 6, the locations of rock samples, boulder track, the LRV parking spot, my Pan 21 and Cernan’s Pan 22.
[The field study and sampling of the boulders at Station 6 and subsequently at Station 7 produced a large number of samples of interrelated impact melt-breccias. The isotopic dating of these samples has produced a similarly large number of initially confusing dates that reflect the long and violent impact history of the materials in the samples. In 2017, my lunar science colleagues and I published a paper in the journal Icarus[22] that attempts to make stratigraphic sense of these dates, relative to the visible structure of the North Massif, as well as adding several new 40-39Ar dates using more precise laser ablation techniques than previously available. The 40-39Ar dates given below, except where otherwise indicated by endnotes, are from this latest work.]
“Hey, Bob, how do you read?” called Cernan.
“Loud and clear, 17. How do you read?”
“Okay. We’re parked on a heading of 107.” I began to laugh. “Are you happy with that?” he continued.
“Sounds great.”
I continued to laugh, saying, “You parked on a slope, too.”
“There’s no level. …There’s no level spot to park, here, though.”
“You want some help getting off?” I asked. I found this very humorous as all I had to do was to control a fall off the Rover, but Cernan, on the upslope, had to climb up and off.
Now, also laughing, Cernan exclaimed, “I’ve got to go uphill!”
“I just about ended up down at the bottom of the hill,” I countered.
“Okay; 192, 3.8, 3.1; 88 and 80; (bearing, distance, range, and battery amp-hours remaining, respectively) 108 and 0 [degrees] on the batteries. The forward motors are 220 and about 270 [degrees], and the rears are off-scale low and 220.”
“You want me to block the wheels? “ I joked and we both laughed. “You got the brake on, I hope.”
“You betcha!” I doubt if Midwesterner Cernan ever had to worry much about parking on hills; but I grew up where you often had to set the parking brake, curb the front wheels, and leave the transmission in gear, as well as block a couple of wheels just to be sure your vehicle did not roll away.
“I don’t know if I can lean uphill enough [to get off]!” he exclaimed while continuing to laugh. “I can’t. Holy Smoley! Boy, are we on a slope!”
“You okay?”
“Yeah. Let me get this thing (foot) set again.”
“I don’t think you can get a [gravimeter reading]…”
“Boy, are we on a slope!”
I had taken the scoop off the Geopallet and moved over to the boulder at Station 6 and begun my reconnaissance and planning (Fig. 12.38 below). “Okay. I’m going to stay out from between the rocks. It’s a beautiful east-west split rock. It’s even got a north overhang that we can work with. …And let me see what it (the rock) is!
Fig. 12.38. View of the blocks and slope at the Station 6 split boulder showing the wide gap and overhang at right. We spent 1 hr, 10 min, 46 sec from the moment we got off the Rover exploring this site until we got on again to head for Station 7, located ~455 m further east. For a larger scale view of this scene in a separate window, click here. (Combination of NASA photos AS17-141-21592, -594, and -596).
“We’re right at station 6,” Cernan exclaimed. “You wouldn’t believe it.”
“I would,” I answered. “Oh, man, what a slope! And this boulder’s got its own little track! Right up the hill, cross contour. It’s a ‘chain-of-craters’ track, and it (the track) looks like it stops (starts) [up slope] off where it started. It (the track) starts in, what looks to be, a lighter-colored linear [boulder] zone. Trying to give you perspective, it’s (the upper end of the track) probably only about a third of the way up the North Massif…”
[The boulder at Station 6 actually consists of five large blocks, suggesting that the tumbling boulder broke apart and stopped rolling when it hit the change in slope where it now lay. Once all the photographs were in hand, the geologists decided to label the individual boulder blocks, 1 through 5, as shown in Fig. 12.37↑.
The interrelated issues concerning the ages and origins of the Station 6 boulders and that at Station 7 are covered in detail in Chapter 13 and in the 2017 paper published in Icarus. (Endnote [13])]
As he turned on the television camera, Cernan asked, “Bob, are you reading us?” We were so used to Parker saying “Copy that” every time we said something that, when he did not say it, Cernan became nervous.[23] Having spent most of my time in the field alone, it did not bother me when no one was talking to me.
“Read you loud and clear; and we’ve got a picture.”
“Oh, man, I tell you, are we parked on a slope!” Cernan said, excitedly. “I don’t know whether your TGE’s going to hack it.”
“It’ll take up to 15 degrees.”
“Well, it’s (the TGE) going to have it [and more].”
Getting to work, with my face as close as possible to a shadowed, northwest facing surface of boulder Block 2 illuminated by backscattered light, I said, “It’s a coarsely vesicular, crystalline rock – finely crystalline. Looks like, probably, an anorthositic gabbro. [I’m] trying to see the zap pits for glass color; I don’t have a good one yet…”
“Say, Bob, you want both the [SEP] recorder and the other switch OFF? On the SEP?” Cernan started to go through his Cuff Checklist housekeeping items, while I continued to determine what might be our sampling plan.
“Roger. Both of those OFF, and dusted.”
“…Oh, man, is it hard to get around here.”
“Bob, it looks like the glass [in the zap pits] is fairly light colored; but it’s not white… Well, no; it’s black. It’s anorthositic gabbro, rather than gabbroic anorthosite [in composition], I think. Yeah, that’s black glass in the pits.” I am talking about the color of zap pit glass at the same time I am getting my bearings relative to the job to be done, so it may not be as coherent as if I were taking notes in a field notebook.
[The fact that I could make these observations in shadow indicates that significant light reflected into the shadow from the Sun’s zero-phase point on the regolith to the west. My previous observations had indicated that a zap pit in pure feldspar or anorthosite left a translucent white glass, while with increasing amounts of magnesium and iron-containing minerals in the rock progressively darkened the impact glass, including all the way to black. I was seeing a range of impact glass colors, indicating a mix of target minerals. ]
“Okay. And, Gene,” Parker enquired, “did you happen to notice the temperature on the SEP when you dusted it?”
“I didn’t dust it yet.”
“Copy that.”
“Bob, some of the vesicles are. …They’re flattened. All of them are flattened. There’s a strong foliation of vesicles in the rock. Most of them are flattened, and they are up to 15 or 20 centimeters in diameter and about 5 to 6 centimeters thick…or wide.” I made these initial observations while standing in the north-facing shadow of the boulder where, as I expected, the back-scattered sunlight provided enough illumination to see rock features quite well.
[The flattened and oriented vesicles would indicate to the Science Back Room geologists that, when released gases formed the vesicles, their formation occurred in at least a partially molten material that was flowing and was too viscous to allow the vesicles to maintain a spherical shape (AS17-141-21628-30). Examination of the three photographs just referenced indicate that there may be two generations of vesicles the large flattened ones that first caught my eye and much smaller, more spherical ones in the rock as a whole. This relationship indicates that the large, flattened vesicles formed while the melt-breccia was flowing and the small, spherical vesicles formed after that flow ceased. White micro-meteor impact locations also stand out in these images. Once I began to examine the south side of the boulder, it became clear that these large vesicles are in a light-gray impact melt-breccia that intrudes or once overlay the top of a slightly older blue-gray impact melt-breccia that has no such large vesicles.]
Fig. 12.39. The three photos discussed above combined to show most of the northwest-facing end of Block 2. The two populations of vesicles are clearly shown. Note also the white zap pits in the more shadowed areas of the boulder. For a higher resolution view of these details, click here. (Combination of NASA photos AS141-21630, -629, and -628 in that order).
“Outstanding.”
“And there’s some beautiful north overhangs all around the block. Well,” I laughed at my oxymoron, “on the north side of the block.”
“That’s the best place to have north overhang; and I guess that means one of you guys might grab the SEC – the small can – before you leave the Rover.”
“Okay, Bob,” Cernan said, “it’s going to take me a while to dust. I tell you…[it’s] hard to get around here.”
“Bob, let’s get it straight,” I said. “You want the north overhang sample in the SEC— or the short can?”
“Miracle of miracles,” our sarcastic Capcom said. “They don’t want the short can. I’m not sure I understand that, Jack, but they don’t want the short can here, they say. …I guess they’re looking for volcanics today [at Station 9].”
“Okay, we’ll put them (shadowed samples) in bags.”
“They’re looking for volcanics today, Jack,” repeated Cernan.
“Oh, they are, huh? We found those yesterday [at Station 4].”
“Well, they’re hoping [to find more] again at Station 9.”
Because of our limited time to sample the orange ash at Shorty, the Science Support Room hoped that Van Serg Crater at Station 9 would provide a better opportunity to use the small, vacuum-sealed can for a sample of volcanic material, possibly rich in the volatiles that drove lunar volcanic eruptions. They were due to be disappointed and, in retrospect, we missed an opportunity to sample and seal permanently shadowed regolith at Station 6. This is the kind of tough decision that I had to leave to Mission Control, as we also did not know what might be found at Van Serg Crater.
“Now, that [vesicle] foliation I mentioned,” I continued as I stood in the north-facing shadow of Block 2[24] of this huge, composite boulder, “does not go all the way through the rock. There are variations in texture. One zone was strongly foliated. There’s another [zone]— it almost looks like a large…it is, a large inclusion of non-vesicular rock within the vesicular rock. There may be some auto-brecciation involved in the formation of this thing. It really looks, mineralogically, like the light-colored [breccia] samples from the South Massif. But I tell you, that’s only because it’s light colored, and…I can’t give you anymore than that right now, until we get a fresh surface.” As later will be apparent, this portion of the boulder probably is the vesicular light gray impact melt-breccia, sampled later. I continued to move west along the shadowed face, at times, letting the sunlight reflect off my suit and illuminate the shadowed rock surface.
“110 degrees [temperature] on the SEP,” Cernan broke in, “and you want the cover CLOSED, right?”
“Cover OPEN, please. Cover OPEN. Both [switches] OFF.”
“Okay! [SEP] Cover’s OPEN.”
“Okay. And did you get the batteries – the LRV battery covers – OPEN? We didn’t copy that, Gene.”
“No, I didn’t copy that you wanted them (the covers) open. I just got 107 [heading]. I was about to ask you that.” Cernan had forgotten that cooling the LRV batteries was the reason we had been given to park with a 107 degrees heading.
“We’d like them OPEN. And, Jack, while I’m interrupting everybody here, …how about a frame count, if convenient.”
“Oh, man!” Cernan was still having trouble maneuvering on the side-hill slope on which he had parked.”
“Well, shoot! Bob,” I replied, somewhat annoyed by the interruption, “I gave you one at the (Turning Point) rock. It’s now 68.”
“Man, I never,” Cernan said to himself. “…You can’t believe how tough it is getting around this Rover, on this slope!! Man, that… I think we’re probably pitched 20 and rolled 20 [degrees]!”
“I think I’ll get over here and get a pan while we’re waiting to sample.” I left the shadow and moved about 15 m uphill toward the northwest to take the panorama that would include the boulder as well as the Rover.
“Oh, I got to dust those radiators,” Cernan said as he finished dusting the battery covers and opened them for cooling. “I can’t leave them [dusty] like that. I tell you, this is not a very good place to dust them, though. Let me try one time… Oh, boy!” Not an easy task.
“Be careful, Geno”, I warned as he slipped, again. “Need some help?”
“Nope. I need a little finesse, though. …It’s one thing to reach over here and do this on level ground [as in training]. …I don’t know if I can do that without falling on the battery.”
“Well, I [finally] found a place to stand where I can take a pan…” I had moved uphill to stand on the south wall of a small crater just west of the boulder track. On this slope, the south wall of the crater is essentially horizontal.
[This pan comprises AS17-141-21575-603. It includes boulder fragments 2 and 4, with the other boulder fragments still out of sight. Several images (AS17-141-21598-601) show Cernan working with the Traverse Gravimeter near the back of the Rover. It is not obvious from the pan that he is working on an ~20º slope.
The images of Henry, Cochise and Shakespeare (each 5-600 m in diameter), in order of increasing relative age, show the boulder concentrations on the walls of Henry (-21599) and many fewer boulders on the walls of Shakespeare (-21598) and Cochise (-21597). Overhead LROC images indicate that Shakespeare is more degraded than Cochise.
The dark line on the south ejecta area of Shakespeare shows the location of Van Serg Crater (Station 9).
A line of shadows in -21597 on the surface to the north of Cochise may be boulders along a degraded fault scarp or flow front. This line is visible on overhead LROC images as a narrow, irregular, ~1 km long trough, extending northwest from the northeast rim of Cochise Crater. Later inspection of traverse photos between Stations 7 and 8 and 8 and 9 do not show that we encountered this line of boulders; however, in the former traverse, we drove some distance from the northern end of the line and, in the latter traverse, we drove along the gap between the line and the east rim of Cochise. The Cochise rim, coincidentally, has the same alignment as the line of boulders.]
Fig. 12.40. The series of photos from my Pan21 sequence is shown as quarters in these next four figures. I am standing on the south rim of a ~10-11 m diameter shallow crater (see Fig. 12.36↑ immediately northwest and adjacent to the boulder track to the right of the photo). The south part of the pan (AS17-141-21596-602) shows Cernan at the LRV unloading the TGE. At left, part of Block 2 (northwest face) is seen, along with the smaller Block 3 tucked underneath the overhang. Block 4 (masking Block 5) is the next large boulder immediately to the right (see planimetric map, Fig. 12.37↑). Henry is the large, darkish crater in the middle right; Shakespeare is the less dark band to Henry’s left; and Cochise is the first part of the curving dark band further left with the smaller crater with the darkish nodule (wall crater) below it— all below the left slope of the East Massif. At far right, the boulder with the overhang pointing downslope is the same boulder seen in Fig. 12.33↑ (left next to the HGA pointing handle). The latter can also be seen in Fig. 12.36↑ ~70 m distant in an ESE direction. For a much higher resolution view of this pan in a separate window, click here. (Composite of NASA photos AS17-141-21596, -598, -600, -601, 602).
Fig. 12.41. The pan view to the east (AS17-141-21588-596), spanning the Station 6 boulder fragments, 1, 2, 3, and 4/5. Other smaller boulders are seen uphill in the boulder track and elsewhere. The dip in the distant hills at left is the Wessex Cleft separating the North Massif (left) from the Sculptured Hills (right). Behind Block 2, the long horizontal, mesa-like hill was called the “hump” in Chapter 8 and in Fig. 12.3↑. We flew over the middle of it on our way to the landing site ~19 km away. For the higher resolution view, click here. (Composite of NASA photos AS17-141-21588, -90, -92, -94, -96).
Fig. 12.42. The view uphill from me to the north (AS17-141-21579-588). Although the surface is brighter on the left half of the pan because of increasing backscatter of sunlight from the regolith, the rim of the small, shallow crater in which I am standing can be delineated, curving across the middle of the pan from left to right. For the higher resolution view, click here. (Composite of NASA photos AS17-141-21579, -80, -84, -86, -89).
Fig. 12.43. The pan view (AS17-141-21576-579) looking towards the west. In the distance, the South Massif is at left. The large boulder at far left is the same one noted at the end of the caption of Fig. 12.40↑. The crater rim I am standing on can be followed from that small, bright rock at bottom left of center around to the upper right of the view past the vesicular boulder close to the top and on this side of the rim. For the higher resolution view, click here. (Composite of NASA photos AS17-141-21576, -77, -78, -79).
“Bob, I’m going to have to give you a good battery brushing at the next site,” Cernan said. “…I can get half of them, but I can’t get the other half. It’s too slopey. …But the covers are OPEN…” He then goes to the Gate and stows the dustbrush and removes the tongs, clipping them to the yo-yo line at his hip. “What are you working on, Jack?”
“I’m taking a pan,” I replied, as I bounced up on my toes and arched my back to take into account the slope for each frame. I had raised my visor to get a better look at the boulder face in shadow and still had it up, incidentally providing a good view of my face on television. I was later told that a flight controller, who glanced up at the TV images at the front of the MOCR, involuntarily yelled out, “That’s Jack Schmitt!”
“Very good. I’m coming right now. …I bet you a dollar to doughnuts that you don’t get a TGE reading [with it on the Rover].”
“Yeah. Gene, if it’s easy enough to take it off, why don’t you take it off the Rover?’ Parker asked. “And we’ll try and level it in the stuff (the regolith).”
“Aw, come on,” I guffawed, not sure that Cernan could find a more level spot than the back of the Rover.
“I’m not sure there’s any place to put it on the ground level,” he agreed.
“No, you have to dig a [level] place,” I asserted.
“Yeah, I’ll do it. …Okay. It’s (the TGE) coming off [the Rover; Fig. 12.40↑]. Well, I’ll set it right up here.”
“It’s going to fall down the hill,” I said. “You’d better stomp off a good place.”
“Yep. …That looks level to me,” reported Cernan. “Can you see it from there?”
“Well, I can see it [for what good that does].”
“I mean, is it [level]?…”
“I don’t know,” I admitted. “I have no perspective anymore.”
“I don’t either.” The slope combined with one-sixth gravity made us both uncertain of what “level” would look like. “MARK, gravity. …It’s flashing. Okay; now let me get to work. …Okay. Straighten out my fender [that] got a little kinked here, which isn’t going to help us.”
As I moved east, across the slope and back toward Block 2, Parker called. “Hey, Jack. And we see your gold visor is up. You may want to put it down out here in the Sun.”
“Well, I think I might [work with it up]. …I can’t see with it down; it’s scratched! Bob, I’ll use it [up]. I think I can monitor that one (my sun exposure). …Hey, I’m standing on a boulder track! How does that make you feel, [Gene]?”
“That makes me feel like I’m coming over to do some sampling. …Think how it would have been if you were standing there before that boulder came by.”
“I’d rather not think about it,” I retorted while pouring some soil from the bottom of the boulder track into a bag. In contrast to the difficulties I had at Station 3 (Ballet Crater), this process of solo sampling went smoothly, probably because I could work against the slope.
“Okay, let’s go,” Cernan said as he peered into the boulder shadow. “You got a spot picked while you’re here?”
“Well, the big thing is, let’s get the boulder [sampled] and then get in that east-west split. Bob, I got an undocumented sample from the middle of the boulder track.”
“Copy that. Soil sample?”
“[Yes,] soil sample. …Gene, if you hit them (any samples) off in there (the shadowed area), it’s going to be awful hard to find them, that’s the problem.”
“Did you pick a spot – a good spot – while you were over here?”
Joining Cernan in the shadow of Block 2, I replied, “No, I didn’t. I just was looking at it (the overall boulder). I think we need to get in the light, though, for sampling].”
“I can see [in the shadow] with my gold visor up.”
“Let me put a sample in your bag (SCB).”
“Okay. Go ahead.” Standing up-slope made it easy for me to drop the sample bag in Cernan’s SCB. “It’s bag… Shoot… It’s 534 (76220-24).” I had almost put the bag in Cernan’s SCB without giving the sample bag number. (See planimetric map, Fig. 12.37↑, for sample locations.)
[Post-mission examination and analysis of 76221 indicated that the regolith at the surface in the boulder track contained no recognizable fragments of subfloor basalt and has an intermediate to high maturity (Is/FeO = 66).[25] The maturity level resembles that of one other sample from the vicinity of Station 6 (76031), but its maturity is significantly lower than the 80-93 indexes of other regolith samples from the much less steep slopes of the North Massif and the Sculptured Hills (Stations 7 and 8, respectively). The lack of identifiable subfloor basalt fragments in 76221, unlike other Station 6 regolith samples, may indicate that the track area has been shielded from ejecta from impacts in the valley for a significant period of time. No cosmic ray exposure age is available.]
“This boulder looks fairly uniform from top to bottom,” Cernan declared. This observation was only true for the one shadowed face he had looked at so far.
“We’ve got to get a reference sample of this soil,” I reminded myself.
“Let’s get where we can get that 90-degree picture, too,” Cernan said. “So we really ought to get on the Sun side.” I guess he had not been listening to me, a moment ago.
“Let me get that slab right there, though, to start with. I can get that one off.”
“Well, there’s no… Let’s go over on the Sun side because we can’t really photograph it [in the shadow].”
“Okay. I got to get out of here first. Let’s go through the split [between boulder Blocks 2 and 4].” Cernan continued to waste time jumping from one thought to another while ignoring my suggestions.
“Well, okay. Be careful, though. …Why don’t we sample the split first so we don’t [waste time coming back].” I was having a heck of a time getting Cernan to focus. The split (i.e., gap) referred to here separates blocks 2 and 3 from Block 4 (Fig. 12.37↑).
“Look at that overhang. Man, I tell you, if you get your shovel (scoop) down there, you’d have a [shadowed sample].”
“Yes, let’s sample in the [regolith of the] split first so that we don’t get it too messed up. And then we can sample some of this [shadowed] stuff (regolith). …We want this overhang over here, Geno— the north facing one. …Yeah. I got to sneak by over there. Whoops! Don’t shuffle too much dirt in there.” Block 4’s almost perfect, north-facing, east-west side provided this permanently shadowed overhang.
“Okay. You [go] by me so I can set the gnomon down?”
“Not quite. Don’t think I can make it – without hitting you. I can’t.” The space was about 3m wide; however, the slope greatly reduced our room to maneuver.
“Okay. Now try it.”
“Okay…” The slope of the ground also made all our movements less coordinated than they had been out in more level areas.
“Ready?”
“Okay.” I had positioned myself on the slope east of Cernan so I could get the scoop into the north-facing shadow of block 4.
“Let me set the gnomon down…”
“Set it down just outside the shadow there,” I directed. “Right. …Whoa. Right there. That’s good. There’s still some good clean (undisturbed) ground there. Okay, [that’s good].”
“Okay. I can get back far enough to take these pictures. I want to go get a stereo pan around the corner anyway. Let’s see if I can’t start here with about (f-stop) 5.6. I’m so close. …I must have a boulder behind me.” Cernan kept bumping his PLSS into block 3.
After Cernan took his stereo pairs (AS17-140-21401-4) and I took down-Sun and locator photographs (AS17-141-21604-5), he said, “I’m going to go around the corner. …I got it now…”
Fig. 12.44. The four photos Cernan took in the gap between blocks 4 (right) – 5 (left) and Block 2 behind Cernan. The larger scale view, which shows more detail on the shadowed faces, is available here. (Composite of NASA photos AS17-140-21401-04).
“Okay. You got a [sample] bag?” I asked.
“All set.”
“Okay. I’m going to get the shadowed material…” I leaned with one hand against the boulder and reached with the scoop as far under the north overhang as I could.
“It’s in bag 312 (76240-46), Bob,” Cernan reported.
“And…it’s from… I think you saw where I got it [with the TV]. It’s about a half a meter back of the limit of the overhang.” To Cernan, I said, “Put it (the sample bag) down. Put it [lower] down.”
“Okay. Can you reach it?”
“I will in a minute,” I said as I jumped uphill while somehow still keeping the soil in the scoop. “You can turn it a little bit towards me. …Okay; [that’s] 312… And the soil outside the overhang will be next.
“Okay. Go get it…”
“And the first one (skim sample) is from the upper 2 centimeters.”
“Bag 313 (76260-65),” Cernan said.
“And the second one is from probably 2 centimeters down to about 8 [centimeters]. Bob, it looks like the block (Blocks 4 and 5) – or [rather] the boulder – just to the south of us has some inclusions in it— light-colored inclusions.” (See Fig. 12.44 above). I continued to look at the Blocks 2 and 5 and made this last comment while waiting for Cernan to put the first sample in my SCB.”
“Bag 472 (76280-86) on that [second soil sample]”.
Fig. 12.45. My “after” photo showing the locations of the three soil samples discussed here. (NASA photo AS17-141-21606).
[Post-mission examination[26] of the shadowed regolith, 76240-46, disclosed that it contained several small impact breccia chips as well as fine-grained regolith. The fine-grained portion appears to be a mixture of material from both the North Massif and the valley floor, including about 48% agglutinate and 3% black and orange glass beads in 76241. The sample has intermediate maturity with an Is/FeO maturity index of 56 versus 58 for the control skim sample (76260) and 45 for the deeper control sample (76280).[27] As will be noted below, the maturity index of the rake sample regolith also is 58, suggesting that 58 represents the steady-state maturity index on the local slope of the North Massif. Agglutinates in the two control samples are both about 45%.[28]
Examination of non-shadowed, control samples 76261 and 76281, taken as skim and 8 cm deep portions, respectively, of the exposed regolith, showed roughly the same distribution of rock, mineral and agglutinate as the shadowed sample, 76241. One noticeable distinction between the deeper sample, 76281, and the others is the presence of 5% orange and black ash versus 3% and 2% for 76241 and 76261, respectively. This may reflect dilution of the pre-boulder regolith (76280) by eroded boulder material added to the skim sample (76260).
As discussed below, cosmic ray exposure ages of rock samples from exposed fracture surfaces indicate that the Station 6 boulder rolled to its present position 17-22 million years ago. In contrast to this range of arrival ages, analysis of cosmic ray induced 26Al and 22Na in permanently shadowed regolith (76240) calculate to an exposure age of less than a million years[29], probably about half a million years[30]. A thermo-luminescence study[31] indicated that the shadowed sample was sheltered only about 65,000 years ago. These two indications of relatively short exposure versus the 17-22 Myr exposure age for the boulder as a whole suggest that Blocks 4 and 5 may have been broken off by a relatively recent impact on Block 2 or by the effects of thermal cycling along a pre-existing fracture.
The induced 26Al in the skimmed control sample, 76260, however, is only 15% higher than that in the shadowed sample, suggesting that small- and micro-meteor impacts have redistributed exposed material from the upper few millimeters of nearby regolith into the permanently shadowed area. On the other hand, the induced 22Na in the exposed control sample measured 3.6 times that of the shadowed sample, indicating to analysts that protons from the large August 1972 solar flare significantly increased the 22Na concentration in the exposed surface regolith.
No cosmic ray induced radionuclides have been measured for the deep control sample, 76280.
Comparative analysis of agglutinates in 76240 (permanently shadowed regolith) and 76260 (regolith exposed to sunlight) show enhancement by a factors of 5 to 22 in the concentration of Mercury in the shadowed sample.[32] Although the measured Mercury concentration generally increases with decreasing grain size, the ratio of Hg enhancement relative to the control sample increases with increasing grain size of regolith particles, as follows in ppb:
| Sample | 38-75 µm
Agglutinate |
38-75 µm
Minerals |
149-350 µm
Minerals |
≥ 350 µm
Minerals |
| 76240
(shadowed) |
8.5 ± 0.7 | 4.1 ± 0.42 | 2.1 ± 0.2 | 5.0 ± 0.5 |
| 76260
(non-shadowed) |
1.7 ± 0.3 | 0.42 ± 0.05 | 0.16 ± 0.02 | 0.22 ± 0.04 |
| Enhancement
In Shadow |
X5 | X9.7 | X13.1 | X22.7 |
Minerals from the two samples also show a slight enhancement of cadmium in the permanently shadowed regolith.
The above measurements of Mercury concentrations came after significant handling, splitting and sieving of the samples from collection to analysis and this may have resulted in some losses of volatile elements. It is not clear why there is a direct correlation of Mercury enhancement with increasing individual particle surface area, unless it relates to greater areas of relatively undamaged crystal surfaces.
These results for Mercury suggest that some volatile elements migrate across the lunar surface, at least for limited distances, and are precipitated preferentially in cold shadows. As a frozen portion of sample 76240 is included in the suite of samples recently released for modern analysis, more information on local volatile migration soon may be forthcoming.
Volatile elements and molecules concentrated in the permanently shadowed areas of lunar polar regions documented by Lunar Prospector and Lunar Reconnaissance Orbiter missions[33] also may be, in part, the result of such migration on a global scale. Migrating volatiles from ancient pyroclastic eruptions, such as that documented at Shorty Crater, solar spalation production of OH–, and from cometary impacts may also have contributed to polar and permanent shadow volatile concentrations.]
Picking up on my comment about inclusions, Parker asked, “…You mean [you are talking about] the south half (blocks 4 and 5) of the split boulder?” (Fig. 12.44↑).
“Yeah. I haven’t seen inclusions in the other half.” Because the large vesicles indicated that this portion of the boulder had been at least partially molten, I had instinctively referred to fragments in the melt-breccia as “inclusions,” a term normally used for exotic fragments in an igneous rock.
“Okay?” Cernan asked, as he put bag 472 in my SCB.
“Okay. Now we need boulder stuff. You happy with that, Houston?” Not waiting for an answer, I said, “Let’s get [on the sunny side of these two big blocks]. Got your hammer?”
“Yeah, we’re happy with that for an east/west split.” Parker apparently did not understand we had sampled a north-facing overhang.
“[This stuff is tough!]…” Cernan was swinging the hammer several times, not giving up on getting a rock sample in the shadow of Block 2.
“It’s a little hard, huh?” I said, a little facetiously. “I think [we’ll do better on the sunny side].”
“I’ve got to find a corner I can get at,” he stated, but then stopped hammering and moved away. “Yeah.” Cernan, like many other field geology novices, tended to hit rocks too far in from an edge or corner, making it very difficult to get a sample. “Let me get an after picture down in this hole (shadowed overhang).”
[Cernan’s after photos (AS17-140-21404-8) do not provide images of the scoop indentation under the overhang due to the deep shadow present; however, reflected light from our suits and the boulder behind us provide good views of the surface texture of the relatively protected face of the tan melt-breccia making up Fragment 4. Enhancement of these images will allow detailed analysis of the size- and type-frequency characteristics of fragments in this melt-breccia. Indeed, there may be enough light reflected into the shadow for such enhancements to show the scoop indentation. (See Fig. 12.44↑ which shows the texture in Fragments 4,5).
The locator photographs for this sample site and the following one (AS17-140-21409, along with As17-140-21412) give great views of the Rover and its equipment. They also include the western horizon of the valley and, consequently, give a good illustration of the steepness of the slope on which the rover is parked. These photos also show the light-colored, Sun-lit face of the Lee-Lincoln Scarp, about 6 km away, and illustrate the significantly higher surface of the valley to the west of the scarp.]
Fig. 12.46. Cernan’s locator photo taken in the gap between Blocks 2/3 (right) and Block 4 (left) showing the steep local slope on which the LRV is parked, and the noticeable Lee-Lincoln Scarp in the distance. (NASA photo AS17-140-21412).
I said, “Oh, that’s right. You almost stepped on the [gnomon]. …I forgot the after, too. …Hey, there are chips up here on top, also – that’s been spalled off.”
“Yeah.”
“We can get some of those, but…” I began. I was getting concerned that we had not examined the whole boulder yet and might run out of time.
“Looks like somebody’s been chipping up there.”
“Looks like there’s been a geologist here before us,” I cracked. In terrestrial fieldwork, once in a while a geologist will run across an outcrop that others obviously have sampled before.
“Let me get the gnomon,” Cernan said. “I think I can get some of these pieces over here. I want to get that 90-degree angular flight line around this boulder, too.”
I moved east around the south-facing and sunny side of block 5. “Bob, the more I look at this thing (block 5)…” I probably started to say that the boulder looked like a large piece of impact melt-breccia, but then interrupted myself. “Now, here’s the piece that fell off. Here’s the piece that was knocked off up there.”
“Yeah.”
“Look at that,” I said, pointing to a large loose rock on the boulder surface that appeared to still be sitting in place.”
“We ought to bring a big piece of that home. That’s obvious, …it’s obvious [where it came from].”
“How about this one up here?” I suggested, pointing to the north side of block 5. “Take your picture. I think we can just lift that [piece] off. See that?”
“Stand by…” The before sampling images (AS17-140-21410-11) are excellent quality and resolution and should provide good estimates of the volume of vesicles larger than a centimeter and thus and estimate of the volume and potentially the mass of fluids that produced them.
Fig. 12.47. (Left): Cernan’s photo of blocks 4/5 showing the in situ rock on Block 5 waiting to be picked up. In the background is Henry crater and Bear Mt. The LM ~3.1 km away is marked by the vertical arrow in the whitish horizontal streak above Henry although it can’t be seen at this scale. (Right): The rock 76015 in the Lunar Sample Laboratory with orientation and lighting of the photo at left. Refer to Fig. 12.37↑ for locations on the planimetric map. (NASA photos AS17-140-21411; S73-19376; arrangement based on Wolfe et al. 1981[34], Fig. 153).
Fig. 12.48. The black arrow in this “after” photo points to the place where sample 76015 was picked up. The shadowed area is the fracture between Blocks 4 and 5, Block 4 to the right. (NASA photo AS17-140-21413).
“I’d better get [a locator],” I said.
“I’ll get a locator [photo] from here.”
“Okay,” I replied. “I was going to get my down-Sun, but I’m afraid I’ll [end up at the bottom of the hill]…”
“You may be ‘down-Sun’ if you do,” punned Cernan, however I did step downhill a few steps and took the picture, looking west. This photo (AS17-141-21607) not only gives good additional detail of the vesicle content of the melt-breccia, but it includes an around-the-corner view of the gnomon and Rover.
Fig. 12.49. My photo standing in the gap between Block 2 (to the right of Cernan’s leg and arm) and Blocks 4/5 (left). The shadow at left is in the fracture between Blocks 4 (right) and 5 (left), better seen in Fig. 12.47↑. Just to the right of this shadow is an apparently vesicle-free, more massive area that may be a relic of auto-brecciation of a rapidly chilled flow top, suggesting that the tan-gray melt-breccia of Block 4 was part of a melt-breccia flow rather than an intrusion. A larger scale version may facilitate this view. Cernan is holding the hammer in his left hand. The sun is reflecting through the translucent sample bag with a soil sample inside. (NASA photo AS17-141-21607).
“Yeah. …We’ll get some [of this loose rock]. …[Can] you get it?” I asked.
“Yes. …Will it come off?” wondered Cernan, after trying to get a grip on this apparently loose rock.
“Let me see [if I can get it]. …Yeah, [I got it] (76015).” I had a better position to grip the rock than Cernan did.
“Just throw it in my bag,” suggested Cernan. It’s broken [off the block], but it’s in place. That’s a nice, big piece, too. It’s about the size of a [grapefruit].”
“Why don’t you put it (the sample) in mine (SCB). I can’t get up to you.” I made this suggestion with a laugh, as I was standing well below Cernan on this steep slope.
“[Turn towards me], okay?”
“Got it [in]?”
“Yeah, I got it,” Cernan said as he backed away to take a series of flight-line stereo photographs of this face of the boulder. “Don’t move.”
Fig. 12.50. Three of Cernan’s flight-line photos combined into a panorama showing the north-facing sides of Blocks 4 (right) and 5(left). Fortunately, sunlight scattered from Block 2 behind Cernan has helped to illuminate the lower, shadowed portion of Blocks 4/5. The distribution of vesicles and clasts throughout is clearly seen. Cf. Fig. 12.44↑. The higher resolution version of this pan can be viewed in a separate window by clicking here. (Composite of NASA photos AS17-140-21414, -415, -416).
[This series of images (AS17-140-21413-33) give additional data on the distribution of vesicles and clasts in the tan melt-breccia of Boulder 4. Photo AS-17-140- 20419 also shows internal structure in the boulder, including a zone of foliated, vesicular breccia on the left next to a more massive breccia on the right. The textural variations in the surfaces shown in AS-17-140-20420-30) suggest that this was a flowing mass with more vesicular, partially solidified surfaces being broken off and re-incorporated into the less vesicular main body (auto-brecciation). These structures may indicate that the tan melt-breccia was part of a flow rather than an intrusion in which more uniform structure might be expected. Mapping the textural boundaries illustrated in these may confirm this impression.
Several of this series show a distant, out of focus view of Henry Crater, but indicating it has relatively smooth walls, at least at this limited resolution.]
[This grab sample, (76015) was identified later from photographs when my SCB was unpacked in the Lunar Receiving Laboratory. It is a large, 2.8 kg sample of greenish gray, vesicular, micro-poikilitic, impact melt-breccia and came from a portion of Block 5 (Fig. 12.47↑). I later identified it as a tan-gray vesicular melt-breccia.[35] LRL examination classified 76015 as a metaclastic (ground up and recrystallized) breccia with the originally melted fine-grained matrix now made up of interlocking crystals of pyroxene that enclose small plagioclase crystals (poikilitic texture). A wide variety of lithic clasts exist in the rock, including various combinations of plagioclase, pyroxene, orthopyroxene, and olivine as well as basalt.
A detailed discussion of the radio-isotopic age determinations of impact melt-breccias from Stations 6 and 7 is contained in the previously cited 2017 Icarus paper [13] and in Chapter 13. There, my colleagues and I hypothesized that melt-breccias comprising the Station 6 boulders (~3.89 Ga) came from the Crisium basin and that one of the melt-breccia that exists in the Station 7 boulder (~3.83 Ga) came from the Serenitatis basin (see below). The principle argument that the source of the Station 6 boulder is Crisium ejecta and the source of part of the Station 7 boulder is younger Serenitatis ejecta arises from the fact that the valley structure of Taurus-Littrow has its origin in the radial fracturing caused by the Serenitatis impact event. Therefore, Serenitatis ejecta must overly any older units in the valley walls exposed by that Serenitatis-age, post-impact, radial faulting. The unique Sculptured Hills materials (Station 8) correlate with ejecta from the Imbrium basin, and, in turn, overly both the Serenitatis melt-breccia and the Serenetatis valley structure. These hard geologic facts appear to rule out any other interpretation.[36]
As my colleagues and I pointed out in the previously referenced 2017 Icarus paper (see also Chapter 13), if the preceding assertions are correct, that is, 1) Serenitatis is roughly 3.83 billion years old, 2) the overlying Sculptured Hills material is from Imbrium, and 3) the Taurus-Littrow maria erupted about 3.74 billion years ago, the Imbrium basin is constrained to being between 3.83 and 3.74 billion years old, the later being roughly the age of the basalt partially filling the valley. This range is significantly less than the ~3.9 billion years broadly assumed to be the age of Imbrium. This, in turn, would further reinforce current skepticism[37] about any pulse of late heavy bombardment hypothesis related to lunar and terrestrial impact basin formation.
As Block 1 appears to have split off the main boulder as it reached the end of its roll down the North Massif, the cosmic ray Kr exposure and cosmic ray track ages of 17-21 Myr approximately date this event. They also give a data point on the rate of impact gardening that will gradually destroy the boulder track it left behind. The exposure age of the boulder with the more subdued track at Station 7 (25-32 Myr) provides another such data point (see below and Chapter 13) as does the absence of tracks behind Station 2 boulders with exposure ages of 70 Myr and greater (see Chapter 11).]
“Okay, Bob, there’s a big spall [rock slab] lying on the ground here that has been knocked off up there, from right on top of the boulder (Block 5). And, I tell you, the more I look at the south half of this boulder (Blocks 2, 4 and 5), the more heterogeneous in texture it looks. It looks as if it may be either a re-crystallized breccia of some kind, or you had a gabbroic anorthosite magma catch up an awful lot of inclusions. I guess I prefer the latter explanation…because of the extreme vesicularity of the rock.” In a sense, both explanations fit, because it turned out to be a crystallized, impact melted equivalent of a pre-existing impact breccia. I only came to realize some years later[38] that significant solar wind volatiles, particularly hydrogen, in the mega-regolith of the pre-impact crust could provide the gas that originally filled these vesicles.
“Now, a few of the inclusions are,” I continued, “…well, they’re all sub-rounded to rounded, and a few of them are very light colored. I’m going to try to get [a sample of an inclusion]…” The rounding of the inclusions, possibly due to melting or abrasion at their edges during flow, further supported the hypothesis that they had been contained in a superheated, impact melt.
“I’m coming around the corner with a flight-line stereo,” warned Cernan, as I had my back to him. He had switched his flight line for stereo to the west end of the sunlit side of Boulder 2. These images (AS17-140-21332-33) complement those of Boulders 4 and 5 discussed above in showing the varied distribution of vesicle concentrations.
Fig. 12.51. Combination of three photos from Cernan’s series showing the edge, or corner of Block 5 (see Fig. 12.37↑). Rock sample 76015 was picked off to the right of and behind the small pyramid-shaped knob at the middle top of the boulder (see Fig. 12.47↑) Henry crater is just visible at the middle left side of the pan. A higher resolution view is available here. (Combination of NASA photos AS17-140-21433, -431, -432).
“Are you going to do it [flight-line] now? …Okay. Well, you know, I ought to get one shot back here with a black and white. I’ll get this half [of the boulder in] black and white. …I think we ought to pick up a piece of that spall there by the gnomon…”
“I can break it off [the] top.” Cernan did not realize that the spall fit into an obvious spot up on Block 4.
“There’s one right by the gnomon we can just pick up. It’s a finer-grained vesicular rock than… Wait. …Where [did that piece come from]… Jeez…” I temporarily had lost sight of where the spall had originated.
“Oh, oh, oh, oh,” Cernan uttered as he started to loose his balance.
“I thought I was going to get this half [of the boulder face in black and white]. Okay.”
“I don’t care [what you do]. I started down, Jack.” Cernan had almost begun a roll down the slope as he completed his flight-line stereo sequence of photographs.
“Well, they like to have some of it in black and white, you know.” Not having seen his stumble, I seemed not to be very worried about what might have been a serious accident. If one started to roll, the best procedure to stop would be to extend arms and legs to the side.
After migrating down the slope a few meters during his near tumble, Cernan started his flight line stereo series again, obtaining several excellent images (AS17-140-21433-37) of what would turn out to be the contact zone between the tan-gray melt-breccia and the blue-gray melt-breccia of Boulder 2 (see below). AS17-140-21336 is the best for showing the contact zone, however, the series as a whole should provide good stereo of that zone. Images AS17-140-21438-40 show the more easterly facing corner of Boulder 2.
Fig. 12.52. A pan made from three of the five photos showing part of the east side of the fragmented boulder at Station 6. From right-to-left, Blocks 2, 3 (in the overhang of 2), and 5 with the LRV just beyond the hidden Block 4 dominate the scene. Note how wide the gap is between Blocks 2/3 and Block 5. The contact zone on Block 2 is marked by the dashed lines. To its left the boulder is tannish-gray. To the right of this zone, the larger part of the block appears bluish-gray. The marked location of sample 76315 is discussed later in text. A higher resolution unlabeled view in a separate window is available here. (Composite of NASA photos AS17-21434, -435, -436).
Fig. 12.53. Combination of two photos showing a close-up of the easterly facing corner of Block 2 (view rotated clockwise ~45° from Fig. 12.52). Most of this view is bluish-gray breccia. A higher resolution view in a separate window is available here (Composite from NASA photos AS17-140-21440, ‑439).
“I’ll get that rock [you pointed out],” declared Cernan.
“I forgot to look at the objectives for the station,” I said, suddenly. “I hope we’re meeting them.” I obviously did not really care very much about other objectives besides the investigation and sampling of this huge boulder. It would be the closest we would get to an actual outcrop, given its size and the fact that we knew where it came from up on the North Massif. There was just too much of geological interest and context contained in the boulder to worry about other things at this point.
“Well, we want to get 500’s (500 mm camera shots) of that boulder track,” Cernan declared. “I know I want to get that…”
“…[This will be] a piece of that spalled rock that was sitting by the gnomon. …Ooh, watch out, gnomon. How about that!?” I was very impressed with myself as I picked up the rock with the scoop and bagged it easily. “[The sample] is in bag 535 (76215).” (Fig. 12.54 below).
“You got one (the sample) in there already?” Cernan asked, incredulous.
“Yup.”
Cernan seemed surprised that I manage to collect a sample without him, probably remembering my bad experiences and frustration the day before at Ballet Crater. I obviously had figured out a better set of arm motions to accomplish this with the scoop; however, being able to work facing a steep slope helped the sampling process a lot.
“You won’t be able to reach…you won’t be able to reach my bag,” Cernan observed, as I was below him, again.
“No, but you can put it in mine. …Can you reach it?” I had maneuvered below him and faced west.
Fig. 12.54. (Upper): Location of the spalled rock sample 76215 on Block 4 (Data from Wolfe et al.[39]). (NASA base photo AS17-140-21416). (Lower): Sample 76215 coincidentally lying next to the gnomon. The red arrows in both views show the approximate trajectory followed by the rock in the recent geological past from its original in situ location on the top of Block 4. (NASA photo AS17-141-21607).
[Post-mission examination of 76215[40] identified it as similar to 76015 (Fig. 12.47↑), that is, it consists of a vesicular impact melt-breccia with a few small, plagioclase-rich rock (lithic) clasts and plagioclase and olivine mineral clasts. The plagioclase clasts have euhedral (showing crystal faces) overgrowths. The matrix is, again, a poikilitic intergrowth of plagioclase and olivine in larger clinopyroxene (pigeonite and augite) crystals. The poikilitic texture grades to ophitic (laths of plagioclase in pyroxene) near the walls of vesicles.
The reported 40-39Ar age of the matrix of 76215 also is in the same ballpark as that for 76015 at 3.896 ± 0.039.
The large vesicle partially contained in 76215 illustrates the range of patination caused by solar wind spallation and micro-meteor impact reduction of FeO to nano-phase iron. As seen in Fig. 12.55, the resulting patina is progressively reduced with depth into the vesicle.]
Fig. 12.55. (Upper): The rock sample 76215, a metaclastic rock with a poikilitic matrix, showing the progressive reduction of solar wind and micro-meteor caused patination with depth in a partial vesicle. The clean surface that contacted the top of Block 2 is seen at far right. The scale is in cm. (NASA Photo S72-56373). (Lower): Sample 76215 turned ~90° to show its contact surface with the top of Block 2 more directly. (NASA photo S72-56374).
“Bob, one of the light-colored inclusions looks like it may be anorthositic, …[that is,] gabbroic anorthosite. …Let me get my terms straight. The host rock (Block 5) has dark-enough zap pits that it’s probably…anorthositic gabbro, if I didn’t say that. Some of the light-colored inclusions have slightly lighter-colored glass [in zap pits], and they may be the gabbroic anorthosite. …Inclusions like this one and that one, [Gene],” I said, pointing out the distinctions to Cernan.
“Yeah. Some of those inclusions get to be bigger than the size of a baseball. There’s one here and a couple up there.”
“Let me borrow your hammer,” I requested.
As I went to work on the rock, Cernan made suggestions. “Yeah. Jack, try a little higher. See that one right on the… Right there. Right… Well, that’s a hard rock.”
“No, [that’s not going to happen]” I said as I gave a corner a couple of whacks.
“That’s a hard rock,” Cernan observed.
“You might be able to do it; I can’t.” Cernan’s larger hands could get a better grip on the hammer handle than mine.
“I can’t get down there. …Okay, we need some of the soil outside the shadow here.” He apparently had forgotten that we already had the control samples and did not need another.
“Yep. How about over where your bag went? Let’s move around here. …I think there is some… Oops! Get on this slope over here. Okay. How about out over here? Are we supposed to get a [rake sample]? Where are we here [in the Checklist]?” I was thinking about what might be on the Cuff Checklist and getting distracted from the study and sampling of the boulder.
“I don’t know. I’d like to get [the 500mm photos]. …Well, when you face uphill, your camera faces down” Cernan noted.
Still looking at the Checklist, I said, “We want to get a rake on the rim of that little crater down there, I guess. And…”
“Okay, 17. Roger. You were asking about objectives. Of course the primary objective is documented samples of the blocks; and then, also, we’d like to get some of the rake and soil sample out in the surface, namely, the rim crater there, if that’s available. And one of the things, of course, we’re looking for is the variety of rocks here, if there’s more than just the one boulder. You can sample the boulder for a while, but we would be interested in seeing if there is more than just the single type of rock. Probably, also, samples from both sides…both halves of the rock.” It was fortunate, in a way, Parker broke in at this point. It refocused my thinking, even though I would ignore much of what he said.
“Let’s get working,” I said quietly to Cernan
“What we said this morning in terms of combining Stations 6 and 7 to an hour and 20 minutes,” Parker added. Fortunately, we did not eliminate Station 7 (see below).
“Come on up here, Geno,” I said, taking charge of events.
“Okay.”
“If you can.” Again, going uphill constituted a major challenge.
Parker continued: “And so it’s sort of your option as to how much time you spend here and how much you go on to Station 7 and spend. If you feel that it’s worthwhile, we could spend essentially all that hour and 20 minutes at this station. But if we did that, we’d like to get a fair variety of blocks, if they’re available.”
“Okay,” I said shortly, as Parker’s monologue now was interfering with us talking together about the sampling.
“Geno, we can sample some of the light-colored group [of clasts]. As a matter of fact, this block (Block 2) looks different [from the one we just sampled].”
“Well, so does that big one (Block 1)…
“It’s grayer [than the vesicular breccia],” I observed.
“That’s why I’ve been photographing it.”
“What it is, I think, …it’s (east portion of Block 1) a big blue-gray rock, itself is crystalline, I believe.” The Sun’s reflections, even on very small crystals in the matrix, made it easy to determine if the rock was crystalline or not. “The inclusions (clasts) are much more sharply defined, and it’s non-vesicular; and it’s intruded [by], or at least it’s in contact with the very vesicular anorthositic gabbro. Right up there… See that, [Gene]?” I referred here to a contact exposed in the face of Block 2, that I had been looking at but had not commented on before this. I also continued to use the term “inclusion” for the light-colored clasts in the blue-gray portion of Block 1 because I had not fully realized that the blue-gray breccia of Block 1 we had begun to examine was not gradational in texture and color with the vesicular melt-breccia we had just sampled.
“It’s a blue-gray. …Yeah, a whole big one (inclusion). I just…”
“Did you get some pictures of it (Block 1)?”
“As I bounced around there, I took pictures of it,” Cernan replied.
“Look, we can get some of that light-colored stuff (clasts) in there, along with the blue-gray.”
“We ought to get as big a piece of that inclusion as we can,” Cernan repeated. “There’s [another one]…”
“See it up in there?”
“Yep.” Cernan looked around for the Rover and its TV and observed, “I think we’re out of line-of-sight with them. We’re behind a boulder.”
“Yeah, sorry about that. But [that’s the breaks].”
“We can hear you loud and clear,” Parker broke in. “We’re just looking at rocks right now [with the TV].”
“Okay, Bob, the boulder down-slope (Blocks 4 and 5) is more of a light-gray, vesicular boulder. The one Jack just talked about (east part of Block 2 and Block 1) with some of the larger white inclusions is less vesicular, and it’s more of blue-gray rock. And if I don’t fall on my tail here, I’ll get [some samples].” This is one of Cernan’s best geological summaries.
“The locator [photograph] is of Henry [Crater],” I reported.
Fig. 12.56. My locator photo of Henry Crater. At right is the corner of Block 5. (NASA photo AS17-141-21610).
[I took the locator (AS17-141-21610) after taking two before photographs of the area we were about to sample. The ~500 m diameter Henry Crater is in much better focus than in the previous images mentioned above. In this view, there are several concentrations of boulders around the south rim and wall that are like, but not as prominent as, those at Camelot Crater, leading to my conclusion that Henry is somewhat older than Camelot. The north two-thirds of Henry, however, show no such boulder concentrations, suggesting that a contact between subfloor basalts and impact breccias may run through the crater.
The two before sampling photographs have angles of the Sun on the surfaces of Boulder 1 and 2 that are different, with a glancing Sun showing enhanced texture on Boulder 2, these images (AS17-141-21608-9) suggest that Boulder 1 is significantly less vesicular than Boulder 2. The contrast in texture may have been the reason that the fracture between the two boulders occurred along this plane due to the shock of the parent boulder coming to rest when it encountered the change in slope from 26º to about 20º. Cernan’s photographs (AS17-140-21440-41) of the same general area between the two boulders do not overlap.
Cernan and I both took a good series of close up before photographs of the area to be sampled (AS17-140-21442-45 and AS17-141-21611-15) with Cernan’s color film showing the blue-gray color and absence of large vesicles in this melt-breccia in contrast to the tan-gray melt-breccia of Boulders 4 and 5. In addition, these images show the distribution of light-colored clasts and fracture irregularities in Boulder 1. The images show that the various light-colored, largely angular clasts to be very similar in texture, having very light, irregular, shard-like sub-clasts in a white matrix when viewed on a fresh surface (see AS17-140-21453 of the after photographs AS17-140-21450-5). The matrix has a light reddish-brown patina on exposed surfaces that accents the shapes of the shard-like sub-clasts within it. These host clasts clearly are breccias in a melt-breccia. At this location within the blue-gray melt-breccia, they all appear to be fragments from the same parent breccia.]
Fig. 12.57. Two of my down-sun “before” views of the sampling area (middle, right of shadow, slab with large white clast, and other smaller clasts) on Block 1. Cernan, at left, is preparing to take his cross-sun “before” photos of the same area (Figs. 12.59, 12.60 below). A high resolution view in a separate window can be accessed here. (Combination of NASA photos AS17-141-21608, -609).
Fig. 12.58. Three more of my “before” photos showing a closer down-sun view of the sampling area noted in the previous figure. A high resolution view in a separate window can be accessed here. (Combination of NASA photos AS17-141-21613, -614, and -615).
Fig. 12.59. Two of Cernan’s cross-sun photos of the corner of Block 1 showing the sampled areas. The dashed oval at upper left encloses the area of a large melt breccia with clasts (76235-39, 76305-07). The three samples are shown marked on the boulder. The insets are Lunar Sample Lab photos with approximate sample orientations and lighting as in situ. The blue-gray color of this part of Block 1 is quite evident. An unmarked, high resolution view in a separate window can be accessed here. (Combination of NASA photos AS17-140-21442, -443; NASA sample photos S73-19375 (76255); S73-19387 (76295); S73-19385 (76275)).
Fig. 12.60. A closer view of the area from which sample pieces (chips) 76235-39 and 76305-07 were taken. A high resolution view in a separate window can be accessed here. (Combination of NASA photos AS17-140-21444, -445).
Fig. 12.61. Combination of the “after” photos of the light gray area from which sample pieces (chips) 76235-39 and 76305-07 (dashed rectangle) were taken, leaving the white matrix background. Also marked are the former positions of samples 76275 (lower right) and 76295 (upper right) discussed below. A high resolution, unlabeled view in a separate window can be accessed here. (Combination of NASA photos AS17-140-21454, -453, -452).
Fig. 12.62. One of the pieces (chips) of sample 76235 photographed in the Lunar Sample Laboratory after the mission. The contact face with the parent boulder is shown. (NASA photo S73-16731).
“Okay, let me try and get up there,” Cernan said. “…Henry? We must be high enough to see something. I haven’t even looked back.”
“Let me get a close-up before you start pounding,” I told Cernan as he approached with the hammer.
“I might go from this angle, too,” Cernan agreed and took several color shots. “That will give them something…” A little different [rock surface] up in there, too, Jack,” he said pointing at another portion of the boulder face. “We ought to try and sample that…”
“Yup. …Let’s get the [white clast, first]. …You want me to get my scoop under there?” I suggested as a question. “[A piece] probably will fall out [when you hit it].” I had noticed that the clast was already fractured.
“Okay. [Let’s] get as many of these pieces as we can. I don’t know how many are going to come out…”
As we both laughed at how easily the sample came loose, Cernan exclaimed, “Outstanding! Outstanding! This whole thing (clast) will come out here in a minute. …I’ll watch it. I’ll watch it.”
“Got it?” I asked. The sample had started to fall, and I caught it against the boulder face with the scoop.
“Move your arm up or down. …Okay. I got it in case we don’t get another one. …Hey, we’re getting good at that.”
“Yeah. Can’t hold that [piece against the rock] much longer,” I warned, as I began to slide downhill.
“Yeah. Let me get up on this…up here. Oh.”
“Why don’t we get a bag out,” I suggested. “Let me put these [sample fragments] in a bag.”
“That’s why I’m getting up here so I can [hold a bag],” Cernan explained as he maneuvered closer to me.
“Oh, okay.” I could not see what he was doing slightly behind me.
“[I need to] just get my balance. Bob, [bag] 556 (76235-39, 76305-07) is one of the light-colored inclusions (clasts) in the blue-gray rock (breccia).” (Fig. 12.62↑). The sample came from near the south corner of Block 1. (Fig. 12.59↑, Fig. 12.60↑).
“It’s [made up of] chips,” I elaborated.
“Chips of it,” repeated Cernan.
“I think we lost that other one (chip). That’s good enough.” I didn’t want to waste time looking for a chip in the regolith at our feet.
“I got it; I know where it is.”
“That’s all right. It’s not a lot of sample, but it’s representative, I think. It looks a lot like that sugary rock (72415; Fig. 11.48↑) I sampled yesterday [at Station 2], doesn’t it? [I] found [it] in the [third boulder] that we sampled in the [blue-gray breccia]…” (Fig. 11.46↑)
“Yeah, it’s pretty easy to break up; it’s really not very coherent at all,” added Cernan.
[Post-mission examination and analysis showed that 76235-39 is a plagioclase-rich, olivine norite member of the Mg-suite[41] of originally very coarse-grained igneous rocks. As is known to be the case on Earth, the developmentof such primary mineral textures of Mg-suite rocks, and their originally coarsely crystalline nature, require an initially undisturbed fractional crystallization and gravitational separation (differentiation) deep in the crust. These constraints require that parent magmas had been emplaced during relatively quiet episodes of lunar history when large impact disruption of the crust was rare. This may be the best evidence that periods of large impacts appear to have occurred episodically between 4.34-4.37 billion years, the span of ages for Mg-suite samples from larger, more coherent rocks than these clasts.[42] Alternatively, the plutons from which the Mg-suite samples have been derived were intruded into the crust after a single large impact event (Procellarum?) and cooled quietly prior to the next large impact event (see Chapter 13).
I have proposed the latter hypothesis to explain the narrow range of ages for Mg-suite rocks, their parent magmas being generated through pressure-release partial melting of magma ocean cumulates. Such pressure-release melting may have been brought about by excavation of the lunar curst by the huge impact that formed the Procellarum Basin (~3200 km diameter).[43] The less dense magmas so formed would rise upward and crystallize in the lower portions of the crust. Subsequent, post-Procellarum large impacts brecciated, crushed and excavated Mg-suite igneous rocks and distributed them over the lunar surface, with other, even younger large cratering events, such as Crisium, Serenitatis and Imbrium, repeatedly mixing and re-mixing them into impact-melt breccias such as we examined at Stations 2, 6 and 7 and that have been sampled on other Apollo missions.
On the other hand, Mg-suite sample 76235 has 40-39Ar ages of 3.96 ± 0.06 and 3.98 ± 0.06 billion years.[44] Given the extremely cataclastic (crushed) nature of this material and the similarity of its 40-39Ar ages with that of its host rock (see 76295 (below), 76235’s 40-39Ar age appears to have been largely reset from an older age by the release of argon due to the heating and crushing by impacts. ]
“You know, I thought last night, Bob, that I should use the word ‘aplitic’ for a [sugary] texture that we saw in that inclusion (greenish white dunite clast) yesterday on the South Massif.” My comment refers to samples 72415-18 from Boulder 3 at Station 2 (see Fig. 11.46↑ and Fig. 11.48↑ in Chapter 11).
“If I could keep from falling on my tail,” Cernan said to himself.
“Can you get a [piece of that other clast]?” I asked him, looking at the block surface and not noticing his current difficulty in staying close to me.
“I want to [but I have to stay close, first].”
“Okay, you going to get some of that?” I pointed at another light colored fragment in the blue-gray breecia.
“Yeah, that’s a different kind; that’s a more beat up inclusion of some sort. …Oh, there’s a nice piece coming out. Oh, wait a minute. …Don’t lose it.”
“I got it. I’ve got it,” I said, holding the fragment against the rock with my glove.
“Got it?”
“Okay…”
“Okay.” Cernan began. “We have another inclusion that, on the surface, has a more reddish-brown texture (color). Interior looks pretty much the same; it’s a very light-gray.” Cernan apparently had become understandably confused by my improper use of the term “inclusion” when looking at a clast, i.e., fragments in the vesicular impact melt-breccia sampled previously. He continued to use that term for clasts in the blue-gray, non-vesicular impact breccia we were now sampling. Also, the “reddish-brown” color probably comes from the ubiquitous glassy patina on the exterior surface of the exposed rock surfaces.
“This looks like a piece of breccia,” I observed, holding the sample close to my helmet. “Looks like a fragment breccia that got caught up in this thing (blue-gray breccia).”
“Yeah, well, the whole thing is obviously a breccia,” asserted Cernan, not understanding the distinction about a “breccia within a breccia” that I was making. “I’d sure like to get that [inclusion]…”
“Well, I’d say… I’m not sure (that) it’s obviously a breccia [overall]. I think it may be an igneous (previously molten) rock with breccia inclusions.” Having seen the light-gray melt-breccia of Block 4, I was considering the possibility that the blue-gray rock might be a variant of that melt-breccia rather than a separate unit. My use of the term “igneous” is confusing, however, as that term normally not only refers to molten material but material that becomes molten through heating other than by impact.
“Well, okay, but look at all these things [clasts]…” Cernan protested.
“Which is sort of in the same class [as ‘breccias’],” I finally agreed.
“[That] sort of makes a breccia…out of the big rock.”
“Okay,” I conceded, just to get on with the sampling.
As this little back and forth went on, I was trying to put the last sample in Cernan’s SCB. “I can’t get in there, Geno, you’ll have to [get lower].”
“Okay.”
“No way [can I reach that high]…”
“Let me [go downhill a little]…”
“Watch it. Hold still. Oops. …I think it’s easier for you [to use my SCB],” I concluded. Cernan stood uphill from me, keeping me from opening his SCB. “Did I give them a number on that? No.”
“Negative,” Parker answered.
“It’s 536 (76255),” Cernan reported. Before photographs of this sample are AS17-140-2147-9 (Fig. 12.59↑) and the after is AS17-140-21456 (Fig. 12.64↓).
“Squash it (the sample bag closure band). …Cramp it a little bit, if you can… A little more…”
“Did you get that 536, Bob?” asked Cernan.
“Roger. 536 for the last one.”
[Post-mission examination and analysis revealed that 76255, as I suspected at the time, is a very complex breccia in a breccia.[45] It is dominantly a crushed plagioclase-orthopyroxene-olivine rock, containing fragments of older polymict (varied clasts) breccia. The sample has a small piece of the blue-gray matrix breccia adhering to one corner. 76255 is strongly foliated and shows evidence, in the form of broken vugs with “spongy” plagioclase intergrown with pryoxene, of having been vesicular, that is, partially melted. The sample also contains clasts of gabbro, troctolite and basalt. The adhering blue gray matrix breccia is very fine-grained and, and in contrast with the large vesicles visible in Block 4, it is very finely vesicular with a large volume of small mineral and rock clasts. Although now very finely crystalline, the matrix material qualifies as an impact melt-breccia.
The principle norite clast has a 40-39Ar age of 4.05 ± 0.04 billion years.[46] The actual age of the clast is probably significantly older due to partial release of 40Ar during various brecciation events recorded in its textures.]
“Okay. Let’s go get the host rock (matrix) here,” Cernan said, anticipating the next logical sample to take.
“How about that… How about that… Whew.” I was climbing back up the slope. “How about that piece?” pointing to a specific spot on the face of Block 1. My desire to get a “pure” blue gray matrix sample from a spot not close to a clast was to avoid as much as possible the effects of the matrix and clast having reacted with one another.
“How about this one, with the inclusion?” Cernan countered, changing his mind. “Maybe I can get this one.”
“Okay.”
“That may have been a little optimistic.” The part of the blue-gray breccia matrix that Cernan worked on proved more resistant to his hammer than he thought it would be. Then, again, experience tells the geologist to take what edges and knobs the outcrop gives you rather than trying to beat it to death.
Parker came in at this point with a question from the Science Back Room. “Do you guys have a feeling that the two halves of the big boulder are different rocks? Or is it the same rock split?”
“No, they were all one boulder, I think,” I answered. “They are just two major rock types in [the combined boulder] wherever they came from. And I tried to describe that to you. We have the contact [between the two] in the central boulder (Block 2). There’re really three big boulders (Blocks 1, 2, and 4+5). The central block (Block 2; Fig. 12.52↑) had the contact between the light-gray rock – or [I mean] the blue-gray rock – and the vesicular anorthositic gabbro (light-gray melt-breccia).”
[I should have never used the term gabbro in describing this melt-breccia, although it was really just an instant reference term to keep what I was seeing straight in my mind as we worked. This is common practice when exploring new geologic units – field terms often do not correspond to what the rock ultimately turns out to be. Although color of the zap pits suggested a gabbroic composition, it clearly was much too fine-grained to be classified as a gabbro in texture. If I could take it back, I would give it a field name of “light tan-gray, vesicular breccia”.]
“Okay. And you guys have that pretty well photo-documented, right?
“Yeah, it’s in pretty good shape. We’re working on it still… Try going on the side [of that fracture] there, Geno.” While I tried to answer Parker, Cernan continued to work on getting a sample of the blue-gray matrix that was significantly more dense and hard than the light-colored clasts.
“Just went from the side, Jack.”
“That’s enough. You got a piece of the…”
“…host rock,” Cernan finished for me.
“I think you can get this one [piece of the matrix] up here, also, can’t you?” I tried to get Cernan to focus on getting a true sample of the matrix, but he kept going for another clast.
“I wanted that one ’cause it had that inclusion wrapped in it,” insisted Cernan. “Let me go to HIGH [on cooling] here for a minute…” I went to HIGH cooling as well at this point, as staying in position on this slope required continuous physical effort. “Which one (piece) are you talking about? This one here?”
“Yeah, I just [want to be sure we have the pure matrix]…It’s about to come… Oh, oh, oh, okay. I’ve got it. I’ve got it.” Sampling a near vertical rock face meant that, as the sample came loose, I had to trap it against the face to keep it from falling to the slope and possibly rolling away.
“Okay.”
“Okay. I need this in a [separate] bag,” I said.
“They’re both host rocks; we can put them in the same bag.”
“No, let’s don’t,” I countered. “No, they’re [from] different places. 537 (76275) (Fig. 12.59↑) is a chip of the blue-gray rock; and the blue-gray host rock… And let me get that other one [you broke off]… Ahh!” I slid down on my left knee as I dropped one sample and reached to pick it up.
“Oop. Be careful,” Cernan warned. “…Pick the rock up while you’re there. It’s right at your hand.”
“I will…Okay.”
“[Let me put] my little hammer somewhere.” Cernan wanted both hands free to handle the sample bag.
“And 538 (76295) (Fig. 12.59↑) is another sample of that material… – a little dustier [sample],” I added with a laugh. “That’s the blue-gray [breccia matrix], Bob, with the inclusions in it. Now the blue-gray, the more you looked at it, it looks like a…”
“Give me your left…[I mean] your right hand,” interrupted Cernan.
“Huh?”
“Give me your right hand. Turn it over. Turn it over. Turn it over.”
“Well, I did. How do you want it over?” I had no idea what was on his mind.
“You kept turning it over in the same direction. Like that”, Cernan said, turning my hand to the left, “so I can fix that [loose watch band]. …Okay. Now give me your bag, and I’ll get it (bag 538) in there…”
“The blue-gray rock,” I continued with my interrupted observations, “on closer examination, looks like a partially re-crystallized fragment breccia. It’s very hard. …Are you going to get the afters in there?”
“Yeah, I’ll get them. I want to do a little bit better documentation on this thing.” (AS17-140-21455, 56, 58, 60,and 62 are the after photographs for both 76275 and 76295.)
Fig. 12.63. A close, direct view of sample site 76275. See Fig. 12.59↑ for the sample in situ; and Fig. 12.61↑ for another view of most of the sampling area. A larger, unmarked view in a separate window is available here. (Combination of NASA photos AS17-140-21455, 457).
Fig. 12.64. A closer, direct view of sample site 76295. The location of sample 76255 in situ was also shown in (Fig. 12.59↑). An unlabeled, larger view is available here. (NASA photo AS17-140-21458).
[Post-mission examination and analysis of 76275 and 76295, samples of the blue-gray matrix of Block 1 breccia, show significant differences between them. Sample 76295 appears to be more homogeneous and may be more representative of the blue-gray breccia overall than is 76275. The former sample is described as a polymict breccia with a very fine-grained (aphanitic) matrix of intergrown plagioclase and clinopyroxene. Scattered small vesicles and vugs exist throughout. Clasts include abundant plagioclase and olivine mineral fragments as well as crushed plagioclase-rich rocks and older clasts of very fine-grained breccia. The blue-gray matrix appears to be cut by a tan, vein-like matrix breccia variety in which mineral fragments are about two times more abundant and include augitic pyroxene (clinopyroxene). Both matrix types consist of about 50% plagioclase.
Although superficially similar in overall color to 76295, 76275 is highly vesicular. The latter also has more of the second variety of tan matrix. The blue-gray matrix has abundant olivine but little clinopyroxene (augite) and the lighter matrix has abundant augite but no olivine.
The 40-39Ar age for 76275 blue-gray matrix is 3.915 ± 0.039 billion years[47]. Other reported 40-39Ar ages probably represent contributions from older clasts. See Chapter 13 for a discussion of the ages of the melt-breccias in boulders at Station 6 that appear to be related to the Crisium basin-forming event.
The internal structure, clast and mineral populations, and 40-39Ar age data from within the blue-gray impact melt-breccia appear highly variable and, on the scale of a few centimeters, may be influenced by argon migration or by reactions with clasts of different compositions and original ages. The matrix ages in 76295 appear consistent with ages from the light-gray melt-breccia and may be close to the age of the Crisium basin-forming event (Chapter 13).]
“I’m going to go over and look at that contact,” I told him, moving toward the center of the south face of Block 2. As I examined the contact zone, I noted that it had vesicles that become larger in the blue-gray melt-breccia closer to the light tan-gray, coarsely vesicular melt-breccia. This relationship indicated that the light tan-gray melt-breccia had enough excess heat to partially remelt the blue-gray melt-breccia east of the contact as it intruded or flowed along the top of the latter. Blocks 1 and 2 had not split from each other along the obvious contact zone, but rather it broke through the blue-gray melt-breccia just to the southeast of the contact zone (see Fig. 12.53↑ right), possibly near where the metamorphic annealing effects of the hot, light tan-gray melt-breccia had dissipated.
“Bob, …I got a few close-up stereos of the inclusion that we tried to sample, and I’m going to see if I can’t give you a little flight-line stereo around this thing (Block 2). If I can stay on my feet. …Do you read me, Jack, okay?”
“Yeah, I hear you.”
“And Houston reads you loud and clear, also.” Cernan always seemed more uncomfortable than I when Parker did not acknowledge a transmission. I just assumed initially that what I was saying was being heard and, if it weren’t being heard, Parker would say something. This difference in concern may be because Cernan had spent most of his professional life flying when you want to be sure that each transmission has been heard and understood.
“You can see [in the photographs] where we’ve been pounding on this rock,” Cernan informed Parker. “We didn’t succeed in getting samples everywhere. …And I’m giving you a 90-degree corner [in this flight-line]. The flight-line sequence consists of AS17-140-21456-81. Cernan took pairs of photographs, one low and one high, as he was too close to Boulder 1 to obtain stereo from the bottom to the top in single frames. (Fig. 12.65 is an example with 3 of the frames).
Fig. 12.65. Assembly of part of Cernan’s flightline series of up-down photos of the east-facing northern corner of Block 1 (see Fig. 12.37↑ for the position of this series of photos). A higher resolution view in a separate window is available here. (Combination of NASA photos AS17‑140-21467, ‑468, -469).
“Bob, it looks to me like there are inclusions of blue-gray [breccia] in the gabbro, [that is,] …in the anorthositic gabbro (light-gray melt-breccia).” I made this comment as I kept stepping upward (treading sand) to maintain my place close to the southeast face of Block 2. I took several close-up photographs (AS17-141-21616-20) across the contact zone in Boulder 2, but apparently did not adjust the focus so the textures cannot be seen as clearly as I was describing them.
Fig. 12.66. Assembly of three of my photos taken of the southeast face of Block 2 across the contact zone (see Fig. 12.52↑ for the contact zone at the bend of the lower part of the dashed lines). The contact zone is also approximated here by the dashed lines. The dashed oval on the right approximates the original location of sample 76315. For an unlabeled version in a separate window, click here. Note also a number of large, white clasts faintly visible in the shadowed area to the left of the unlabeled, enlarged photo. (Combination of NASA photos AS17-141-21620, -616, -618).
“Are you saying you think this whole big,” Cernan began to ask, “…you think this whole big blue-gray thing (Block 1) is an inclusion?”
“Yes, sir,” I affirmed. “And there’s some little ones (clasts of blue-gray melt-breccia) over here [in the contact zone].”
“Yeah, but then within the blue-gray, we’ve got all these other fragments.” Cernan was referring to the light-colored clasts, some of which we had sampled.
“Well, that’s right. It’s just several generations of [impact brecciation] activity; and it looks like the [anorthorsitic] gabbro ([light tan-gray] melt-breccia), though, picked up the fragmental [blue-gray] breccia as inclusions [as it moved along the contact]. …Bob, it really looks that way right now. There’s a small one (blue-gray melt-breccia) here in the…”
[Some years later, similar 30Ar-40Ar age dates reported for the matrixes of the two melt-breccias suggested the more likely alternative that the tan-gray melt-breccia with inclusions of blue-gray melt-breccia is a flow of contemporaneous impact melt-breccia, created by the same basin-forming event as the blue-gray melt-breccia. This alternative would explain the internal variations in vesicle content between the two melt-breccias as well as the lineation of the large vesicles in the slightly younger, tan-gray melt-breccia. ]
“Okay, Charlie [Duke] is here mumbling something about it looking just like House Rock,” interrupted Parker, referring to a much larger boulder on the rim of Apollo 16’s North Ray Crater.
“It’s (the rock matrix) very crystalline,” I responded. “I’ll tell you, it’s not a breccia, not like House Rock. Not to take anything away from House Rock, though.”
[By saying, “its not a breccia”, I meant that the rock as a whole had not been broken up since it crystallized from a melt, in this case, an impact melt. I may have temporarily confused the geologists in the Science Back Room. In my descriptions, I did not clearly distinguish between a true igneous magma containing inclusions of its wall rocks and an impact melt (tan-gray) containing inclusions of previously ejected and solidified impact melt (blue-gray) over which the later melt-breccia flowed.]
“Hey, Bob,” called Cernan, as he worked his way around the east end of Block 1, “there’s a lot of [regolith] mantling on a very shallow slope of a fracture (rock surface) here on one of the upslope blocks (Block 1). I would assume it’s (the regolith mantling) just part of the talus picked up as it (the boulder) rolled down. But if it’s worth sampling, you might think about it.” Cernan’s instincts were good in this case; however, he should have just sampled it and reported that he had done so, instead of wasting time asking.
After waiting a few moments for a response from the Science Back Room, Parker said on his own, “Okay, Gene, if you can get that fairly readily, why don’t you. …You can perhaps just scoop it up with the bag.” Good call on Parker’s part.
“That’s exactly what I can do,” Cernan replied.
“If you can get up to the rock there.” Parker meant if he could reach far enough to get the sample.
“It will be [documented before sampling] in my flight line stereo (AS17-140-21474, and it’s going to be bag 557 (76320). And I’ll take an after and show you where it came from.” Cernan supported himself with his left hand and took two passes with the open bag to get the sample. The after photograph of this sample location on Boulder 1 is AS17-140-21482.
Fig. 12.67. Cernan’s “after” photo of the regolith sample scoop locations on the Block 1 shelf. The “paw-shaped” disturbance at the lower left marks the position where Cernan braced himself with his left hand as he leaned over the shelf with the open sample bag in his right hand to scoop up the soil. (NASA photo AS17-140-21482).
Fig. 12.68. Part of Cernan’s Pan 22 (see Fig. 12.70↓ for the complete context view to the South) of the Block 1 shelf rotated 90º from Fig. 12.67. ‘H’ is the disturbance caused by Cernan’s left hand. Arrow 1 marks the first pass from right-to-left as Cernan scooped up some soil from the shelf with the plastic bag he was holding in his right hand (bottom-to-top in this view). Arrow 2 marks the second, shorter pass in the same direction as no. 1. (Crop from NASA photo AS17-140-21496).
[Post-mission examination of 76320[48] showed that the sample contains fragments of valley basalt (2.7%) and orange and black ash (3.6%), which indicate some impact induced mixing of material from the valley floor, similar to that shown by other regolith samples from Station 6. The sample is from regolith thrown onto the Block 1 either when the block came to rest or by a nearby impact. The cosmic ray exposure age for immediately post-rolling fracture surfaces sampled in 76015, 76215 and 76315 measure 17-21 million years (locations in Fig. 12.37↑; Blocks 5, 2, respectively). The fragment size-frequency distribution in this static regolith sample (76320), however, resembles 76501, the slope (dynamic) regolith sample associated with the nearby rake sample (Fig. 12.37↑, square symbol to the lower left of the Pan 21 crater).
76320 contains about 39% agglutinates and has an exceptionally high Is/FeO maturity index of 93, unusually high relative to other regolith from nearby slopes that have agglutinate contents of ~45% and maturity indexes between 20 and 50. A somewhat higher maturity index is to be expected as the sample location on the boulder limits contributions of young regolith from the slope above. The rate of increase of maturity indexes of about 0.178 per million years calculated from the deep drill core (see Chapter 13) would indicate that 76320’s maturity index should be only less than 5 points higher than that of 58 for the slope rake sample regolith, 76501, rather than 35 higher. Either the reported maturity index measurement for 76320 is in error, or the sample has accumulated excess nano-phase iron. This excess may have come from ejected fragments of the iron-rich patina on surrounding boulder faces (see e.g., Fig. 12.55↑ of sample 76215).]
“This is the easiest part of the rock in the world to work,” reported Cernan. “Man, here’s a big white clast. There’s one on top about a foot and a half across, and here’s one. (It) must be 2 feet across…[maybe] 3 feet. And that’s in the blue-gray. …Feel like a kid playing in a sandbox…” Cernan’s photographs do not show these large white clasts but do show many smaller such clasts.
At the same time that Cernan was obtaining the flight-line stereo and sample 76320, I was jumping about a foot high, trying to move up the slope and get a closer view of the contact zone between tan-gray and blue-gray melt-breccias (Fig. 12.52↑, Fig. 12.66↑).
“Well, Bob, I think I’ve done the best I can [in observing the contact]. I’d say that they’re pretty clearly inclusions of blue-gray in the [light gray] anorthositic gabbro here near the contact.” I made this comment, balancing on my downhill leg, and then walked slowly up the slope, using the scoop to assist the climb, moving toward where Cernan had been looking at the large white clasts. The bottom of my SCB had come loose and was causing some concern in the MOCR.
“Okay. And Gene, your bag is hanging by one hook there. Be careful, if you can. …Or, [is it the] LMP [bag]…
“Okay. I gave you 557, I believe. Didn’t I?” Cernan asked.
“Roger. We have that one. …And whoever is giving us [bag] 557…” How Parker had lost track of who was who, I can’t imagine. The TV had been watching me look at the southeast face of Block 2 by aiming through the gap between Blocks 3 and 4.
“Okay, I’ll have Jack fix my bag.”
As I worked my way up the slope, I reach down and picked up a sample from the surface. “Okay, Bob, by accident, ….I didn’t think I could do it, but I got a sample of the [blue-gray] inclusion [in the tan-gray]. And it’s in bag 539 (76315).”
Fig. 12.69. (Upper): Rock sample 76315 I picked up below the contact zone shown in Fig. 12.52↑, Fig. 12.66↑. The blue-gray color of the matrix is clearly seen on the right. A very large white clast dominates the left side of this view of the sample. A smaller white clast is in the blue-gray matrix at right. (NASA photo S73-17109) (Lower): Anaglyph made from a convergent stereo pair rotated clockwise 45° from the upper view. A larger scaled view in a separate window is available here. (Derivative of NASA photos S73-18732, -732b).
[Post-mission examination of 76315 appeared to confirm that it represented blue-gray breccia and an enclosed clast in the third of the contact zone closest to the blue-gray melt-breccia in Block 2 (Fig. 12.52↑, Fig. 12.69 above). The sample contains a large white plagioclase-rich clast that is veined by impact melt that is now very finely crystalline. The blue-gray portion of 76315 is very finely vesicular (vesicles less than 1 mm across) and very fine crystals of olivine and pyroxene enclose plagioclase. Lines of vesicles define a consistent foliation through the sample.
40-39Ar age determinations on 76315 gave 3.933 ± 0.039 billion years for the blue-gray matrix.[49] This probably is the age of the Crisium basin-forming event (see Chapter 13).
The cosmic ray Kr exposure age of 21.7 ± 1.2 million years and the track exposure age of 21 ± 3 million years are older than the 17-18 million year exposure ages of 76015, 76215, and 76315 samples more clearly from fresh fracture faces of the boulder fragments.]
“Hey, Jack, that’s your bag (SCB) that’s hanging by one hook. Let me go get it.”
“Oh, they’re talking to me, huh?”
“Yeah, because I didn’t…think they could see me. I’m way up on top!”
While I waited for Cernan to come to my aid, I looked at the sample I had just bagged. “And it’s blue-gray with light colored…inclusions in it. …But the whole thing (Block 2) seems to be pretty well altered or metamorphosed…compared to the major rock (Block 1) we just sampled, [that is, compared] to the other blue-gray rock.”
“Put these (bag 539) in my bag,” Cernan said as he arrived back near Block 2 and in view of the TV camera.
“All right,” I replied. “This bag [cover] is terrible. I can’t…It won’t latch.
Looking toward Block 4, Cernan said, “Man, there’s a dark hole in there (under Block 4) where you [got the shadowed sample].”
“Don’t let me [slip]. …Ah! I’m not [tall enough]…” Cernan seemed to often forget that he needed to be level with me or, better yet, downhill when I worked on his SCB.
Handing me his regolith sample from the top of the boulder, Cernan said, “Here’s another bag to put in there before you go away.
“Oh, okay. …It (the SCB) won’t latch,” I complained with a grunt. “…Not at this angle.”
“Just put the thumb on one side, and I’ll…”
“It’s (the cover frame) bent or something. …There,” I said, finally getting the cover in position. “that’s pretty good.”
“Now let me fix your bag,” Cernan said. “…That’ll stay on.” He did not fix the problem at the bottom of my SCB, however.
“Okay, Bob, I think that inclusion (bag 539) will give you an example of what…what the [light-gray] anorthositic gabbro (melt-breccia) did to the blue-gray breccia.”
While Cernan moved back around Block 2 toward the east, and I went back to Blocks 4 and 5 for another look, Parker suggested what we might do to close out activities at Station 6. “Okay, …and we’re ready for you guys to leave this rock and press on and either get the rake soil and cores near that crater down below the rock just a shade (short distance), or else go on to some other different variety rocks in the area.
“Well,” I responded, “I tell you, going down to that crater is not a problem. Getting back up is.”
“Okay, well, find a decent area to get the rake soil from and a couple of cores.”
“Tell you what, Gene, I could go down there and start a rake [sample], and you could come down there [with the Rover].”
“Okay. Yeah, I don’t think you ought to try and walk back up, Jack. Let me get a pan from right here where I got this sample [from the top of the boulder]. Cernan had positioned himself upslope from Block 1.
“Okay. I’m going to come over [to the Rover] and, …I’ll go get the rake and get the gnomon.”
“Seventeen,” Parker interjected, “it’s not that vital to get to that [specific] crater. We just need a good place for a rake soil and a double…[that is,] a single core.”
As I stood in the gap between Blocks 2 and 4, and out of sight of Cernan, I had a thought about his panorama. “Hey, get uphill a little bit, if you can, for the pan, so that you don’t, …so you see my other pan station.”
“Where was it (my pan station)?”
“It was over there in that crater, just uphill from the Rover,” I replied.
“I’m going up there.”
As I moved west along the slope and out of the TV frame, Parker called and repeated himself. “Hey, and, Seventeen, we aren’t all that gung-ho about that particular crater, …if it’s that much of a job to get down to it and back up. We just need a decent place for a rake soil sample and a single core.”
“Okay.”
“Bob, we don’t move around from here too much,” Cernan explained. “I tell you, these slopes are something else.”
“Yeah. We agree with that, from what we see on the television. So use your judgment, and get them where it’s the best place.”
“Well, you might take a look at me walking up,” suggested Cernan. “But I don’t think I can get to the top [of the Massif]. …I just got to get a place I can get a pan from. Right here. Right in this little hole. …Okay, now I left the gnomon down there.”
“Okay. I’ll have to go get it,” I told him. “I think we’ll setup [for the rake sample] right here near the Rover.
“I think I’ll go [to INTERMEDIATE on cooling] and save some water,” Cernan said, positioning himself, as I had previously, on the flat, down-slope wall of a crater before beginning the panorama. “Back on INTERMEDIATE [cooling]…” This color panorama constitutes one of the best of the mission, showing the blocks of Station 6 their boulder track, but also, equally as esthetically, it encompassed the Rover, Challenger and, across the valley, the towering South Massif.
Fig. 12.70. Portion of Cernan’s Pan 22 looking south and taken from a position up the slope to the north of the blocks at Station 6 (location, Fig. 12.37↑). The Challenger and the lightened regolith surface around it are just to the right of the highest point of Block 2 (white vertical arrow). The Rover, Traverse Gravimeter (TGE), and rake (white arrow) are in the middle foreground. The author’s footprints are visible going into the track at left (better seen in Fig. 12.71, looking east) and also coming down from the lip of the crater where I took Pan 21 at right. In this view I am returning with the gnomon to the Rover through the wide gap between blocks 2/3 and 4/5 where I will obtain a regolith sample with the rake. A higher resolution, unmarked view in a separate window can be viewed here. Combination of NASA Photos AS17-140-21497, -96, -95, -94).
Fig. 12.71. Part of Pan 22 looking east. In the background, the East Massif is at right; The “hump” over which we flew to the landing site is the plateau sloping down from middle left; the beginning of the Sculptured Hills is at left. In the foregound at right is part of Block 1. Then, our mixed footprints where we sampled and photographed Block 1, with the single line of Cernan’s footprints directed uphill to the spot where he took this panorama. The arrows mark 3 boulders seen from the boulder at Station 6. The Sta. 7 boulder, ~455 m away, apparently lies hidden by the terrain somewhere between boulders a,b,c. A more detailed discussion of the location of the Sta. 7 boulder in this particular view is given in the ALSJ. These 3 boulders are also discussed again with the photos made at Sta. 7. A higher resolution unmarked view of the above image is available here. (Combination of NASA photos AS17-140-21504, -03, -02, -01, -00).
Fig. 12.72. Part of Pan 22 looking north. Two of the frames were sun-struck, or accidentally exposed to light, which caused the orange coloration. They were frames near the end of the magazine. Cernan ran out of film while taking this part of the pan. The large boulder next to the crater on the North Massif slope is ~95 m away. The small crater itself is ~10 m across. The dip in topography at right is the Wessex Cleft. A higher resolution view is available here. (Combination of NASA photos AS17-140-21509, -08, -07, -06, -05.)
Fig. 12.73. Part of Pan 22 looking west. The ~10 m diameter shallow crater where I took Pan 21 forms part of the foreground from the center to the left part of the pan. In the distance at left, the South Massif rises from the south to its height of ~2100 m before its northeastern slope drops down to meet the avalanche and the Lee-Lincoln Scarp (horizontal bright and dark bands at arrow). The nearest part of the scarp is ~8.0 km away. The large boulder marked by TPR is Turning Point Rock, ~435 m distant. A higher resolution view is available here. (Combination of NASA photos AS17-140-21492, -85, -89, -88, -86).
[Some of the details of Taurus-Littrow geology shown in Cernan’s panorama are as follows:
The pan to the west, Fig. 12.73, shows the reduction in slope of the North Massif from about 26 degrees, the angle of repose, to about 20 degrees. This change results in concentrations of large boulders, including the Station 6 Boulder, along that line.
Frame AS17-140-21492, the left end of Fig. 12.73 above, shows the full, northeast-facing slope of the South Massif. Below the right crest of the massif, there is an apron of slightly darker albedo that corresponds with an area of boulder concentrations shown in low-Sun LROC images. This area has been suggested as being a superposed, relatively thin deposit or splatter of melt-breccia. (It can also be seen by enlarging (clicking on) the separate, higher resolution view of Fig. 12.73).
The foreground of the left side of Fig. 12.73 includes (from left to right) the right edge and shadow of Block 2 of the Station 6 Boulder, the Rover, the TGE on the surface, and the rake partially behind a small boulder. It also shows my footprints leading from the Rover, into the track behind the Station 6 Boulder, and climbing the west side of that track (see the higher resolution version in the separate window). Regolith scuffed up along those footprints is very slightly darker than the surrounding, undisturbed surface. This difference in albedo may be due to the undisturbed surface having what has been termed a “fairy castle” structure. That structure creates the high back-scatter optical characteristic (Lambertian reflectance) that makes the edges of a full Moon, viewed from Earth, essentially as bright as the center. Those footprints, by the way, should be recognizable several million years from now.
The pan to the south, Fig. 12.70↑, shows Block 2 and Block 1 of the Station 6 Boulder. Just to the right of the peak of Block 2, the Challenger’s landing site (white vertical arrow) is visible as a streak of white where the Descent Engine effluents have winnowed away fine-grained, dark dust leaving higher albedo, slightly courser grained regolith behind. The Challenger is visible in enlargements of this streak of white. (The higher resolution download shows it). This pan also includes me with the gnomon in hand on the other side of Block 1. I am headed back to the Rover area to collect a rake sample. My image provides a good visual reference as to the size of the Boulder at Station 6.
Enlargement of the west-facing slope of the East Massif in the distance on the right of Fig. 12.71↑ (click on the higher resolution version to enlarge it) shows repeated cliff-slope indications of eight or more apparent layers in that massif. The next four frames in the pan suggest that the layers extend throughout the East Massif; however, the glancing sun-angle in frame 21496 (Fig. 12.70↑, left; also click on the higher resolution version of Fig. 12.94↓) provides the best definition. These layers resemble terrestrial piles of basaltic lava flows, such as those exposed in the Rio Grande Gorge west of Taos, New Mexico. The layers also could be a sequence of pyroclastic or lithoclastic welded ash flow deposits, such as those surrounding the Valles Caldera west of Los Alamos, New Mexico. Their uniformity and apparent lateral continuity argues against these layers being superposed ejecta blankets from cratering events that occurred in the region; however, this ejecta hypothesis cannot be rejected totally without more study. An alternative hypothesis, suggested by the interpretation that the Sculptured Hills consist of a more or less coherent Mg-suite pluton contained in Imbrium ejecta (see Chapter 13), is that the layers are relics of primary mineral layering in such a pluton. Remote sensing by the Moon Mineralogy Mapper (3M) indicates that the high albedo hill lying in front of the East Massif is composed of rocks rich in plagioclase.
If any of the hypotheses that the East Massif sequence of layers are superposed basaltic lava flows or welded ash flows or ejecta blankets proves correct, their deposition not only would have been pre-maria, but also both pre-Serenitatis and possibly pre-Crisium. The East Massif’s orientation orthogonal to the Taurus-Littrow valley may indicate that it is a remnant of a second outer ring of the Serenetatis Basin, the first ring now defining the main basin and through which the fault bounded valley of Taurus-Littrow was cut. In this case, breakage of the lunar crust as such a second basin ring formed, exposed the pre-existing strata imaged in AS17-140-21496-500 (Fig. 12.94↓ enlarged for a clearer view).
Up-sun images in the pan to the east, such as frame AS17-140-21501 in Fig. 12.71↑, show the possible north-south trending flow front on the valley floor, discussed previously.
The pan in Fig. 12.71↑ includes Wessex Cleft and the Sculptured Hills to the left and the slope of the North Massif further left, also shown in the pan to the north, Fig. 12.72↑. When enlarged, these two pans illustrate the significant difference between the hummocky surface of the nearest knob of the Sculptured Hills and the relative smooth but boulder covered slope of the North Massif.
Some of the source-crops from which boulders near the base of the North Massif originated, such as the boulders at Station 6 and 7, can be identified near the crest in enlargements of the north pan (Fig. 12.72↑) above and to the right of the left orange sun-struck area (click on the higher resolution version to enlarge it).]
“Hope my lens is clean. …Bob, from up here, the light mantle is not evident until you see the angular reflection up on the scarp. Very thin, light patches might be evident out on the valley, but not nearly as pronounced as I might have thought from this altitude. …Oh, and there’s Challenger! Holy Smoley! …You know, Jack, when we finish with Station 8, we will have covered this whole valley from corner to corner!
“That was the idea.” Sometimes, I can get too pragmatic, even when working in a magnificent valley on the Moon.
“Yeah, but I didn’t think we’d ever really quite get to that far corner. Not [Station] 2, but this other one (Station 8). And we’re going to make it!”
Having already assimilated my memories of this wonderful valley and mountain scene when I took my black and white panorama, and now concentrating on my last look at Block 2, I reported, “Bob, that blue-gray rock near the contact with the [light-gray] anorthositic gabbro does get some [visible] vesicles in it. I think they’ll show up in Gene’s pictures…”
[My thinking about what we saw in the Station 6 blocks evolved as the investigation proceeded. Normally, a field geologist would record in a notebook the multiple hypotheses that came to mind as new observations were made. In the case of a lunar EVA, I had to verbalize my evolving thinking that began with wondering if the coarsely vesicular, foliated light-gray breccia might be a fine-grained, igneous anorthositic gabbro. Then, upon further examination of the light-gray breccia’s light-colored clasts, as well as the blue-gray breccia clasts and vesicles in the contact zone, I began to realize that we might be dealing with two varieties of impact melt-breccias. This, indeed, proved to be the case once the samples could be examined closely and dated isotopically back on Earth.
The blocks at Station 6 tell a very complex story about the interplay of ejecta and impact-generated melt from a large basin-forming event, probably Crisium (see Chapter 13). This story will be made even more complex by the relationships observed at Station 2 (EVA-2, Chapter 11) and in the boulder at Station 7 discussed below. The broad field evidence at Station 6, however, seems clear: the finely vesicular blue-gray melt-breccia with its light colored Mg-suite clasts had been intruded, enclosed or flowed over by the coarsely vesicular light-gray melt-breccia. The light-colored clasts in the blue-gray breccia, therefore, constitute the oldest materials in the blocks, followed by blue-gray melt-breccia, followed by light-gray melt-breccia. The relative age of light-colored clasts in the light-gray melt-breccia with respect to the blue-gray melt-breccia and its clasts cannot be determined from the observed field relationships. On the other hand, similar argon ages suggest the two melt-breccias are related to the same large basin-forming event but had different ejected trajectories with the light-gray melt-breccia taking longer to arrive than the blue-gray melt-breccia. ]
“…I just ran out of film at 160,” reported Cernan. “And I’m about two pictures short of the pan, and they’re (the additional frames) upslope. I think I can cover most of that with the 500 [mm camera]…”
“Okay, Gene. You going to go to the Rover and change your mag now?” Parker enquired.
“Well, Jack’s going to need some help from me [with the rake sample].”
“I’m starting to rake,” I informed them as Cernan moved across slope in my direction with his foot forward, hopping gait.
“Let me know,” Parker said, “when you get to the Rover to change the mags, [and] after you get done with that [rake sample], and I’ll tell you what mag to change [to]. …But, press on and help Jack with those [samples] first.”
“Jack, if you got enough film, I’ll just come and help you.”
“Okay,” I replied just as Cernan tripped going cross the slope and caught himself with his hands and knees.
“Okay?” I asked, having seen the fall.
“Yup. …Remind me to dust my camera, too, will you?”
“Don’t forget to dust your camera,” I immediately joked.
“Okay. We’ll keep track of that for you, Gene.”
“Okay. Did you get any before pictures?” Cernan asked me.
“I’m getting them now…’T ain’t easy, McGee,” I laughed, remembering a stock expression from the Fibber McGee and Molly radio program I listened to as a boy. (a short video of his fall and my comment can be seen here) These before sampling photographs are AS17-141-21622-24. The vertical gnomon in image 21624 gives a good indication of the ~20º slope on which we worked at Station 6.
Fig. 12.74. My “before” sampling photo of the gnomon near the area I will rake several times. The shadow of the rake handle can be seen to the left of the shadow of my helmet. The Rover is behind me. (NASA photo AS17-141-21624).
“Man, I tell you, these slopes are great. I wouldn’t mind being up on top coming down, but… Hey, that boulder track is quite a trench!” Cernan may have been trying to talk his way through his fall, hoping the TV camera missed it. No such luck for him. “That thing must be a meter or two deep, huh!?”
“Okay; the ‘big’ rake,” I said. “Well, I think I’ll try [raking uphill].” I stood on the ejecta from a small crater.
“Wouldn’t it be easier to rake downhill?” Cernan asked.
“It would, but the stuff (rocks) wouldn’t stay in,” I said with a laugh at Cernan’s logic slip. Right?”
“Well, I don’t know. It’s a thought. …Make sure you get that one (rock) by the [gnomon] (Fig. 12.74).”
“Yeah, I will. We’re not really supposed to be selective about raking,” I reminded him.
“No you’re not [being selective], you’re just covering the area.”
“That’s why I set up there,” I replied, as I continued to rake in swaths uphill.
“A selective sample is better than no sample at all.”
“Let me put some [rocks] in there,” I said, terminating this fruitless discussion. “Okay?” Cernan had a sample bag open and waiting.
“Bag 558 (76535-39, 45-49, 55-59, 65-69, 75-77).”
“Let me go another couple of swipes,” I said.
“Okay. There’s one (rock) a couple of inches [across]. Most of them are an inch or so or smaller. They’re angular to sub-rounded fragments. Some of them look like the inclusions (clasts). As a matter of fact, the ones that are broken open look like some of the light-colored inclusions we saw in the big boulder. The others are too dust covered to say anything about.
“A couple of them look fairly coarsely crystalline,” I added, possibly having noticed the famous troctolite, 76535. “Okay. Put these [rocks] in there.”
Fig. 12.75. The troctolite sample 76535 collected in one of the rake sweeps. It is discussed below. (NASA photo S73-20397).
Fig. 12.76. Anaglyph of the same sample prepared from a Lunar Sample Laboratory convergent stereo pair. A higher resolution version, which gives an attractive view, is available here. Structural areas in the sample can be enlarged by clicking on the area of ijnterest. (Derivative of NASA photos S73-20397, -23097b).
[Post-mission examination of the 23 rock fragments in the rake sample, identified 17 impact breccias, 4 basalts, one norite cataclasite, and one troctolite. 76535, the meta-troctolite, has attracted the most attention, so far. It is a mixture of very coarse-grained Ca-plagioclase (anorthite) and olivine with few percent orthopyroxene. The rock contains worm-like intergrowths (symplectites) of orthopyroxene and Cr-spinel and clinopyroxene and Cr-spinel as partial coronas at the boundaries between plagioclase and olivine. These intergrowths are similar to ones observed in dunite 72415 and both may be replacements of Cr-garnet, a form of garnet stable at high pressure (see Chapter 13; also see Fig. 11.46↑ and Fig. 11.48↑ for the sample location on the small boulder and the sample itself, respectively).
Like the dunite from Boulder 3 at Station 2 (72415), this Mg-suite troctolite has had a complex history; but, unlike the badly crushed dunite, its primary texture, including plagioclase twinning and homogeneous mineral compositions, have been preserved. 76535’s Rb-Sr isochron age of 4.51 ± 0.07 billion years[50] makes it one of the oldest rocks, along with 72415, yet dated in the Apollo collection. Other age determinations, however, are younger: Sm-Nd isochron ages of 4.26 ± 0.06 and 4.330 ± 0.064; U-Pb concordia age of 4.236 ± 0.015; Pb-Pb age of 4.27 ± 0.03; and three K-Ar ages of 4.27 ± 0.08, 4.19 ± 0.02 and 4.16 ± .04. All these dates suggest that 76535 crystallized about 4.51 billion years ago, but then was subject to a moderate heating event about 4.3 billion years ago This heating event may have been the proposed overturn of the lunar mantle triggered by the formation of the Procellarum basin.[51] The younger K-Ar dates probably reflect one or more other impact-related losses of Argon.
76535 also has an imprinted remnant magnetism, suggesting a very early lunar dynamo in a liquid core[52]. Other remnant magnetism data and the very limited maturation of the 3.5 billion year old regolith protecting the orange and black ash deposit sampled at Shorty Crater (EVA-2, Chapter 11) also indicate an active lunar magnetic field up to at least 3.56 Ga[53] (see discussion in Chapter 13).]
“Big deal!” exclaimed Cernan with a laugh after seeing the results of my last two rake swaths. “We ended up with [only] three more [rocks].”
Ignoring his crack, I said, “Let me get an after, such as it is. Oh, we want the…”
“They want the soil here,” Cernan finished my thought.
“…Soil, that’s right. …Okay. You want to put that [bag of rocks] in [my SCB].”
Yeah, I’d better put it in before I [try to bag the soil]. …Okay. Let’s try for the soil. … 559’s (76500-06) the soil.”
[Post-mission examination of 76501 indicated that the regolith includes about 2.7% ash and basalt from the valley floor, significantly less than the 6.3% in 76320, the sample Cernan took from the top of Block 1 of the Boulder (Fig. 12.67↑, Fig. 12.68↑). Agglutinate accounts for 47.2% of 76501 and the intermediate Is/FeO maturity index is 58.
The Rare Earth Element concentrations in 76501 are several factors lower than those concentrations in regolith samples (76240) taken close to the Station 6 boulder (Fig. 12.45↑). This indicates that the latter samples contain significant material derived from the boulders. 76501, therefore, is more likely to encompass the average composition of the Massif front above Station 6. That average would indicate that Rare Earth Element concentrations significantly lower than the average of the boulder are abundant in the Massif’s stratigraphic column. Strata variability, however, would affect the regolith composition. Units with lower Rare Earth concentrations may be those that are more friable, contributing significantly more to the average regolith on the Massif. Friable units would be less likely to form resistant boulders that can roll to the Massif apron near the valley floor.]
“And, 17, our present plans from the [Science Support Room] are… We’d like to get the single core, the 500 millimeter shots, and, I guess, maybe one [of you] could do one, and one could do the other. And then we’d like to press on and do a short Station 7, unless you think you have got a fair variety of rocks here. The feeling is that you have [gathered a] significant variety of rocks.”
“Here [is the soil],” I said to Cernan, as I gradually filled the bag he held. “Little more, little more, little more…”
“Okay, Bob,” Cernan replied to Parker’s last transmission. I’ll get the core and let Jack get the 500’s. …559 is the kilogram of soil. I think we’ve pretty much covered the general variety we’ve seen here. I think we’re seeing most of them in that boulder.”
“Okay. And so we’d like to go on to Station 7 then – when you get the 500 [mm photographs] and the core – in hopes of finding a variation of boulders along the front.”
“Okay. …[Jack,] let me know when you get it (after photograph)…”
“Schmitt: Okay. …After [photo is done].” These images are AS17-141-21625-27.
Fig. 12.77. One of my cross-sun “after” photos of the rake area. The small rock to the left of the gnomon was mentioned by Cernan earlier. (NASA photo AS17-141-21625).
“Okay, why don’t you get the 500, and I’ll get the core.”
“And the LMP’s on (frame count) 120,” I reported.
“…And, Gene,” Parker called, “if you want to change, we recommended magazine Foxtrot or Fran (Magazine 146), as the case may be.”
“Okay. Will try Foxtrot Franny. …[Jack,] don’t forget to get [a 500 mm photo of] that boulder track.”
“This once,” I replied, “I’m going to have to lean [back] against the Rover to do it.”
“…[Gene,] you might remember to dust your camera when you’re leaning over the seat,” Parker broke in, remembering Cernan’s recent fall that drove his camera into the regolith surface.
“Let me look at your camera [lens],” I told Cernan.
“Oh, man. If this Rover wasn’t here, we’d roll downhill,” he commented.
“Hey, Bob,” I said. “I think we could use an upper [drive tube] here if you want to save the lowers.” The “lower” drive tubes had the reinforced ends, but I had lost track of what the actual count of the available different tubes might be. I depended on Mission Control to remember those housekeeping details.
“I think so, too,” agreed Cernan.
“Whichever you (Mission Control) want,” I added. “Do you want your [drive tube]?” I asked Cernan.
“No, I’ll get it. Why don’t you get your 500, and I’ll…”
“Okay. But do you want a core [tube]? Watch the fender!” I called as Cernan sidestepped downhill around the front of the Rover. The last thing we needed was to break another fender this far from the Challenger.
“The core’s [drive tube] in there (my seat) isn’t it?”
“Well, there’s some under my seat if you want to use those,” I replied.”
“I’ll use those.”
“Standby, Jack,” Parker requested, finally getting the count on drive tube sections from Ray Zedekar at the EVA console. “We have three lowers and two uppers, so we’d just as soon use the extra lower here in the single core. That’ll give us two uppers and two lowers left for doubles.”
“Okay.”
“There should be a lower in there, Geno.”
“Yeah. Bob, any special place you want that? Just out here on the slope?”
“That’s affirm…
“Should have put the gnomon up,” I thought out loud as I took the 500 mm Hasselblad camera from under Cernan’s seat. “Well, …you don’t have any film to document [with], either.”
“Just [get the core] out there on the slope,” Parker continued. “I guess if you saw a crater you might look at that, …but primarily, we’re looking at the crater.”
“I’ll get it (the gnomon). I’ll get it, Jack. Don’t worry. …We have a couple of dents in our wheels. That’s better than having a flat tire. …Did he say ‘in a crater’?”
“I’m not sure what he said,” I replied. “[I’m] Thinking [the rim area]…” Hypothetically, a core at the rim would give an upside section of the slope layers penetrated by the crater.”
“How do I get this doggone [extension handle] turn to come off [the scoop]?” Cernan struggled with a connector he normally did not have to deal with.
“You got to unlock it.”
“Yeah, it is unlocked.”
“Okay. Now push down and turn.”
“Okay. I got it.”
“How am I going to see up there to shoot this thing (500 mm camera)?” I mused.
“Well, why don’t you lean against the rock?” Cernan suggested. “Go over there and lean against it.”
“Well, I have to do something. I was trying to get so I could lean against the Rover, but that ain’t going to work.”
“The Rover isn’t steady enough for you to lean against.”
“Well, it’s steady enough,” I countered. “There’s just no place to lean.”
“And, Jack, and if you’ll listen for a minute,” inserted Parker, “I’ll tell you some possible 500-millimeter targets the people have in mind: one, the LM, if you can see it from there; two, Nansen, if you can see it from there; three, Lara; and four, Shorty. In other words, I guess they’re talking about looking along your traverse from yesterday. It would be mostly the back shots, apparently. And then, also, the South Massif, and I don’t know what you can get of boulder tracks leading up the North Massif. And most of those will be looking downhill towards the LM, Stations 2, 3, and 4. Over. Nansen, Lara, and Shorty.”
“I got you, Bob.” I was probably thinking that these were unnecessary instructions.
“Yeah, the LM is visible by the way,” added Cernan.
Leaning the back of the PLSS against the uphill side of Block 2 of the Station 6 boulder (Fig. 12. 78 below), I said, “Okay. I got a set of [photos of]…what looks like the outcrop from which the boulder came. …I’m afraid they’re moved a little bit…” Trying to point the camera higher up the North Massif, I added, “No, I can’t; that’s it. I got a few pictures looking up the boulder track and then off to the left a little bit; and one off to the right. And I think… I’m not sure how well they overlap; that’s just an awful hard shot.”
Fig. 12.78. My stance next to Block 2 as I took the 500 mm photographs discussed below. (NASA Photo AS17-146-22294).
Fig. 12.79. Two of my 500 mm photos taken in a northwesterly direction of boulders on the North Massif. The slope is somewhat exaggerated because I must carefully keep my balance by leaning into the slope where I am standing, i.e., lean to my right, as well as brace my PLSS against Block 2 (see Fig. 12.78). As I turn counter-clockwise to take more photos towards the South Massif and finally towards the LM, the apparent tilt of the images changes depending on how much I have to lean into the slope on which I am standing. A high resolution version in a separate window is available here. (Combination of NASA photos AS17-139-21188, -21186).
Fig. 12.80. Two more photos of an area to the right of Fig. 12.79. The large, triangular boulder to the left of center is noteworthy because I targeted it from Station 9 to produce the more direct view in Fig. 12.81 below. Numbers correspond to those in Fig. 12.81. A high resolution, unlabeled version in a separate window is available here. (Combination of NASA photos AS17-139-21190, -21191).
Fig. 12.81. The 500 mm photo from Station 9 of the same group of boulders photographed from Station 6. The image in text is cropped in order to approximate the scale of Fig. 12.80. The numbers indicate a few of the boulders common to both photos picked out visually (angular directions between the two photos can be deceptive to the eye). The reader can view the full frame, higher resolution, unlabeled version for comparison here. (NASA photo AS17-139-21250).
Fig. 12.82. Panorama made from four of the 500 mm images taken in the direction of the light mantle avalanche and Shorty Crater. The contrast has been stretched to bring out albedo differences. A higher resolution view in a separate window is available here. (Combination of NASA images AS17-139-21199, -200, -201, -202).
Fig. 12.83. Two of the photos combined taken in the direction of Shorty Crater (dark raised rim at the base of the South Massif below the obvious boulder). The right edge of the images is obscured in places by dust particles. The blurred object at the lower left in this view and in Fig. 12.84 below is part of the rake head which has been stowed upside down in the geopallet on the back of the Rover. A higher resolution view in a separate window is available here. The boulder track on the South Massif is apparent in the enlarged view. (Combination of NASA images AS17-139-21196 and -194).
Fig. 12.84. A similar view rotated counter-clockwise from Fig. 12.83. The dark Shorty rim is at the upper right edge of the image. Here dust obscuration of the film in the valley floor is absent, but not at the top or bottom. A higher resolution view in a separate window is available here. (Combination of NASA images AS17-139-21206, -207).
Fig. 12.85. The Challenger Lunar Module seen from a distance of ~3.1 km. The brighter surface on which the LM rests was caused by the exhaust plume as we landed. Visible details of the ~7 m high LM, such as the struts, ladder, and docking antenna on top, are a testament to the effectiveness of the 500 mm lens compared with the 60 mm lens in, e.g., Fig. 12.70↑. The two craters, Powell (P) and Mackin (M) are marked by the arrows. They both exhibit extensive concentrations of boulders in the north-facing walls. Geophone Rock is labeled ‘GR’ and the dispersed area of the ALSEP is also marked. A higher resolution, unlabeled view in a separate window is available here. (Combination of NASA photos AS17-139-21204, -205).
Fig. 12.86. Concentrations of boulders on the slopes near the top of the South Massif. The triangular darker area at left containing the boulders may be the remnants of a splatter of impact ejected melt-breccia. The separate window view is available here. (Combination of NASA photos AS17-139-21209, -210, -211).
[500 mm images AS17-139-21186-93 do not show the track in the regolith that leads to the boulders at Station 6. This track, otherwise obvious to us and from a distance, trends across the slope from a source crop about a third of the way up to the North Massif. With more sophisticated comparison with other images of the massif, however, it may be possible to identify the track in these photographs. The images also show the distribution of other boulders across the slope (Fig. 12.79↑, Fig. 12.80↑), including one very large boulder that is visible in images taken from Station 9 (Fig. 12.81↑; AS17-139-21250).
AS17-139-21194-202 in this series of 500 mm images cover the Shorty Crater, Light Mantle, and South Massif areas explored on EVA-2. The shape of Lara Crater under the light mantle avalanche also is faintly visible in these images. As these shots were taken at a low phase angle relative to the Sun, they highlight the albedo differences between and within various features (Fig. 12.82↑). The images also provide a downward perspective on the Light Mantle due to the higher elevation of Station 6 relative to the views we had during EVA-2. 139-21194 and ‑21196 (Fig. 12.83↑) show the sharp contrast between the Light Mantle and the dark ejecta surrounding Shorty Crater and a smaller dark crater to the west. The albedo contrast between Shorty and the Light Mantle is shown even more clearly in AS17-139-21206-7 (Fig. 12.84↑). The absence of any other impact craters large enough to penetrate the Light Mantle is well illustrated by the full series, with the exception of the dark crater near the northwest end of the Nansen Moat. Due to photometric darkening of the slope, these latter images also bring out the northeast-facing wall of the Nansen Moat near Station 2.
Near the left edge of images 21197-202, the darker albedo of the surface of the old light mantle avalanche deposit is clear (Fig. 12.82↑), as is its extension across the images southeast of the younger light mantle avalanche deposit (Chapter 13).
500 mm images AS17-139-21203-5 are centered on the Challenger and its surroundings (Fig. 12.85↑). They highlight better than any other photographs the remarkable, isolated context of our ingenious spacecraft in the valley of Taurus-Littrow. Powell and Mackin Craters beyond the Challenger (Fig. 12.85↑, P, M) make up the western portion of the relatively young Steno-Sherlock-Powell Crater Cluster we visited on EVA-1. Their blocky interiors are characteristic of this group of relatively young impact craters in the valley the ejecta from which also appears to have a unique spectroscopic signature relative to the remainder of the valley’s dark mantle regolith (Chapter 13).
Finally, 500 mm images AS17-139-21208-11 show large boulder concentrations on the upper slopes of the South Massif that may be derived from the splash of impact melt from an unknown source (Cf. the enlarged view of Fig. 12.86 with the enlarged view of Fig. 11.56, which was taken much closer to the South Massif at Sta. 2a).]
“Okay; good on that… And if you’re done with that, have you got a frame count – or, you’re still taking them, I guess, it looks like.”
“Yeah…”
“My camera is clean,” Cernan reported. “Magazine Foxtrot is on about frame 2, and I cycled through it. And I’ve got the core all set, and I’m going to go get it. And I didn’t hear where you said to put it, Bob.”
“Anywhere.” Flight must have told Parker to get us moving, and I was too busy to direct Cernan to the crater rim.
“Oh, man, you’re easy. ‘Anywhere’? Not the bottom of a small crater, huh?” Cernan, at least, remembered that he ought to be geologically selective.
“Any place. And did you get your camera dusted?”
“Yeah. I got it all dusted and the mag’s changed. …It’s core 48 (76001). …Okay. I’ll even get you a picture of it. …Oh me, oh my…” Cernan was having trouble with the drive tube cap. “Can you get the LM from there?” he asked me as I continued to fire away with the 500mm camera.
“Yep.” The Challenger sat about 3.1 km to the south southwest (see Fig. 12.85↑).
“That core went in very easy, Bob.” Cernan had driven the single core into the regolith about 6 m south of the Rover. “I pushed it in about a quarter of the way. And about another five or six whacks, and it’s in all the way. (Long Pause as he takes two pictures of the core tube) Okay. Come on out now, baby.” Cernan’s before images are AS17-146-22291-92 and his after image, showing the core hole, 22295.
Fig. 12.87. The core tube inserted into the regolith near the Rover. (NASA photo AS17-146-22292).
Fig. 12.88. After the core tube extraction, a stable, cohesive hole remains. (NASA photo AS17-146-22295).
[Post-mission examination of the core, 76001, indicated it is quite uniform and distinguished only in that the upper 20 cm has more noritic breccia and less anorthositic breccia fragments than the lower 12 cm. The upper section also appears to have a larger KREEP component than the lower. Minor amounts of basalt and orange ash fragments exist in both sections, indicating only limited mixing of impact debris from the valley floor relative to the down-slope movement of material from the North Massif. Gravity plus impact cratering has a greater effect on particle introduction at Station 6 than does impact cratering alone, as should be expected.
Relative to the surface regolith sample 76501, the core has essentially identical Rare Earth Element concentrations, but they also are low relative to rock samples from the Station 6 boulder.
The Is/FeO maturity index varies from 60 to 90 with a trend upward toward increased maturity from 32 to 8 cm and then a decrease from 8 to 0 cm. This trend indicates a gradual increase in maturation prior to 8 cm, where the index reaches 90, and then a significant reduction, subsequently. There may have been an increase in the rate of new material transported down slope above 8 cm, or the upper 8 cm represents ejecta from the nearby impact crater, both capable of reducing maturity.]
“Okay, Bob. [Photographs of] Shorty, and Station 3, and Station 2, and what else?”
“And any sort of outcrop you see in the South Massif,” suggested Parker.
“I thought we shot those,” I responded.
“Okay. If you got those, fine.”
“No, I mean the other day (EVA 2).”
“Well…”
“I’ll try again.”
“Stereo is stereo is stereo, I guess.” Parker may have lost an argument with the Science Back Room.
“Well, but it’s not stereo; it’s right along the same line,” I added. Also, the difference in resolution would be significant. (Cf. the slopes of the boulder groups in the enlarged view of Fig. 12.86 with those in the enlarged view of Fig. 11.56. The latter was taken much closer to the South Massif at Sta. 2a, as noted, so the angles looking towards the massif top are quite different.).
“Okay, and I got you a…little soil mechanics of the hole,” Cernan continue his discussion of the core, “which stayed intact; very nice and round.” (Fig. 12.88↑).
“Okay!” Cernan exclaimed, panting, as he reached the Rover after a short climb from the drive tube core site, directly below.
“Oh, man!” I also exclaimed, as I finished the 500 mm photography. “My hands have had it. You aren’t going to get anything else out of me if I keep taking pictures.”
“Yes, sir, we got a couple of dented tires!” noted Cernan, again.
“Okay; good enough,” Replied Parker. “And, Gene, what’s a ‘dented tire’?”
“A dented tire is a little, oh, a little golf-ball size or smaller indentation in the mesh. How does that sound to you? Doesn’t hurt anything.”
“That sounds like a dented tire,” Parker joked. “That’s how it sounds.”
“That’s sort of like what it is…”
“Frame 31 [on the 500 mm magazine], Bob,” I reported. “LMP [camera] was what? 120? I guess we can get to the next station with that.”
“Yeah, I got a brand new mag on,” Cernan agreed.
“And we’d like to get you guys rolling as soon as feasible there.” Parker stated the obvious, again.
“Yes, sir. It’s our policy,” I responded.
Cernan had begun to finish up on the drive tube, first taking it off the extension handle. I came over to him to assist. “Okay. I’ll need your rammer, so if you’ll just turn right. …Good timing. Pin’s out; core tube is safe,” he joked, “…and full! I knew it was.”
“Okay. You take this [core sample] and put this under your seat, if you want, Jack. And I’ll get the TGE. …Oh, let me put your shovel (scoop) back on [the extension handle] for you. I’ll get it.”
As I went to my seat with the core tube, I admonished Cernan, “Don’t lose that [scoop]. [Without it,] I wouldn’t know what to do. …Okay. Did you give them the [core tube] number?”
“Yeah, they got the number.”
“[Core is] under the LMP’s seat.”
Cernan laughed as he slowly worked his way down to where he had set the TGE. “I’m sneaking up on the TGE.”
“You need some help?” I asked.
“No. No, I was just ‘sneaking up’, that’s all.” Cernan was making a joking reference to John Young’s effort to collect an uncontaminated sample by, and Charlie Duke referred to it, “sneaking up” on it.
“[I’ll] come and let you lean on me,” I offered, suspecting that the slope would make it difficult to read the TGE screen.
“No, I got it. 670, 109, 801; 670, 109, 801.
I suddenly thought of something. “I wish we… The one thing I didn’t do. While you’re doing that [picking up the TGE]…”
“What didn’t you do?
“Didn’t get pictures of those foliated vesicles. I don’t think the ones (photos) you had were in that kind of rock…” I moved over to block 2 and took several photographs of the foliation formed by the large, flattened vesicles. The foliation gave clear evidence that the light-gray impact melt-breccia initially flowed along its contact with the blue-gray breccia. Enough back-scattered light existed in the block 2 west facing shadow to get these shots.
[Size frequency analysis of the vesicles imaged in these photos (AS17-141-21628-30; Fig. 12.39↑) probably would indicate that there are two generations of vesicle formation. The large, flattened and irregularly shaped vesicles may have formed when the impact melt-breccia was less viscous and in motion and volatile migration was relatively easy, while the small, roughly spherical vesicles and chains of vesicles formed after motion had largely stopped and cooling had progressed.
After taking photos in shadow, I took four photos (AS17-141-21631-4) of the boulder in sunlight, presumably to show the contrast (Fig. 12.89 below).]
Fig. 12.89. Having taken the photos of the vesicles on the shadowed west face of Block 2, I moved downslope and into the gap between blocks 2 and 4/5, and took four photos of Block 3 in the sunlight under the overhang of Block 2. Three of them are assembled here. A higher resolution version in a separate window is available here. (Combination of NASA photos AS17-141-21631, -632, -633).
“I don’t want to lose that thing (the TGE) [off the Rover], so I guess…” Cernan made sure he fully fastened the TGE to the back of the Rover.
“Okay, 17, when you get back on [the Rover] here, we don’t need any charges, and we’ll leave the SEP turned off.”
“I’m not sure… Did you turn it OFF, Gene?” I verified.
“Yeah, I turned it OFF,” Cernan replied but checked it again to be sure. “I turned it OFF. Okay. Let me see,” he continued as he checked his Cuff Checklist while standing facing the Rover gate. “We want to move on to [Station] 7 here. Rake; talus; documented core; you got your stereos; we got two pans; TGE; camera. …Okay, we’re going to head east and look for Station 7: [check] block variation; [subfloor] contact change; and get a different sample of rocks. Okay, I sure want to get one or two of those nice ones in the Big Bag while you’re over there.”
“Open the gate,” I said, still over near block 2, “and I’ll bring one.” We had placed the Big Bag behind the gate at the start of EVA-3.
“Seven[teen]…,” Parker began then changed his mind. “And let me know when you get ready to get back on the Rover there, 17.”
“Guess what isn’t opening again. …[It] should, though. It’s all set right.” Dust had become a permanent problem with the gate latch.
“You could put them under Jack’s seat if it’s easier,” Parker suggested.
“Okay. What do you want done to the SEP while I’m here? Do you want the blanket left OPEN?” Cernan asked.
“Negative. We’d like the blankets CLOSED and taped down again, if possible, and both switches left OFF. We won’t touch it again until Station 8.”
“Oh, the tape’s not going to stick anymore, I’m afraid.”
“Well, try,” Parker ordered, unnecessarily.
“Big Bag open?” I asked.
“Yeah, it’s all open. All set.” I put this 6.4 kg, light gray breccia sample (76055) in the Big Bag.
Fig. 12.90. (Upper): Laboratory photo of the light gray breccia sample 76055. Note a number of zap pits (dark spots surrounded by light halos) over the exposed surface. Some vesicles are apparent at lower left underneath the upper surface; and small, irregularly-shaped dark and light clasts can be seen in the underneath middle to lower right. (NASA photo S73-15717). (Lower): Anaglyph of the same view made from a convergent stereo pair. The 3D structure of the sample, particularly on the left and at bottom, is apparent. A larger scale anaglyph is available here. 3D areas of interest can be further enlarged by clicking on the area. (Derived from NASA photos S73-21458, -21458B).
[Post-mission examination found 76055 to be a relatively homogeneous melt-breccia with minute mineral clasts. Lenticular, small, en echelon vesicles of varying concentrations give a variable and curving foliation through the rock. This texture to the vesicles suggests that there were streams of vesicles moving upward through the impact-generated melt. Larger rock clasts in the very finely crystalline matrix consist of meta-troctolite (plagioclase+olivine), crushed dunite (olivine), crushed anorthosite (Ca-plagioclase), and impact melt rock. The matrix consists of about 10% Ca-plagioclase and olivine crystals in a sub-matrix of intergrown orthopyroxene and plagioclase. This predominantly Mg-suite breccia has measured 40-39Ar ages of 4.01 ± 0.05, 4.08 ± 0.07, and 4.00 ± 0.04 billion years and a Rb-Sr isochron age of 3.78 ± 0.04 billion years. 76055, however, appears to be texturally and compositionally distinct from the light-gray breccia in Blocks 2 and 4.
Reported cosmic-ray exposure ages for this sample, 125, 120 ± 15, and 140 million years, are significantly older than those for the Station 6 boulder, indicating that it came down from the Massif, or thrown from some other location, on the order of 100 million years earlier.]
“I need a normal sample bag for one (additional sample) here,” I added. “It’s pretty fragile.”
“Okay. …Oh, that doggoned thing’s (SEP cover) not going to [stay closed]. …That tape is full of dust now. …Okay. Wait a minute, Jack.” Future missions might carry a suite of elastic bands to deal with problems like this.
“Here, let me get this big one (meaning 76055). I’m about ready to drop it. …It looks like a gabbro.” I continued to use the “gabbro” terminology I started even though I knew it to be confusing. Sometimes consistency helps in communication.
“Here’s sample bag 560 (76335).”
“And 560 has an undocumented, except by the pans, very white [rock]. … [It] looks like a crushed anorthosite. It looks like some of the inclusions in the breccia…[that is, the light] gray, re-crystallized breccia.”
Fig. 12.91. A tray containing pieces of the white rock sample 76335 (see discussion below). It was picked up near where I obtained the rake samples of which the largest rock was the troctolite 76535 (Fig. 12.75↑). 76335 was highly fragmented by the time it was returned to the Lunar Sample Lab. (NASA photo S73-19384).
[Sample 76335 is reported to be a highly crushed, but apparently pristine, troctolitic rock with significant plagioclase, olivine, orthopyroxene and small amounts of merrillite (phosphate), chromite, high Co iron-metal (not meteoritic) and keiviite-Y (REE-rich yttrium silicate). The plagioclase, olivine and orthopyroxene are relatively coarse-grained. A Sm-Nd date of 4.278 0.060 billion years suggests that this material may have been associated with Mg-Suite magmatism; however, that association appears to have been complicated, given the unusual mineralogy.]
“Jack, when you get around [here], and we close this gate, you might try and hit that top of that SEP down again.”
“I will…”
“Hey, Bob, you’re staying keyed (on transmit) an awful long time,” Cernan alerted Parker that he had a foot on his floor switch. “We can hear a lot of what’s going on back there. …[Jack,] wait a minute. Let me get this [Big Bag] out of the way. …Okay. Close it. ….Yeah. That’s got it.”
“Okay, that’s tight,” I said, giving the gate a tug.
“That’s got it. Okay.”
“Oop, oop, oop. Why’d that come off [the gate]?” I wondered as an extension handle came loose from the gate.
“Well, because it’s (the gate) not locked. It’s [seems] that never was locked.”
“We lucked out,” I laughed. Had the gate come loose, we probably would have lost several tools.
At this point, Cernan took two photographs of me standing by the downhill side of the Rover. In addition to showing many aspects of the vehicle that carried us across Taurus-Littrow, they show why later I decided not to try to climb into my seat while on this steep slope.
Fig. 12.92. A view of the Lunar Rover at Station 6 with me standing on the downhill side of the vehicle. From right to left, the rake, sample scoop, and seismic charges are in the geopallet behind Cernan’s seat. Behind my seat is the SEP receiving antenna. The rod between the SEP antenna and me is the collapsed gnomon. The u-shaped bar from the floorboard next to Cernan’s seat is a hand hold. On my side, it is a useful tool for hopping onto my seat (except in this instance on a steep slope), and also holding on as the LRV bounces through craterlets. The T-shaped hand controller can be seen next to my SCB in front of the console which holds the navigation instruments. The rod leaning toward me with the L-shaped handle is my LRV sampler that I use to lean out and scoop up rocks during a traverse. Lastly, the cylinder with holes around the base is the omni-antenna. Note that my gold visor is raised and that my facial features are visible (see excerpt below). (NASA Photo AS17-146-22296).
Fig. 12.92a. A crop from the previous photo showing my face more clearly. I was contemplating how I might climb up into my steeply sloping seat.
“Okay. We’re moving (hustling),” Cernan said to placate a nervous MOCR.
“Sort of,” I corrected.
“And, before you get on,” Parker inserted, “remember to close the battery covers if they [haven’t been closed, yet.]”
“Yeah.”
As I draped my seat belt over the SCB on the Rover to be sure I could grab it without it getting twisted, I said, “Your camera lens looks all right, Geno?”
“Yeah, I dusted it already.”
“Oh… Okay. [SEP] Cover CLOSED, [they said]. …Okay. Do they want it ON or OFF? Leave it OFF, huh?”
“OFF,” Parker responded.
“Leave it OFF, but try and close that cover as best you can,” Cernan added.
“Well, I’m afraid the tape has had it,” I lamented.
“I know it.”
“You want us to tape it again, Bob?” I asked. …[Gene,] what did you do with the tape?”
“If you can grab the tape right off,” Parker said, “but don’t spend a lot of time on it.”
“What did you do with that tape?” I repeated.
“Let’s worry about it at Station 7,” Parker suggested, “if we’re going to worry about it. Press on.”
“Okay.”
“Yeah. Let’s forget it now,” Cernan agreed. “It’s too hard to work on here [on this slope], and it’s not going to take just a minute. It’s going to take too much time.” We are both sounding physically and mentally tired from the effort of working on this slope.
“I’m not sure I can get back on [the Rover] here,” I said as I looked up at my seat on the Rover, rolled about 20 degrees toward me. It was easy getting off, “like falling off a log”, but getting back on was another thing entirely.
“Well, let me give you a hand,” Cernan offered.
“We need any a… We don’t need any [thing else]?” I asked. I looked down to the east in the direction of what would become Station 7, thinking that I would be better off just “skiing” to it. Meanwhile, the Flight Controllers had a chance to see my face on TV with the gold visor up.
“No.”
“Nothing? As a matter of fact, [I may walk],” I concluded. Station 7 lay about 455 m and partly downhill from Station 6.
“I can drive, Jack.”
“Why don’t you drive down and get so you’re not [at such a tilt]. …You can get on, [but I can’t].”
“You can go (walk) downhill very easy,” he agreed.
“Yeah.”
“Okay. Let me get the TV. The battery covers are CLOSED.”
“Let me carry… I’ll carry the Rover sampler, just in case,” I told him.
“Why don’t you just go down there.”
As I reached across my seat for the sampler, Cernan said, “Got it? Okay. I’ll get that [SCB] out of your way, too.”
“Okay. I’ll head down to that [big boulder]. …Actually, I’ll side-hill over to those boulders right over there and then see if that’s any change [in rock type].” Saying this, I started to leave.
“Okay. You might… If you get another sample, a large sample, you might grab it, and we’ll throw it in the footpan here. …And I’ll see if I can’t find a level spot to [pick you up].”
With a second thought, I stopped short of leaving and said, “I sort of ought to have my scoop, too.”
“[I still could] help you get on. No, don’t take too much; just take that [LRV Sampler]. That’s all you need.”
“How about letting me have your hammer, then?” This field geologist felt incomplete before setting out on a long traverse without sampling gear.
“Okay; and, Seventeen,” broke in Parker. “Can you verify that the gnomon is back in the Rover?”
“Gnomon is on the Rover. The TGE is on the Rover,” reported Cernan.
“The rake?” I asked as I moved rapidly away.
“The rake is on the Rover. The scoop’s on the Rover. We got the [core]. …You put the core under your [seat] pan, right?”
“Yep, that’s right.”
“Okay. I’m going to power up and see if I can’t come down and get you… [I’ll bet] it’s fun walking downhill! Boy, that boulder track is impressive – very symmetrical.”
“Okay; and, Seventeen, when you get moving, …we want to get, and I quote, ‘a maximum variety of hand samples with a minimum amount of documentation, in a minimum amount of time at Station 7’. It’s just an attempt to see what kind of variety we can get along the face of the front. Over.”
“Roger. …Okay. Well, I’m not sure I can get on without ending up in your seat.”
“Need some help?” I asked, hoping that I would not have to climb back up hill.
“No.”
“I shouldn’t have left.” Indeed, moving so far apart violated the “buddy” rule of always being able to help each other.
[I am surprised that Slayton had not said something, but my spur of the moment plan to walk to Station 7 may have not been clear to anyone other than Cernan. An experience coming up at Station 8 emphasizes how much of a mistake this was not to wait until Cernan was securely on the Rover.]
“No, no. I don’t need any help. I’ll get on. …I probably ought to turn my water off of MAX if that’s where it is. It’s cold. I don’t want to run out today. …Well, the roll indicator says 15 degrees; and the pitch indicator says about 12. I don’t know if I believe all that. Bob, you with us?”
“Go ahead. Right. We’re with you.”
“Okay. I’m rolling. …Man, this is still a slope. Jack, I’m going to pull around and in the front of the way you’re facing.
“I can go down. …There’s a crater over here, [where you might park]. …Oh, there you are.” Cernan had come up behind me.
“This is much better. How is this?”
“That’s great.” The Rover was level enough for me to get into my seat.
[In 1960, I had badly strained the inside left knee ligament while skiing on Mount Washington in Vermont with John Miller, an outstanding, young Harvard professor of geomorphology. (Miller later died of bubonic plague he contracted during field work near Santa Fe, New Mexico. Modern Boston doctors did not diagnose the disease, whereas, had he stayed in New Mexico, where the plague is endemic in various rodents and coyotes and occasionally contracted by humans, he probably would have lived.) During this run across the slope of the North Massif, that leg remained bent on the uphill side, increasing the stress on the knee. The tiredness I felt in that ligament during this run was the first time in twelve years that I had ever felt the effects of the injury.]
“We ought to be able to pick up lots of those fragments out in that field out there,” observed Cernan.
“Be right with you.” I had found an interesting sample to work on.
“Okay. …Bob, I just came down-slope reading 193/3.1; [I moved] just about 100 meters to pick up Jack.”
“Okay. Bag 48 Yankee (76030-37) has a sample of about a one-third-meter boulder that was lying in…that’s sitting right smack dab in a little crater of it’s own.” I may have snapped off an unreported, down Sun, stereo pair of this rock (AS17-141-21635-6), as such a pair exists between my last photos of Fragment 2 and my first traverse photos. When viewed in stereo, the boulder appears to be in a small crater about 6 times the width of the boulder.
Fig. 12.93. One of the pair of photos referred to in text showing the boulder lying in a shallow crater . The photos were taken down-sun, increasing the brightness by back-scattering. The image shown in the figure was contrast stretched to bring out the details. Footprints at right obscure some of the crater rim. Note also the slope as exemplified by its appearance in the upper left corner of the photo. (Modified from NASA photo AS17-141-21635).
[Post-mission examination of 76030-37 has been limited. Besides the regolith collected with the sample, 76031, the main fragment of the sample, 76036, has been described as another complex polymict (multiple types of clasts) breccia with a vesicular, aphanitic (very finely crystalline) matrix. A fragment, 76037, in the regolith portion of the sample consists of basalt, probably ejected from the subfloor.
Regolith sample 76031 has an intermediate-high Is/FeO maturity index of 64. Its Rare Earth Element concentrations resemble those of 76501 in also being several factors lower than found in the Station 6 boulder.]
“Oh, Jack!” Cernan exclaimed, as I kick up my left leg to get into the Rover seat.
“What?”
“Oh, you just kicked a snowstorm of dust across here.
“I’m sorry. I just fell, too,” I explained. I also missed the seat on my first try.
“Did you? You all right?”
“Yeah. Want your hammer?”
“Yeah. …I got to drop it (the hammer) in the pan here. Hold on to it, I think…”
“Couldn’t help that one (fall),” I said.
“Yeah. I think, [when] we get some more level spots, I can dust this thing (battery cover) back there.”
“Am I really on?” I asked, feeling that something wasn’t right with attaching my seat belt.
“You’re high. You’re [seat belt is] twisted. Go away from you one twist. Okay. …Is it caught in something? Yeah, it is. You’re… Oh, wait a minute. Get up, get up, get up. You’ve got…you’re sitting on…get up.” Cernan was trying to get me to arch my back so that I was off the seat.
“What am I sitting on?”
“You’ve got to get out. You didn’t put this [Rover Sampler; Fig. 12.92↑] away [before you got on]. Wait a minute. Get up. …Out. …All the way.” He now wanted me to get back off the Rover and take the Sampler off my yoyo attached to my left side.
“Oh, that thing.” I finally realized that I had forgotten that I had attached the Rover Sampler to the yo-yo on my left hip.
“Yeah, this thing.”
“That’s right.”
“That’s why you’re setting high,” Cernan explained.
“I knew I’d forget that [Sampler].”
“Okay. Now, let me get this thing out [from under you]. Okay…”
“Okay. Let’s press,” I said. “Better get [the seatbelt] latched. …Okay.”
“All set?” Cernan asked.
“Yep.” The time lost because of this lapse on my part could never be recovered.
“We’re rolling, Bob.”
“LMP frame [count] is 130.”
“You got a lot of static now?” Cernan asked me.
“Yup.”
“Okay.”
“Hey, you got a rock on your right of your [right wheel].”
“Yeah, I got them. …I got the low-gain [antenna] set.”
“Hello, Houston,” I called. “Do you read?”
“Roger. We read loud and clear.”
[I took traverse photos AS17-141-21637-45 on the way to Station 7. All the images appear tilted to the left, probably because I was pulling myself left and away from the right slope of the Rover. The first of these images is a view of the East Massif that again shows the apparent cliff and slope structure of that cross-valley feature discussed above. The other images are of Wessex Cleft, the area of Station 8, or the boulder field that includes the Boulder at Station 7. The shadowed outline of the Station 7 boulder appears at the right edge of the last image and in several more distant earlier images.]
Fig. 12.94. The first of my photos as we started our traverse to station 7. The East Massif appears across the valley (bearing was 193 when I got on the LRV). The layering in the East Massif described in the discussion with Fig. 12.70↑ is quite clear in this photo, especially the enlargement linked in a separate window. Shakespeare is the large crater appearing just beneath the first line of three reseau crosses at the top of the image. Part of Henry is at the right edge marked by the 4th cross in that row. The line-of-sight distances to the small hill right of center in front of the massif is ~15 km, while that to the outcrop boulders at the top of the massif just above is ~19 km. (NASA photo AS17-141-21637).
Fig. 12.95. We then turned more toward Station 7 entering a field of many boulders. The view here is to the northeast. Wessex Cleft is the dip to the left, rising up to part of the Sculptured Hills at right. Note the patterns or lineaments of what may be lines of relatively small boulders along shattered layers in the Sculptured Hills. (NASA photo AS17-141-21638).
Fig. 12.96. Continuing to the right of the previous view, the moderately large boulder beneath the central reseau mark is the same as that on the middle right of Fig. 12.95 above. (NASA photo AS17-141-21639).
Fig. 12.97. We are headed in a more northerly direction weaving around craters as we approach the Station 7 boulder. The large boulder at the right edge of the photo is north-northwest of the Station 7 boulder and can be seen in the next figure and in Cernan’s Pan 24 in the next section. (NASA photo AS17-141-21643).
Fig. 12.98. This view is the last of my traverse photos. The Station 7 boulder is at the right edge of the photo, and the large boulder of Fig. 12.97 appears in the center of this photo just under the central reseau mark. (NASA photo AS17-141-21645).
“Okay. …How about that field [of blocks],” I said, calling his attention to a significant collection of boulders in the distance. “Not this block [close in], but [out where] there’s sort of a collection of there…way out there.” (Fig. 12.95↑, Fig. 12.96↑)
“[Way out there] about 300 meters or so?”
“Oh, at least. Yeah. …Oh, going into the Sun, I can’t see a thing to tell you about Wessex Cleft, that we haven’t already said.
“Station 7 is nominally 208 and 3.3,” updated Parker, “but it’s any group of any significant boulders you want to stop at in reality.”
“Understand. …Ohhh, easy,” I admonished Cernan as he hit a small crater with me still leaning steeply downhill.
“You feel like you’re on a down-slope over there?”
“Yeah. I feel like you’re about ready to spin out downhill any minute.”
“Do you?” Cernan said as he slowed down a little. “I don’t feel that at all up here…”
“Bob, it’s hard to give you much [on the terrain],” I said, ignoring Cernan’s kidding, “looking into the Sun the way we are.”
“We must be about 200 meters up the slope, looking at that little valley (swale) down there, Jack, on the right?”
“Yeah. I think you’re right. The pattern on the slope really doesn’t look much different than on the light mantle. Matter of fact, it looks very much like light mantle, except for these large blocks that are in it.” This observation is not surprising, as the light mantle we traversed on EVA-2 consists of an avalanche of similar regolith off the side of the South Massif, with large boulders probably having drifted to the base of the avalanche.
“Okay. Copy that. And you guys may still have your visors up. We can’t tell, but you might be better off with them down, if you’ve forgotten that they’re up.”
“Well…boy, I can’t see. My hands work just as well as my visor [as an eye shade], as a matter of fact.” I kept the lower edge of my scratched and dusty gold, UV visor at about eye level and used my right hand for additional shading. As the space suit had a detent in which I could rest my arm at shoulder height, keeping my hand up as a shade did not take significant effort. Due to the slope to the right, my left hand had a grip on a bar projecting from the console.
“No, I can’t believe mine could be up,” Cernan commented.
“You’ve got a crater right in front of you,” I warned.
“Yeah. I got it.”
“Okay. That [bunch of boulders] looks like a pretty good pile to work on,” I said, pointing slightly to my right toward a group of boulders with one particularly larger than the others.
“Yeah. Let’s go over in there.”
“Hey, wait a minute.” Something had caught my eye for a second. “…Okay.”
“Bob, what heading are you going to want me to park on?” Cernan asked Parker. “Why don’t we get in that flat area, Jack, so I can dust the radiators.”
“Yeah.”
“We have no constraints, Gene. This is going to be a very short station – probably not more than 10 or 15 minutes. Just to grab, as I say a maximum variety of hand samples with a minimum amount of documentation and a minimum amount of time.” Little did he know!
“Okay. We do a pan, and pick up a lot of those small ones, Jack.”
“Yep.”
“Rather than trying to chip…”
“We would like to have the TV camera and its mirrors and stuff dusted there, however,” Parker said, “but we won’t do anything to the battery.”
“[How about here?]”
“I’d like to see us a little more level,” Cernan replied.
“I thought you were going to stop back there.”
“I was going out here around this big one (boulder).”
“I’m sorry. I misunderstood you.”
“Yeah. …See, there’s a lot of little ones (rocks) up in here I want to [pick up]. …Okay. Do not do anything to the batteries. Understand.”
“I can’t figure out where you’re going to stop.” I was ready to get off and go to work, but Cernan kept moving from one place to another.”
“Right in here. Right here to give you as much of a level spot as I can. That’s about as level a spot as I can find. I’m inside the slope of a crater. Bob, I’m at 200/3.3.”
(Continue to Section 2⇒)
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In the quoted dialog and annotation directly related to the Apollo 17 Mission, black = normal mission activity and commentary; red = anomaly discussions; blue = Earth observations, brown = Lunar Module Challenger discussions; green = Public Affairs Office transcripts or news updates from Mission Control; purple = lunar observations; italics = onboard recorder transcripts (Data Storage Equipment or Command Module DSE and Data Storage Electronics Assembly or Lunar Module DSEA); and turquoise = probable dialog derived from the author’s memory, checklist requirements, or logical inferences.
In addition, parentheses (-) in the text are used to clarify the meaning of a preceding word or phrase. The use of text inside brackets [-] provides completion of an unspoken or unrecorded transcript thought. Brackets [-] enclosing letters or words quoted from a checklist complete abbreviated words to clarify what the word in question means. Also, double-indented paragraphs that set off explanatory details are enclosed in brackets.
The CMC (Command Module Computer) commands are referred to occasionally in text as Pxx (Program i.d. number), Nounxx (data specification), or Verbxx (action number) to be carried out by the CMC when entered by hand. ↑
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Müller, P. M., and W. L. Sljogren, 1968, Masscons: Lunar mass concentrations, Science, 161, 680-684. ↑
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Zuber, M. T., et al., 2013, Gravity field of the Moon from the Gravity Recovery and Interior Laboratory (GRAIL) mission, Science, 339, 668-671. ↑
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Jones, E. ALSJ, Apollo 17, Preps. for EVA-3 between GET 160:47:00 and 160:47:12. ↑
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Jones, E., ibid.: ALSJ, Apollo 17, Preps. for EVA-3 between GET 160:47:00 and 160:47:12. ↑
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Low, G. M., 1967-1970, Personal Diary, Archives of Rensselaer Polytechnical Institute, Troy, NY. ↑
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Kraft, C. C., Flight, Dutton, New York, 371 p. ↑
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Cernan, E. A.,and D. Davis, 1999, Last Man on the Moon, St. Martin’s Press, New York, p. 277. ↑
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Cernan, E. A., and D. Davis, 1999, Last Man on the Moon, St. Martin’s Press, New York, p. 287-290 ↑
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Kraft, C. C., Flight, Dutton, New York, p. 347. ↑
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Kovach, R. L., et al., 1973, Lunar Seismic Profiling Experiment, Apollo 17 Preliminary Science Report, NASA SP-330, p. 10-4 to 10-6. ↑
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Jones, E., 2015, Apollo Lunar Surface Journal, Apollo 17, GET 163:27:48. ↑
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Schmitt, H. H., Petro, N. E., Wells, R. A., Robinson, M. S., Weiss, B. P. and Mercer, C. M. (2017), Revisiting the field geology of Taurus-Littrow, Icarus, 298, 2-33. ↑
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Walker, R. M., et al. (Part A) , Woods, R. T., et al. (Part B), and Price, P. B., and J. H. Chan (Part C). 1973, Cosmic Ray Experiment. Apollo 17 Preliminary Science Report, NASA SP-330, p. 19-1 to 19-19. ↑
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Walker, R. M., et al. (Part A) , Woods, R. T., et al. (Part B), and Price, P. B., and J. H. Chan (Part C). 1973, Cosmic Ray Experiment. Apollo 17 Preliminary Science Report, NASA SP-330, p. 19-1 to 19-19. ↑
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Fisk, L. A., 2013, personal communication. ↑
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One purpose of this Diary lies in the integration of field observations with post-mission examination and analysis of the returned samples. In this effort, the author has drawn heavily on the extraordinary compilation work of the Lunar Field Geological Experiment team (Wolfe, E. W., et al., 1981, The Geologic Investigation of the Taurus-Littrow Valley: Apollo 17 Landing Site, U. S. Geological Survey Professional Paper 1080, US Government Printing Office, 279 p.) as well as that of the Lunar Receiving Laboratory (Meyer, C., 2012, The Lunar Sample Compendium) and the Lunar Sourcebook (Heiken, G. H., et al., 1991, Lunar Sourcebook: A Users Guide to the Moon, Cambridge University Press, Cambridge, 736 p). Specifically for Apollo 17 regolith samples, the work of Korotev and Kremser (Korotev, R. L., and D. Kremser, 1992, Compositional variations in Apollo 17 soils and their relationships to the geology of the Taurus-Littrow site, Lunar Planetetary Science Conference 22, 275-301) also has been used extensively. For the reader interested in details about specific samples, these references provide key information to the official sample numbers given in the text of this book. Some sample data may not have been included in these four compilations. In that case, specific references to the relevant literature are given. Also, original Rb-Sr age determinations made prior to 1985 have been reduced by factor of 0.979 due to a subsequent change in accepted time constant for 87Rb decay (See Heiken, et al., 1991, Lunar Sourcebook, Cambridge University Press, Cambridge, Table 6.9, p. 229). Similarly, 39-40Ar ages determined prior to 2008 have been increased by a factor of 1.0065 (See Kuper, K. F., et al., 2008, Synchronizing rock clocks and Earth history, Science, 320, 500-504). It should be noted that, before the advent of laser microprobe enhanced targeting of very small portions of samples, isotopic ages of impact melt-breccias risked including isotopic contributions from clasts of significantly older ages than the crystallized melt. (See Mercer, C. M., K. E. Yound, J. R. Weirich, et al., 2015, Refining lunar impact chronology through high spatial resolution 40Ar/39Ar dating of impact melts, Science Advances, 1, DOI: 10.1126/sciadv.1400050.) Earlier, less precise age determinations, therefore, probably are biased, toward older ages. ↑
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Is/FeO maturity indexes are a measure of the ratio of nano-phase free iron to the FeO content of a lunar regolith sample (Morris, R. V., 1978, The surface exposure (maturity) of lunar soils: Some concepts and Is/FeO compilation, Lunar Science Conference 9, Geochimica et Cosmochimica Acta, Supplement 10, p. 2287-2297). Maturity indexes can be found at Meyer, C., 2012, The Lunar Sample Compendium and in Heiken, G. H., et al., 1991, Lunar Sourcebook: A Users Guide to the Moon, Cambridge University Press, Cambridge, p. 320. For generalized comparison of different soils, the author has defined the following breakdown in maturity indexes:
Relative Maturity Is/FeO Maturity Index
Low 0-20 Low-intermediate 21-40 Intermediate 41-60 Intermediate-high 61-80 High 81-100 -
Morris, R. V., 1978, The surface exposure (maturity) of lunar soils: Some concepts and Is/FeO compilation, Lunar Science Conference 9, Geochimica et Cosmochimica Acta, Supplemennt 10, p. 2287-2297. ↑
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Schmitt, H. H. (2014) Apollo 17: New insights from the synthesis and integration of field notes, photo-documentation, and analytical data. LPSC 45, Lunar Planetary Inst. Abstr. ↑
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Woofe, E. W., et al., 1981, The Geologic Investigation of the Taurus-Littrow Valley: Apollo 17 Landing Site, USGS Professional Paper 1080, p. 125. ↑
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Schmitt H. H., Petro N. E., Wells R. A, Robinson M. S., Weiss B. P. and Mercer C. M. (2017) Revisiting the field geology of Taurus-Littrow. Icarus, 298, 2-33. ↑
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Throughout the text, many of these “copy that” transmissions have been dropped to tighten the flow of the dialogue. ↑
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Although we did not refer to the five largest fragments of the boulder at Station 6 by the number scheme given by Wolfe et al. (USGS PP 1080), that scheme is used in the text to clarify which fragment Cernan and I refer to at various times and to make clear where samples were taken. ↑
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Morris, R. V., 1978. The surface exposure (maturity) of lunar soils: Some concepts and Is/FeO compilation, Lunar Science Conference 9, Geochimica et Cosmochimica Acta, Supplemennt 10, p. 2287-2297. ↑
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Wolfe, E. W., et al, 1981, The Geologic Investigation of the Taurus-Littrow Valley: Apollo 17 Landing Site, USGS Professional Paper 1080, p. 130-135. ↑
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Morris, R. V., 1978, The surface exposure (maturity) of lunar soils: Some concepts and Is/FeO compilation, Lunar Science Conference 9, Geochimica et Cosmochimica Acta, Supplemennt 10, p. 2287-2297. ↑
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Meyer, C., 2012. The Lunar Sample Compendium, 76240. ↑
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Keith J. E., et al, 1974, Determination of natural and cosmic ray induced radionuclides in Apollo 17 lunar samples, Lunar Science Conference 5, p. 2121-2138. ↑
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Rancitelli L. A., et al., 1974. Solar flare and lunar surface process characterization at the Apollo 17 site, Lunar Science Conference 5, p. 2185-2204. ↑
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Durrani S. A., K. A. R. Kazal. and A. Ali (1976) Temperature and duration of some Apollo 17 boulder shadows. Proc. 7th Lunar Sci. Conf., p. 1157-1177. ↑
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von Guten H. R., et al. (1982) Low temperature volatilization on the Moon. Lunar and Planetary Conference 13, Journal of Geophysical Research, 87, p. A281. ↑
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Feldman, W. C., et al., 2000. Polar hydrogen deposits on the Moon. Journal of Geophysical Research, 105, 4175–4195; Colaprete, A., et al., 2010. Detection of Water in the LCROSS Ejecta Plume”. Science 330 463–468. ↑
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Wolfe, E. W., et al., 1981, The Geologic Investigation of the Taurus-Littrow Valley: Apollo 17 Landing Site, USGS Professional Paper 1080, Fig. 153, p. 130. ↑
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Wolfe, E. W., et al., 1981, The Geologic Investigation of the Taurus-Littrow Valley: Apollo 17 Landing Site, USGS Professional Paper 1080, p. 122-125. ↑
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Schmitt H. H., Petro N. E., Wells R. A, Robinson M. S., Weiss B. P. and Mercer C. M., 2017. Revisiting the field geology of Taurus-Littrow. Icarus, 298, 2-33. ↑
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Hartmann, W. K., 2019. History of the terminal cataclysm paradigm: Epistemology of a planetary bombardment that never (?) happened. Geosciences, 285, p.1-77. doi.10.3390./geosciences9070285. ↑
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Schmitt H. H., 2003. Apollo 17 and the Moon, In: Encyclopedia of Space and Space Technology, H. Mark, ed., Wiley, New York, pp. 46-48. ↑
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Wolfe, E. W., et al., 1981, The Geologic Investigation of the Taurus-Littrow Valley: Apollo 17 Landing Site, USGS Professional Paper 1080, Fig. 158, p. 134. ↑
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Wolfe, E. W., et al., 1981. The Geologic Investigation of the Taurus-Littrow Valley: Apollo 17 Landing Site, USGS Professional Paper 1080, p. 127-128. ↑
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Shearer, C. K, P. C. Hess, M. A. Wieczorek, et al., 2016. Thermal and magmatic evolution of the Moon, in B. L. Jolliff, et al., eds., New Views of the Moon, p. 365-518. ↑
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Borg L. E., Gaffney A. M., and Shearer C. K. (2015) A review of lunar chronology revealing a preponderance of 4.34 – 4.37 Ga ages. Meteor. and Planet. Sci. 50, 715-132 ↑
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Schmitt, H. H. (2016) A continental-scale Procellarum impact’s potential relevance to many unresolved issues of lunar and terrestrial history. Annual meeting, Geological Society of America, (abstract) ↑
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Cadogan P.H. and G. Turner (1976) The chronology of the Apollo 17 Station 6 boulder. Proc. 7th Lunar Sci. Conf., p. 2267-2285. ↑
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Wolfe, E. W., et al., 1981, The Geologic Investigation of the Taurus-Littrow Valley: Apollo 17 Landing Site, USGS Professional Paper 1080, p. 131; Warner, et al., 1976, Apollo 17 station 6 boulder sample 76255: Absolute petrology of breccia matrix and igneous clasts, in Lunar Science Conference 7, 2, Geochemica et Cosmochemica Acta, Supplement 7, p. 2233-2250. ↑
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Cadogan P. H. and Turner G., 1976. The chronology of the Apollo 17 Station 6 boulder. LSC, p. 72267-2285. ↑
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Schmitt H. H., Petro N. E., Wells R. A, Robinson M. S., Weiss B. P. and Mercer C. M. (2017) Revisiting the field geology of Taurus-Littrow. Icarus, 298, 2-33. ↑
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Wolfe, E. W., et al, 1981, The Geologic Investigation of the Taurus-Littrow Valley: Apollo 17 Landing Site, USGS Professional Paper 1080, p. 141-142. ↑
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Schmitt H. H., Petro N. E., Wells R. A, Robinson M. S., Weiss B. P. and Mercer C. M. (2017) Revisiting the field geology of Taurus-Littrow. Icarus, 298, 2-33. ↑
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Original Rb-Sr age determination of 4.61 ± 0.1 billion years reduced due to subsequent change in accepted time constant for 87Rb decay. ↑
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Schmitt, H. H., 2003, Apollo 17 and the Moon, in H. Mark, editor, Encyclopedia of Space and Space Technology, Wiley, New York, Chapter 1, p. 32; Schmitt H. H. 2016, A continental-scale Procellarum impact’s potential relevance to many unresolved issues of lunar and terrestrial history. Annual Meeting, Geological Society of America, (abstract). ↑
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Schmitt, H. H., 2003, Apollo 17 and the Moon, in H. Mark, editor, Encyclopedia of Space and Space Technology, Wiley, New York, Chapter 1, p. 49-51. ↑
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Tikoo S. M., Weiss B. P., Shuster D. L., Suavet C., Wang H. and Grove T. L. (2017) A two-billion-year history for the lunar dynamo. Res. Article, Science Advances. 3:e1700207, 1-9. ↑
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