The passing of John Glenn on December 8, 2016, following that of Neil Armstrong on August 25, 2012, mark milestones in the remarkable history of space exploration in the last half of the 20th Century. Glenn, as the first American to orbit the Earth, and Armstrong, as the first person to step on the Moon, have assured their places in history and in the hearts of their colleagues and countrymen. It was my honor and privilege to have assisted Neil Armstrong in his preparation for landing on and exploring the Moon and to have served with John Glenn in the United States Senate. Both men set the stage for the Apollo missions of exploration that followed and for the remarkable missions back to the Moon and on to Mars that will take place in the 21st Century. The No. 56 essay posted here examines how that future may unfold and how the new challenges can be overcome.
(Left) John Glenn and his Mercury spacecraft, Friendship 7, prior to launch on February 20, 1962. Glenn, the first American to orbit the Earth, successfully completed 3 orbits before splashing down in the Atlantic. (NASA photo). (Right) Only 7 years later Neil Armstrong became the first astronaut to set foot on the Moon. Here, he is seen packing 17 scoops of bulk lunar soil into a rock box just before leaving the lunar surface. This soil was one of the most important of the returned samples because it allowed calibration of the volatile content of the lunar regolith. (NASA photo AS11-40-5886).