Back to the Moon Back to the Moon Back to the Moon is a science fiction novel and Homer Hickam's first fictional book. Published in June 1999, Hickam wrote Back to the Moon using insider information he learned from NASA. The prologue of the novel begins with a dramatized account of the second EVA of Apollo 17. Astronaut Jack Schmitt discovers orange soil in Shorty Crater at the very end of the EVA and gathers samples in a race against time to get back to the LEM. Meanwhile, Wernher von Braun is watching the end of the mission on TV with other NASA engineers.
Gravitation of the Moon mascons, which are large positive gravity anomalies associated with some of the giant impact basins. These anomalies significantly influence the orbit of spacecraft around the Moon, and an accurate gravitational model is necessary in the planning of both manned and unmanned missions. They were initially discovered by the analysis of Lunar Orbiter tracking data: navigation tests prior to the Apollo program showed positioning errors much larger than mission specifications. Mascons are in part due to the presence of dense mare basaltic lava flows that fill some of the impact basins. However, lava flows by themselves cannot fully explain the gravitational