Free Astronomy Magazine July-August 2019

14 JULY-AUGUST 2019 ASTRONAUTICS the first multi-target mission. Send- ing a previous flight on such a rich site would have been wasteful, as the LRV was essential to exploiting such potential. On Earth, the process of orogenesis is the result of plate tectonics, and the southeastern edge of Mare Im- brium, with the steep slope facing the basin of this chain known as the Apennine Front. To appreciate the importance of this mountain range, it is necessary to consider its position between the basins of Im- brium and Serenitatis. The Moon can be studied by strati- graphic analysis based on the su- perposition principle. This analysis shows that before the Imbrium it takes millions of years to create a mountain range. The lunar surface, conversely, is shaped by the bom- bardment of meteorites, and the mountains surrounding the impact basins were instantly lifted when the shock broke the crust, produc- ing a series of crisscrossing radial and peripheral fissures. In this rapid-origin scenario, the formed mountains are unique, individual masses. The Apennine represents A POLLO 16 − Charles Duke walking in Plum Crater. [NASA, Project Apollo Archive]