We choose to go to the Moon a week after Kennedy's assassination. The idea of a joint Moon mission was abandoned after Kennedy's death, but the Apollo Project became a memorial to him. His goal was fulfilled in July 1969, with the successful Apollo 11 Moon landing. This accomplishment remains an enduring legacy of Kennedy's speech, but his deadline demanded a necessarily narrow focus, and there was no indication of what should be done next once it was achieved. Apollo did not usher in an era of lunar exploration, and no further missions were sent to the Moon after Apollo 17 in 1972. Subsequent planned Apollo missions
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