Japanese Lunar Exploration Program 2007, after being delayed several times. SELENE-2, Japan's first lunar lander and rover, is expected to be launched in the 2020s. The program also includes a lunar sample return mission (SELENE-3), a mission to Mars to collect data for future manned expeditions (MELOS), participation in the Mars international sample return mission, and an advanced lander for future human missions to the Moon. The eventual goal is to participate in an international lunar outpost program, in which Japanese crews would stay on the lunar surface for a prolonged period of time and promote scientific research and environment utilization. SELENE (Selenological and
Lunar orbit to become the nominal circular when the LM made its return rendezvous with the CSM. But the effect was overestimated by a factor of two; at rendezvous the orbit was calculated to be by . Study of the mascons' effect on lunar spacecraft led to the discovery in 2001 of "frozen orbits" occurring at four orbital inclinations: 27°, 50°, 76°, and 86°, in which a spacecraft can stay in a low orbit indefinitely. The Apollo 15 subsatellite PFS-1 and the Apollo 16 subsatellite PFS-2, both small satellites released from the Apollo Service Module, contributed to this discovery. PFS-1 ended up