Apollo 15 went unused, due to the explosion that damaged the Apollo 13 spacecraft. Apollo 14's CMP, Stu Roosa, was enthusiastic about geology, but the mission commander, Alan Shepard, less so. Scott, once assigned as Apollo 15 commander, was determined that his crew bring back the maximum amount of scientific data possible, and met with Silver in April 1970 to begin planning the geological training. The assignment of Schmitt as Apollo 15's backup LMP made him an insider, and allowed him to spark competition between the prime and backup crews. The cancellation of two Apollo missions in September 1970 transformed Apollo 15
Apollo Applications Program pilot was a concern for mission planners, so proposals that it would be a three-man landing team or that the CSM would rendezvous with an orbiting module were considered. The following phases were considered: The "Apollo LM Taxi" was essentially the basic Apollo LM modified for extended lunar surface stays. This was expected to be the workhorse of both "Apollo Applications Extended Lunar Surface Missions" beginning in 1970 and to larger "Lunar Exploration System for Apollo" in the mid-to-late 1970s. The "Apollo LM Shelter" was essentially an Apollo LM with ascent stage engine and fuel tanks removed and replaced with