was concerned about losing the 400,000 workers involved in Apollo after landing on the Moon in 1969. A reason von Braun, head of NASA's Marshall Space Flight Center during the 1960s, advocated a smaller station after his large one was not built was that he wished to provide his employees with work beyond developing the Saturn rockets, which would be completed relatively early during Project Apollo. NASA set up the Apollo Logistic Support System Office, originally intended to study various ways to modify the Apollo hardware for scientific missions. The office initially proposed a number of projects for direct scientific study, including an extended-stay lunar mission which required two Saturn V launchers, a "lunar truck" based on the Lunar Module (LM), a large, crewed solar telescope using an LM as its crew quarters, and small space stations using a variety of LM or CSM-based hardware. Although it did not look at the space station specifically, over the next two years the office would become increasingly dedicated to this role. In August 1965, the office was renamed, becoming the Apollo Applications Program (AAP). As part of their general work, in August 1964 the Manned Spacecraft Center (MSC) presented studies on an expendable lab known as Apollo X, short for Apollo Extension System. Apollo X would have replaced the LM carried on the top of the S-IVB stage with a small space station slightly larger than the CSM's service area, containing supplies and experiments for missions between 15 and 45 days' duration. Using this study as a baseline, a number of different mission profiles were looked at over the next six months. Wet workshop In November 1964, von Braun proposed a more ambitious plan to build a much larger station built from the S-II second stage of a Saturn V. His design replaced the S-IVB third stage with an aeroshell, primarily as an adapter for the CSM on top. Inside the shell was a cylindrical equipment section. On reaching orbit, the S-II second stage would be vented to remove any remaining hydrogen fuel, then the equipment section would be slid into it via a large inspection hatch. This became known as a "wet workshop" concept, because of the conversion of an active fuel tank. The station filled the entire interior of the S-II stage's hydrogen tank, with the equipment section forming a "spine" and living quarters located between it and the walls