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However reality was to interject and NASA found themselves with a rapidly plunging budget. Rather than stepping back and looking at their future as a whole given their new financial situation, they attempted to save as many of the individual projects as possible. The mission to Mars was quickly eliminated, but the Space Station and Shuttle continued on. Eventually only one of them could be saved, so it stood to reason that a low-cost Shuttle system would be the better bet, because without it a large station would never be affordable.

List of human spaceflights
3 Mercury Missions 4 Shenzhou Missions 5 Skylab Missions 6 Soyuz Missions 7 Space Shuttle Missions 8 Voskhod Missions 9 Vostok Missions 10 Space stations 11 Spacecraft not yet flown with crew Apollo Missions Apollo 1 - crew perished in fire during training Apollo 7 Apollo 8 - first human flight around the moon Apollo 9 Apollo 10 Apollo 11 - first human moon landing Apollo 12 Apollo 13 - explosion en route to Moon forced emergency return to Earth by using free return trajectory Apollo 14 Apollo 15 Apollo 16 Apollo 17 Apollo-Soyuz - first joint Soviet-US mission Gemini Missions Gemini 3 Gemini 4 Gemini 5 Gemini 6A Gemini 7 Gemini 8 first docking in space Gemini 9A Gemini 10 Gemini 11 Gemini 12 Mercury Missions Mercury 3 Mercury 4

NASA had conducted a series of paper-projects throughout the 1960s on the topic of reusable spacecraft to replace their expedient "one-off" systems like Mercury, Gemini, and Apollo.