STS-400 was the Space Shuttle contingency support (Launch On Need) flight which would have been launched using Space Shuttle Endeavour if a major problem occurred on Space Shuttle Atlantis during STS-125, the final Hubble Space Telescope servicing mission (HST SM-4).
Due to the much lower orbital inclination of the HST compared to the ISS, the shuttle crew would have been unable to use the International Space Station as a "safe haven" and NASA would not have been able to follow the usual plan of recovering the crew with another shuttle at a later date. Instead, NASA developed a plan to conduct a shuttle-to-shuttle rescue mission, similar to proposed rescue missions for pre-ISS flights. The rescue mission would have been launched only three days after call up and as early as seven days after the launch of STS-125 since the crew of Atlantis would only have about three weeks of consumables after launch.
This patch is an unofficial reproduction based on original artwork.
