| This only became true after the loss of the shuttle Columbia on the STS-107 mission in 2003. After Columbia, a rigorous process was put in place for checking the heat tiles on the underside of the orbiter for damage. If damage was discovered, the shuttle crew would shelter aboard the International Space Station for about 40 days until a rescue shuttle came to get them. This mission profile was known as Launch On Need or Contingency Shuttle Crew Support. The rescue missions were numbered in the STS-3xx range. [0] A different rescue mission profile was needed for STS-125, which serviced the Hubble Space Telescope and couldn’t reach the orbital inclination of the ISS. This rescue mission, STS-400, had to be ready to launch within three days of a problem being found. The last planned shuttle mission was STS-134, with STS-335 as the LON mission. Since the hardware for 335 existed, NASA decided to fly it as an operational mission, STS-135. At this point there could be no backup shuttle, so 135 was flown with just four crew members who would shelter on ISS and come down one at a time via Soyuz over the course of about a year if the shuttle couldn’t re-enter. What about the damaged orbiter stuck at ISS? Orbiters were quite expensive, so NASA developed hardware (which was stored on ISS) to attempt a landing of the empty orbiter via remote control. Whatever the probability of success, it was better than zero. After the loss of STS-107, the investigation board asked NASA to devise a rescue that could have been attempted if the damage had been identified early in the mission. [1] The result was an audacious rescue plan that would have pushed two orbiters, their crews, and NASA itself to the absolute limit. We will never know if it could have been done. [0] https://en.m.wikipedia.org/wiki/STS-3xx
[1] https://arstechnica.com/science/2016/02/the-audacious-rescue... |