Saturday, April 18, 2009
STS-400 LON (Launch On Need)
There are two shuttles on two pads at KSC now. Atlantis is in preparation to launch on the final Hubble service mission on May 12 (STS-125), and Endeavour has been rolled out to serve as the rescue shuttle in the unlikely event that Atlantis is unable to return from orbit (due to heavy thermal tile damage or some other major problem). This would be STS-400 LON "launch on need," and it's needed because if Atlantis has such a bad problem, it would be unable to reach the ISS as a "safe haven." All other recent shuttle missions have been space station missions, allowing the visiting shuttle crew to take refuge in the ISS for up to three months should a severe shuttle problem prevent reentry. Universe Today yesterday published a good, brief explanation of how this rescue mission would work.
I actually played around with simulating this in Orbiter last summer (picture above, more here) when STS-125 was still planned for a fall 2008 launch. I just installed and tested the latest Shuttle Fleet add-on package (4.1.5) along with the necessary expansion and payload packs and a small service pack that was released today on Orbit Hangar, bringing it up to v4.1.9. There are no STS-125 or STS-400 scenarios yet, but the launch autopilot now allows targeting an apogee of around 600 km, the altitude necessary to reach the Hubble's orbit.