"Mini Shuttle extension"?
NASA are considering adding two additional missions to the Shuttle's manifest - STS-135 and STS-136.
STS-135 was originally called STS-335, and was intended to be the LON mission for STS-133. Given that, if flown, this would be the final Shuttle mission (so there would be no more opportunities to resupply the ISS via Shuttle), NASA decided to add an MPLM to STS-335 to replenish the ISS’s supplies after the increased consumption by the STS-133 crew’s extended stay.
However, NASA then decided that it would be a bit wasteful to retire the Shuttle with an Orbiter, an external tank, a set of SRB’s, and an MPLM ready to go, and so they threw together a mission – STS-135. There is also some speculation about a possible STS-136
If STS-135 is flown, it will have a crew of 4, so that in the event of tile damage during launch, the crew could be returned to Earth on the Soyuz's (two Soyuz would fly, each with a Russian commander plus two Shuttle crew). Of course, if these Soyuz flights were flown, it would significantly impact downstream ISS Expedition launches.
If both STS-135 and STS-136 are flown, STS-135's LON will be STS-136. STS-136 would then launch with a crew of 4, and its rescue would be by two Soyuz.
STS-135 would be flown by Atlantis.
Both missions would be flown sometime in late 2010/early 2011.
The payloads for both the missions would be an MPLM.
However, due to a problem with the ISS's software not liking two MPLMs being berthed to ISS at the same time, another option is to move STS-133's payload, the PMM, to the final Shuttle flight, and have STS-133 fly with an MPLM.
Whatever happens, Steve Lindsey will definitely command the final Space Shuttle mission!
Sources:
www.nasaspaceflight.com/2009/12/nasa-evaluating-sts-135-addition-to-shuttle-manifest
www.nasaspaceflight.com/2009/12/nasa-direction-extra-shuttle-flights-commerical-launcher
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Pretty exciting times for the SSP at the moment, with this "mini-extension" being considered!
