NASA is saying that the problems they have been having getting External Tanks produced on time is going to lead to a postponement of the HST Servicing Mission. While no new date has been announced BBC News reported on 1May08 that the launch is likely to slip 4-5 weeks which would place it in the late Sept08/early Oct08 timeframe. Spaceflight Now says that the likely launch date is 8Oct08 or possibly later, with STS-125 slipping from 16Oct08 to 15Nov08, STS-119 from 4Dec08 into 2009 with delays to subsequent launches.
NASA says that construction of the ISS is expected to be completed before the Shuttle fleet is retired before the end of FY10 on 20Sep10. The current flight schedule places the last construction flight in Jun10 so there are only about 100 days in the slush fund.
The ET that is intended for the ISS construction flight following the HST Servicing Mission (that would be STS-119) is going to be the rescue mission tank for STS-125 (the HST mission). If there is a problem with the Shuttle on the HST mission they can't go to ISS, where there are enough supplies for them to hang out for several months, and wait for rescue so a rescue mission would need to be launched quickly before the meager life support supplies on board the Shuttle run out.
STS-124 is expected to be launched on schedule at 1702:05 EDT on 31May08, with the launch window extending through 14Jun08 (launch occurring about 22 minutes earlier for each day of delay). Docking with ISS should occur around 1300 EDT on 2Jun08 and undocking around 1200 EDT on 10Jun08. If the launch goes off as scheduled it will be too early for us to see the fly-by. CalSky is predicting some possible visible passes before docking so it might be possible to see a tandem pass, but none of the passes predicted are really favorable. There may be some more ISS altitude boosts before the launch of STS-124 so it is still too early to tell. Landing at KSC is scheduled for 1137 EDT on 13Jun08. Master Flight Plan Launch Window
