While Discovery awaits Tuesday’s scheduled launch, her sister Atlantis has started to rollover from her Orbiter Processing Facility (OPF) to the Vehicle Assembly Building (VAB) today.
Atlantis was due to begin the short journey earlier in the week, but the move was delayed due to main gear and tyre pressure issues.
Atlantis is currently set to launch on STS-121 in the September window, although that is currently at the mercy of Discovery’s attempts to kick start NASA’s Return to Flight missions, with any delay to her STS-114 flight moving Atlantis into a November window.
Processing with Atlantis is continuing as normal, given her secondary requirement of being a back-up to Discovery, should anything go critically wrong with STS-114. Atlantis would then switch to becoming STS-300, which involves picking up Discovery’s crew from the safe haven of the International Space Station.
While in the VAB, Orbiter processing will continue before she is stacked with her External Tank (ET-120) and its twin Solid Rocket Boosters (SRBs). One note of interest will be the replacement of one of her three Space Shuttle Main Engines (SSMEs) for reasons currently unknown.
Meanwhile, Endeavour – in preparations for her launch next year – is undergoing reassembly. Vehicle power up is scheduled for September.