NASA Shuffles Shuttle Stack For Hubble Flight

The external tank-solid rocket booster stack for the launch of Atlantis on the STS-125 mission is being moved from one high bay to another in the Kennedy Space Center Vehicle Assembly Building, clearing the way for the build-up of another stack for a subsequent Endeavour mission.

The roll-around leaves open an option to begin the build-up of the Ares I-X rocket for a test-flight now scheduled for launch July 11.

The STS-125 stack is moving from High Bay 1 on the southeast side of the Vehicle Assembly Building to High Bay 3 on the northeast side of the building. Now in Orbiter Processing Facility Bay No. 1, Atlantis will be added to the STS-125 stack and then rolled out to launch pad 39A for NASA's fifth and final Hubble Space Telescope servicing mission, which now is scheduled to fly on May 12.

The bay-to-bay move in the VAB will enable NASA to start the build up in High Bay 1 of a stack for the June 13 launch of STS-127. Endeavour will be added to that stack for a mission to deliver the final segment of the Japanese Kibo science research facility to the International Space Station.

Moving the STS-125 stack to High Bay 3 enables NASA to retain the option of launching the Ares I-X test flight in July.

High Bay 3 has been modified for the stacking of the Ares I-X rocket and launch pad 39B is being modified for the first in a series of test flights aimed at qualifying the Ares I rocket as NASA's Crew Launch Vehicle for Project Constellation, the agency's effort to return American astronauts to the moon by 2020.

To maintain a July launch date for Ares I-X, NASA would have to use launch pad 39A for both the launch of Atlantis on the Hubble mission and then Endeavour, if required, on a subsequent rescue mission. The plan had been to roll Endeavour out to pad 39B for the rescue mission.

A single-pad operation for both the Hubble mission and the STS-400 Launch-On-Need rescue mission would require a roll-out to pad 39A of Endeavour in advance of Atlantis so it could be loaded with hypergolic fuels and then returned to the Vehicle Assembly Building. Doing so would enable NASA to roll Endeavour to pad 39A and then launch a rescue mission in time to save the Hubble crew.

NASA will decide by early April whether to carry out a single-pad operation for STS-125 and STS-400. The decision will be based on whether the agency will be ready to launch the Ares I-X test flight as scheduled in July.

NASA's eight remaining station assembly missions all would slip about a month if the agency decides to press ahead with the Ares I-X flight in July. The Ares I-X flight likely would slip to October if it's not ready to fly in July.

ABOUT THE IMAGES: Click to enlarge the cell phone photo (top) of the STS-125 stack moving backing out of High Bay 1 at the Kennedy Space Center Vehicle Assembly Building today for a roll-around to High Bay 3. You can also click to enlarge the subsequent NASA images of the external tank for the STS-125 mission being lowered onto a mobile launcher platform for attachment to a pair of shuttle solid rocket boosters. The move leaves open an option to stack the Ares I-X rocket for a test flight in July. Top Photo: Florida Today/Todd Halvorson. Subsequent Photo Credit: NASA/Jack Pfaller.