Will Discovery Be 'Go for Launch' or Forced to Roll Back?

Over the weekend, NASA engineers will conduct additional tests to determine if Discovery can launch "as is" or have to be rolled back for repairs — which would mean a three-month delay for the STS-131 mission. Helium regulator assemblies downstream from a failed isolation valve in the shuttle's right rear maneuvering engine pod must [...]

A wide angle view of Discovery and the payload canister on the rolled back Rotating Service Structure. Credit: Alan Walters (awaltersphoto.com) for Universe TodayOver the weekend, NASA engineers will conduct additional tests to determine if Discovery can launch "as is" or have to be rolled back for repairs — which would mean a three-month delay for the STS-131 mission. Helium regulator assemblies downstream from a failed isolation valve in the shuttle's right rear maneuvering engine pod must work perfectly to provide a system redundancy that would justify proceeding with the flight. If the valve needs to be repaired or replaced, neither can be done at the launchpad – meaning Discovery would have to be rolled back to the Vehicle Assembly Building, de-mated from the SRBs and external tank, and sent to the Orbiter Processing Facility for repairs. But if the regulators check out, and no ...