Discovery has a leak!

While attempting to load propellant Friday night, a leak was detected in Discovery's RCS (Reaction Control System) Helium Isolation Value – on the right-hand OMS (Orbital Maneuvering System) fuel system. Further testing and troubleshooting steps are being planned at the launch pad to examine two helium system regulators, which maintain pressure to the fuel tank and are further down the plumbing from the isolation valves.

If the regulators are functioning correctly, which will be tested later this week when the necessary equipment is ready, engineers could determine Discovery can safely fly 'as-is' despite the isolation valve problem.

If a repair or replacement to the valve is required, we would not be able to access it out at the pad...which means...rolling the shuttle back to the Vehicle Assembly Building, demating Discovery from its external fuel tank and solid rocket boosters, then towing Discovery to the Orbiter Processing Facility....AND removing the OMS pod.

Even with the planned testing, the April 5 launch date still stands. It's what comes out of these test results that will determine if we need to roll back the shuttle which would cause a delay.