Although a leak of fuel from Discovery's orbital engine system stopped overnight, NASA has decided to replace a set of seals to be sure the problem doesn't reoccur. The work, expected to be completed by Monday, will exhaust all the contingency time available to keep Discovery on track for a Nov. 1 launch to the International Space Station.
Overnight Monday, technicians checked the tightness of bolts on a flange where propellant lines meet near the Orbital Maneuvering System pod on the right side of Discovery's tail fin.
The bolts were already at the proper torque, but the testing seemed to stop the leak of toxic monomethyl hydrazine fuel, perhaps setting two seals in the flange into proper position.
Pressure tests to confirm no further leakage were planned, but managers ultimately chose to replace the flange seals instead.
The leak's cause was unknown, and engineers want more confidence that the problem is resolved heading into a final review of Discovery's flight readiness planned Monday. Some were concerned that launch vibrations could open the leak again.
Preparations for the seals' replacement will begin tonight, with four fuel tanks in the two orbital engine pods likely being drained Thursday. Work will continue through each shift over the weekend.
Discovery and six astronauts are targeted to launch at 4:40 p.m. Nov. 1.
IMAGE: The connecting point in a fuel line, which had been leaking, for space shuttle Discovery’s right-side orbiter maneuvering system engine. Two seals will be replaced in the flange. Credit: NASA/KSC
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