NASA Moves To Repair Shuttle Wiring

NASA contractor technicians are busy repairing a damaged electrical cable in shuttle Discovery's rear engine compartment while agency engineers conduct tests aimed at clearing suspect valves for flight.

Discovery will remain grounded until at least Feb. 19 while NASA conducts tests to determine whether cracked valves could shed enough debris to sever gaseous hydrogen lines in the shuttle's main propulsion system.

The tests are part of an ongoing investigation into a valve failure that occurred during the launch last November of shuttle Endeavour on a supply run to the International Space Station.

One of three gaseous hydrogen flow control valves in the orbiter's main propulsion system failed to work as intended. Subsequent inspections showed a crack in the lip of the valve. The ongoing tests are intended to determine whether debris from a crack could rupture tubing that routes gaseous hydrogen from the shuttle's main engines to its external tank.

The recirculation valves are key to maintaining proper pressure levels within the 15-story tank as propellant within it is exhausted during a shuttle's uphill climb into orbit. Check out our story on NASA's decision to await test results and delay a planned Feb. 12 launch: Discovery Launch Delayed.

In the meantime, NASA prime shuttle fleet operator United Space Alliance is repairing damaged pyrotechnic wiring that was uncovered during preparations for final ordnance installation at launch pad 39A, where Discovery is being prepped for flight.

Technicians discovered flawed connectors within the wiring, which routes commands from shuttle general purpose computers to small explosive charges that detonate to detach the orbiter from its launcher platform, solid rocket boosters and external tank in flight. Additional damage to the wiring was detected during initial repairs and engineers are evlauating the situation.

NASA Launch Director Mike Leinbach said the agency will press ahead with the wiring repairs and then remain in a holding pattern until senior agency executives set a new launch date.

"We're in a really good posture to react to this deal, and (we) don't see any issues from the ground processing perspective," Leinbach said. "When we get the flight date, we'll react to that and be ready to go."

Discovery and seven astronauts are scheduled to fly a mission to deliver a fourth and final set of massive American solar wings to the International Space Station.

Lifoff time on Feb. 19 would be 4:41 a.m.

NASA shuttle program managers will meet next Tuesday to review test data. Senior agency executives will be briefed in a mini-flight readiness review on Feb. 12. A new launch date could be set at that time.