CAPE CANAVERAL, Fla. (AP) — NASA will try to launch Discovery on the first shuttle mission in more than two years on Tuesday after tracing last week’s fuel-gauge failure to, most likely, an electrical grounding problem lurking inside the spacecraft.
Shuttle program manager Bill Parsons said the only way to thoroughly check the system is to fuel Discovery and have all its equipment running.
“We believe the best way to go through this is to do a countdown,” he said. “If the [gauges] work exactly like we think they will, then we’ll launch on that day. If anything goes not per the plan that we’ve laid out in front of us, then we’ll have a scrub and we’ll have to talk about it.”
In what likely would be a much-criticized move in the wake of the 2003 Columbia explosion, NASA also may proceed with the liftoff if the fuel-gauge problem recurs but is considered well understood.
That would mean revoking a launch rule requiring all four hydrogen fuel gauges at the bottom of Discovery’s external tank to be working properly, and instead relying on just three out of four. That looser three-out-of-four rule was thrown out after the 1986 Challenger launch explosion.
The fuel gauges are intended to keep a shuttle’s main engines from shutting down too early or too late after liftoff, both potentially disastrous situations.
Mr. Parsons said there are considerable “safety nets” to protect against launching a seriously flawed spacecraft, if an exception to the fuel-gauge rule is made at the last minute.
“Right now, we think we have eliminated all the common causes that we believe could do this, and we’ve done everything we possibly could on the vehicle,” he said.