Associated Press
Fuel gauge failures in the shuttle Atlantis's tank have been traced to a bad connector, NASA announced Tuesday, and a top manager said he did not know how long it would take to replace the part or when the spaceship might fly.
The erratic shuttle fuel gauges—part of a critical safety system—forced back-to-back launch delays earlier this month. Before Tuesday's tanking test, NASA was aiming for a January 10 liftoff of Atlantis, which was scheduled to carry a European lab to the International Space Station.
"We're going to follow this trail where it leads us and we're going to solve this problem, and then we'll go fly ... whether it's January 10 or February 10 or March 10," shuttle program manager Wayne Hale said.
In orbit, meanwhile, spacewalking astronauts helped pinpoint the source of a flawed mechanism in the international space station's power system. But they unearthed few clues about an even bigger problem with a fouled rotating joint for the solar wings.
(Related story: Astronauts Take Hundredth Space Walk From Space Station [December 18, 2007])
Spacewalking astronauts Peggy Whitson and Daniel Tani stopped first to inspect a solar wing-tilting mechanism that experienced circuit breaker trips on December 8. Engineers initially suspected a piece of space junk may have damaged it, but Whitson and Tani found no signs of impact. They temporarily disconnected cables for a test that exonerated certain parts, leaving the motor most likely at fault.
NASA's space station program manager, Mike Suffredini, said a spare motor already on board will be installed during Atlantis's visit, a difficult spacewalking job.
Repairs to the damaged solar rotary joint, on the other hand, will be a massive effort requiring as many as four spacewalks and likely will not be attempted until next fall, Suffredini said. That's how long it will take to figure out what's wrong and train a crew on the repairs, he said.
The joint is supposed to automatically rotate 360 degrees to keep the solar wings facing the sun. It's been used sparingly over the past three months, ever since it began vibrating and exhibiting electrical current spikes.
Whitson and Tani spent most of their seven-hour spacewalk inspecting the clogged rotary joint, removing covers and peeking deep inside with a dentist-style mirror on a rod. They found more of the metallic grit that was first detected by Tani during a spacewalk in October, and they collected more samples.
All the gears, motors and bearings looked fine, although some were dirtier than others. The spacewalkers removed one bearing for return to Earth on the next shuttle flight, for engineering analysis.
NASA had hoped to learn what was grinding against the rotating ring.
