But APU Issues Causing Some Concern

Everybody deserves a day off once in awhile... even in space.

The six remaining astronauts aboard Discovery got just that on Thursday -- a day to relax, and just look out the window as the orbiter remains docked with the International Space Station.

The Discovery crew worked hard for its day of rest... performing three spacewalks and unloading more than four tons of material onto the station since they lifted off on July 4.

But while the astronauts took some time for rest... that doesn't mean NASA workers on the ground got the day off. In fact, they were hard at it, trying to figure out what's troubling two of Discovery's three auxiliary power units.

NASA says there may be a fuel leak on APU Number One, where pressure has dropped about three times faster than normally expected. APU Number Three has a problem that's lead to the failure of its backup generator.

The problem there is thought to be caused by a new thermal wrap around the APU. Engineers believe it somehow may have come loose. Despite the glitches, however, NASA does not believe the APU problems will pose a threat to Monday's scheduled return of Discovery to earth.

FMI: www.nasa.gov