CAPE CANAVERAL, Fla. -- A gyroscope that went bad on the space station Alpha locked up because its bearings might not have been lubricated enough, NASA said Tuesday.
The gyroscope, one of four that keep the space station positioned correctly, will be brought back on a future shuttle mission and examined further to determine why it froze. The station is keeping the part heated so it will be reusable once fixed.
In trying to explain what went wrong, station flight director Bryan Lunney compared the gyroscope's internal mechanics with that of a bicycle. Bearings that keep the moving parts spinning smoothly apparently were not lubricated enough, and it locked up.
The station is operating fine with three gyroscopes. It can maintain position with two working gyroscopes if necessary, but more propellant would be needed to keep Alpha aligned.
In other repairs, station managers said they expect to upload a software patch in early July to fix a glitch in the Canadian robotic arm's power when it "walks" onto the station's new railcar. The computer that controls the arm is looking too quickly for confirmation that it has power. The patch will introduce a delay in the response.
Managers in Houston will test the patch July 9. The first walk-off of the arm onto the mobile base system, which spacewalkers installed on shuttle Endeavour's recent mission, is slated for July 10. Further testing will follow before Atlantis arrives on the next ISS construction mission. However, Atlantis' scheduled Aug. 22 launch is in doubt because of fuel-liner cracks that are forcing safety inspections of the entire shuttle fleet.
Atlantis' mission was to follow a July 19 launch of Columbia. NASA has indefinitely postponed that flight because it needs at least three weeks to inspect hydrogen fuel lines for cracks similar to those found last week in Atlantis and Discovery.
Lunney would not say what effect the delay of Columbia's launch would have on future shuttle launches and the work astronauts were scheduled to do on the space station.
"Obviously, we're anxious as everyone else is for the shuttle program and everyone to figure out what's going on with the space shuttles," he said, "and we're going to sit tight and let the teams do the assessment they've got to do. . . . At this point, we're not going to do a whole lot of speculation on the different options."
Endeavour has yet to return to Kennedy Space Center from Edwards Air Force Base in California. For security reasons, NASA officials will not discuss Endeavour's departure until after it has occurred.
The gyroscope replacement, scheduled for a January mission, would be difficult to move to an earlier mission because the part will not fit in a shuttle cargo bay with the pieces the shuttles will be hauling during other space-station trips.
The new crew in Alpha is keeping busy with scientific experiments and preparing for two upcoming spacewalks. The Progress 7 service module left the station Tuesday morning, and another Russian Progress ship is due to arrive Saturday morning.
Published under license from FLORIDA TODAY. Copyright © 2002 FLORIDA TODAY. No portion of this material may be reproduced in any way without the written consent of FLORIDA TODAY.
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