HOUSTON - The International Space Station crew have been preparing for the planned arrival next week of the Space Shuttle Discovery on a complex mission to rewire the station's electrical system.
Shuttle Discovery is due to launch at 8:35 p.m. CST Thursday, Dec. 7 on mission STS-116. In addition to work that will bring power online at the station from solar arrays delivered to the complex in September, Discovery also will bring a new crew member to the outpost.
Expedition 14 Commander Mike Lopez-Alegria and flight engineers Mikhail Tyurin and Thomas Reiter reviewed the STS-116 mission plans this week. They prepared the station's Quest airlock, spacesuits and tools for three spacewalk planned for the shuttle mission. The crew packed equipment that will return to Earth aboard the shuttle, including Reiter's personal items since he will get a ride home aboard Discovery. STS-116 astronaut Sunita Williams will replace him as an Expedition 14 flight engineer.
Flight controllers worked on two problems aboard the station this week, neither of which is expected to affect Discovery's launch or mission.
An attempted reboost of the space station's altitude was cut short Wednesday. Russian flight controllers suspect that sensitive software detected a slight shift in the orientation of the station as the thrusters were fired. The change in orientation is believed to be normal, but it is new for the station due to the changes in its mass and balance resulting from the addition of the new solar arrays and truss segment in September.
The Progress cargo craft's thrusters fired for 3 minutes, 16 seconds before automatically shutting off. They had planned to fire for 18 minutes, 22 seconds. Russian controllers plan to complete the reboost Monday with a 21-minute firing of the Progress thrusters and a software adjustment. The reboost next Monday, planned for around 3:35 p.m. CST, will optimize Discovery's rendezvous with the station.
Flight controllers are analyzing a problem that occurred during testing of a new software package used to detect and solve problems with the station's giant Solar Alpha Rotary Joint. The joint is used to rotate the new solar arrays, allowing them to track the sun. The new software is designed to automatically realign the teeth of the joint's gears should they become misaligned, rather than requiring controllers to send commands for the realignment.
However, while running through a test of the software on Tuesday, a remote power controller, or station circuit breaker, opened. The circuit breaker was successfully reset on Thursday. Extensive analysis and troubleshooting appears to indicate there is no problem with any equipment aboard the station. Work continues, however, to refine the new software.
Unless events warrant, the next station update will be included in status reports for the STS-116 mission beginning on Thursday, Dec. 7 after Discovery's launch. For more about the crew's activities and station sighting opportunities, visit:
http://www.nasa.gov/station
