A series of technical glitches is hampering the work of the crews of the International Space Station (ISS) and the Space Shuttle Atlantis. NASA reported today that the current crew of the ISS, known as Expedition 15, is working hand in hand with their visiting colleagues aboard the docked shuttle, called STS-117, to investigate the causes of a power failure, computer shutdowns, and a false alarm in a fire-control system over the last couple of days.
Back on Earth, engineers in the Russian space agency are scrambling to repair backup navigation computers. The primary computers were restarted this morning. Flight controllers continue efforts to bring all units back up to full operation, NASA stated. Officials of the two agencies said they still don't know why the computers failed, adding that they had not heretofore seen that type of failure on the space station, which they believe may be related to the loss of electrical power. In the meantime, systems onboard Atlantis are being operated to keep both orbiting platforms in proper orientation.
The U.S space agency also reported today that before this morning's scheduled wakeup call, the crews were awakened by a false fire alarm on the station, most likely caused by the restart of the Russian computers that provide backup attitude and altitude adjustments.
The crew of Atlantis successfully deployed an 18-ton solar array truss on Monday, attaching it to the side of the ISS. Subsequently, they have worked outside the shuttle to activate the Starboard 3 and 4 (S3/S4) truss segment and its rotating control joint (which positions the array to face the sun). During these two spacewalks, they also retracted arrays on the Port 6 (P6) truss. NASA said a future shuttle crew will finish the job of relocating the P6 from atop the space station to the end of the Port 5. Two more spacewalks are scheduled for this week to work on the arrays.
In addition to the new truss segment, NASA Astronaut Clayton Anderson joined the Expedition 15 crew on Sunday, replacing Flight Engineer Suni Williams. Williams spent six months as an Expedition 15 crew member. Atlantis is scheduled to undock from the station June 19. However, late word on Thursday indicates that this return date may be postponed to help deal with the unexpected problems that have cropped up.