Encyclopedia Astronautica
2001.04.25 - STS-100 Mission Status Report #13


Troubleshooting efforts designed to restore full capability to the International Space Station's three redundant command and control computers continue in Mission Control, even as the 10 astronauts and cosmonauts on board the outpost worked together today to install new experiments in the Destiny laboratory.

Shortly after the ISS crew went to bed last night, the ISS flight controllers reported a loss of Command and Control Computer number one (C&C 1), one of three systems management computers on board. Overnight, flight controllers inititiated a procedure to re-string those functions through one of the two remaining backup computers that route data for systems management. This morning when Expedition Two Flight Engineer Susan Helms sent commands to transfer data files from the mass storage device, which houses the files for station systems management for the operation of the robotic work stations, the command was rejected.

After initial troubleshooting efforts failed to resolve the problem, flight controllers once again worked a procedure to re-string data management functions to the third computer, but the computer problem continued and flight control teams continued to evaluate the situation throughout the day.

Following a power cycle of command and control computer 1, the first of a series of diagnostic commands - this to turn on and off a light on board the Destiny laboratory - was successfully transmitted from the ground to the space station shortly before 7:30 p.m. Overnight the space station flight control team will attempt to reset the computers by commanding them from the "primary" to "standby" mode in an effort to clear any software interaction that might be causing the problems. If successful, this would allow the Expedition Crew and ground controllers to again interface with the command and control computers. The diagnostic troubleshooting will continue through the night.

The primary result of today's computer problem was a loss of communication and data transfer between the Space Station Flight Control Room and the station. Communication capability was routed through Endeavour enabling the crew and flight controllers to talk to one another.

Despite the difficulties encountered with the computer system today, all systems on board the spacecraft continued to function properly.

Several of the activities planned for today, including the handoff of a 3,000 pound pallete from the station's new robotic arm, back to the shuttle's arm, were postponed until Thursday, pending resolution of the computer issue. A reboost of the complex, using Endeavour's small thrusters, also was delayed. The crew members instead turned their attention to offloading experiment racks and equipment from the Raffaello logistics module, and transferring the experiments and hardware to the station.

Once the computer difficulties are resolved, Helms and crew mate Jim Voss will command the station's new Canadarm2 to maneuver the pallet within reach of Endeavour's robotic arm under control of mission specialists Chris Hadfield and Scott Parazynski.

Shortly before 7 p.m. Central, Mission Control said goodnight to both crews following a busy day on orbit. Expedition Two Commander Yury Usachev, Voss and Helms are slated to wake up about 2:30 a.m. Thursday; the seven astronauts on board Endeavour will receive a wake-up call from Mission Control about 10 minutes later.

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