Jun 12 2007
From The Space Library
Over the course of 10 hours, NASA’s Mission Control remotely unfurled the S3/S4 solar arrays located on the new truss segment. Tip to tip the solar arrays spanned a distance of 240 feet (73 meters). With the solar arrays added to the left and right sides of the new power module, the ISS achieved an unprecedented symmetry in its appearance. In the midst of the solar-array- deployment operation, a fire alarm sounded in the Russian sector of the ISS, but crew and mission managers quickly determined that a computer malfunction was the cause. Russian computers, working in conjunction with American computers, had failed, and attempts to reboot the Russian computers had triggered the false fire alarm. However, because of the computer failure, the small maneuvering jets on Atlantis had assumed control of the ISS’s attitude, placing the station’s solar panels in a poor position for gathering sunlight and causing power levels to drop. Mission Control ordered the crew to turn off some nonessential equipment until the ISS regained attitude control. Thereafter, engineers successfully reestablished gyroscope control, and the left-side array began tracking the Sun properly.
Houston Chronicle, “New Solar Array,” 13 June 2007; John Schwartz, “Glitch Blamed for Fire Alarm on Orbiter,” New York Times, 13 June 2007; William Harwood, “Computer Glitches Impact Station Attitude Control,” Spaceflight Now, 12 June 2007.
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