Station computers brought to life after impromptu repair
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: June 15, 2007
In a possible breakthrough, space station commander Fyodor Yurchikhin and flight engineer Oleg Kotov used a jumper cable to bypass a suspect secondary power supply switch today and successfully activated four of six navigation and command computers that appeared to malfunction earlier this week, NASA officials said.
Details were not immediately clear, but two channels, or "lanes," in the Russian central command-and-control computer appeared to operate normally after the improvised power supply repair, along with two of three lanes making up the station's guidance and navigation computer, known collectively as the terminal computer.
"Fyodor, go ahead and activate the central computer power... one, two, three," ground control called. A few moments later, after reviewing diagnostic data, a controller (speaking through an interpreter) radioed: "Well, good news, it's good news that it's working."
Each system includes three redundant computers that work in concert to avoid faulty data or incorrect results. The terminal computer system operates the station's Russian rocket thrusters to re-orient the lab complex as required to keep sunlight on solar arrays and to keep sensitive systems from getting too hot or too cold.
The central computer is used to control the Russian segment's Elektron oxygen generator, its Vozdukh carbon dioxide removal system and a variety of other critical functions. While both computer systems are triply redundant, the systems can safely operate the station with a single channel, or lane, in each computer.
Earlier this week, around the time the Atlantis astronauts were installing a new solar power truss, the terminal computer crashed. An automated reboot procedure was then executed to shut down and restart all three terminal computer lanes and all three central computer channels. The reboot procedure didn't work, however, and engineers have been struggling ever since to restore the computer system to normal operation.
After the power supply bypass surgery today, Russian flight controllers told their NASA counterparts lanes one and three were had been successfully repowered in the terminal computer, along with lanes two and three in the central computer. The systems then were shut down to close access panels and apparently restarted in self-test mode as planned. Controllers said they plan to operate the computers throughout the evening and to collect telemetry for additional analysis during passes over Russian ground sites early Saturday.
Earlier this afternoon, U.S. flight controllers told spacewalker James Reilly to disconnect a power cable in a newly installed solar array truss to help engineers determine whether the cable might have played a role inthe computer malfunctions earlier this week. The miscues began right around the time the cable was connected Monday.
But late today, astronaut Megan McArthur radioed the crew from Houston saying that might no longer be necessary.
"They did have good fortune over there on the computers," she said.
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