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Atlantis shuttle computer recovers from glitch
by Dipankar Roy - July 16, 2011 - comments
The Atlantis mission is on track and has completed about 70 percent of equipment and supply transfer to the International Space Station (ISS).
Astronauts on board of Atlantis space shuttle has successfully recovered one of the four main computers after a glitch caused a crash and set off the alarm on Thursday, said National Aeronautics and Space Administration (NASA) official.
Shuttle commander Chris Ferguson and pilot Doug Hurley managed to fix the shuttle's General Purpose Computer (GPC) 4 after the duo went into troubleshooting mode immediately after the failure which triggered the on-board master alarm.
NASA stated, "Atlantis Commander Chris Ferguson and Pilot Doug Hurley have reloaded software into general purpose computer 4 and recovered the computer," which "has been added to the common set of GPCs and is operating normally, processing data."
The troubleshooting involved the transfer of duties from GPC 4, which was running system management software, to another GPC on the shuttle.
The crew also implemented a data dump of the computers for analysis of the failure by NASA experts at the Mission Control.
"Mission Control is evaluating the 'dump' of data from the computer that Atlantis transmitted earlier this morning to determine what caused the Thursday evening failure. GPCs 1, 2 & 4 are in 'run' and GPC 3 is in 'standby'. All four of the primary computers are processing data." -- NASA
About GPC
According to NASA officials, the GPC is “slow” and has "little memory compared to modern home computers. GPC has "a storage capacity of one megabyte,” and "runs at a speed of 1.4 million instructions per second".
NASA said, "The shuttle's primary flight software contains about 400,000 lines of code. For comparison, a Windows operating system package includes millions of lines of source code."
NASA explained, "No one straps the latest-and-greatest desktop computer inside a machine that vibrates like an old truck on a washboard road while requiring it to get a spacecraft into orbit and back safely."
Cause of failure yet to be identified
The space agency is investigating the cause of failure.
NASA stated, "Mission Control is evaluating the 'dump' of data from the computer that Atlantis transmitted earlier this morning to determine what caused the Thursday evening failure. GPCs 1, 2 & 4 are in 'run' and GPC 3 is in 'standby'. All four of the primary computers are processing data."
"Right now there's no smoking guns that they've identified as the cause of the failure," said NASA officials on NASA TV.
Officials also said that a fifth GPC with backup software can be used in case of an "endemic problem" with one of the main computers.
NASA official described the glitches, including an earlier problem with GPC 3, as "little hiccups.”
However, the Atlantis mission is on track and has completed about 70 percent of equipment and supply transfer to the International Space Station (ISS).