Potential critical problems have been looming for the International Space Station, but a ray of hope was delivered today when Russians were able to make contact with a troubled computer. ALSO: Solar array halfway folded; third spacewalk tomorrow.
Carpenter Newton reporting for Digital Journal –– The big story of flight day seven revolved around three Russian computers that control critical systems aboard the International Space Station and trying to get them back running after a
major crash on Wednesday.
The three computers control the space station’s guidance and navigation systems. Since those went offline yesterday, the station has relied on space shuttle Atlantis for attitude control.
Russian engineers could not troubleshoot the problem until the space station began making passes over Russian ground stations, which typically happens each day around 2:00 a.m. EDT.
The problem is particularly worrisome because if it is not fixed by the time the shuttle is scheduled to leave, the ISS could have to be unmanned with no attitude controls available and a limited supply of oxygen.
Russian cosmonauts Fyodor Yurckikhin and Oleg Kotov were up well past working hours trying to help the ground work the problem. Around 7:00 a.m. EDT, Russian flight controllers reported they were receiving downstream telemetry from the affected computers. A few minutes later, a fire alarm went off after a power switch was thrown. This marks the second false fire alarm this week.
Around 8:45 a.m., communications to at least one of the computers was restored and critical systems were once again functional. However, much work is left to resolve the problem and figure out exactly why the computers went down. It is suspected the new S3/S4 truss,
connected during a spacewalk on Monday, might be making ‘noise’ that interferes with the computers and causes them to crash. NASA compares this noise to AM radio noise, or taking a Blackberry and placing it next to a speaker phone.
At tonight’s Mission Status Briefing, NASA said they were continuing to work on the problem but have stood down for today as the station was no longer making passes over Russian ground sites. Overnight, steps will be taken to isolate and find the problem using tools on board the ISS and by systematically unhooking power supplies.
Meanwhile, shuttle Atlantis is conserving cryogenic oxygen in case the vehicle is needed to stay extra time. Some systems aboard the shuttle have been powered down and a waste dump, scheduled for today, has been put off until flight day 10 due to the possible attitude upset the dump could cause.
This problem is a first for the Russians and NASA, who say at least one of the three computers is always working. Typically, the computers work in tandem together -- one will fall out of sync, then some time later, another. When the third loses sync, all three are restarted without any hiccups. However, none of the computers are restarting after failure.
Although a decision has not been made whether to extend the STS-117 mission yet another day, NASA officials are saying they are “holding onto all cards” at this point and the situation should become more clear by tomorrow or Saturday. The agency remains confident the source of the problem will be found and fixed by mission end next Thursday.
Solar Array Retracted Halfway, Preparations for Third Spacewalk
Today, this solar array was retracted halfway. Photo: NASA TV
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Astronauts on board the ISS and Atlantis successfully retracted a stubborn solar array 15 of 30 bays this afternoon and plan to finish the retraction during tomorrow’s scheduled spacewalk by James Reilly and Danny Olivas.
Retracting the array only a few bays took nearly five hours after guide wires that run through each bay became slack and grommets on the wires were hooked in the wrong direction. Flight controllers in Houston were able to ‘wiggle’ the array and free it for further retraction.
Plans continued for tomorrow’s spacewalk, the third of the mission. Astronaut Danny Olivas will be in charge of making a repair to a thermal protection blanket on Atlantis, while James Reilly will install a vent valve. Both men will take part in helping to completely fold the solar array, and should any time be left after the array fold, some get ahead tasks will be started.
As described yesterday, Olivas will repair the damaged blanket on the shuttle using stainless steel surgical staples. The shuttle’s robotic arm will carry him to the point of damage. NASA regards this repair as general maintenance, something that all astronauts undergo training to do.
