An unprecedented computer failure in the Russian segment of the International Space Station has engineers at space centers in Houston and Russia scrambling to solve the problem before the Space Shuttle Atlantis undocks on June 19.
This morning the computers were beginning to send signals to the ground — not a fix, but the first good news since the problem appeared Tuesday.
The station's commander, Russian cosmonaut Fyodor Yurchikhin, stayed up all night to work with flight controllers in Russia's Mission Control to repair the problem.
All three computers for command and control, plus three guidance computers, which provided triple redundancy for vital space station functions, failed; astronauts and ground controllers made repeated attempts to force them to reboot.
There is speculation that new solar arrays, which were installed earlier this week by the visiting shuttle crew, may have triggered the computer shutdowns. These computers stabilize the space station on orbit. They also control the systems that generate oxygen for the crew and scrub deadly carbon dioxide from the atmosphere inside the space station.
Without the guidance and control computers, rocket thrusters cannot be used to adjust the space station's orientation. Much of the time, the station is stabilized by large gyroscopes, but the gyros and thrusters have to work in tandem.
In the meantime, Atlantis' thrusters were being used, but the shuttle was supposed to leave the space station Tuesday.
Program Manager Mike Suffredini said he had never seen a failure like this before, and it was baffling to him. What would he do if the computers did not return to full operation?
"If we are in that position, we have an option to depart. We always have an option to do that," he said.
Suffredini said he was confident the problem could be solved. "It's not an urgent situation, but clearly it needs to be resolved before our shuttle friends leave."
A Soyuz "lifeboat" is always docked to the space station, so if the space station crew must abandon ship, it has a way home.
Mission Management Team Chairman John Shannon says his team was looking at ways to keep the space shuttle docked to the station for an extra day or two, if necessary, by conserving power on the shuttle. Atlantis cannot stay docked to the space station indefinitely, though, and managers like to preserve two contingency days in case of bad weather at landing sites in Florida, California and New Mexico.
Meanwhile, Shannon's team finalized plans to repair the damaged thermal blanket on Atlantis. During the third spacewalk of the shuttle's mission Friday, astronauts have been told to use a surgical stapler from the space shuttle's medical kit. Wind tunnel and arc jet tests showed the staples would hold up on reentry. A corner of the thermal blanket on the port orbital maneuvering system peeled back as Atlantis rocketed into space Friday, leaving a triangular 4-inch-by-6-inch gap.
Shannon prefers not to let the shuttle fly home without fixing the damage because he is afraid the heat of reentry could cause even worse damage — damage that could take weeks to repair on the ground, but just a couple of hours for a spacewalking astronaut crew to fix on orbit.
The damage isn't considered life threatening, but managers want the crew to tuck the blanket back down to avoid damage to the shuttle as Atlantis flies through the searing heat of the atmosphere before landing.
NASA only has three shuttles left in its fleet, and needs to keep all three flying on schedule with little turnaround to finish 12 construction missions to the space station by 2010, when the shuttles, the only vehicles capable of launching and assembling the major components, are forced into retirement.
NASA would like to fly two resupply missions to the station and make one last servicing call to the Hubble Space Telescope. Since the loss of Shuttle Columbia in 2003, NASA has been meticulous about examining shuttles' heat shields for damage.
Columbia was hit by a piece of foam insulation that fell off its fuel tank during launch. The strike punched a hole in the shuttle's left wing, allowing superheated gases to penetrate the shuttle as it flew back through the atmosphere to land on Earth.
The shuttle broke apart over Texas in 2003, killing all seven astronauts aboard.