NASA may call for spacewalk to fix space station problem

Engineers worked on malfunctioning cooling system over the weekend, waiting results; spacewalk would begin Thursday if it's deemed necessary

NASA engineers are still trying to figure out how to fix a cooling system problem on the International Space Station. The space agency now says it may call for a spacewalk to get the work done.

While the crew living on the space station, as well as the scientific experiments underway there, are not in danger, NASA is pushing hard to find a cause and get a fix in place.

According to the space agency, the trouble began Wednesday, Dec. 11, when the pump module on one of the space station's two external cooling loops automatically shut down after reaching a pre-set temperature limit. The loops are used to circulate ammonia, a coolant, outside of the orbiter to keep the internal and external equipment cool.

Engineers suspect a flow control valve inside the pump is malfunctioning.

Last week, the ground team moved some electrical systems from the problematic loop to a second one. They also powered down some non-critical systems inside the Harmony node and two laboratories.

On Sunday, NASA engineers continued the efforts to regulate the temperature in the cooling loop. The space agency says it's still waiting to see if those efforts have worked.

NASA has not yet issued another update on the project.

Now the agency says it may have astronauts Rick Mastracchio and Michael Hopkins make a series of spacewalks to replace the faulty pump. The two astronauts are preparing their spacesuits and other gear in case they are called on to leave the space station to work on the pump. The spacewalks would begin on Thursday, NASA said.

It's still unclear whether NASA commercial partner Orbital Sciences will be able to launch its cargo spacecraft, Cygnus, later this week to carry supplies to the space station.

Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin, or subscribe to Sharon's RSS feed . Her email address is

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