A cooling system failure aboard the International Space Station may require a spacewalk, NASA officials said Wednesday.
One of two ammonia cooling loops on the station's exterior shut down Wednesday morning, NASA spokeswoman Brandi Dean said.
"You need the cooling in space because heat doesn't dissipate like it does on the ground," she said.
Authorities think that an excess of ammonia triggered a safeguard to shut the loop down.
[Update, 9:05 p.m. Dec. 11: NASA's Johnson Space Center used Twitter to update followers on the situation.
"The pump module on one of #ISS two external cooling loops automatically shut down today when it got too cold," the center tweeted this afternoon.
"The pump was brought back online, but they think a valve may not be working correctly inside it."]
The main modules affected are the Japanese laboratory, the European laboratory and their connecting node, Harmony, Dean said. Some of those systems have been moved to the other cooling loop, and non-critical systems have been shut down.
"There's no danger to the crew at all, all the science is running just fine, all the freezers that hold the scientific samples — it's just a matter of us taking the time to figure out how to get the first loop back up and running at capacity," Dean said.
Flight controllers at NASA's Johnson Space Center in Houston are exploring whether the issue is hardware or software. There are no immediate plans for a spacewalk, but if any parts need replacing, it may become necessary to send an astronaut out to replace the part with spare systems carried on board.
"The crew is safe and preparing to begin a normal sleep shift while experts on the ground collect more data and consider what troubleshooting activities may be necessary," NASA spokesman Josh Byerly said in an email.
The space station experienced an unprecedented scare in July when Italian spacewalker Luca Parmitano came dangerously close to drowning in space. The European Space Agency astronaut managed to find his way back to the station door as his helmet began filling with water.
"You can imagine, you're in a fishbowl. So go stick your head in a fishbowl and try to walk around – that's not anything you take lightly," NASA flight director David Korth said at the time.
In a strange parallel, the malfunction in Parmitano's suit was also linked to a cooling loop.