The International Space Station is leaking the chilled ammonia coolant it uses to cool its power systems into space, but there’s no danger to the crew, NASA announced on Thursday. The four solar arrays that provide power to the station are each cooled independently with their own thermal control systems (pictured above), meaning that the rest of the arrays can continue to function normally while everyone troubleshoots the problem. The faulty loop is the same one that astronauts worked on during a November spacewalk, but it’s not clear whether the leak is now coming from the same location or somewhere else on the structure. Speaking to Space.com, NASA spokesman Kelly Humphries said, "it is in the same area, but we don’t know whether it’s the same leak."
Plans are being worked out to reroute the affected power systems
According to early analysis, the leak might require a shutdown of the affected cooling loop within 24 hours, but plans are being worked out to reroute the affected power systems so everything can continue to run normally. Commander Chris Hadfield, the Canadian astronaut leading the station’s Expedition 35 crew, is scheduled to return to Earth on Monday along with astronauts from the US and Russia, and so far it doesn’t sound like the leak will affect the undocking plans.
Update: Hadfield said on his prolific Tumblr account that preparations are underway for astronauts to do another spacewalk to fix the source of the leak on the outside of the station. The spacewalk is scheduled for Saturday, May 11th, Hadfield noted on Twitter.
Good Morning, Earth! Big change in plans, spacewalk tomorrow, Chris Cassidy and Tom Marshburn are getting suits and airlock ready. Cool!— Chris Hadfield (@Cmdr_Hadfield) May 10, 2013
Update 2: NASA held a news conference Friday afternoon to say that the spacewalk was scheduled for 8:15 AM ET on Saturday, May 11th, and repairs would take up to six hours. The agency reiterated that there was no risk to astronaut safety, but noted that if the cause of the leak could not be identified and fixed during Saturday's spacewalk, NASA might have to turn off one power system, which could hamper research aboard the station. "If we have to be down one power system, that has a pretty significant impact on us," said NASA International Space Station Program manager Michael Suffredini during the news briefing. "It could potentially have an impact on research. It would be big challenge to the team."
Update 3: Here's a video of the leak, seen by an exterior camera on the space station.