Spacewalk planned to fix space station leak
Two astronauts will make a hastily planned spacewalk today to try to fix an ammonia leak in the International Space Station’s power system. Officials emphasized the six-member crew is not in danger.
The leak in a cooling system was discovered Thursday when “snowflakes” of ammonia were seen flying away from the station.
Spacewalks are rarely done on such short notice, but the U.S. space agency wanted to check out the leak before all the ammonia escaped. They also want to take advantage of a spacewalking crew member who is about to return home.
Officials said the space station has plenty of power, even though the leak forced NASA to shut off the power channel from one of eight solar panels that supply electricity.
The station can operate fine with only seven electrical channels, space station program manager Michael Suffredini said Friday. Power from the affected panel was re-routed to the other seven systems.
Suffredini said the chief suspect for the leak is space junk hitting a cooling tube, but he said the area had a slow small leak for many years that suddenly accelerated Thursday.
“You’re talking a very, very, very small hole,” Suffredini said.
NASA hopes the leak is in a small pump box. During the six-hour spacewalk this morning, U.S. astronauts Chris Cassidy and Tom Marshburn will replace the 260-pound box with a nearby spare.
While NASA has had to do impromptu spacewalks before, they haven’t been done on the space station since it was built and operating as a finished lab, chief flight director Norm Knight said.
Station Commander Chris Hadfield of Canada told NASA flight controllers Friday the crew is ready for the spacewalk.
“It’s the right thing to do,” he radioed down to Earth.
Hadfield tweeted that the crew was working “like clockwork” and said the two spacewalkers were already getting their spacesuits ready.
If the cooling system can’t be fixed in today’s spacewalk, it can be fixed in later spacewalks, Suffredini said. NASA can and has operated the station fully on seven power channels, he said.
But that would leave the station little margin for error. If there are more problems, some experiments on board may have to be shut down to conserve power.
NASA spokesman Rob Navias said the repair is what the agency calls one of the “Big 12” types of emergency repair work that all spacewalking astronauts train for in advance.
In 2009, Cassidy and Marshburn flew to the space station on the shuttle Endeavour and walked in space together to swap out a battery in the same location, so “they know this worksite inside and out,” Navias said.
Marshburn, Hadfield and Russia’s Roman Romanenko are set to return to Earth on Monday. NASA Administrator Charles Bolden told reporters Friday that their return will go ahead as planned.
