May 11, 2013
Spacewalk To Fix ISS Ammonia Leak Approved For Saturday
redOrbit Staff & Wire Reports — Your Universe Online
A spacewalk to inspect and possibly replace a pump controller box believed to be the source of an ammonia leak on the International Space Station´s (ISS) external cooling system has been approved and will take place on Saturday, NASA officials have confirmed.The decision to go ahead with the spacewalk, which will be conducted by Expedition 35 crewmembers Chris Cassidy and Tom Marshburn, was made by the ISS managers and their international partners late Friday night, the American space agency said in a statement. The final approval for the spacewalk came following a day-long review of procedures and the crew´s preparations to support the journey.
As previously reported on redOrbit.com, the ammonia leak was first detected by Expedition 35 crewmembers at approximately 10:30 CDT on Thursday. They had reported spotting white flakes floating away from the far port (P6) truss structure of the orbiting lab, and used a handheld camera to document the issue for Mission Control.
The crew´s footage, combined with additional video shot by Mission Control using external television cameras in an attempt to zero in on the exact location of the leak, helped to confirm the coolant´s leakage rate was increasing. NASA officials emphasize the station is operating normally and the ISS crew is in no danger.
For Saturday´s spacewalk, Cassidy and Marshburn will exit from the Quest airlock of the space complex´s US segment, where they will then inspect the pump controller on the P6 truss.
Cassidy has been designated as Extravehicular crew member 1 (EV 1) and will wear a spacesuit distinguished by red stripes, while Marshburn will be Extravehicular crew member 2 (EV 2) and will wear a suit with no stripes, NASA said. Expedition 35 Commander Chris Hadfield of the Canadian Space Agency will serve as the Intravehicular crew member (IV), meaning he will choreograph the suit up of the spacewalkers as well as their tasks outside.
“The P6 truss was launched to the station as the oldest component of the station´s backbone aboard the shuttle Endeavour on the STS-97 mission in November 2000,” the US space agency said. “It was relocated from its original installation position to the far left side of the station during the STS-120 mission of the shuttle Discovery in October/November 2007.”
This will be the 168th spacewalk in support of the assembly and maintenance of the ISS, and the third for both Cassidy and Marshburn, they added. The spacewalk is scheduled to begin at 7:15 CDT and last approximately six and one-half hours.