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Space Station Cooling System Restored Christmas Day

By  //  December 26, 2013

ISS cooling system RESTORED Christmas Day

ABOVE VIDEO: Expedition 38 astronauts Rick Mastracchio and Mike Hopkins ventured outside the space station on Dec. 24, for the second in a series of spacewalks to remove and replace a faulty coolant pump module. The pump is associated with one of the station’s two external cooling loops, which circulate ammonia outside the station to keep both internal and external equipment cool.

NASA.gov – Following two spacewalks to replace a degraded pump module on the truss, or backbone, of the International Space Station, flight controllers in the Mission Control Center at NASA’s Johnson Space Center in Houston successfully restarted the new pump Tuesday night.

Flight Engineers Rick Mastracchio and Mike Hopkins continue preparing for a series of spacewalks to remove a failed pump module and install a spare pump module. (NASA video image)
Flight Engineers Rick Mastracchio and Mike Hopkins continue preparing for a series of spacewalks to remove a failed pump module and install a spare pump module. (NASA video image)

The pump module controls the flow of ammonia through cooling loops and radiators outside the space station, and, combined with water-based cooling loops inside the station, removes excess heat into the vacuum of space.

Expedition 38 Flight Engineers Mike Hopkins and Rick Mastracchio removed the degraded pump module during a 5 hour, 28 minute spacewalk Saturday, Dec. 22. They retrieved a replacement pump from an external stowage platform near the end of the station’s backbone, and installed it during a 7 hour, 30 minute spacewalk on Christmas eve, Dec. 24.

The new pump now is considered fully functional, but it will take some time to fully reintegrate the pump and Loop A of the two-loop external cooling system. Teams at mission control are following a schedule that should allow the restored cooling loop to be fully activated and integrated into the station’s cooling system on Christmas Day, Dec. 25.

Electrical systems that depend on cooling from Loop A will be repowered or moved back from temporary support on Loop B gradually on Thursday, Friday and throughout the weekend.

Expedition 38 Flight Engineers Mike Hopkins and Rick Mastracchio removed the degraded pump module during a 5 hour, 28 minute spacewalk Saturday, Dec. 22. They retrieved a replacement pump from an external stowage platform near the end of the station’s backbone, and installed it during a 7 hour, 30 minute spacewalk on Christmas eve, Dec. 24.

› Read more about the Dec. 24 spacewalk
› Read more about the Dec. 22 spacewalk

On Saturday, the crew had moved the old pump module to a temporary stowage platform on a rail car on the station’s mobile base system, where it can remain indefinitely. (NASA image)
On Saturday, the ISS crew had moved the old pump module to a temporary stowage platform on a rail car on the station’s mobile base system, where it can remain indefinitely. (NASA image)

Engineers at mission control sent a series of commands to the new pump module at the end of Tuesday’s spacewalk to ensure that ammonia – an excellent thermal conductor – was flowing to the new pump module. Beginning about 4:30 p.m. EST on Christmas Day, remote commands started the process of pressurizing the new pump. Reactivation of the pump is now complete, and it is performing its job regulating the flow and temperature of the ammonia in Loop A of the two-loop cooling system.

On Saturday, the crew had moved the old pump module to a temporary stowage platform on a rail car on the station’s mobile base system, where it can remain indefinitely.