December 12, 2013
The International Space Station’s Expedition 38 crew worked Thursday with the team on the ground to deal with a malfunction that occurred Wednesday on one of the station’s two external cooling loops that uses ammonia to prevent station systems from overheating.
On Wednesday, the pump module on one of the space station’s two external cooling loops automatically shut down when it reached pre-set temperature limits. These loops circulate ammonia outside the station to keep both internal and external equipment cool. The flight control teams worked to get the cooling loop back up and running, and they suspect a flow control valve actually inside the pump module itself might not be functioning correctly.
That flow control valve regulates the temperature of the ammonia in the loop so that when the ammonia is re-introduced into the heat exchanger on the Harmony node it does not freeze the water also flowing through the exchanger.
At no time was the crew or the station itself in any danger, but the ground teams did work to move certain electrical systems over to the second loop. Some non-critical systems have been powered down inside the Harmony node, the Kibo laboratory and the Columbus laboratory while the teams work to figure out what caused the valve to not function correctly and how to fix it.