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Astronauts replace broken ISS cooling system

Other News Materials 17 August 2010 03:38 (UTC +04:00)
Two US astronauts on Monday undertook their third spacewalk in 10 days, to complete the replacement of a cooling system aboard the International Space Station (ISS), dpa reported.
Astronauts replace broken ISS cooling system

Two US astronauts on Monday undertook their third spacewalk in 10 days, to complete the replacement of a cooling system aboard the International Space Station (ISS), dpa reported.

Doug Wheelock and Tracy Caldwell Dyson retrieved and installed a spare ammonia cooling loop pump that was stored outside the station during the 7-hour, 20-minute long spacewalk, NASA said.

"We've got our station back," Wheelock said as the spacewalk concluded, bringing to an end the complex process of fixing the crucial system.

The new pump was functioning properly and the cooling system would again be working as normal no later than Thursday, NASA said.

The astronauts had last week removed a defective, 350-kilogramme cooling pump that had broken down last month, prompting the shutdown of some systems aboard the station.

A previous removal attempt on August 7 had been interrupted after a hose proved difficult to disconnect and leaked dangerous ammonia.

The cooling system is one of two used to keep electronics on the ISS from overheating. Alarms were triggered on July 31 signalling that the ammonia-based refrigeration system on the ISS had failed due to a power surge.

Wheelock and Dyson ran out of time Monday to complete a secondary task to prepare for another spacewalk in November when astronauts will install a new module to the ISS.

   NASA officials stressed that the six crew members were in no danger due to the broken cooling system, and all critical and many non-critical systems on the ISS have since been operating as normal despite the malfunction.

   The ISS could continue to operate without the cooling system indefinitely, but would be in trouble if the second ammonia cooling loop were to also fail before the first is replaced.

   The US space agency had known that the cooling unit would eventually need to be replaced after about 100,000 hours of use and had installed four extra units outside the ISS as a precaution.

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