Article Posted on : - Aug 12, 2010

NASA astronauts Doug Wheelock and Tracy Caldwell Dyson working to replace a failed ammonia pump module outside of the International Space Station. A NASA TV photo

WASHINGTON (BNS): NASA astronauts have successfully removed the failed ammonia coolant pump module of the International Space Station (ISS) during their second spacewalk.

The spacewalk, conducted by Expedition 24 members Doug Wheelock and Tracy Caldwell Dyson, ended at 1953 GMT on Wednesday, lasting for seven hours and 26 minutes.

“Wheelock successfully closed the quick disconnect valve for the final fluid connector for the failed ammonia pump module. Then he successfully detached the final fluid line from the failed ammonia pump module.

“Caldwell Dyson disconnected five electrical and data cables while Wheelock broke torque and removed four bolts from the old pump. The pump module then was extracted from the truss through the use of a grapple bar and installed on a payload bracket on the Mobile Base System on the station’s truss,” NASA said.

The new pump will be installed during the third spacewalk lined up for Sunday.

A fourth spacewalk may be required to clean up the work site, NASA said.

The spacewalks became necessary after one of the ISS’s two cooling systems shut down on July 31. Serving the US, European and Japanese laboratories, the system was being used to keep electronic equipment from overheating.

The astronauts, during their first spacewalk last Saturday, ran into trouble while trying to unhook and remove the busted module that has caused the cooling problem.

This necessitated a third spacewalk.