Space station breakdown has NASA scrambling

CAPE CANAVERAL, Fla. (AP) " NASA is scrambling to come up with a repair plan for a serious malfunction that's knocked out half of the cooling system on the International Space Station.

Engineering teams have been working nonstop since one of two cooling loops shut down Saturday night. A pump that drives ammonia coolant through the lines on the right side of the space station has failed.

NASA plans a news briefing Monday.

Astronauts Douglas Wheelock and Tracy Caldwell Dyson will venture out Thursday to replace the pump. A second spacewalk will be needed to finish the job, probably Sunday. Astronauts on the ground will test potential repair procedures Monday afternoon.

NASA says the six residents are safe and the outpost is stable. But lots of equipment remains shut off to prevent overheating.

Copyright 2010 The Associated Press.