NASA astronauts begin urgent spacewalking repairs

By By MARCIA DUNN

CAPE CANAVERAL, Fla. (AP) — Astronauts have stepped out on the first of a series of urgent repair spacewalks at the International Space Station.

The two Americans on the crew floated outside Saturday morning. They will disconnect an ammonia pump that contains a bad valve. The breakdown has crippled the space station's critical cooling system for the past 1½ weeks.

The pump replacement is a huge undertaking attempted only once before, in 2010. NASA has ordered up three spacewalks to complete the job. The next one will be Monday.

Astronauts Rick Mastracchio (Muh-STRACK-ee-oh) and Michael Hopkins will go back out again Christmas Day, if any work remains.

The six-man crew had to turn off all nonessential equipment inside the orbiting lab following the malfunction on Dec. 11. Scientific research came to a near-halt.

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