Astronauts on spacewalk at ISS
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Third ISS repair spacewalk begins to repair cooling system

Astronauts are continuing repairs on the International Space Station's cooling system.

Douglas Wheelock and Tracy Caldwell Dyson ventured out on Monday morning, on their third spacewalk in just over a week.

They removed a faulty pump during the two previous walks, the first of which was complicated by an ammonia leak.

The spacewalkers must now replace the pump, which cools station equipment.

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