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Emergency spacewalk to repair ammonia leak

Two astronauts from the International Space Station are out on an emergency spacewalk to inspect and possibly repair an ammonia leak from a power-cooling system.

The problem was discovered on Thursday when the crew spotted a steady stream of small white frozen ammonia flakes floating away into space.

The two astronauts, Chris Cassidy and Tom Marshburn, described what they saw when they went out to investigate.

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