In this image made from video provided by NASA, astronaut Rick Mastracchio performs a space walk outside the International Space Station on Saturday, Dec. 21, 2013. Mastracchio and Michael Hopkins

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In this image made from video provided by NASA, astronaut Rick Mastracchio performs a space walk outside the International Space Station on Saturday, Dec. 21, 2013. Mastracchio and Michael Hopkins ventured out of the station to try to revive a crippled cooling line. (AP Photo/NASA) less 

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Associated Press
Mon, Dec 23, 2013 8:01 PM EST