Photo by AP Photo/ NASA
In this Saturday, Dec. 21, 2013 photo provided by NASA and tweeted Sunday, Dec. 22, by NASA astronaut Michael Hopkins, Hopkins work to repair an external cooling line on the International Space Station on a spacewalk 260 miles above Earth. The external cooling line — one of two — shut down Dec. 11. The six-man crew had to turn off all nonessential equipment, including experiments.