Astronaut Mike Hopkins tweeted out this photo taken while he was on a Dec. 24, 2013 spacewalk Hopkins, Expedition 38 Flight Engineer, participated in the second of two spacewalks designed to allow the crew to change out a degraded pump module on the exterior of the Earth-orbiting International Space Station. NASA said he was joined on both spacewalks by astronaut Rick Mastracchio, whose image appears in Hopkins’ helmet visor.