PHOTOS: Astronauts venture outside for repair spacewalk

Astronauts Chris Cassidy and Tom Marshburn floated outside the space station Saturday for a five-and-a-half hour spacewalk to replace a coolant pump suspected of being the culprit for a major ammonia leak.

Canadian astronaut Chris Hadfield, the current commander of the space station, tweeted these photos of the spacewalk Saturday evening.

Hadfield is set to return to Earth with Marshburn and cosmonaut Roman Romanenko on Monday. You can follow him at Twitter at @Cmdr_Hadfield.

See our Mission Status Center for the latest news on the mission.

"Dr. Tom Marshburn, well-dressed for a day's work outdoors. Friend for life." Photo credit: Chris Hadfield/CSA/NASA

"Chris Cassidy, Navy SEAL and lead spacewalker today. The nicest iron man you'll ever meet." Photo credit: Chris Hadfield/CSA/NASA

"Climbing out of the airlock, quite the commute to work! " Photo credit: Chris Hadfield/CSA/NASA

"Chris and Tom, helmet lights doing their best to light the universe on the dark side of the Earth." Photo credit: Chris Hadfield/CSA/NASA

"Here's looking at you. Chris and Tom take a minute with visors to look up-sun at my camera in the window. " Photo credit: Chris Hadfield/CSA/NASA

"Approaching orbital sunset, the harshest of light, a blackness like endless velvet." Photo credit: Chris Hadfield/CSA/NASA
Expedition 29 Patch
Space models