This December 24, 2013 NASA TV still image shows astronaut Mike Hopkins on the robotic arm (Lower-R) and Rick Mastracchio (front) during a spacewalk outside the International Space Station (ISS).

Americans Rick Mastracchio, 53, and Mike Hopkins, 44, floated outside the orbiting lab for seven and a half hours to replace an ammonia pump whose internal control valve failed on December 11.

"We have a pump that is alive and well," said a NASA commentator on the US space agency's live television feed after a successful jumpstart test on the newly installed pump module, a bulky piece of gear the size of a refrigerator.

More checks will be done later Tuesday, but the pump appeared to be "in good shape" and would be fully activated in the coming hours, a NASA commentator said from mission control in Houston.

Despite recent concerns about leaking spacesuits, neither astronaut reported any problems.

The suits "have functioned perfectly and have been bone dry throughout the course of today's spacewalk," a NASA commentator said.

Hopkins, making his second career spacewalk, rode the 57-foot (15-meter) robotic arm, operated from inside the station by Japanese astronaut Koichi Wakata.

With his boots affixed to the Canadian-made arm, Hopkins grasped the bulky pump module as Wakata maneuvered him over to its installation location.

Then, Mastracchio, who was making his eighth career spacewalk, helped push the module into its slot and the pair began affixing it in place.

Five electrical connections and four fluid connections followed, and a brief test, like a jumpstart, was done to test the pump's connections and electronics.

Originally posted here:

NASA astronauts wrap up successful spacewalk on Christmas Eve to fix station