JOHNSON SPACE CENTER — NASA astronauts will spend Christmas Day conducting one of three spacewalks to fix a cooling pump on the International Space Station.

Rick Mastracchio and Mike Hopkins are expected to take three walks Saturday, Monday and Wednesday to replace a faulty module that caused one of the station’s two cooling pumps to shut down Dec. 11.

Noncritical systems on the space station were shut down, which has impeded the progress of some research, space station Flight Director Dina Contell said. The partial shutdown poses no danger to crew members, however, she said.

NASA engineers at Johnson Space Center had hoped to fix the problem remotely but were unable to find a solution. 

The space agency has not conducted a spacewalk since July, when a leak in Italian astronaut Luca Parmitano’s helmet rendered the spacewalker unable to see or hear.

Officials are still investigating the cause of the leak, but do not believe problems will occur in the suits being used for the upcoming spacewalks. Extra precautions will also be in place, lead spacewalk officer Allison Bolinger said at a news conference.

Astronauts will venture into space with helmet absorption pads designed to provide an early indication of potential water leaks. A “squishy” helmet indicates that the mission should be cut short, Bolinger said.

Crew members on the station have also made improvised snorkels and vent tubes with onboard material and input from the ground, she said.

The repairs will delay the launch of Orbital Sciences Corp.’s Cygnus spacecraft, which was scheduled to take off Thursday and dock with the station several days later. The commercial resupply mission has been postponed until at least January, a NASA spokeswoman said.

Contact reporter Alex Macon at 409-683-5244 or

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