Two NASA astronauts embark on spacewalk to repair space station cooling system.
IN SPACE (NASA TV) - Two NASA astronauts, their spacesuits rigged with snorkels in case of a water leak, floated outside the International Space Station for 5-1/2 hours on Saturday (December 21), successfully completing the first steps to fix the outpost's cooling system.
No such leaks were detected in Saturday's spacewalk, although flight engineer Rick Mastracchiocomplained about three hours into the repairs.
The operation was prompted by the Dec. 11 shutdown of one of the station's two U.S. ammonia cooling systems, which forced the crew to turn off non-essential equipment and shut down dozens of science experiments.
While the six-member crew is not in danger, the remaining cooling system cannot support the three laboratories and other modules on the U.S. side of the $100 billion station, a project of 15 nations. The Russian side of the station has a separate cooling system.
Engineers at the Johnson Space Center in Houston tried devising ways to bypass a suspected faulty pump valve, but with time running short, managers decided to have astronauts replace the pump, located outside the station, with a spare.
They were able to not only disconnect the old pump, but also remove it from its pallet on the station's exterior truss, a task originally slated for a second spacewalk on Monday (December 23). A third spacewalk, if needed, is scheduled for Wednesday (December 25).
"Beautiful day. Awesome view," Mastracchio, a veteran of six previous spacewalks, said as opened the airlock's hatch and saw the view from 260 miles (418 km) above the southern Atlantic Ocean.
He and Hopkins wore spacesuits that were modified to protect them from another possible water leak. The problem in July was traced to contamination in piece of equipment called a fan pump separator that circulates water and air in the spacesuit and removes moisture from air.
How the water-separator portion of the device became clogged remains under investigation.
Hopkins, who was making his first spacewalk, wore Parmitano's spacesuit, but it had been outfitted with a new fan pump separator.
In addition, both Hopkins and Mastracchio rigged their helmets with homemade snorkels, fabricated out of pieces of plastic tubing and Velcro, which they could have used for breathing in case of another water leak.
The helmets also included water-absorbent pads.
During Saturday's spacewalk, Mastracchio and Hopkins disconnected electrical and fluid lines and removed the 780-pound (354 kg), 5-foot (1.5 metre) wide cooling system pump.
The failed pump, which was then anchored in a temporary storage site, will remain on the station for possible future repair and reuse.
It was installed in 2010 during an unexpectedly difficult series of spacewalks.