Astronauts from the U.S. space agency are preparing for the first of a series of three spacewalks to repair a faulty cooling pump on the International Space Station.
NASA says two astronauts will step out of the ISS Saturday (at 1210 UTC), spending nearly seven hours working on the orbiting spacecraft. They will start by disconnecting the faulty ammonia pump.
A second spacewalk is scheduled for Monday before they finish their work on Wednesday. The malfunctioning pump shut down the space station's cooling system several days ago.
The station has been using a backup system for cooling both internal and external equipment since the pump failure. The problem has forced the astronauts to turn off all non-essential equipment, including some science experiments.
NASA says the two U.S. astronauts have attached snorkels to their spacesuits to use for breathing in case of a helmet water leak.
A helmet worn by an Italian astronaut filled with water in July, causing him to nearly drown. Spacewalks have been suspended since then.