Two US astronauts wrapped up a speedy spacewalk outside the International Space Station yesterday, replacing a failed computer that backs up one used to control critical systems such as the station’s solar panel wings.

Flight engineers Rick Mastracchio and Steve Swanson left the station’s Quest airlock just after 10 am EDT (1400 GMT) for what ­­­was expected to be a 2-1/2-hour spacewalk. They replaced the failed computer and got back into the space station with an hour to spare.

Computer is one of two that control critical systems outside the station

“Nice and clean. Great job,” Canadian astronaut Jeremy Hansen from NASA’s Mission Control in Houston radioed to the spacewalkers as they prepared to close the hatch.

The computer, about the size of a small microwave oven, is one of two that control critical systems outside the station. These include sending commands to rotate the solar panel wings to track the sun and positioning a mobile base for the station’s robotic crane.

“I don’t see any obvious damage,” Mastracchio said as he and Swanson inspected the unit, which failed on April 11.

US spacewalks generally last more than six hours, but except for emergency repairs, NASA spacewalks remain suspended while engineers assess last year’s spacesuit failure that nearly drowned Italian astronaut Luca Parmitano after his helmet filled with water.

The leak was traced to a blocked filter, and Nasa flew parts to the station for astronauts to make spacesuit repairs before a pair of emergency spacewalks in December to fix the station’s cooling system. Those astronauts also had snorkels and absorbent pads in their helmets in case of similar leaks.

Mastracchio, making his ninth spacewalk, and Swanson, on his fifth, also included snorkels and pads in their helmets. A new spacesuit is among the cargo aboard the Space Exploration Technologies’ Dragon capsule that reached the station on Sunday.