Two NASA astronauts embarked on a spacewalk Thursday to repair the International Space Station's aging robotic arm, the US space agency said.

The outing by Americans Randy Bresnik and Mark Vande Hei began at 8:05 am (1205 GMT) when the duo switched their bulky white space suits to battery power before floating out of the airlock.

The two men will focus on removing and replacing the latching end of the Canadian-made arm, known as Canadarm2.

The 57.7 foot-long (18 meter) arm was instrumental in assembling the space station and is used to reach out and grab approaching cargo ships.

The robotic arm has been a key piece of equipment at the orbiting outpost for more than 16 years, but has recently lost its ability to grip effectively.

NASA wants to restore its full capability before the next US cargo ship arrives next month, carrying supplies for the six astronauts living in orbit.

The spacewalk is expected to last about six and a half hours.

It is the first of three scheduled spacewalks this month, aimed at repairing and maintaining various equipment outside the ISS, and the 203rd spacewalk in the history of the space station.

source: AFP