Two astronauts aboard the International Space Station (ISS) have completed a spacewalk to instal a new camera system on the orbiting laboratory's robotic arm, replacing a blown fuse and installing a new high definition camera on the starboard truss of the station.

During the spacewalk lasting for six hours and 49 minutes, Flight Engineer Joe Acaba of NASA greased the new end effector on the robotic arm and Expedition 53 Commander Randy Bresnik installed a new radiator grapple bar, NASA scientists wrote in a blog post late on Friday.

Bresnik completed preparatory work for one of two spare pump modules on separate stowage platforms to enable easier access for potential robotic replacement tasks in the future.

In picture: A NASA astronaut out on a spacewalk.Twitter/NASA

"He nearly finished prep work on the second, but that work will be completed by future spacewalkers," the post said.

This was the fifth spacewalk of Bresnik's career (32 hours total spacewalking) and the third for Acaba (19 hours and 46 minutes total spacewalking).

Space station crew members have conducted 205 spacewalks in support of assembly and maintenance of the orbiting laboratory.

Spacewalkers have now spent a total of 53 days, 6 hours and 25 minutes working outside the station.