Thursday's spacewalk was the first of three scheduled spacewalks this month aimed at repairing and maintaining various pieces of equipment outside the ISS, and was the 203rd spacewalk in the history of the space station.
NASA says USA astronauts on the station are taking part in the walk - Expedition 53 Commander Randy Bresnik and Flight Engineer Mark Vande Hei.
These spacewalks will include lubricating the new LEEs on the robotic arm and replacing cameras on the ISS's truss and on the U.S. Destiny lab.
This came as no surprise, however, as the two LEEs on Canadarm2 have already exceeded their life expectancy, said Tim Braithwaite, the ISS program liaison for the Canadian Space Agency. Bresnik and Vande Hei will conduct the second spacewalk together. The LEE works as the "hand" of Canadarm2 and is used to grapple incoming cargo spacecraft. One LEE is connected to the ISS by attaching the arm to the station; the other is extended into space and grabs the objects. Joe Acaba arrived at the space station September 12 for his third mission to space.
The astronauts will fix the latching mechanism on the end of the Canadian robotic arm which is not functioning properly. The arm also can mount itself atop a mobile transporter that runs on rails along the front side of the station's solar power truss to move the arm to various work sites. The Canadarm2 has started experiencing some wear and tear. The malfunction hasn't impacted any operations, but it needs to be replaced.
Vande Hei and Bresnik plan to step out on another spacewalk Oct 10, with the third set for Oct 18.
In the near term, two more spacewalks are planned October 10 and 18 to lubricate the newly attached LEE-A fitting, to replace two cameras with degraded color and to carry out other routine maintenance.