NASA commander Randy Bresnik and astronaut Mark Vande Hei have spent seven hours upgrading one of the International Space Station's robot arms.
The pair worked to attach a new Latching End Effector – the “hand” at the end of the Canadarm2 – to replace one that wore out.
Canadarm2 is any old gripper: as well as performing maintenance, it's other job is to catch supply ships.
Once a supply vessel is in its grip, the 17 metre arm is also the channel for the ISS to supply the vessel with power and data. Canada's space agency has a compendium of its catches here.
After 16 years in orbit, its original latching mechanisms had been used nearly 400 times, giving rise to the wear and tear that necessitated replacement.
NASA explains that in September, the LEE replaced in the spacewalk “experienced a stall of its motorized latches”.
In another spacewalk next week, the astronauts will apply lube to the new LEE; and a third venture outdoors is planned to replace cameras on the left side of the ISS's truss and on the right side of the US Destiny laboratory.
When he left the airlock, Vande Hei became the 221 st spacewalker; Bresnik was already a veteran of two spacewalks, and on October 18 he'll be joined by flight engineer Joe Acaba on his third spacewalk.
If you've got a really dull day ahead, the whole seven hour livestream of the spacewalk is on YouTube below. ®