17 Aug 2016

Dextre, the Canadian robotic handyman on board the International Space Station (ISS), will have a very important job to do from August 17 to 19, 2016. Dextre will convert an existing docking port on the ISS into a spaceport able to welcome the upcoming new US commercial crew vehicles. This means that crew vehicles other than the Russian Soyuz will be able to dock to the ISS. An International Docking Adapter (IDA) was designed to convert the port and was shipped to the ISSon board SpaceX's latest Dragon cargo ship. Next, Canada's robots are being called in to do the heavy lifting.

Dextre's job
The IDA was brought up on board SpaceX's Dragon-9 spacecraft. Both Canadarm2 and Dextre (riding on Canadarm2) are capable of removing equipment from Dragon's trunk, but because of the way Dextre moves, he is the only robot on the ISS that can reach and handle the IDA.

Here are the steps that he will go through during the mission:
★ Extract the IDA from Dragon's trunk using his Arm2.
★ Ride on Canadarm2 to the installation position, in front of the existing docking port calledPMA2 (Pressurized Mating Adapter-2).
★ Using Arm2, maneuver the IDA as close as possible to PMA2.

★ Wait for the two astronauts to begin their spacewalk by exiting the Station's airlock and making their way to PMA2. They will then strap their feet into foot restraints and grab theIDA.
★ Open his grippers (fingers) to "hand" the IDA to the astronauts so they can finish the installation.
★ Back away from PMA2 and provide camera views of the astronauts' work for ground controllers to see.

The animation below shows "in fast-forward" how this will be done.

This delicate operation will mark the first time that Dextre will hand off a payload directly to an astronaut. This operation cannot be done by Dextre alone, simply due to the design of the IDAand PMA2. The work requires extreme care on the part of the ground controllers and the astronauts to ensure that neither the IDA nor Dextre are damaged. The installation must be done properly to allow future astronauts and cargo to move safely from docked vehicles at this port to the ISS in a pressurized environment.
Expedition 48 Commander Jeff Williams and NASA astronaut Kate Rubins will conduct the spacewalk to install the equipment. This will be the fourth spacewalk in Williams' career, the first for Rubins, and the 194th for the Space Station.

Implications for the future
In addition to being yet another first for robot-kind, the new spaceport will be a gateway for the future of US spacecraft built by Boeing and SpaceX that will carry astronauts to the ISS. This will increase the number of opportunities to fly astronauts, and consequently, allow for more crew time dedicated to science. The new IDA will allow vehicles to dock in a gentler manner and will be more efficient than existing ports.
Watch Dextre at work live starting on August 17 around 6:30 p.m. EDT on UStream. Coverage of the spacewalk will begin on August 19 at 6:30 a.m. EDT on NASA TV.

Image:
(Left) Dextre and Canadarm2.
(Right) SpaceX Dragon, Canadarm2 and Dextre. The ISS crew captured this view of Dextre at the end of Canadarm2, prepared to remove cargo from Dragon.