> Whereas the first arm looked and functioned quite literally like an arm mounted at the shoulder, the Canadarm2 was like two arms connected to one elbow. This

> Whereas the first arm looked and functioned quite literally like an arm mounted at the shoulder, the Canadarm2 was like two arms connected to one elbow. This configuration would eventually allow it to move along rails running the length of the ISS, making it a 1,500-kilogram multi tool for the space station—a crane, grabber, and camera, all in one. I think the author may have missed or misunderstood one of my favorite features of Canadarm2: it's symmetrical! The same mechanical/power/data connection (PDGF) on the end of the arm that grabs payloads is used to connect the base to ISS. The ISS has multiple PDGF points around the station, so it can bend over, grab onto the station with the end-of-arm-tool gripper, release the base of the arm, and walk itself end-over-end like an inchworm. The Mobile Transporter/Base System/Servicing System do allow the arm to move along the main truss, but I think the end-over-end mode is way cooler.