CHAPTER 15 SYSTEMS: ROBOTICS—THE CONSTRUCTION EQUIPMENT FOR THE INTERNATIONAL SPACE STATION 252 performed using the shuttle arm. This included installing the Port 6 (P6) and zenith (Z1) truss segments on STS-97/ISS-4A and the laboratory module on STS-98/ISS-5A. The SSRMS did not arrive on the space station until STS-100/ISS-6A in April 2001 (Figure 2). Even after the SSRMS arrived, the shuttle arm was often used to hand, back and forth, modules and other equipment going to, or returning from, the ISS (Figure 3). Space Station Remote Manipulator System The core part of the station robotic systems is the SSRMS, shown in Figure 4. The SSRMS elbow joint (the joint in the middle of the arm) is offset, or side-by-side, which allows for greater mobility. For comparison, human arms are attached to the shoulder with “in-line” joints. If the elbow is bent, a person can touch a finger to his or her shoulder, but can’t rotate past the point where the forearm touches the bicep. The Canadarm also had joints that could rotate only up to 160 degrees. The amount of possible rotation depended on the joint. The offset elbow joint of the station arm allows the booms on the arm (the “forearm” and the “bicep”) to rotate past each other. The joint can rotate a total of 540 degrees. The pitch and yaw joints at the end of the booms are also offset and have 540 degrees of rotation, with the yaw joint being slightly longer to help reduce the chance of the arm hitting itself in what is known as a self- collision. The final joint on either end of the arm, underneath the end effector, is called a roll joint. The roll Figure 1. This artist’s rendering shows the robotic equipment discussed in the chapter. The SSRMS is outlined in orange. The Robotics Workstation (RWS) is outlined in blue. (Note: in this graphic, the pressure shell of the US Lab is cut away to show the location of one RWS. The second RWS is located in the Cupola attached to Node 3 [the blue dome near the white SSRMS.]) The MBS is outlined in green. The Mobile Transporter and rails are outlined in purple. The SPDM is outlined in yellow. Drawing courtesy of CSA Figure 2. This photograph, taken from the space station during rendezvous operations, shows the Space Shuttle Endeavour payload bay. The SSRMS, in its launch configuration, is seen folded up on a pallet (outlined in yellow) in front of the Raffaello Multi-Purpose Logistics Module (MPLM). For scale, the MPLM is 6.6 m (21.6 ft) in length and 4.6 m (15.1 ft) in width. During the mission, the shuttle arm removed the pallet with the SSRMS from the payload bay and installed it on the ISS. Spacewalking astronauts later unfolded the arm. The first payload ever handled by the SSRMS was the pallet on which it flew. The SSRMS removed the pallet from the space station. The pallet was then handed back to the shuttle arm, which placed it in the shuttle payload bay for return to Earth.