257 SYSTEMS: ROBOTICS—THE CONSTRUCTION EQUIPMENT FOR THE INTERNATIONAL SPACE STATION CHAPTER 15 location along the truss. It can stop and “plug in” to the power and data networks at specific locations. Altogether, there are 10 transporter worksites on the ISS numbered 0 (W0) through 9 (W9), but only eight of them are actually used. The last two worksites (W0 and W9) are located outboard of the Solar Array Rotary Joint (see Chapter 9). The rails were never installed on those outer segments thus far, those outboard worksites have never been required for operations. Drawing courtesy of CSA Figure 10. Locations where the Mobile Transporter can park along the truss of the ISS are listed as Worksite (W)1 through W8. W1 is located on the Starboard 3 (S3) truss segment. Worksites W0 and W9 are not shown and would be on the S4 and Port 4 (P4) trusses, respectively. SSRMS is attached to an MBS PDGF SSRMS is holding the SPDM, which is holding another piece of hardware POA is holding a piece of hardware Figure 11. This picture taken during Expedition 26 shows the SSRMS based on an MBS PDGF holding the SPDM, which is attached to an Orbital Replacement Unit. The Payload Orbital Replacement Unit Accommodation (POA) is also holding another Orbital Replacement Unit.