CHAPTER 13 SYSTEMS: COMMUNICATIONS AND TRACKING—THE VITAL LINK TO THE INTERNATIONAL SPACE STATION 230 Video The video system on board the ISS generates and distributes high- definition and standard-definition video. As with audio, video signals can be routed from a variety of sources and directed to an assortment of destinations—whether it be to a computer monitor for the crew or to the ground. Standard definition cameras that are mounted externally are known as the External Television Camera Group (Figure 8). This group consists of the camera that can be panned, tilted, and zoomed, a light that moves with the camera, and a controller. These cameras operate continuously on the ISS and provide video of spacewalking astronauts, views of visiting vehicles, or views of the outside of the space station for the ground controllers to monitor (see Chapter 17). The crew on board the ISS and by the flight control teams and engineering support teams around the world use the video system to monitor spacewalks, robotics operations, and arrival and departure of visiting vehicles, as well as for inspections of the ISS. Recall that there are very few windows to actually allow the crew to see outside. Live video of the astronauts can be useful for the ground team to monitor activities and assist the astronauts in their work. When the ISS bandwidth allows (i.e., not all in use by payloads or telemetry), one video feed from the ISS is streamed live on the internet. Occasionally the external cameras are used to track hurricanes and typhoons since the ISS provides a unique, real-time vantage of such situations. The video system is a key part in conducting media outreach- type events on board the ISS to help educate the public about life on the ISS. Often, the astronauts participating in the live event serve as their own camera crew. They will set up the camera in advance. Then, the flight control team will configure the video and Ku-band system to bring the view from the camera to the ground where the NASA Public Affairs Office distributes the video to the client. Figure 9 shows Expedition 31 flight engineer and European Space Agency astronaut Andre Kuipers setting up a camera in preparation for a Public Affairs Office event in the US Laboratory. Two other cameras are visible in addition to the one Kuipers is setting up. Over time, the camcorders on the ISS were replaced with more recent models. The video from these cameras and the video from the Wireless External Transceiver Assemblies go external to internal by way of one of three external video switching units. Once internal to the ISS, the video is further distributed by one of four video switching units. High-definition video recorders are typically distributed throughout the USOS modules inside the ISS. The video from these recorders is also distributed throughout the ISS and are connected to the Ku-band system, allowing video to be downlinked to the ground. The video units are also connected to the Robotic Workstation monitors in the Cupola and the US Laboratory, thereby allowing the crew to view the live video from the External Television Camera Groups or from the Mobile Service System (see Chapter 15). Usually, the flight controllers will configure the video system when it is needed, leaving the crew to only power up and position internal cameras. Figure 8. View of the S1 truss segment External Television Camera Group. The white oval is the light attached to the camera (tan rectangular box directly to the left of the light). If there is nothing critical to watch at the ISS, the flight controllers will point the cameras at the Earth to allow the team to enjoy the view from above in the control center.