CHAPTER 17 SYSTEMS: EXTRAVEHICULAR ACTIVITIES—BUILDING A SPACE STATION 288 on the ISS) to ensure communications are not lost. Crew members wear a communication cap (i.e., a “Snoopy” cap) with a microphone boom. The microphone is set to transmit without requiring the crew member to push a button on the suit. Everything he or she says can be heard, assuming the communication links are good. Each crew member’s electrocardiogram data are also transmitted over UHF so that flight surgeons in Mission Control can monitor the health of each astronaut during the activities. EVAs are strenuous. Prevention of a serious health issue is critical since treatment is difficult, if not impossible, until the crew member is back inside the space station. The Display and Control Module is the brains of the suit and includes a Liquid Crystal Display readout, switches, and a pressure gauge. The crew display is somewhat similar to a car or cockpit’s computer readout system. It gives the crew member insight into the health of his or her suit, including audible alarms through the Snoopy cap, when required. Since a crew member can’t see the front of his or her chest when in the suit, a wrist mirror is used to look at the controls on the front of the suit, which is why the labeling is backward. The Cuff Checklist—a small binder attached to the crew member’s wrist—contains reference instructions and emergency procedures (Figure 8). Cuff Checklist Photo credit: NASA/Dina Contella Figure 8. The EVA Cuff Checklist (bottom) is a small book worn on the wrist (top) that the crew can reference for steps to perform during normal operations and in emergency situations. The crew often prints out new pages sent from Mission Control Center or writes on blank pages with some additional reminders just before an EVA. The EMU is sized for each crew member through a modular approach, with various sizes and lengths for the main torso and other parts. Fit is further improved with sizing spacers and fine adjustment tabs in the suit, although EMUs are still notoriously