297 SYSTEMS: EXTRAVEHICULAR ACTIVITIES—BUILDING A SPACE STATION CHAPTER 17 of a larger module called the Joint Airlock (Quest). The Joint Airlock houses the Crewlock and also has an Equipment Lock that holds EVA suits and equipment for storage and allows for suit donning and doffing. A Russian-designed depress pump is used to reclaim most of the Crewlock air for continued use in the cabin, rather than depressing the volume of the Crewlock by opening a valve to space in order to equalize with the vacuum of space (Figure 18). Figure 18. Astronaut Doug Wheelock exits through the EVA hatch of the Joint Airlock. A thermal cover (shown directly behind him) keeps the airlock and its hatch at a stable temperature. This flap is closed by a Velcro fixture and must be opened when a crew member goes into or comes out of the hatch. The hatch itself cannot be seen in this photo because the hatch opens into the airlock. Airlock systems also provide vital consumables via umbilicals, or hoses, prior to the crew exiting the airlock. This allows the astronauts to complete their work before starting the spacewalk without using the limited quantities in the spacesuit. These consumables include oxygen and water, as well as power to avoid battery usage, “hardline” (i.e., not using radio) communication, and crew member cooling via an umbilical that attaches to the EMU on one end and an airlock panel on the other. When the team is ready to start the EVA, the astronauts disconnect the umbilical. If need be, the crew members can return to the airlock during an EVA to briefly connect the umbilical and refill oxygen, but this might not fit into a tight timeline if the worksites are far from the airlock. Figure 19. The EMU is donned by putting on the pants (Lower Torso Assembly) and then coming up from the bottom of the shirt (Hard Upper Torso). The crew member puts his or her arms through the sleeves and puts his or her head in the neck of the suit. The astronaut is usually assisted by an unsuited crew member when putting on the communications cap, mating the pants and shirt, and installing helmet and gloves. The morning of an EVA, the crew members get into the EMU by putting on the Maximum Absorption Garment, then a two-piece thin body undergarment resembling long johns for comfort under the LCVG, which will be put on next, followed by the pants (i.e., the Lower Torso Assembly) (Figure 19). The crew member gets into the upper portion