289 SYSTEMS: EXTRAVEHICULAR ACTIVITIES—BUILDING A SPACE STATION CHAPTER 17 difficult to size perfectly (Figure 9). Crew members often have their own gloves made to fit their hands, or they use another crew member’s gloves if they are a good approximation and available for their flight. The spacesuits cannot stay on orbit indefinitely, and there is not enough storage space to accommodate multiple sets of every sized piece. Thus, ground teams work on EMU logistics to ensure the various parts, including spares, get launched and are on orbit for each crew member. Wrinkles in these complicated logistics can occur, as was the case in the destruction of the Cygnus cargo vehicle on October 28, 2014, when the rocket carrying Cygnus exploded shortly after liftoff (Chapter 14). The cargo mission was carrying EMU equipment, including a sized LCVG for one crew member, as well as a SAFER unit and several tools and suit maintenance items that had to be sent up on a later mission. A SpaceX cargo vehicle was also lost during launch on June 28, 2015, resulting in the loss of an EMU life support system and upper torso that was being sent up for its freshly refurbished parts. Figure 9. EMU components are specifically picked out for each crew member so the suit can be appropriately sized. Shown are: (left) the Lower Torso Assembly, with boots and metal sizing rings pictured (center) an EMU glove and (right) a sizing ring for lengthening an arm. The EMU offers quite a bit of functionality, considering its small size as a spacecraft. It has a rechargeable battery for powering the various components when out on an EVA. A crew member can pull down a sun visor on the front of his or her helmet to act as sunglasses when orbital night turns into brilliant orbital day approximately every 90 minutes (a sunrise or sunset occurs approximately every 45 minutes). Helmet lights are used for operations at night, and a television camera is mounted to the helmet so the ISS crew inside and the flight controllers on the ground can monitor the extravehicular crew’s activities. Crew physiology support includes a drink bag with a straw and a maximum absorbency garment (i.e., a diaper). After an incident where water entered a crew member’s helmet on US EVA 23, NASA equipped the EMU with a helmet absorption pad to absorb water on the head, as well as a snorkel similar to those used by scuba divers. The snorkel extends from near the mouth down to the waist so the astronaut can breathe oxygen from the body of the suit if the helmet fills with water. The Orlan (Figure 10) provides similar capability but is packaged differently. Example differences include rear entry through a hatch for quick self-donning instead of the EMU shirt-and-pants design, adjustable length sizing rather than modular parts, and a higher operating pressure (295 mm Hg [5.7 psi]). Figure 10. US astronaut Mike Fincke is working in a Russian Orlan spacesuit. Some US tools were used during this EVA, with adapters installed as needed so they could be used with the Orlan.