for evaluation, but most are loaded into a cargo ship that burns up on re-entry through Earth’s atmosphere. Currently, fecal waste is not processed for water recovery, but NASA is studying this capability. Basic parts There are four basic parts in a space toilet: the liquid-waste vacuum tube, the vacuum chamber, the waste storage drawers, and the solid-waste collection bags. The liquid-waste vacuum tube is a long rubber or plastic hose that is attached to the vacuum chamber and connected to a fan that provides suction. At the end of the tube is a detachable urine receptacle, which comes in different versions for male and female astronauts. The male urine receptacle is a plastic funnel in width and about deep. A male astronaut urinates directly into the funnel from a distance of away. The female funnel is oval and is wide at the rim. Near the funnel's rim are small holes or slits that allow air movement to prevent excessive suction. The vacuum chamber is a cylinder about deep and wide with clips on the rim, where waste collection bags may be attached and a fan that provides suction. Urine is pumped into and stored in waste storage drawers. Solid waste is stored in a detachable bag made of a special fabric that lets gas (but not liquid or solid) escape, a feature that allows the fan at the back of the vacuum chamber to pull the waste into the bag. When the astronaut is finished, he or she then twists the bag and places it in a waste storage drawer. Samples of urine and solid waste are frozen and taken to Earth for testing. Designs Space Shuttle Waste Collection System The toilet used on the Space Shuttle is called the Waste Collection System (WCS). In addition to air flow, it also uses rotating fans to distribute solid waste for in-flight storage. Solid waste is distributed in a cylindrical container, which is then exposed to vacuum to dry the waste. The WCS required many hours of training. For urination, a hose was used. For defecation, with a diameter for the hole in the seat—much smaller than in a conventional toilet—the user's bottom needed to be exactly centered on the seat. NASA built a simulator with a video camera in the hole; those training used a crosshair to learn how to position their bodies, while other astronauts watched and made jokes.