Astronauts aboard the space station celebrated a space first on Wednesday by drinking water that had been recycled from their urine , sweat and water got from air. They said "cheers," clicked drinking bags and toasted NASA workers on the ground. The urine recycling system is needed for astronaut stations on the moon and Mars. It also will have NASA money because it won't have to ship up as much water to the station by space shuttles or cargo rockets. Besides, it's important as the space station is about to expand from three people living on board to six. The recycling system had been brought up to the space station last November by space shuttles Endeavour, but it couldn't be used until samples  were tested back on earth. So when it came time to actually drink up, NASA made a big deal of it. The three-man crew stood holding their drinks and congratulated engineers in two NASA centres that worked on the system. "This is something that had been the stuff of science fiction," American astronaut Michael Barratt said before taking a small mouthful. "The taste is worth trying." The new system takes the combined urine of the crew from the toilet, moves it to a big tank, where the water is boiled off, and the vapor  is collected. The rest of the urine is thrown away. Then the water vapor is mixed with water from air, and then it goes through filters  . When six crew members are aboard it can make about six gallons from urine in about six hours. "Some people may find the idea of drinking recycled urine distasteful, but it is also done on earth, but with a lot longer time between urine and the tap," said Marybeth Edeen, the space station's national lab manager. The technology NASA developed for this system has already been used for quick water purification after the 2004 Asian tsunami. From Para. 5 we can know   _  .
the theory behind the recycling system the effect of the recycling system the process of recycling urine an opinion on recycling urine