CAPE CANAVERAL — A textbook-sized kit that can convert urine into drinkable water will accompany NASA's last space shuttle mission this Friday. Soldiers already use similar technology to filter out parasites, bacteria, viruses and other contaminants from dirty fluids, including urine, but NASA's adapted baggie system has yet to prove itself in space. "This could be a first step toward recapturing the humidity from our sweat, from our breath, even from our urine, and recycling it and making it drinkable," said NASA project scientist and experiment leader Howard Levine, who made a reference to water-recycling "stillsuits" used on a desert world in the science fiction series Dune. Astronauts aboard the International Space Station already drink water from a pee-recycling machine delivered several years ago, but it saps power from the orbital laboratory's limited supply. The space-ready water conversion kit, however, won't need an external power source because it relies on a passive property of fluids called forward osmosis. NASA's recycler will use a sugary solution injected into a semi-permeable inner bag, which is nested inside an outer bag. Dirty fluid that's pumped into the outer bag will slowly pass through the inner bag and into the sugary solution, leaving behind its contaminants. On Earth, the double-sack system makes about a liter of sports drink-like fluid in four to six hours. One of the four astronauts aboard space shuttle Atlantis will test the recycler — with an experimental fluid, not their own urine — toward the end of their 12-day mission, scheduled for launch this Friday at 11:26 a.m. EDT. Levine and engineer Monica Soler of the Bionetics Corporation, who helped NASA retrofit the recycler for space, gave a demonstration here at Kennedy Space Center. We show the steps in this gallery. Above: Osmotic Bag The key to NASA's recycler is a bag-within-bag. The blue liquid is a potassium-rich solution made to test the experiment's filtration abilities.

Sugary Syringe The recycler relies on an electrolyte-filled solution to pull water molecules across a semi-permeable membrane.

Powering Osmosis Soler injects the electrolyte solution into the semi-permeable inner bag. Once dirty fluid is added to the outer bag, osmosis proceeds. Levine said "urine simulants" have already been tested in the double-bag system, but urea — a chemical in pee that can build up in kidneys and disrupt their function — still gets through. "We'd need to add some sort of carbon filtration on the bag to make it really safe" for drinking urine regularly, rather than on a short voyage, Levine said.

Mess Management In space, moving fluids around is tricky business. To help astronauts, NASA created a T-shaped, syringe-and-valve system. After fluid in a bag of waste (right, tip visible) is sucked into a syringe, a switch is flipped and the waste is pushed into the recycler's outer bag (left). Four to six hours later, a sugary drink is ready.

The Results Levine said astronauts aboard Atlantis won't drink the product yet. So far, only a member of a Japanese TV crew has ever tried it. "We strongly advised him not to, but he did it anyway. He's still alive and walking around," Levine said. "He said it tasted like Capri Sun." Above, Levine and Soler hold up the completed forward osmosis experiment.