Two critical aspects of living in space is being able to have enough fresh water aboard your ship and to be able to dispose of urine. Early NASA missions didn’t require extensive bathrooms and any water the astronaut needed for the daily mission was carried up with them. On the apollo missions, astronauts got water as a by-product of a fuel cell, and were given a urine ‘bag’ system that used a tube, since all astronauts were male at the time, attached to a one-way valve with an attachable bag. They eventually revised this urine bag system so that the urine could be ejected out of the capsule, simply disposing the urine into space where it would appear as streams of water vapor coming off the ship. One fun fact about the water filter on apollo 11 is that its hydrogen filter was broken, thus all the water they drunk was ‘bubbly’ and appeared as club soda.
This system of making water with fuel cells and then simply ejecting the urine afterward right into space lasted for quite some time for two reasons. First, NASA was not running long-term missions, nor was much of its manned equipment staying in space forever like the ISS. Secondly, using a typical distiller, like most urine on earth is recycled, is not as easy or practical in zero gravity, thus until it wasn’t necessary nor worth the effort. The distilling process on earth relies on the fact that water evaporates and the vapor rises while the solutes that pollute the water are held in the bottom of the chamber by gravity, thus without gravity the water vapor never separates from other substances within.
NASA has been working on recycling urine for use as long as the ISS became a project. In 2009, a distiller and purifier for urine was installed on ISS that used a spinning chamber to generate a ‘gravity’ with centripetal acceleration. In addition, it used several charcoal filters that filtered additional pollutants out. Because the spinning distiller requires a fair amount of energy, many are looking into filters and membranes specific for urine that rely on a process called ‘forward osmosis’ that can be used to recycle the water and convert the waste products, urea and other compounds, into energy using fuel cells. Thus, as technology advances, astronauts, might not only be able to recycle their pee for hydration use later, but get energy in the process. These purifiers might even have practical uses on earth as well.
Sources:
http://www.sciencedaily.com/releases/2014/04/140409103409.htm
http://motherboard.vice.com/blog/when-you-gotta-go-you-gotta-go-even-in-space
