Imagine that you were on the adventure of a lifetime, exploring outer space
and – literally – going where no one has gone before. Oh, and there’s just
one catch; you’ll need to recycle your own urine into drinking water. That’s
now reality for the astronauts aboard the International Space Station. In
November, the space shuttle Endeavor delivered NASA’s Water Recovery
System (WRS) and after a few initial glitches, it appears to be functioning well.

Orbiting 250 miles above our planet, the International Space Station is an
outpost for humanity tethered to our world only by gravity. Supplying the
station with water has always been an issue; the cost per pint tops $15,000 US.
As such, the astronauts had always relied on recycling and water reclamation
was a necessary fact of life. The crew of the station had to recapture
every possible drop: water evaporated from showers, shaving, tooth brushing
and hand washing, plus perspiration and water vapor that collects within
the astronauts’ space suits. In a pinch, they even transferred water from
the fuel cells that provide electric power to the space shuttle, but one
frontier of reclamation lay untapped: the astronauts’ own urine.
Image courtesy of NASA

The WRS mimics the water cycle of our own planet, evaporating and
re-condensing the water and then passing it through filters that capture
and remove any remaining contaminants. Going into a bit more detail, the
new system distills urine then shunts it to join the rest of the recovered fluids
in the water processor. The processor filters out solids such as hair and lint
and then sends the wastewater through a series of multifiltration beds, in
which contaminants are removed through adsorption and ion exchange.
After that, a reactor that breaks down any remaining compounds to carbon
dioxide, water and a few ions. After a final check for microbes, the water is
again clean and ready to drink.
NASA, the Russian Space Agency and most scientists see urine recycling as
a logical ‘must have’ for interplanetary travel. Furthermore, once at their
destination – say Mars – the explorers will most likely need to continue water
recycling until a permanent settlement is in place, even if local water sources
exist. While every effort would be made to land the exploration crew near ice
deposits, until that ice is proven ‘clean’ and fit to drink, the crew will need to live
as they had for the journey.
The initial few days of testing the new WRS were frustrating to the crew and
mission controllers. The WRS seemed to be unable to run for more than four
hours without being restarted. Finally, the problem was identified as a
poorly-mounted centrifuge. Astronauts Mike Fincke and Don Pettit changed
how the centrifuge was mounted in the unit and the WRS began running smoothly.
NASA has stated that it plans to test the recycled urine for any contaminants
and to make sure that the system works as well in microgravity as it did on Earth.
If all goes well, the crew of the International Space Station will get the go-ahead
to use the WRS unit full-time in 2009.