Water on the Space Station
Every Drop Counts
Once the water is purified, astronauts will do everything possible to use
it efficiently. "On the ground, people flick on the faucet and
they probably waste a couple of liters of water just because it's
free and the water pressure is high," notes Carter.
"On the ISS, the water pressure will be about half what you might experience
in a typical household," Carter said. "We don't use faucets on
the ISS, we use a wash cloth. It's much more efficient. If you're
an astronaut, you'll wet the wash cloth with a spray nozzle and
then use the cloth to wash your hands."
One of the "nodes" that will become a part of the Space Station.
The ECLSS life support equipment will be housed in Node 3,
which is scheduled to be attached to the station in October
On the space station, people will wash their hands with less than one-tenth
the water that people typically use on Earth. Instead of consuming
50 liters to take a shower, which is typical on Earth, denizens
of the ISS will use less than 4 liters to bathe.
Even with intense conservation and recycling efforts, the Space Station
will gradually lose water because of inefficiencies in the life
"We will always need resupply, because none of the water reprocessing technology
that is available right now for space flight ... is 100 percent
efficient. So there's always some minimal loss," said Marybeth
Edeen, deputy assistant manager of environmental control and life
support at NASA's Johnson Space Center.
Water is lost by the Space Station in several ways: the water recycling
systems produce a small amount of unusable brine; the oxygen-generating
system consumes water; air that's lost in the air locks takes
humidity with it; and the CO2 removal systems leach some water
out of the air, to name a few.
Lost water will be replaced by carrying it over from the Shuttle or from
the Russian Progress rocket. The Shuttle produces water as its
fuel cells combine hydrogen and oxygen to create electricity,
and the Progress rocket can be outfitted to carry large containers
NASA scientists will continue to look for ways to improve the life support systems
of the Space Station, reducing water losses and finding ways to
reuse other waste products. If the water recycling systems can
be improved to an efficiency of greater than about 95 percent,
then the water contained in the Station's food supply would be
enough to replace the lost water, Edeen said.
"It takes processes that are slightly more efficient than we have developed
for the space station to do that," Edeen said. "Those are the
next generation water processing systems. Those are being developed
now, but they're not ready for space flight yet."
The ECLSS life support system will join the Space Station as part of Node 3, which
is scheduled to launch in October 2005. Until then, the environment
inside the ISS will be maintained primarily by life support systems
on the Russian Zvezda Service Module.