Nicole Stott, a flight engineer on Expedition 21 of the International Space Station, tests the quality of drinking water using chemistry and procedures developed by Iowa State University and Ames Laboratory researchers. NASA photo.
Bob Lipert held up a syringe, attached a plastic cartridge and demonstrated
how chemistry developed at Iowa
is helping astronauts and cosmonauts make sure they have safe drinking water at
the International Space Station.
Each cartridge contains a thin, 1-cm disk that’s loaded with chemistry,
says Lipert, an associate scientist with Iowa State’s
Institute for Physical Research and Technology and an associate of the U.S.
Department of Energy’s Ames Laboratory. Run a 10-mL water sample through a disk
and it will change color in the presence of iodine, which NASA uses to inhibit
the growth of microorganisms in the drinking water stored at the space station.
The disk will turn from white to yellow and, as it’s exposed to higher
concentrations of iodine, it will turn to orange and finally to a rust color.
A handheld device—a diffuse reflectance spectrometer—can read the disk’s
color changes and precisely measure the concentration of molecular iodine. The
whole process is called colorimetric solid phase extraction.
Starting in late September (2011), Lipert says astronauts at the space
station will use new developments and procedures that convert all forms of
iodine in the water samples to molecular iodine. That will give astronauts a
more precise reading of total iodine in their drinking water. Lipert says
they’ll know in real time whether there’s too much, too little, or just enough
iodine in the water.
Disks loaded with different chemistry can also measure and record
concentrations of silver, which the Russian Federal Space Agency uses as a
biocide in its water supply at the space station. As silver concentrations
increase, disks turn from yellow to purple.
Before Iowa State chemists helped develop the new
tests, the only way to test the space station’s drinking water was to send
samples back to earth.
“We figured out the chemistry and put it into a form that can be used in
space,” Lipert says. “We also took lab techniques and simplified them
as much as possible. And we developed procedures that can be used in the
absence of gravity.”
The result is a quick, accurate test that doesn’t use up much drinking
water or much astronaut time.
“What’s neat about what we came up with is that all the chemistry we
need to do can be accomplished in about one minute per sample using a little,
1-cm cartridge,” Lipert says.
It took some work to develop the test’s chemistry and procedures. The
NASA-sponsored project began more than a decade ago under the direction of Marc
Porter, a former Iowa State professor of chemistry and chemical and biological
engineering who is now a USTAR Professor at the University
of Utah in Salt Lake City. Lipert has worked on the
project since 2000.
The university researchers have also collaborated with the Wyle Integrated
Science and Engineering Group, a NASA subcontractor that helped develop and
certify the water-testing hardware that has been deployed on the space station.
After a series of successful space tests in 2009 and ’10, the researchers’
water-testing equipment is now certified operational hardware and is part of
the space station’s environmental monitoring toolbox.
Lipert says the testing technology can also be a useful tool in many earthbound
applications, including forensics tests for drugs, environmental tests for
heavy metals, and water quality tests for pesticides or herbicides.
“This is a very flexible platform,” he says. “You just have
to work out the chemistry for each substance you’re analyzing.”