A team of ISU scientists invented a new way to detect water contaminants in astronauts’ drinking water — a process that was funded by NASA.

“The general idea is to provide the space station with a means for monitoring their drinking water to make sure that it’s safe to drink,” said Robert Lipert, an associate scientist for the Institute for Combinatorial Discov-Iprt here at Iowa State. “There’s a need for ensuring the health and safety of the astronauts — to have something on board where they can check the water themselves.”

After a long development period, the instrument was finally launched for testing two years ago, and was just recently approved for actual use.

“After spending years developing and refining methods, then fabricating and certifying hardware, it was really nerve-racking waiting for the first use of the system in-flight,” said Daniel Gazda, senior environmental scientist in the Water and Food Analytical Laboratory at the Johnson Space Center.

Most of the drinking water on the U.S. segment of the International Space Station is recovered condensation and urine, so the need for a purifying agent is necessary.

For the safety of their astronauts, NASA adds iodine to the water to help keep harmful microbes from growing. However, if the concentration of iodine is too high, consumption is dangerous.

“Iodine presents a unique challenge from a water-quality monitoring standpoint because it must be maintained at levels sufficient to inhibit microbial growth during storage, but then it must be removed prior to consumption because it can affect thyroid function,” Gazda said.

The device that was developed is called a Colorimetric Water Quality Monitor Kit. It is a membrane that is designed to change color when molecular iodine, or I2, passes through it.

The membrane is white at first but slowly darkens from yellow at low levels of iodine to an orange-red rust color at higher concentrations. This helps make sure that the astronauts are not drinking water that will be harmful to their health.

The color-changing membrane in the device is impregnated with a polymer called polyvinylpyrrolidone that binds the iodine, creating a high concentration on the membrane so that it can be measured even if there is not enough in the water to be seen with the naked eye.

“If you’re familiar with iodine it’s a dark-colored material, and the key here is that this polymer binds this iodine and it holds onto it, strongly, and it has a large capacity for binding,” Lipert said.

The problem with testing for iodine, though, is that it reacts with water and forms many different compounds. Therefore, just testing for molecular iodine in the water yields an inaccurate measurement that could adversely affect astronauts’ health.

“To get a good picture of the amount of iodine that’s going to [be] available, you need to try to monitor all the forms of iodine and not just molecular iodine,” Lipert said.

To solve this problem, a second membrane was developed that converts all of the iodine contained in the water into molecular iodine.

Lipert said that these tests are very flexible platforms that can be adapted to be used in many ways.

There are currently ideas on how to apply this same technique to detect other water contaminants such as heavy metals, including lead and cadmium, to give astronauts a convenient way to do other checks on their water.

These new tests will be used in conjuction with current tests as a more convenient counterpart.

Scientists are hopeful that this research will provide good ground for detecting even more harmful contaminants in the future.

“By far, the biggest reward is knowing that our technology is being used to help ensure a safe supply of potable water is available to the crew on the ISS,” Gazda said.