Lowa State Chemists Help Astronauts Make Sure Their Drinking Water İs Clean

Bob Lipert held up a syringe, attached a plastic cartridge and demonstrated how chemistry developed at Iowa State University is helping astronauts and cosmonauts make sure they have safe drinking water at the International Space Station. Each cartridge contains a thin, one-centimeter disk that's loaded with chemistry, said 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-milliliter 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, or I2. The whole process is called colorimetric solid phase extraction.

Starting in late September, Lipert said 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 said 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.