Christina Morrison seeks answers to a down-to-earth problem for space travelers: how to keep their clothes clean. Image credit: Irma Perez

For those who wonder how astronauts perform the mundane, such as using the lavatory in microgravity or keeping up with their Twitter feeds—here’s another head-scratcher: how do they wash their clothes on long missions?

According to Astronaut Don Pettit, items were worn for months at a time while living on the International Space Station because doing laundry was not an option. Eventually, soiled clothing was stowed and then launched with other debris to be incinerated upon entering Earth's atmosphere.

A clean clothing solution has been devised by a University of Arizona undergraduate research assistant. Realizing that water is too precious a commodity to be used for this purpose, Christina Morrison turned to the application of silver and hydrogen peroxide, both known germ-fighters.

Her research team applied low concentrations of hydrogen peroxide to swatches of antimicrobial socks embroidered with silver-ion threads and exposed the treated material to Staphylococcus aureus, a bacterium often found in the nose and on the skin. Within an hour, a nearly 5-log reduction, or about 99.999 percent reduction of the bacteria on treated antimicrobial socks was achieved compared with a 0.25 log reduction, or 43.76 percent reduction on untreated silver-ion socks.

"The clothes will stay germ-free longer, because of the silver ions, and can be laundered by adding hydrogen peroxide," Morrison said. "Washed just twice, one shirt could stay microbe- and odor-free in the same length of time an astronaut would normally wear and discard three shirts. This saved mass would drastically reduce the amount of clothing needed to launch into space and allow longer missions."

In the next phase of the research project, a group of subjects will wear antimicrobial socks or regular socks and remove them for the researchers to treat with hydrogen peroxide. A second group will serve as an "olfactory panel" to assess freshness—that is, to smell randomly assigned swatches from treated or untreated antimicrobial socks and treated or untreated regular socks.

"We hope it won’t be too hard to find volunteers," Morrison joked.