Of course, NASA ranks comfort well below safety and health. And the station has a ways to go before it resembles Mir, which "had its own odor, like 12 years in a sock closet," quips Marsha Ivins, a veteran of five shuttle flights who is currently assigned to the Johnson center. Future manned flights, however, will demand extended togetherness: a round-trip to Mars should last at least 18 months. That's a problem, because space alters an astronaut's sense of taste and smell. "Things that don't bother you normally may nauseate you over time," explains Jeff Jones, a Houston-based flight surgeon for the ISS.
Today's astronauts use various off-the-shelf waterless products, such as body wipes and no-rinse shampoos developed for hospitals. All conform to strict station parameters. "We send up nothing with alcohol in it, because the environmental-control system can't get the alcohols out," Walker says. Propylene glycol, commonly used to keep cleansing ingredients in the proper physical state, also poses a problem in large quantities. Most space soaps are herbal instead.
As for astronauts and their laundry, "they can wash clothing with soap and rinse it out with a water-bag system and let it air-dry," Jones states. "Things dry pretty quickly" with good air movement, he adds, thanks to an onboard humidity that hovers around 30 to 40 percent--a relative Sahara compared with Mir's 80 to 90 percent. Clothes drying is especially popular in the station's Zvezda service module, where airflow is best.
Higher-tech hygiene might be possible. NASA astronauts have tried two T-shirts woven with silver thread. The metal inhibits bacterial growth. The results, though anecdotal, seem promising: the shirts "were encrusted with salt, but they did not smell," Ivins reports. Last year NASA began testing silver-laced bedsheets, blankets and other items in its Aquarius underwater habitat, off the Florida coast.
Ivins downplays the idea of silver-suited space travelers. But she notes that "we have now the opportunity to look at new materials and new technologies, and one of these may turn out to be the Velcro of the future." A springtime-fresh Velcro, perhaps.