Preventing "Sick" Spaceships
In the late 1990s, NASA joined the Russian space program in its evaluation of the microbial activity aboard Mir. For planning long-duration missions, they wanted to learn about the kinds of organisms that can grow in spacecraft occupied for long periods of time and where air and water are recycled. They were especially interested because several times during its 15 years in low Earth orbit, Mir had had the misfortune to suffer several power outages, so the temperature and humidity rose well above normal levels and air circulation was inadequate until the electricity was restored.
In 1998, U.S. astronauts participating in the NASA 6 and NASA 7 visits to Mir collected environmental samples from air and surfaces in Mir's control center, dining area, sleeping quarters, hygiene facilities, exercise equipment, and scientific equipment. Imagine their surprise when they opened a rarely-accessed service panel in Mir's Kvant-2 Module and discovered a large free-floating mass of water. "According to the astronauts' eyewitness reports, the globule was nearly the size of a basketball," Ott said.
Moreover, the mass of water was only one of several hiding behind different panels. Scientists later concluded that the water had condensed from humidity that accumulated over time as water droplets coalesced in microgravity. The pattern of air currents in Mir carried air moisture preferentially behind the panel, where it could not readily escape or evaporate.
Nor was the water clean: two samples were brownish and a third was cloudy white. Behind the panels the temperature was toasty warm—82ºF (28ºC)—just right for growing all kinds of microbeasties. Indeed, samples extracted from the globules by syringes and returned to Earth for analysis contained several dozen species of bacteria and fungi, plus some protozoa, dust mites, and possibly spirochetes.
But wait, there's more. Aboard Mir, colonies of organisms were also found growing on "the rubber gaskets around windows, on the components of space suits, cable insulations and tubing, on the insulation of copper wires, and on communications devices," said Andrew Steele, senior staff scientist at the Carnegie Institution of Washington working with other investigators at Marshall Space Flight Center.
Aside from being unattractive or an issue for human health, microorganisms can attack the structure of a spacecraft itself. "Microorganisms can degrade carbon steel and even stainless steel,” Steele continued. "In corners where two different materials meet, they can set up a galvanic [electrical] circuit and cause corrosion. They can produce acids that pit metal, etch glass, and make rubber brittle. They can also foul air and water filters." ...