Jun 28 2019
Mold In Space
There are bacteria and mold aboard the International Space Station (ISS). This should come as no surprise, as these organisms follow humans everywhere we go. In fact it’s claimed that the ISS astronauts spend several hours per week cleaning mold off the ISS and wiping everything down. However, this first hand report by ISS astronaut Clayton C. Anderson says he did his cleaning duty every Saturday, but not as thoroughly as requested.
Still, as we spread into space, we need to carefully consider the microscopic ecosystem we will bring with us. A space ship or station is a self-contained environment, and as we plan trips back to the Moon and on to Mars, there will be longer and longer missions. Something as simple as a fungus may threaten those missions. A recent study of the resilience of mold spores highlights how challenging this may be.
The study looked at the effects of ionizing radiation on mold. They looked at the two most common species of mold aboard the ISS, Aspergillus and Pennicillium. They found:
The spores survived exposure to X-rays up to 1000 gray, exposure to heavy ions at 500 gray and exposure to ultraviolet light up to 3000 joules per meter squared. Gray is a measure of absorbed dose of ionizing radiation, or joules of radiation energy per kilogram of tissue. Five gray is enough to kill a person. Half a gray is the threshold for radiation sickness.
Those are some hardy fungi. For context a one-way trip to Mars is expected to expose travelers to 0.7 gray. That will be a problem for the humans aboard, not so much the molds.
As an aside, the exposure to radiation is a major limiting factor for space travel. The ISS is still within the Earth’s magnetic field, and so is somewhat protected. But anything beyond low earth orbit will be slowly fried by radiation. We need to figure out how to shield our ships and colonies if we are going to have a prolonged presence outside of low earth orbit. This, by the way, is why lava tubes may be the best location for stations on the Moon or Mars.