Besides a nonexistent atmosphere, freezing temperatures and heavy metals in the soil, there is one danger associated with living on Mars that doesn’t even come from the Red Planet itself, but spawned on Earth.
The International Space Station is a model for what we can expect from Martian habitats. Astronauts have been experiencing extended stays on the ISS for almost 20 years, and every human who comes aboard is also bringing trillions of bacterial freeloaders who hitch a ride inside and outside said human’s microbiome (no wonder there was speculation about some of them being alien bacteria for a second).
Isolation can warp the balance of bacterial communities that is critical to our survival, which is why a group of researchers conducted a study during Expedition 39 to magnify some of the potential problems that could arise from these invisible passengers.
“It is perhaps not surprising that the insular environment of the ISS would be unlike homes on Earth,” said the study. “Unlike the ISS, homes on Earth are exposed to a variety of sources of microbes.”
When you hypothesize that there will be fewer types of creepy crawlies in a space habitat than that of a mechanically ventilated hospital room, your outlook is pretty grim, because the absence of certain bacteria can be just as dangerous as an infestation of others. Never mind that factoring out interactions that expose an existing microbe population to new microbes can result in competition that creates superbugs. Imagine coming down with the superflu on Mars without enough time for a cure to be developed on Earth and blasted over there.
The scientists were relieved to find much more microbial diversity than expected on the mothership. ISS surfaces tested included audio terminal units, handrails, air vents and frequently touched objects on the astronauts’ work stations such as keyboards and hand controllers.
“The most abundant organisms on the ISS are human-associated,” the study concluded, with most found on our skin or in our mouths. So no aliens, but wait.
We still need to hold a microscope up to microbes even with this breakthrough. When six “Marstonauts” cut off all contact with the outside world for 250 days in the Mars500 spacecraft module, the diversity of the microbe population declined, though not enough to violate the ISS human system standards. We have still hardly found out anything about how they mutate when exposed to microgravity for months on end. How the chemical makeup of Mars could affect them remains unknown. Just one mission is not enough to really give us an idea of what could really happen while living in a bubble 33.9 million miles away—and that doesn’t include the seventeen-month round trip.
At least we don’t have any extraterrestrial bacteria to contend with. Yet.