The Space Age isn’t immune from disease outbreaks. Apollo crews were quarantined before and after returning from the Moon to limit the exposure and spread of pathogens (terrestrial and otherwise). More recently, NASA and the commercial space industry have responded to COVID-19, the disease caused by the novel coronavirus (SARSCov- 2), by “social distancing” and other means. As humanity moves out into the solar system, pathogens and their human hosts will square off in unprecedented ways shaped by the environment and technology. Nowhere would an infectious contact be more extraordinary than on Mars.
COLONISTS OF THE MICROSCOPIC KIND
Novel pathogenic and virulent microorganisms can emerge in new or unusual habitats. The SARS-Cov-2 virus, for example, is thought by many researchers to have arisen in “wet markets” from the spillover of an animal coronavirus to humans. The proximity of humans and non-domesticated (exotic) animals in unsanitary conditions can be a breeding ground for a new infectious disease. Conditions there were rife for the emergence of new viruses.
On the surface at least, Mars couldn’t be more different from our home planet. The Red Planet is bone-chillingly cold and has a desiccated, chemically oxidizing exterior exposed to galactic cosmic rays (GCRs) and solar wind. Microbes from Earth are unlikely to survive there, but long-term inhabitants of a Mars outpost will live underground protected by several meters of regolith. Inside the habitat, microbes will be at home. Humans and microorganisms will share the same habitat with an atmosphere replenished by a closed environmental control and life support system (ECLSS), while small animals may be reared for food nearby.
Today, the closest analogue to a Mars outpost is the International Space Station (ISS), which is a confined and closed habitat characterized by microgravity. New microorganisms (bacteria, viruses, and fungi) are introduced through the arrival of new crew, cargo, or hardware. A number of different microbes have been isolated onboard the ISS from environmental surfaces, air filters, and even the potable water system. Samples from the Russian segment, for example, contained more than 70 different species (both bacteria and fungi). In the U.S. segment, 318 microbial species were isolated including several human pathogens.