MIcrobial Airborne Simulation and Measurements for MArs (MIASMMA): Constraining Planetary Protection Risk for Crewed Exploration

Humans will contaminate Mars when we visit. Yet human exploration of Mars is likely to occur before the search for life on that planet has concluded. Space suits and habitats are leaky, and human-associated microbiota and other biogenic particles that escape into the environment could compromise search-for-life missions that screen for low-concentration organic compounds and other potential biomarkers. It is therefore essential to make accurate estimates of the rate at which contaminants would be released by human explorers and disperse through the environment, to facilitate the development of effective mitigations.

Here we present the MIASMMA (MIcrobial Airborne Simulation and Measurements for MArs) project, which aims to address a pressing need for crewed exploration of Mars: how to predict and mitigate microbial contamination from astronaut activities. We will contribute the first-ever empirical measurements of the rate at which microbes and other biogenic particles leak from an extravehicular activity (EVA) suit, by measuring leakage rates of a) fluorescent tracer particles from an EVA suit under Mars atmospheric pressure and b) real human-associated particles from an overpressurized EVA suit in a clean room at Earth atmosphere. Then, we will use the Mars Global Climate Model to calculate the extent of biogenic particle dispersal for several different potential mission scenarios and different models of microbial viability loss. Modeling will also be used to assess the effectiveness of potential engineering mitigations (i.e. reducing leakage rates) or procedural mitigations (i.e. reducing the duration of human activities) in controlling the spread of contamination on Mars.

Preliminary modeling results based on literature values of microbiome density and leakage rates indicate that biogenic contamination released from a single mission could disperse through the entire Martian environment within a year; however, factors such as landing location and estimated microbial viability influence dispersal patterns, and the impact to search-for-life missions depends on instrument sensitivity. Preparations are currently underway for empirical measurements of space suit leakage measurements in the coming year, which will be used to refine the model results. MIASMMA findings will lay the groundwork necessary to facilitate both the greatest journey humans have ever taken, and also the search for one of the most important discoveries of humankind.