첥Ƶ researchers Grace Bischof and John Moores, from the , are developing new tools to ensure future missions to Mars do not accidentally contaminate the planet with microbes from Earth.
Mars has been a focus of space exploration for more than six decades, with multiple international exploration expeditions studying the planet’s geology, atmosphere and potential habitability using spacecraft, rovers and orbiters.
As more missions are planned, new research from York highlights an important risk: the possibility that Earth's microbes – tiny forms of life such as bacteria – could travel aboard spacecraft and survive on Mars.
Preventing this type of contamination is a central goal of international planetary protection guidelines, which aim to avoid this contamination between Earth and other planets.
“Keeping the Martian environment in pristine condition is crucial for proper scientific characterization,” says Bischof, a PhD student and researcher in York’s Centre for Research in Earth and Space Science. “If Earth microbes are able to survive on Mars, they could potentially confound Martian biomarkers, lead to false positive detections of life and/or alter the environment itself.”
To better understand the risks, Bischof worked with Moores, an associate professor and planetary scientist who studies the environmental conditions of planets, to develop the Mars Microbial Survival (MMS) model. The research was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), including a Vanier Canada Graduate Scholarship for Bischof and an NSERC Discovery Grant for Moores, as well as funding from NASA’s planetary protection program and 첥Ƶ’s Research at York program.
The idea was inspired by the Mars Sample Return (MSR) mission, a joint NASA and European Space Agency effort designed to retrieve geological samples collected by the Perseverance rover and return them to Earth for analysis.
“At the time we began creating the model, the mission was expected to land on Mars in the early 2030s, so understanding the potential for contamination beforehand was important,” says Bischof.
Using the bacterium Bacillus subtilis – a common soil microbe often used in research – Bischof and Moores applied their model to estimate how microbial populations might decline under Mars-like conditions such as intense ultraviolet radiation, extremely low atmospheric pressure, cold temperatures and the planet’s dry surface environment.
The researchers then used the model to analyze past Mars expeditions and landing sites, simulating how microorganisms might behave – and how long they might survive – if carried on spacecraft that land on the Martian surface.
The tool was used to examine microbes in two main locations on spacecraft: exterior surfaces, such as outer shells or exposed hardware; and interior surfaces, including instruments or sheltered components.
Their findings, published in , suggest that Mars presents harsh conditions for Earth-based microbes. Unlike Earth, the planet lacks a thick atmosphere and protective ozone layer, leaving the surface exposed to strong ultraviolet radiation from the sun.
Results showed that exterior spacecraft surfaces would likely be sterilized relatively quickly due to this radiation. In many cases, ultraviolet exposure alone would rapidly destroy most microorganisms.
However, microbes located in interior or shielded areas of spacecraft could experience different conditions and may survive for extended periods, Bischof says. The model predicts that other factors – including low atmospheric pressure and temperature fluctuations – would gradually reduce microbial populations over time, but at a much slower rate than on exposed surfaces.
The fact that some microorganisms may persist for decades on Mars, Bischof says, “is important to consider when making policy decisions regarding the sterility of spacecraft pre-launch.”
Although the Mars Sample Return mission that inspired the research is currently on hold, Bischof says the work remains highly relevant. The researchers say their innovation can inform spacecraft design and cleaning strategies by identifying components that pose the greatest contamination risk and where additional precautions may be needed.
“Human-led missions to Mars remain a high priority for NASA, and these results can be applied to any future mission landings on Mars’ surface,” she says.