Anna Hartz
Exploring Mars is not just about rockets and rovers. Scientists must also worry about tiny stowaways—microorganisms from Earth that might hitch a ride on spacecraft.
Even the smallest bacteria could interfere with the search for life on the Red Planet. A team from York University used a new Mars Microbial Survival (MMS) model to see how long these organisms could survive on the journey to Mars and after landing, according to WP.
Radiation exposure
The researchers focused on two stages: the trip through space and the time spent on the Martian surface. During the flight, spacecraft are exposed to strong ultraviolet radiation from the Sun. This radiation wipes out microbes on outer surfaces. Inside the spacecraft, microbes get more protection but still face challenges from low pressure and fluctuating temperatures.
The team analyzed data from fourteen past Mars missions, including Viking, Pathfinder, Spirit, Opportunity, Curiosity, and Perseverance. They wanted to see how well sterilization methods worked under real Martian conditions. Surfaces facing upward are easiest to clean. On these surfaces, most bacteria are destroyed within a single Martian day.
Heat vs cold
Sterilizing the whole spacecraft takes much longer. According to the MMS model, external surfaces are fully cleaned after about one Martian year, which is roughly 687 Earth days. The toxic soil, low humidity, and thin atmosphere of Mars help kill microbes as well.
Inside landers, heating components can sterilize microbes within about 100 Martian days. Cold, unheated areas are much harder to clean. The model predicts that it could take up to 25 Martian years—almost fifty Earth years—for these spots to become microbe-free.
The findings show why planetary protection is so important. Scientists in NASA’s Biotechnology and Planetary Protection group keep improving sterilization methods to lower the risk of bringing Earth life to Mars. Without strict measures, there’s a chance that future missions could mistake Earth microbes for Martian life. Avoiding contamination is crucial if we want to accurately discover life on another planet.
