The search for life on Mars is the main goal of almost every mission that humanity sends to our neighboring planet. But scientists have a paradoxical fear: what if we ourselves prevent our own discovery? The fact is that even the most sterile spacecraft can accidentally pick up Earth microorganisms as “hitchhikers.” This phenomenon is called “direct contamination.”
If our bacteria survive on Mars, it will create two huge problems. First, the instruments may confuse them with real Martian creatures, giving us a “false discovery.” Secondly, Earth microbes could physically contaminate or even destroy the Martian organisms we are so eager to find. That is why NASA carefully sterilizes its rovers, but are these measures sufficient?
MMS model
A team of researchers from York University in Canada decided to answer this question. They created a unique computer model called the “Mars Microbial Survival” (MMS). Their study, published in The Planetary Science Journal, literally calculates how long it would take to destroy microbes on spacecraft.
Scientists analyzed two stages of the journey:
- Flying through space. This is where the spacecraft is exposed to harsh ultraviolet radiation (UVC), solar wind, vacuum, and extreme temperatures.
- Life on the surface: After landing, there is the Martian environment with its thin atmosphere, lack of magnetic field (and therefore no protection from radiation), toxic soil (regolith), and dehydration.
For accuracy, they took data from 14 different landing sites where Viking, Curiosity, and Perseverance had previously landed.
Where will the bacteria hide and when will they die?
The simulation results provide a fairly optimistic answer for planetary defense, but with important nuances.
External sterilization. Anything outside the device that is exposed to direct sunlight will die very quickly. The MMS model shows that only one Martian sol — 24 hours and 39 minutes — is needed to completely sterilize exposed surfaces. Yes, solar radiation is extremely deadly.
Sterilization of the entire device. If we look at the hull as a whole, the process will take longer — approximately one Martian year (687 Earth days). This is where temperature and pressure fluctuations come into play.
Internal “safe.” The most interesting situation inside the device. The components that heat up during operation will be free of bacteria in approximately 100 sols. But for cold interior parts that do not warm up, the time can stretch to an incredible 25 Martian years.
The most effective sterilizer
Researchers conclude that direct sunlight on Mars is the most powerful sterilizer. It fights germs even more effectively than vacuuming or cold temperatures.
However, scientists warn that a very small number of microorganisms hidden deep inside the device could theoretically remain there for decades. This does not mean that they will break out and colonize the planet, but it is an important signal for engineers. Today, NASA’s Biotechnology and Planetary Protection Group (BPPG) is already working to make future spacecraft even more sterile, taking these new findings into account. Therefore, the question is not whether Mars will kill our bacteria, but how long they will have to wait for their inevitable demise.
Earlier, we explained why humanity is searching for life on Mars.
According to universetoday.com
