If there is subsurface water across Mars, where is it safe to avoid contamination?

If Mars is a potential home for alien life, can we safely land anywhere on the surface without introducing contamination from terrestrial bacteria? A new study has good news and bad news. The good news is that Mars is probably extremely inhospitable to life. The bad news is that Mars is … probably completely inhospitable to life.

As we continue to poke and poke at the Red Planet, we humans have two primary goals: to self-store there, eventually build for permanent human habitation, and maybe even a self-sustaining colony one day.

The two goals are a bit exclusive of each other. As we send more junk-originated junk in this direction, we increase the chances of our own bacteria, viruses and fungi reaching the millions of miles and starting their own microscopic colonies on Mars. This terrestrial life would contaminate any available niches on the planet.

This can be a very bad thing for two reasons. One, Earth Life would start competing with any (potential) Martian life, and we are not in the mood as a species to kick off the first interplanetary game of survival of the fittest. Secondly, the presence of ground microbes would contaminate any signs of real Martian life forms. If we see something wiggling in the red dirt under our microscopes, we will know that we are seeing the real deal.

We do not know if it is alive on Mars right now, or ever was. We think life might have an opportunity there in the distant past, because in that day Mars was equal to water: lakes, rivers, streams, oceans, the whole trade. And where there is water, there is a potential home for life.

But today’s Mars is a completely different story. Planetary scientists continue to debate if there is generally water on or near the surface, and if so, in what state it is (for example, if it is super-salty or relatively clean) and how long it lasts.

Knowing where the water could be can tell us where life could be. With this information, we can close these areas and secure them for contamination-free research, while we are busy building our colonies somewhere more barren.

According to new research, it looks like we may have more freedom on the red planet than we originally thought. Pure liquid water is totally unstable on the Martian surface: without a significant atmosphere, pure water evaporates just as quickly. But there are possible solution solutions, where water mixes with magnesium perchlorate or calcium perchlorate, either on the surface itself or just below it.

But even these brines do not last long. According to research, the brine can only last for a few weeks out of the year, and even then they are only stable for a handful of hours. And I need to mention how cold the brine is: -50 degrees Fahrenheit (and roughly the same in Celsius).

No matter how you slice it, the conditions are inhospitable to all forms of earth life, even the hardest extremophiles. So it appears that Mars is free from terrestrial contamination … but that also means that Mars is likely a dead, frozen world.

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