Martian surface may not support life

Chemical compound on the surface of Mars kills bacteria when exposed to UV.

In a new Scientific Reports study, researchers looked at whether the chemical compounds called perchlorates found on the surface of Mars are bacteriocidal, under Martian conditions. They found that they are, meaning it’s unlikely bacteria could survive on the planet’s surface. The study finds that the planet’s toxic cocktail of oxidants, iron oxides, perchlorates, and UV irradiation could mean we need to look under the planet’s surface for life. We spoke with author Jennifer Wadsworth about the study’s implications for life on Mars and human exploration.

ResearchGate: Can you tell us what you discovered?

Wadsworth: We discovered that percholorate, a compound that is usually only activated at high temperatures, can also be activated with only UV light. While this compound is abundant on Mars, the planet is also very cold, so we weren’t sure if it was possible to activate it under Martian conditions. These compounds are lethal to bacteria when activated, so, if we want to find life on Mars, we have to take this into consideration.

RG: How did you discover this?

Wadsworth: We irradiated bacteria with UV in the presence of perchlorate at Martian concentrations. We then measured how many bacteria survived in comparison to the controls. After finding out it could be activated, we tested it under various Martian environmental conditions such as a lack of oxygen and cold temperatures.

RG: Does this discovery rule out the possibility of life on Mars at present? In the past?

Wadsworth: I can’t speak for life in the past. As far as present life, it doesn’t rule it out, but probably means we should look for life underground where it’s shielded from the harsh radiation environment on the surface.

RG: Could this discovery impact our exploration of Mars?

Wadsworth:  Not necessarily. Perchlorate is dangerous to humans, so we’d just have to make sure we keep it out of the living quarters. We could potentially use it in sterilization processes.

RG: Does this affect the risk of bringing samples back from Mars?

Wadsworth: I don’t think so. We also have perchlorate on Earth. Any sample return mission would be carefully quarantined, perchlorate wouldn’t increase the risk of bringing it back.

RG: What's next for your research?

Wadsworth: So far, my research has been in high-radiation environments, but I’ve recently started investigating ultra-low radiation environments and the effect on bacterial growth. As we start to look at lower radiation environments on other planets in search of life, it’s important we build up our knowledge of such conditions on life as we know it, which will help us understand what such ecosystems might look like.

Featured image courtesy of ESA/DLR/FU Berlin / Bill Dunford.