Mars Soil

The Martian soil isn’t conducive to life, says a new study published in Scientific Reports wherein scientists looked at whether Bacillus subtilis, a robust microbe, would be able to survive on the Martian surface.

B. subtilis is a robust microbe that has a high resistance to environmental dangers. The bacteria, as noted by study authors, “is a common spacecraft contaminant.” In this study from the UK Centre for Astrobiology, researchers replicated conditions on Mars, based on data returned from the Viking Lander, Phoenix Lander, and Curiosity Rover.

The substance perchlorate is known to naturally, and plentifully, exist on Mars. Here on Earth, perchlorate occurs naturally and also takes the form of a toxic industrial chemical commonly used in solid rocket fuel, fertilizer, and fireworks.

Replicating known conditions on Mars, researchers combined B. subtilis with components commonly found on the Martian surface, including magnesium perchlorate in a liquid solution. When subjected to UV light similar to an exposed Martian surface, it wasn’t good news for B. subtilis.

The combination of chemicals and conditions proved to have a bacteriocidal effect on the bacteria, which means — according to study authors — that “cell viability was completely lost after 30 seconds.” In comparison, B. subtilis exposed to UV light without perchlorate survived 60 seconds. By contrast, bacteria cells combined with perchlorate, without the UV light, remained viable for up to an hour.

Ramping up the experiment, study authors carried out the process to simulate a rocky, anaerobic (without oxygen) environment, placing the bacteria in silica discs. In this mode, the bacteria survived slightly longer, declining in viability by 60 seconds. Researchers also simulated the colder conditions of Mars, but even then, the perchlorates did their damage just as well. Experiments that combined materials presumed to naturally exist on the Martian surface, like hematite, hydrogen peroxide, and perchlorates, were documented as causing the “greatest loss of viability” in the bacterial microbes.

While research suggests microbes may have existed on the Red Planet three billion years back, other studies may be gently closing the door on the viability of life on Mars today.

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