Martian Surface Photochemistry, Render The Present-Day Surface More Uninhabitable Than Previously Thought

Researchers have had their suspicions over whether or not microorganisms can really survive on the surface of the Red Planet, and currently laboratory tests are spelling doom for any potential very little green microorganism. the matter here lies with perchlorates – chlorine-containing chemical compounds that we first detected on Mars back in 2008. These salty compounds also are what makes water on the Martian surface stay liquid, basically turning it into brine.

Perchlorates are thought of toxic for people, however they do not essentially cause a problem for microbes. and since they keep surface water liquid, on Mars the presence of those compounds might even be useful for life – or so we tend to thought.

Researchers from the University of Edinburgh have now confirmed that when irradiated with a simulated Martian UV flux, perchlorates become bacteriocidal. Perchlorate, though stable at room temperature, could be a powerful oxidizer once activated, for example at high temperatures. One method to turn a perchlorate into an oxidizer is to expose it to ultraviolet radiation light, and since Mars has a much thinner atmosphere than Earth, there is plenty of this type of radiation on its surface. The scientists took a typical spacecraft-loving bacteria, Bacillus subtilis, and subjected them to Mars-like conditions.

At concentrations related to Martian surface regolith, vegetative cells of Bacillus subtilis in Martian analogue environments lost viability inside minutes. two other components of the Martian surface, iron oxides and hydrogen peroxide, act in activity with irradiated perchlorates to cause a 10.8-fold increase in cell death compared to cells exposed to UV radiation once sixty seconds of exposure. These information show that the combined effects of at least three elements of the Martian surface, activated by surface photochemistry, render the current surface more uninhabitable than previously thought, and demonstrate the low chance of survival of biological contaminants discharged from robotic and human exploration missions.

None of the bacteria survived this test. In fact, they died inside 30-60 seconds. The team additionally exposed the bacteria to UV rays without the presence of perchlorates, however even that also wiped the colony out inside a couple of minute. Of course, a planet’s surface isn’t as barren and wet as a Petri dish. With that in mind, the researchers conjointly tested a situation within which the microbes hung out on Mars ‘rock analogues’ created out of silica. These conditions made it slightly easier on Bacillus subtilis, however sadly most of them still died out. which implies that if there is life on Mars to be found, it’s most likely hiding quite way down beneath the surface of the planet.

Researchers says though the toxic effects of oxidants on the Martian surface are suspected for some time, our observations show that the surface of contemporary Mars is very harmful to cells, caused by a toxic cocktail of oxidants, iron oxides, perchlorates and UV irradiation

If the salty brines trickling across the rocks on Mars really are concentrated perchlorate streams, that is not an atmosphere acceptable for sustaining life. And since perchlorates are everywhere on the Martian soil, the team says this essentially renders much of the planet’s surface uninhabitable.

Source: ScienceAlert, Nature

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