Life on Mars has a Problem: The Wind and Sand

credit: NASA JPL

There have been a lot of experiments to test whether life can survive on Mars. Some of those tests have placed lichens or bacteria in simulated Mars-like environments to see if they survive: similar atmospheric pressure, similar regolith ("soil") chemistries and similar light, including UV, have been simulated. In some cases, life survived. Even the lichens did so if they were not in direct "sun" light. Fungi have done so.

However, all of these were done in static environments. Mars, like any world, is anything but. A group of researchers thought to take a different approach: could life survive on Mars with the simulated environment and the winds and shifting sands. Could life survive the Martian saltation?

In the experiment, the scientists used spores of Bacillus subtilis. Bacillus subtilis is noted for being a very hardy bacterium. It is very tolerant of radiation. It's also very resistant to oxidizing chemicals. That makes it a great test subject for extreme environments: if Bacillus subtilis can't live there, then few, if anything else, can.

Unfortunately, the results of the experiment were not encoruaging. Within one minute of the simulated environment, 50% of Bacillus subtilis spores were destroyed. By the end of the experiment, all the spores the experiments could find under the scanning electron microscope were destroyed. Bacillus subtilis had been eradicated, not by chemical means or by radiation exposure, but rather through simple abrasion.

This puts a rather different light on whether life could survive on Mars. Or at least its surface. This research brings to light that it is not just the chemical and radiation environment that must be considered when experimenting to determine whether a off world location is habitable, but also the physical environment. Things like the wind and sand (or more properly, the regolith) can be just as important.

Wind-Driven Saltation: An Overlooked Challenge for Life on Mars
https://www.liebertpub.com/doi/full/10.1089/ast.2018.1856

LICHEN ON MARS
https://www.astrobio.net/extreme-life/lichen-on-mars/

Antarctic fungi survive Martian conditions on the International Space Station
https://www.agenciasinc.es/en/News/Antarctic-fungi-survive-Martian-conditions-on-the-International-Space-Station