Let's begin with a hard truth: Mars is a long, long way away, and it's still a few decades until we set up there,. Fortunately we can, sort of, visit Mars here on Earth -- as long as we can get to northern Chile. In that part of the planet, the very Mars-like Atacama Desert resides. As one of the driest, dustiest places in the world, it provides a close analog to test what happens on Mars without ever leaving the comfort of our gravity and atmosphere.
A team of international scientists, led by Armando Azua-Bustos, have taken to the Atacama to test how microscopic organisms, such as bacteria and fungi, may have been able to use dust to move across vast distances in the desert. Their research, published in the journal Scientific Reports on Thursday, describes the "very simple experiment" they devised to test how these microbes could survive the harsh conditions, like high levels of ultraviolet radiation and extreme aridity, found in the Atacama.
That very simple experiment saw the scientists set up plates of "broth," a cocktail of nutrients for microbes to grow in, across six specific sites from the coast into the desert. The first site was 63 kilometers (40 miles) long, while the second was 50 kilometers. The scientists looked at the dust that accumulated in empty plates and were able to isolate four species of fungi and five species of bacteria.
Afternoons in the Atacama are particularly windy and dusty. Not quite to the same level as Mars, which, but windy enough to carry particles of dust vast distances. The bacteria and fungi found in the core of the Atacama then, may have originated elsewhere, particularly closer to the coast. Based on the species of bacteria, the researchers suggest, the marine environment of the coastal range may be a starting point.
Intriguingly, the team also found two bacterial species growing in their broth that have been previously reported as airborne bacteria. The species were originally spotted in China and India -- which means they may have come from even further away. The team writes that future work will investigate their origin.
How does this all relate to life on Mars? Well, as a great analog, the Atacama desert provides a good testing ground for these kinds of theories. It's impressive that miniature beasts like bacteria and fungi can move distances that would make humans wince, and it's all thanks to the dusty winds. Based on what the researchers saw on Earth, they say there's a possibility that Martian dust could have carried microbes across the red planet in the past.
Mars doesn't seem particularly kind to life. It's desolate, arid and lacks a protective atmosphere. However, in the past, there may have been pockets where life could exist. Azua-Bustos and his colleagues suggest the transport system they propose could have allowed microbial life to survive and even to evolve, by dispersing from habitable location to habitable location.
Of course, the speculative Mars microbe transport system is, for the time being, impossible to put to the test on the red planet. For now, we just have. However, two new rovers will settle in on the Martian surface in the coming years. The will search for signs of life on Mars, as will , which is scheduled to land in Jezero Crater in 2021.
Updated 4:40 p.m. PT