Down desolation road
IT DOES not rain much in the Atacama desert. A 1,000km strip of land running along the Chilean coast, it is Earth’s driest desert outside its poles. Average annual rainfall in certain parts can be as low as a millimetre or two a year, and some Atacaman weather stations have never seen a drop of water.
Yet it does rain occasionally. And as Dirk Schulze-Makuch, an astrobiologist at the Technical University of Berlin, and his colleagues report in Proceedings of the National Academy of Sciences, a desert downpour in 2015 offered the perfect natural experiment for probing the limits of what sorts of conditions life can tolerate.
The Atacama is not quite lifeless. A few specialised animals and plants scrape a living in the less arid parts. And scientists have found evidence of microbial life even in the very driest areas. What is less clear, though, is whether those microbes are natives able to endure such extreme...