Earth & Sky

Atacama Desert is nearest Mars analog on Earth

This bird's-eye view of the Atacama desert offers a glimpse into another world. In fact, its “soil” is the closest analog here on Earth to that of the planet Mars, according to NASA scientist Chris McKay. (Courriel Vert)

Parts of Chile’s Atacama Desert contain the driest, most lifeless soil on Earth. It’s the closest analog here on our planet to the soil on the planet Mars, according to NASA scientist Chris McKay.

These areas get no rain at all, not even any fog. What’s more, the soil contains a chemical oxidant – a substance that decomposes organic matter. Think of bleach or hydrogen peroxide.

Chris McKay: It’s this double whammy of not being able to grow, because there’s no water, and having to fight off this oxidant which is there in the soil. We think the same conditions would apply on Mars.

But even the Atacama soil is not devoid of life.

Chris McKay: There are organics in the soil in the Atacama, even in the driest region. But if Viking had landed there, it would not have detected those organics, because its instruments are not as capable as those that we would carry down to the field with us now.

Recently, scientists conducted tests in the Atacama soil, similar to those that the Viking spacecraft conducted on Mars in 1976. The researchers found that the Vikings’ organic detection instruments weren’t sensitive enough to perceive the minute bits of organics in this earthly desert.

McKay said it’s important that instruments destined for Mars are tested thoroughly on Earth. He said it makes no sense to send an instrument to Mars in search of life that can’t detect earthly life.

Written by Eleanor Imster