Atacama Desert has
DB: This is Earth and Sky. The Viking spacecraft landed on the surface of Mars in 1976.
JB: Its instruments scooped up soil samples and analyzed them for signs of life, but they found no evidence of organic compounds. Now, almost 30 years later, NASA scientists are scooping up soil in Chili’s Atacama Desert – a place that gets no rain, not even any fog. Its soil is the driest, most lifeless soil on Earth. That’s what gives it our planet’s nearest analog to the soil on Mars, according to Chris McKay at NASA’s Ames Research Center.
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…
DB: Another inhospitable feature of this Atacama soil is that it 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.
_JB: And for today, that’s our show. Special thanks to NASA explore, discover, understand. We’re Block and Byrd for Earth and Sky.
The image at left is Chili’s Atacama desert as seen from space. (NASA)
Twenty-five years ago, on July 20, 1976, Viking soft-landed on the surface of Mars, becoming the first U.S. spacecraft to land successfully on the surface of another planet. Read Earth & Sky’s radio show about looking for life on Mars, or check out NASA’s web site on its Mars Exploration Program.
Chris McKay told Earth & Sky:
“When we say that the Atacama soil is ‘Mars-like,’ we really mean like the soils measured at the two Viking sites. The question is, how typical of Mars are those two Viking sites? Our guess is that it’s probably typical of the soils in the equatorial and mid-latitude regions. But near the ice-rich polar regions, things might be very different.”
Our thanks to:
Chris McKay
Space Science Division
NASA Ames Research Center
Additional Teacher Resources
Carnegie Mellon University/NASA: Atacama Desert Trek: A Planatary Analog Field Experiment
This site explains the Nomad project which was chartered to traverse 200 kilometers across the Atacama Desert in Chile, exploring a landscape analogous to the surfaces of the Moon and Mars. Operating both autonomously and under the control of operators thousands of kilometers away.
NASA: Mars Exploration Program: Home
Since the first close-up picture of Mars in 1965, spacecraft voyages to the Red Planet have revealed a world strangely familiar, yet different enough to challenge perceptions of what makes a planet work. This site provides comprehensive coverage of NASA’s Mars Exploration Program.
