Earthsky Interviews
Bethany Ehlmann says Mars mineral may mean life-friendly past
02-17-2009 - Space
Bethany Ehlmann: Ancient Mars, like the Earth today, hosted a variety of watery environments.
That’s Bethany Ehlmann. Ehlmann led a study that’s opened up the possibility that life existed on the planet Mars deep in its past. She’s on the science team of a NASA mission that looks at minerals on Mars’ surface. What Ehlmann found were patches of magnesium carbonate.
Bethany Ehlmann: Carbonate is kind of like a signature mineral of neutral to alkaline pH conditions in the waters from which they’ve formed.
Scientists have thought that, long ago – 3.5 billion years ago – Mars was intensely acidic and inhospitable to much possibility for life. But Ehlmann’s study suggests otherwise. EarthSky asked her why….
Bethany Ehlmann: Because carbonate tends to dissolve in acid. And the fact that we see carbonate persisting to the present means that it never experienced these acid conditions, and instead it preserves the record of ancient Mars that was perhaps more clement to life.
The carbonate is similar to limestone on Earth. And like limestone fossils, fossils of early Martian life might be preserved in the carbonate found on Mars.
Bethany Ehlmann: I think that’s a possibility that all of us dream about.
Ehlmann added that future landed missions to Mars might answer questions of whether life ever existed on the crimson planet.
Our thanks to:
Bethany Ehlmann
Brown University
Providence, RI
Photo Credit: NASA/JPL/JHUAPL/University of Arizona/Brown University
Are there any magnesium carbonate patches in the areas where the methane plumes have been discovered?
I think you’re spot on Dave; the calcium carbonate that Ehlmann found with CRISM is in the Nili Fossae region of Mars – one of the regions reported in the New York Times as a source of the methane plumes. Here’s what Ehlmann told us when we talked with her at the 2008 meeting of the American Geophysical Union:
“We’ve looked at the surface of the planet from thousands of images from the CRISM instrument, but we really see that only in a particular region on Mars, near the Isidus basin, which is a large impact basin early in Mars history, and in particular on the western portion of that basin, in an area called Nili Fossae, we see in over two dozen CRISM images the carbonate in a rock layer that’s about 20 meters thick, and it’s sandwiched in between iron-magnesium smectite clays below, which also form from alteration of water, and an unaltered cap rock above. So sandwiched in between is this layer that has both carbonate and in some places olivine. And so what we think we’re seeing here is evidence that an olivine-rich rock layer in the Nili Fossae region of Mars altered, in some places, by water, to form carbonate.”