Could Dust Devils Create Methane in Mars’ Atmosphere?

by Nancy Atkinson on September 10, 2012

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A Martian dust devil roughly 12 miles (20 kilometers) high captured on March 14, 2012 by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Image credit: NASA/JPL-Caltech/UA

Methane on Mars has long perplexed scientists; the short-lived gas has been measured in surprising quantities in Mars’ atmosphere over several seasons, sometimes in fairly large plumes. Scientists have taken this to be evidence of Mars being an ‘active’ planet, either geologically or biologically. But a group of researchers from Mexico have come up with a different – and rather unexpected – source of methane: dust storms and dust devils.

“We propose a new production mechanism for methane based on the effect of electrical discharges over iced surfaces,” reports a paper published in Geophysical Research letters, written by a team led by Arturo Robledo-Martinez from the Universidad Autónoma Metropolitana, Azcapotzalco, Mexico.

“The discharges, caused by electrification of dust devils and sand storms, ionize gaseous CO2 and water molecules and their byproducts recombine to produce methane.”

Graph from the paper Electrical discharges as a possible source of methane on Mars: Lab simulation, Geophys. Res. Lett., 39, L17202, doi:10.1029/2012GL053255.

In a laboratory simulation, they showed that that pulsed electrical discharges over ice samples in a synthetic Martian atmosphere produced about 1.41×1016 molecules of methane per joule of applied energy. The results of the electrical discharge experiment were compared with photolysis induced with UV laser radiation and it was found that both produce methane, although the efficiency of photolysis is one-third of that of the discharge.

The scientists don’t rule out that methane may indeed come from other sources as well, but the way that dust devils and storms can quickly form means they can also quickly generate methane. “The present mechanism may be acting in parallel with other proposed sources but its main advantage is that it can generate methane very quickly and thus explain the generation of plumes,” the team writes.

Methane has been observed in Mars’ atmosphere since 1999, but in 2009, scientists studying the atmosphere of Mars over several Martian years with telescopes here on Earth announced they had found three regions of active release of methane over areas that had evidence of ancient ground ice or flowing water.

They observed and mapped multiple plumes of methane on Mars, one of which released about 19,000 metric tons of methane. The plumes were emitted during the warmer seasons — spring and summer — which is also when dust devils tend to form.

Methane on Mars is enticing because it only lasts a few hundred years in Mars’ atmosphere, meaning it has to be continually replaced. And in the back of everyone’s minds has been the possibility of some sort of Martian life producing it.

“Methane is quickly destroyed in the Martian atmosphere in a variety of ways, so our discovery of substantial plumes of methane … indicates some ongoing process is releasing the gas,” said Dr. Michael Mumma of NASA’s Goddard Space Flight Center in Greenbelt, Md in 2009. “At northern mid-summer, methane is released at a rate comparable to that of the massive hydrocarbon seep at Coal Oil Point in Santa Barbara, Calif.”

The researchers in 2009 thought that the methane was being released from Mars’ interior, perhaps because the permafrost blocking cracks and fissures vaporized, allowing methane to seep into the Martian air.

The unknown has been where the methane has been coming from; if it is being released from the interior, it could be produced by either geologic processes such as serpentinization, a simple water/rock reaction or biologic processes of microbes (or something bigger) releasing methane as a waste product.

But if dust devils and dust storms can also produce methane, the mystery becomes a little more mundane.

The new research by the team from Mexico also mentioned fissures in the surface, but for a different reason, saying that the electric field of dust devils is amplified by the topology of the soil: “The electrical field produced by a dust devil can not only overcome the weak dielectric strength of the Martian atmosphere, but also penetrate into cracks on the soil and so reach the ice lying at the bottom, with added strength, due to the topography of the terrain,” the team wrote.

At a concentration of about 10 to 50 parts per billion by volume, methane is still a trace element in the Martian atmosphere, and indeed the sharp variations in its concentration that have been observed have been difficult to explain. Hopefully the research teams can coordinate follow-up observations of methane production during the dust devil and dust storm seasons on Mars.

Read the team’s abstract.

Read our article from 2009 about Mars Methane.

About 

Nancy Atkinson is Universe Today's Senior Editor. She also is the host of the NASA Lunar Science Institute podcast and works with Astronomy Cast. Nancy is also a NASA/JPL Solar System Ambassador.

Tim McDaniel September 10, 2012 at 9:54 PM

Typo: “A Martian dust devil roughly 12 miles (20 kilometers) captured on March 14, 2012…” 12 miles what? High? Wide? (Handsome?)

tenstripe September 11, 2012 at 5:52 AM

I belive you got it correctly as high.. There was a story that may still be found online.

Torbjörn Larsson September 10, 2012 at 11:47 PM

So the details is in the devil.

But yes, this is a reasonable model if methane is regional. (The observations are arguable, so the distribution is too.) Another model would be that it has to do with thaw actions on abiotic or biotic processes. But wind action is known to be present, so this should be the more substantiated pathway for now.

Aqua4U September 11, 2012 at 3:24 AM

If tribo electric charges in Martian dust devils can produce Methane, then think what the gigantic lightning bolts at Jupiter and Saturn are producing?

Aqua4U September 11, 2012 at 6:12 PM

Just back from the MSL RAW Images page where I viewed the newest images of the mast and robot arm(s). http://mars.jpl.nasa.gov/msl/multimedia/raw/

The close up images/Full Data Product close ups, make me wonder why Curiosity’s designers did not include dust covers for external wire runs and mechanisms? With dust devil activity inevitable, one would think? better best be double or triple sealed?

tenstripe September 11, 2012 at 5:46 AM

Where there is methane plumes there is water that is being converted by dust devils from the surface, and water is found under the surface. It’s ok, but the water would seem to have to replenish itself to keep up the process. How deep can a dust devil’s electrical influence penetrate martian soil and how many years have dust devils churned these areas.

Mpj Marsphotojournal September 11, 2012 at 8:05 AM

Electrical (dis-)charges in dust “storms” of a near vacuum atmosphere producing methane in discrete locations? The observed methane plumes are not in the dust devil most active zones. There is lots more of dust devil action in the higher latitudes (north/south) which are also more rich in ice near the surface.
Interesting model for academic studies though. :)

Torbjörn Larsson September 11, 2012 at 1:03 PM

But it is correlated with spring and summer, so temperature should be a factor. I imagine in their model the immediate water source is vapor in atmosphere and soils (and possibly the fraction that is redeposited as water films on soil particles) if the field penetrates, not the ground ice as such.

Near surface ice speaks of little vapor attrition during a year (as well as being initially affected by the original deposition process of course).

Olaf2 September 11, 2012 at 3:54 PM

A title with a question mark in it. This does not sound very convincing or good.

Jeffrey Scott Boerst September 11, 2012 at 6:23 PM

What an odd criteria by which to judge something…

Olaf2 September 11, 2012 at 7:01 PM

Look at all the news articles that misrepresent science.
They all use the word “could” “would” and a question mark.

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