Looking for Life in Mars Methane

This artist’s concept features NASA’s Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars’ past or present ability to sustain microbial life. Image Credit: NASA/JPL-Caltech

An astronomy graduate student at New Mexico State University spoke about her research studying the possible detection of methane gas on Mars at a presentation during the American Astronomical Society’s Division for Planetary Sciences meeting in Reno, Nev.

Malynda Chizek is working on computer simulations using the NASA/Ames Mars Atmospheric General Circulation Model to replicate trace gases in the Martian atmosphere. She is using these simulations to predict the amount of methane that might be seen by the Mars Science Laboratory.

"There is an instrument onboard the Curiosity Rover — which landed on Mars in August — capable of measuring methane, but the scientists operating that instrument haven’t made any public announcements of their results yet," said Chizek. "There have been several claims of methane detection in the past decade, but it is controversial whether or not there is really methane on Mars, because we do not understand how it would get there, and scientists’ observations suggest that it’s varying in abundance on a very quick time scale, which is unexpected."

The significance of detecting methane on Mars is exciting, Chizek said, because it could lead to evidence of life. Approximately 95% of the methane in Earth’s atmosphere is a product of biology.

Malynda Chizek of New Mexico State University. Credit: New Mexico State University

To help people understand the volume and significance of methane on Mars, Chizek uses a very earthly creature that produces the gas — cows.

"In a couple of my presentations, I show how many cows would be required to equal the amount of methane that astronomers have observed on Mars," she said. "Depending on which observations I am looking at, that number is close to five million cows, or roughly 200,000 tons of methane production."

Researchers are using telescopes on Earth and spacecraft in orbit around Mars to observe methane on Mars.

The Earth-based observations are considered controversial because Earth’s atmosphere has a significant amount of methane, a factor of 100 to 1000 times higher than the published Martian methane detections have stated, which may interfere with the Martian methane signal. The instruments on spacecraft orbiting Mars used for methane detections have a lower methane detection capability than do the Earth-based instruments. Some scientists consider the orbiting instruments to be inadequate for detecting Martian methane.

Roughly 95% of the methane in Earth’s atmosphere is thought to be produced by biology. Scientists are don not yet know where Mars methane would come from. Image Credit: NASA/JPL-Caltech

Chizek said she is using her model to try and trace back the detected methane to its source location to see if it is coming from something like a volcanic source, water chemistry interaction, or bacteria living on or near the surface.

"Mars is thought to be a geologically dead planet," she said. "If the methane detections are confirmed, and we do not find any signs of bacterial life, this means there are likely some interesting geological processes happening on Mars that we don’t yet know about."

Chizek is now finishing simulations of her observations and is finishing a paper on the topic co-authored by her adviser Jim Murphy, an associate professor of astronomy, and former NMSU student Melinda Kahre. Kahre now works at the NASA Ames Research Center.

Chizek’s work is funded by a $15,000 NASA space grant. Chizek, who plans to complete her PhD in 2013, is using her Mars research for her dissertation.

"I am now providing predictions on what Mars Science Laboratory scientists might see, based on the other past observations," she said. "More confirmation will come from MSL itself when it eventually announces whether or not it has observed methane and what sort of variations it might or might not have seen."