June 1, 2012

Meteorites Have Brought Methane To Martian Atmosphere

Lee Rannals for RedOrbit.com

New research suggests meteorites may be the culprit behind how methane became present in the atmosphere of Mars.

Using meteorites found on Earth, researchers from the University of Edinburgh, the Max Planck Institute in Germany and Utrecht University set out to find how Mars' environment started hosting methane gas.

The meteorite samples used landed on Earth 40 years ago, but Dr. Andrew McLeod, of the University of Edinburgh's School of GeoSciences told redOrbit in an email that the meteorites were safe from contamination.

"The samples were stored, handled and prepared very carefully but contamination on Earth must always be considered," McLeod said. "However, we have described how the hydrogen isotope ratio measured in the methane generated is clearly distinct from any known biogenic or abiogenic methane source on Earth source and therefore indicates an extraterrestrial source of the organic matter from which the methane is derived."

The team found that meteorites contain enough carbon compounds to generate methane when they are exposed to sunlight.

They said their findings give scientists insights into the planet's atmosphere, and could help with planning future Mars missions.

Scientists could use the latest findings to help fine-tune their experiments before setting off their spacecraft towards the Red Planet.

The researchers carried out experiments on the meteorite samples, taking particles from the rock and exposing them to ultraviolet radiation equivalent to sunlight on Mars.

The team found a significant amount of methane given off by the samples, which could account for a large part of the methane found in Mars' atmosphere.

"Our demonstration of UV-driven methane generation from the organic content of the meteorite suggests that one would expect to see some methane in the atmosphere of Mars," Dr. McLeod told redOrbit. "Observations of methane in the atmosphere of Mars are therefore not necessarily indicative of microbial life forms."

He said carbon isotope ratio of the UV-generated methane is not easily distinguished from the carbon isotope ratio of methane formed on Earth.

"Consequently the scientific community should exercise caution when interpreting data on carbon isotope ratios in methane from future Mars missions because it is not proof of biological activity," he told redOrbit.

McLeod said future studies should take into account the role of sunlight and debris from meteorites in shaping the Martian atmosphere.

The study, which was supported by a Royal Society Leverhulme Trust Fellowship and the Natural Environment Research Council, was published in the journal Nature.