Mars methane linked to meteorites

May 31, 2012 By Tamera Jones
Mars methane linked to meteorites
Fragment of the Murchison meteorite and isolated individual particles (shown in the test tube).

Tiny amounts of methane in the Martian atmosphere may come not from living things, but from meteorites on the red planet's surface, the latest findings suggest.

An international team of scientists show for the first time that meteorites continually bombarding Mars contain enough carbon compounds to generate when exposed to .

The findings could help inform future missions searching for Martian life.

Since the of methane in Mars' atmosphere nearly a decade ago, there has been much discussion of where it comes from. The gas contains carbon – a substance found in all living things – so some researchers have suggested it may have a biological source.

"Methane doesn't persist in the atmosphere, which means there must be some sort of process that continuously produces it," explains Dr. Andy McLeod from the University of Edinburgh, one of the co-authors of the study, published in Nature.

"Whether this process is biological or merely chemical or geological has been a subject of intense debate over the years."

A biological source for the methane would imply a possibility of life on Mars.

Previous studies have found that the amount of methane released from meteorites when they vaporise and break-up on entering a planet's atmosphere is negligible. Other researchers have suggested a geological, chemical or biological origin.

"All these ideas have their shortcomings, because the estimates for the amount of methane produced don't explain the level of methane in Mars' atmosphere," says McLeod.

This chart depicts the calculated methane concentrations in parts per billion (ppb) on Mars during summer in the Northern hemisphere. Violet and blue highlights are indications for little quantities of methane, red highlights for larger ones. Credit: NASA

Until now no-one had thought to check whether exposing meteorites to sunlight would create methane. But McLeod and his colleagues' work on ultraviolet radiation's role in releasing methane from vegetation on Earth led them naturally to question its source in Mars' atmosphere.

"A few years ago, we discovered that methane is released from both living and dead vegetation when it's irradiated with ultraviolet radiation," says McLeod. "So we wondered if we exposed extraterrestrial matter to UV radiation, we'd see methane being produced."

The team used samples from a that fell on Australia more than 40 years ago in 1969, named the Murchison meteorite after the town nearest where it landed.

They chose it because it has a similar chemical content to the type of meteorite that regularly lands on Mars and is known to contain a small percentage of organic matter.

"If the many meteorites that bombard Mars also contain several per cent organic matter, there is potential to explain some of the methane we see there," says McLeod.

He and colleagues from the Max Planck Institute for Chemistry and the universities of Utrecht and West Hungary exposed meteorite particles to the same levels of ultraviolet radiation expected at the Martian surface. They found that the particles gave off significant methane, and say this could account for much of the gas present in Mars' atmosphere.

"The amount of methane we measured from the meteorite was much higher than we expected," says McLeod.

"We can't say where this organic matter comes from, but our results show that it definitely has an extraterrestrial origin," he adds.

The researchers say a significant amount of weathering would be necessary to convert any meteoritic to methane. This is because ultraviolet rays cannot penetrate far into minerals.

They're also keen to add that while meteorites contribute to the production of methane in the , this doesn't mean they're the only source.

"We're not ruling out a possible biological origin for some of the methane in the Martian atmosphere, but our results don't add support to that idea," says McLeod.

What the findings do suggest is that the presence of methane isn't enough to say that life exists on .

Explore further: The two faces of Mars

More information: Frank Keppler, et al., Ultraviolet-radiation-induced methane emissions from meteorites and the Martian atmosphere, Nature, published 30 May 2012, doi:10.1038/nature11203

Journal reference: Nature search and more info website

Provided by PlanetEarth Online search and more info website

4.7 /5 (3 votes)

Related Stories

Life on Mars theory boosted by new methane study

Dec 08, 2009

Scientists have ruled out the possibility that methane is delivered to Mars by meteorites, raising fresh hopes that the gas might be generated by life on the red planet, in research published tomorrow in Earth an ...

Just How Significant Is Methane On Titan?

Sep 12, 2005

Titan's second most abundant constituent, methane, is critical to the maintenance of an earth-like nitrogen atmosphere on this satellite. Without methane, Titan's nitrogen would condense, leaving behind a puny amount in ...

Mars methane lasts less than a year

Sep 21, 2010

A new study indicates that methane in the atmosphere of Mars lasts less than a year. Methane is replenished from localized sources that show seasonal and annual variations. This pattern of methane production ...

Recommended for you

The two faces of Mars

1 hour ago

A moon-sized celestial object that crashed into the south pole: ETH researchers use a simulation to demonstrate why Mars consists of two notably different hemispheres.

The electric eye of Cyclone Bansi

1 hour ago

Though this image may look like they come from a science fiction movie, it is in fact a photograph of tropical cyclone Bansi as seen at night by astronauts on the International Space Station (ISS). The image ...

Dawn spacecraft captures best-ever view of dwarf planet

23 hours ago

NASA's Dawn spacecraft has returned the sharpest images ever seen of the dwarf planet Ceres. The images were taken 147,000 miles (237,000 kilometers) from Ceres on Jan. 25, and represent a new milestone for ...

Image: Striking lightning from space

Jan 27, 2015

Lightning illuminates the area it strikes on Earth but the flash can be seen from space, too. This image was taken from 400 km above Earth in 2012 by an astronaut on the International Space Station travelling ...

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

2.1 / 5 (7) May 31, 2012
Methane doesnt mean life, look at venus.
3 / 5 (2) May 31, 2012
Very interesting....
1.7 / 5 (6) Jun 01, 2012
Cool. This is interesting.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.