Examination of a meteorite that’s believed to have fallen to Earth around 3,000 years ago has provided clues as to how Mars lost its atmosphere, previously rich in carbon dioxide (CO2).
Analysis of the processes which took place on Mars eons ago has implications for curbing global warming on Earth caused by greenhouse gases, one being CO2.
The research was carried out by a group of scientists, led by Dr Tim Tomkinson of the Scottish Universities Environmental Research Centre (SUERC). His scientific team examined pieces of the Lafayette meteorite, an 800-gram lump of nakhlite rock “rediscovered” among the geological collection of Purdue University at Lafayette, Indiana in 1931.
The original Lafayette meteorite 'discovered' in a geological collection in 1931, is classed as a Martian meteorite having originated from Mars.
The Lafayette meteorite is documented as a Martian meteorite in NASA’s Martian Meteorite Compendium. Martian meteorites are thought to have originated on Mars since their chemical and isotopic composition is similar to rocks and atmospheric gases analyzed by unmanned missions to Mars. They are believed to have been ejected from the surface of Mars when the Red Planet suffered a massive impact from a comet or asteroid millions of years ago.
Of more than 41,000 meteorites that have so far been found on Earth, only around 61 have been documented as being of Martian origin, according to SUERC figures.
Around 4,000 million years ago, Mars is believed to have been significantly warmer and certainly much wetter than today. In January 2013, the European Space Agency published a series of images from its Mars Express mission showing the Reull Vallis region of the planet. These provided strong evidence that rivers once flowed on the Martian surface.
During Mars’ warm and wet period, the planet’s atmosphere is believed to have been rich in CO2. With Mars being roughly half as much again further from the sun than the Earth, the CO2 may at one time have provided Mars with a comfortable, though not breathable, snuggle-blanket.
What happened to the Red Planet’s swaddling CO2 insulation is something of a Martian mystery but what is obvious is that over millions of years, Mars lost most of its atmosphere. In the process, the Red Planet became the cool, arid world we see today. The new research, published under the title Sequestration of Martian CO2 by mineral carbonation, Oct. 23 in Nature Communications, may help dispel some of the mystery.
In examining sections of the Lafayette meteorite, the researchers found that carbonation, basically the same process whereby carbon dioxide is dissolved in fizzy drinks, may have been a major factor contributing to the disappearance of Mars’ once CO2-rich atmosphere.
In a Martian context, carbonation could affect rocks containing volcanic minerals such as olivine. Olivine reacts with water and CO2 turning the original rock into a carbonate. As part of this process, CO2 which was formerly free in the atmosphere becomes ‘locked’ in the solid form of the carbonate. It’s this process that may have implications for research into locking down CO2 as a greenhouse gas here on Earth.
Naturally occurring mineral carbonation is widespread on Earth. BBC Science cites the example of Oman's Samail Mountains where weathering of peridotite rocks is estimated to bind in excess of 10,000 tons of CO2 per year.
Commenting on the research, Tomkinson told Environmental News Network that “Lafayette was previously known to contain carbonate, but this is the first evidence that it formed by carbonation.”
Tomkinson continued, “On Earth, we have the problem of where to store increasing levels of atmospheric carbon dioxide contributing to global warming. However, for decades researchers have been questioning where all the ancient carbon dioxide in Mars' atmosphere has gone. This discovery is significant in terms of the way in which scientists will study Mars in the future but also in providing us with vital clues of how we can limit the accumulation of carbon dioxide in the Earth's atmosphere and so reduce climate change.”