Discovery could reveal ‘what Earth and Mars were like 100m yrs ago’

Tuesday, November 9, 2010

WASHINGTON - It could now be possible to know what the atmospheres of the Earth and Mars were like hundreds of millions years ago, thanks to a new chemical reaction uncovered by scientists.

Chemists at UC San Diego have uncovered a new chemical reaction on tiny particulates in the atmosphere that could allow scientists to gain a glimpse from ancient rocks of the atmospheres of the Earth and Mars.

The discovery has also provided a simple chemical explanation for the unusual carbonate inclusions found in a meteorite from Mars that was once thought by some scientists to be evidence of ancient Martian life.

“We never knew before how the atmosphere could be trapped in carbonate,” said Mark Thiemens, of UC San Diego’s Division of Physical Sciences.

“This chemical reaction, which takes place on the surface of aerosols in the atmosphere, not only provides us with an understanding of how these carbonates can form on the Earth and Mars. It gives us a new tool to better understand climate change, as our planet warms and becomes more dusty,” said Thiemens.

Robina Shaheen, of the Thiemens’ laboratory, discovered the chemical reaction. She found that a higher than expected proportion of oxygen 17 isotopes in the carbonates found on dust grains, aerosols and dirt from various parts of the world.

Martian meteorites, such as ALH84001, which was once thought to exhibit evidence of extraterrestrial life, have carbonates with similarly high oxygen 17 anomalies.

Scientists have long attributed those anomalies to photochemical processes involving ozone and carbon dioxide in the thin atmosphere on Mars, which is bathed by intense ultraviolet radiation.

“What she found is that the tiny little layer on the outside of the grain is where this chemistry all happens.

“It’s the ozone in the atmosphere mixing with water and carbon dioxide that drives a completely different kind of chemistry, one that’s not in any of the models,” said Thiemens.

“You can do chemistry on a grain that’s a lot quicker and easier in many respects than is possible in other atmospheric processes,” he said.he findings were published in the Journal of the Proceedings of the National Academy of Sciences. (ANI)

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