When the gods dance...

Monday, May 6, 2013

Meteorite ‘mosaic’ hints at life on Mars

The various colors in a microscopic image of a slice of a meteorite that formed on Mars more than a billion years ago indicate the sizes, shapes, and orientations of minerals in the rock. (Credit: NASA)

MICHIGAN STATE (US) — To figure out if conditions on Mars were ever right for life, scientists have examined a meteorite that that formed there more than a billion years ago.

Although the work is not specifically solving the mystery, it is laying the groundwork to answer this age-old question in the future, researchers say.

The problem is that most meteorites that originated on Mars arrived on Earth so long ago that now they have characteristics that tell of their life on Earth, obscuring any clues they might offer about their time on Mars.

Researchers examined a meteorite similar to this one to look for clues that life may have once existed on Mars. (Credit: NASA)

“These meteorites contain water-related mineral and chemical signatures that can signify habitable conditions,” says Michael Velbel, professor of geological sciences at Michigan State University.

“The trouble is by the time most of these meteorites have been lying around on Earth they pick up signatures that look just like habitable environments, because they are. Earth, obviously, is habitable. If we could somehow prove the signature on the meteorite was from before it came to Earth, that would be telling us about Mars.”

Specifically, the team found mineral and chemical signatures on the rocks that indicated terrestrial weathering—changes that took place on Earth. The identification of these types of changes will provide valuable clues as scientists continue to examine the meteorites.

“Our contribution is to provide additional depth and a little broader view than some work has done before in sorting out those two kinds of water-related alterations—the ones that happened on Earth and the ones that happened on Mars,” Velbel says.

The meteorite that Velbel and his colleagues examined, known as a nakhlite meteorite, was recovered in 2003 in the Miller Range of Antarctica. About the size of a tennis ball and weighing in at one-and-a-half pounds, the meteorite was one of hundreds recovered from that area.

Past examinations of meteorites that originated on Mars, as well as satellite and Rover data, prove water once existed on Mars, which is the fourth planet from the sun and Earth’s nearest Solar System neighbor.
“However,” Velbel says, “until a Mars mission successfully returns samples from Mars, mineralogical studies of geochemical processes on Mars will continue to depend heavily on data from meteorites.”
Velbel is currently serving as a senior fellow at the Smithsonian Institution’s National Museum of Natural History in Washington DC.
The research is published in Geochimica et Cosmochimica Acta, a bi-weekly journal co-sponsored by two professional societies, the Geochemical Society and the Meteoritical Society.

Source: Michigan State

Straight from the Source

DOI: 10.1016/j.gca.2013.02.024

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