Scientists hail unique, surprisingly damp Mars find

Discovered in the Sahara Desert, the rock called NWA 7034 is unlike any of the 110-odd Martian meteorites yet found on Earth, according to a report published online Thursday by the journal Science. Experts said it provides an unprecedented close-up view of the Red Planet's surface and may help scientists understand what NASA's Curiosity and Opportunity rovers are seeing as they roam the Martian surface.

“This opens a whole new window on Mars,” said Munir Humayun, a cosmochemist at Florida State University in Tallahassee who was not involved in the study.

Though planetary scientists have sent several spacecraft to Mars most recently Curiosity, which is equipped with an on-board chemical laboratory there's no substitute for a sample in hand, said study leader Carl Agee, director of the Institute of Meteoritics at the University of New Mexico in Albuquerque. Scientists on Earth can run sophisticated tests and glean a wealth of information about the rock's history and the environment in which it formed tests no rover could do.

NWA 7034 came to Agee in 2011 by way of a meteorite collector who bought it from a meteorite dealer in Morocco. The planetary scientist said he was immediately struck by the 319.8-gram sample, which is about the size of a baseball and twice as heavy.

Even though most space rocks become blackened on the outside during their blazing descent through the Earth's atmosphere, they often remain light on the inside. NWA 7034, on the other hand, was dark all the way through, earning the nickname “Black Beauty.”

“I had never seen anything like it,” Agee said.

Perplexed by the strange specimen, he put it on his bookshelf and let it sit there for about a month as he wrestled with the best way to approach his analysis. Once he got started, he examined the meteorite for nearly a year.

At first, NWA 7034 appeared to be very un-Mars-like. Laser fluorination revealed that its ratio of heavier-to-lighter oxygen isotopes, usually a handy fingerprint of a meteorite's origins, didn't match any of the Mars meteorites described in the scientific literature. Those meteorites seemed to come from volcanic deposits formed deep inside Mars, because their chemical makeup was different from the data sent back by rovers and spacecraft examining the Red Planet's surface.

If Agee's team had looked no further, the space rock might have been classified as an oddball piece of asteroid and quite possibly forgotten. But rubidium-strontium dating indicated that NWA 7034 was just 2.1 billion years old far too young to come from an asteroid.

Meteorites that come from asteroids are typically more than 4 billion years old, since these small rocky bodies quickly cooled after the solar system's formation. Planets, on the other hand, were volcanically active for much longer, and many of their rocks formed much later.

Black Beauty must have come from a planet, the team members concluded.

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