Rare Martian Meteorite Reveals Mars Formed Its Crust At The Same Time As Earth's
A rare piece of Mars' crust that fell to Earth has revealed a rough timeline of the planet's formation, suggesting its crust grew around the same time as the Earth's did, researchers from Florida State University announced Wednesday. They say the meteorite, discovered last year in Africa, may be the first example of ancient Martian crust to be analyzed. And in their new research, to be published in the journal Nature, they show for the first time that Mars' crust is about 4.4 billion years old.
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"This date is about 100 million years after the first dust condensed in the solar system," said FSU Professor Munir Humayun, a researcher at the National High Magnetic Field Laboratory, in a statement. "We now know that Mars had a crust within the first 100 million years of the start of planet building, and that Mars' crust formed concurrently with the oldest crusts on Earth and the Moon."
The meteorite's journey tells the story. Around 4.6 billion years ago, our solar system was condensing, probably from a nebula, into its component parts: the sun, planets, moons, asteroids, etc. Pieces of Mars, along with the other four rocky planets, were assembling themselves from heavier elements, like silicon, iron and magnesium, as the solar winds swept the lighter gases out to space. At some point — as happened often in the solar system's adolescent years — a meteorite slammed into the Southern Highlands, a crater-pocked region of Mars. The impact sent fragments of the planet's crust flying into space. Eventually, at least one of them crashed into the Sahara Desert.
In 2012, a Beduin tribesman dug the three-ounce meteorite out of the sand and, according to The Meteoritical Society, brought it to Agadir, Morocco, where it was purchased in June of that year and given the name NWA 7533, for Northwest Africa. Now you can buy yourself a centimeter slice of it for $8,540 online. The same company posted a video of the meteorite on YouTube.
Meanwhile, Humayun, a geologist whose interests include cosmochemistry, began examining its composition. He discovered it contained trace amounts of iridium, the telltale component of meteorite strikes. That told him the meteorite came from the planet's crust and from the little-explored Southern Highlands. "This cratered terrain has been long thought to hold the keys to Mars' birth and early childhood," Humayun said.
Pieces of soil that traveled along with the meteorite revealed clues about the thickness of the crust, confirming spacecraft measurements and proving definitively that Mars never sustained a massive impact that melted the entire crust. Then they used what's called a microprobe, borrowed from Curtin University in Australia, to suss out the components of the rock's minerals and examine its zircons. Zircons are crystals, and, like a more powerful carbon-14, they can be used to date objects. That's how Humayun could tell Mars' crust formed just 100 million years after the dust settled on the planet construction.
FSU says this research is only the beginning of what NWA 7533 can tell us. "Further studies may reveal more clues about the impact history of Mars, the nature of Martian zircons and the makeup of the earliest sediments on the Red Planet."
Above photo courtesy of Shutterstock
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