By Lisa Grossman, Science News April 15, 2010 | 5:47 pm | Categories: Space
The Allan Hills meteorite, named for the site where it was found in Antarctica, was once thought to contain fossil traces of life. That idea has been mostly dismissed, and now the rock also appears to be not quite as old as previously thought.
The oldest known Martian meteorite isn’t so old after all. Though it’s still the oldest chunk of Mars scientists have ever found, new research suggests the Allan Hills meteorite — officially known as ALH84001 — is about 400 million years younger than previously estimated.
A new analysis published in the April 15 Science pegs the meteorite’s age at a mere 4.091 billion years. Previously the meteorite was commonly accepted to have formed 4.51 billion years ago, when the planet’s surface was still solidifying out of its primordial magma ocean. But the new age indicates the rock would have formed during a later, chaotic period when Mars was being pummeled by meteorites that fractured and shocked the planet’s solid surface.
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