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Recipe for life possibly landed on Earth in crash of comet

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By San Jose Mercury News
Monday, Sept. 16, 2013, 9:03 p.m.

LIVERMORE, Calif. — Life started with a dirty snowball, tossed at Earth from space.

That is the conclusion reached by a group of international scientists, confirming a theory conceived by a Lawrence Livermore Laboratory researcher. The team fired a speeding projectile into a special ice mixture, generating a hot and high-pressure environment — akin to the comets that streak through the heavens, piercing our atmosphere.

And presto: Out of the explosion came life's raw materials, called amino acids.

This final product — a pound of “goop,” said Livermore Lab researcher Nir Goldman — is a modest ancestor to our now-gloriously lively Earth.

But it is not the only explanation for how our home took its first halting steps to becoming alive. Dozens of other teams are exploring alternate theories.

“But these studies prove that this is one avenue in which amino acids were produced, early on,” said Goldman. “It is exciting to ponder the different avenues that could have been the origin of life.”

Using computer simulations performed on lab supercomputers, Goldman proposed in 2010 and again in 2013 that an icy comet crashing into Earth billions of years ago could have produced amino acids.

It is known that comets bombarded the Earth between 3.8 billion and 4.5 billion years ago. It is likely that the comet that triggered life hit us at an oblique angle, rather than a direct smash, he said.

Amid the ice, the comets bore carbon dioxide, methane, ammonia and other trace gases — precursors of amino acids.

These simple molecules could have supplied the raw materials of life, Goldman believes. And the impact with early Earth would have yielded the energy to drive this prebiotic chemistry.

Goldman's idea was put to the test and proven by British collaborators, whose findings are published in the latest issue of the journal Nature Geosciences.

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