Comets may have 'seeded' life on Earth

LIVERMORE, Calif., Sept. 14 (UPI) -- The building blocks of life on Earth may have been brought to the planet by special delivery -- by comets slamming into the Earth's surface, researchers say.

Scientists at the Lawrence Livermore National Laboratory in California say comets that crashed into Earth millions of years ago could have produced amino acids, the precursors of life, a laboratory release said.

Their computer simulations show long chains containing carbon-nitrogen bonds can form during shock compression of cometary ice in an impact. After expansion, the long chains can break apart to form complexes containing the protein-building amino acid glycine, scientists say.

Amino acids are the building blocks of proteins, which are linear chains of amino acids.

Earth's early atmosphere consisted mainly of carbon dioxide, nitrogen and water, and research has shown the synthesis of organic molecules needed for amino acid production would have been difficult in this type of environment, researchers say.

But comets could have kickstarted the process, researchers say.

"There's a possibility that the production or delivery of prebiotic molecules came from extraterrestrial sources," LLNL scientist Nir Goldman said. "On early Earth, we know that there was a heavy bombardment of comets and asteroids delivering up to several orders of magnitude greater mass of organics than what likely was already here."