Genesis by Comets?

They filled the small cavity with water saturated with five amino acids: three from the list of 20 that comprise all proteins in humans (phenylalanine, proline and lysine) and two varieties detected in the Murchison meteorite (aminobutyric acid and nor-valine). That meteorite plummeted to the ground in 1969 in Australia and is thought to be from the core of a comet.

The liquid contents were analysed afterwards at Argonne using liquid chromatography and mass spectroscopy to determine the species and concentrations of molecules present.

The survival of a large fraction of the amino acids and their polymerization during the collision makes the idea of an extraterrestrial origin of organic compounds a strong contender against Miller-Urey style theories, Blank said.

"About one comet per year arriving in a low-angle impact would bring in the equivalent of all the organics produced in a year in an oxidizing atmosphere by the Miller-Urey electric discharge mechanism," Blank estimated. "An advantage is you get all of it together in a puddle of water rather than diluted in the oceans."

The next hitchhikers she plans to subject to a shock test are bacterial spores, which some have proposed arrived on Earth via comets to jump-start evolution.

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