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Test boosts notion that comets brought life


(CNN) -- Organic molecules hitchhiking aboard comets could have survived violent collisions with Earth, sowing the seeds of terrestrial life, according to a new report.

The finding boosts the theory that the chemical precursors of life came from space, contrary to the more traditional view that they sprang from a primordial soup already on the planet.

"Our results suggest that the notion of organic compounds coming from space can't be ruled out because of the severity of the impact event," said lead scientist Jennifer Blank of the University of California, Berkeley.


Blank and colleagues conducted an experiment in which amino acids survived a high-speed impact simulating a comet crash. The team fired a bullet the size of a soda can into a metal target containing a watery mix of amino acids.

In addition to surviving the simulated comet crash, many amino acids bonded into longer peptide chains, prototypical proteins.

The test was designed to mimic impacts that would have been commonplace on Earth in its infancy. Some 4 billion years ago, the solar system was riddled with comets, some of which slammed into the planet faster than 16 miles per second (25 km/sec), according to scientists.

Scientists created these cell-like structures in an environment simulating the harsh cold of interstellar space  

Meteorites, many thought to be the cores of comets, have been found to contain more than 70 kinds of amino acids, including all those necessary for life. Scientists speculate that amino acids originate in interstellar clouds of dust.

The report was presented Thursday at a meeting of the National Chemical Society. Blank plans to test the more controversial theory that the cosmos seeded the planet with ready-made life.

The next hitchhikers she intends to subject to a crash test -- bacterial spores, which some astronomers believe sparked evolution after their arrival via comets.

Another new report this week advanced the so-called panspermia theory, albeit with a different twist. British scientists announced they had evidence that organic compounds could survive atmospheric entry encased in small, tarry meteorites.

The heated tarry clumps could release organic chemicals into the atmosphere, which would drift down the surface. Tons of such gooey meteorites still rain into the atmosphere each year, the scientists said.

In a related experiment in January, NASA scientists simulating the harsh conditions of interstellar space were able to create organic structures similar to simple cells.

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University of California, Berkeley

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4:30pm ET, 4/16

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