Comets helped bring about life on Earth

By Adrian Bishop - 27 Mar 2012 21:0:0 GMT
Comets helped bring about life on Earth

Credit: Don Davis, NASA

Comets colliding with the Earth billions of years ago may have helped bring about life on Earth. Amino acids, energy and water could all have been present inside the comets that crashed to Earth, the American Chemical Society heard at its National Meeting & Exposition.

Amino acids create proteins that form the basis of life in all creatures from microorganisms to humans.

Thanks to computer modelling and experiments with powerful 'guns', a team of scientists in California, USA, led by Dr Jennifer Blank reconstructed the conditions inside the comets.

The comets would have been travelling at nearly 25,000 miles per hour as they struck the atmosphere and crashed down to Earth, but the chemicals could still have survived.

Dr Blank says, "Our research shows that the building blocks of life could, indeed, have remained intact despite the tremendous shock wave and other violent conditions in a comet impact.

"Comets really would have been the ideal packages for delivering ingredients for the chemical evolution thought to have resulted in life. We like the comet delivery scenario because it includes all of the ingredients for life - amino acids, water and energy."

Comets consist of frozen gases, ice, water, rock and dust and can measure more than 10 miles across. Some astronomers call them 'dirty snowballs'.

They originate way beyond the furthest planets of the solar system and move around the sun, but, sometimes, they break away and career inwards, where they can be seen in the sky.

Around 3.8 billion years ago, the Earth was struck by showers of comets and asteroids in the 'late heavy bombardment'. Previously, Earth was too hot to support life. Life, as seen in the first-know fossils, arrived around 0.3 billion years later.

Dr Blank and her team from Bay Area Environmental Research Institute and the NASA/Ames Research Center, at Moffett Field investigated if amino acids could endure the plunge through the atmosphere and the impact with Earth.

Powerful gas guns simulated the high temperatures and huge shock waves the amino acids would have faced by blasting capsules filled with water, amino acids and additional materials, with high-pressure gas at supersonic speed.

The amino acids survived and started to create "peptide bonds" that join amino acids into proteins. The pressure of the impact provided the energy to create the bonds.

Dr Blank suggests the material for the basis of life may well have come through many years of comets, meteorites and asteroids.

The ACS is the largest scientific society in the world. The non-profit organisation has more than 164,000 members and is a world leader in chemistry research.

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