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Wednesday, 27 March, 2002, 21:14 GMT
Life's origins among the stars
Nasa
A salt inclusion in a meteorite is evidence of water
test hello test
By Dr David Whitehouse
BBC News Online science editor
line
New evidence that the building blocks of life are scattered in clouds between the stars is reported in two research papers in the journal Nature.

By simulating the supercold conditions found in space, researchers have shown that tiny ice grains can play host to important reactions when irradiated by ultraviolet light.

In the experiments, atoms were assembled into amino acids, the basic components of proteins, the sophisticated molecules that build and maintain living organisms.

The researchers say it is possible that such ice grains could have become incorporated into the cloud that formed our Solar System and ended up on Earth, helping life to start.

In between the stars

Several lines of evidence suggest that some of the building blocks of life were delivered to the primitive Earth via meteoroids.

But scientists would still like to know how they got into the meteoroids in the first place.

There appear to be two ways. One suggestion is that complex chemical reactions involving water took place on, or in, the rocky bodies that formed when the Solar System was young.

These reactions produced a variety of amino acids. For example, analysis of the famous Murchison meteorite shows that it contains 70 kinds of amino acids.

But writing in the journal Nature, two independent groups, one led by Max Bernstein of the Seti Institute in the US and the other by Uwe Meierhenrich of Bremen University, Germany, put forward another scenario.

Life out there

This involves chemical reactions on the ice grains that inhabit interstellar space.

The researchers carried out experiments that simulated the conditions found between the stars, using ultraviolet radiation and temperatures around minus 258 degrees Celsius (that is 15 degrees above absolute zero).

Into these conditions they introduced some of the molecules that are known to be drifting in space, such as carbon monoxide and ammonia.

Both teams reported the formation of amino acids, such as glycine, alanine, serine and proline.

The experiments were not identical, however. One team used an initial mixture that was rich in water; the other team used a water-deficient compound that produced far more amino acids.

This research adds to the growing body of evidence that the formation of complex molecules occurs in many different environments in the cosmos, and will it will encourage those who believe that life is widespread in the Universe.

See also:

20 Dec 01 | Sci/Tech
Life's sweet start
08 Sep 00 | Festival of science
Rare space rock in British lab
05 Sep 00 | Sci/Tech
Meteorite records early Solar System
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