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According to many scientists, the organic chemicals found in meteorites played a fundamental role in the appearance of life on Earth. Given the presence of certain chemicals in meteorites, there is little reason to suppose that they are unique to our own planet, and a logical conclusion would be that similar organic compounds are found throughout the solar system, given their common origin in a protostellar cloud.
This hypothesis is supported by various lines of evidence, such as the similarity between the organic contents of certain carbonaceous chondrites (rich in silicates and organic compounds originating from the birth of the solar system) and the tail of comet 81P/Wild-2, antarctic micrometeorites and interplanetary dust.
Despite this similarity there are large chemical variations within the carbonaceous chondrite group, thought to be due to processes that acted on their parent bodies after their formation.
A study in this field, led by Christopher Herd of the University of Alberta (Canada), with researchers at the Carnegie Institution for Science, published today in Science, shows that these variations have their origin in hydrodynamic activity that occurred when our solar system was in its infancy, and the meteorites were part of much larger bodies, such as asteroids.
Among the samples studied by Herd are 4 pieces of a meteorite that fragmented during its fall onto the frozen Tagish Lake in Canada, in January 2000. After being recovered they have been continually kept below freezing temperature to minimise possible terrestrial contamination.
The variations in the chemical makeup within these samples (including amino acids and monocarboxylic acids essential for biochemistry) supports the hypothesis of chemical and hydrothermal alteration within a larger parent body.
It would seem then, that the compounds essential for life were widely distributed throughout the primordial cloud from which the solar system formed, and so could equally well be present in other planetary systems.
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