Life appears early in the geological record of the Earth. This implies that either the origin of life was rapid or that life was carried to Earth from elsewhere. Comets have been suggested as the likely vectors for transporting life to Earth. The origin of life may have occurred in an initial phase of comet evolution when radioactive heating may have produced a liquid water core. However, a strong case cannot be made for the origin of life in comets. If life originated beyond the solar system and was carried along with interstellar organics to the solar nebula by unknown mechanisms, then comets are ideal for the collection of these lifeforms, as well as their storage and distribution to planetary surfaces. If comets were responsible for introducing life to Earth, then Earth-like life should be detectable in comets as well as in interplanetary dust particles originating from comets. The limited organic analyses of cometary material available from the missions to Comet Halley failed to detect amino acids and hence do not support the presence of Earth-type life in comets. Remote spectral analyses are virtually useless for this identification.
KeywordsSolar System Liquid Water Solar Nebula Interstellar Space Complex Organic Molecule
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