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Liquid water and organics in Comets: implications for exobiology

Published online by Cambridge University Press:  17 July 2009

J.T. Wickramasinghe ,
N.C. Wickramasinghe  and
M.K. Wallis
J.T. Wickramasinghe
Affiliation:
Centre for Astrobiology, Cardiff University, 2 North Road, CF10 3DY, UK
N.C. Wickramasinghe*
Affiliation:
Centre for Astrobiology, Cardiff University, 2 North Road, CF10 3DY, UK
M.K. Wallis
Affiliation:
Centre for Astrobiology, Cardiff University, 2 North Road, CF10 3DY, UK
*
e-mail: ncwick@googlemail.com
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Abstract

Liquid water in comets, once considered impossible, now appears to be almost certain. New evidence has come from the discovery of clay minerals in comet Tempel 1, which compliments the indirect evidence in aqueous alteration of carbonaceous chondrites. Infrared spectral indication of clay is confirmed by modelling data in the 8–40 μm and 8–12 μm wavebands on the basis of mixtures of clays and organics. Radiogenic heating producing liquid water cores in freshly formed comets appears more likely on current evidence for solar system formation. A second possibility investigated here is transient melting in comets in the inner solar system, where thin crusts of asphalt-like material, formed due to solar processing and becoming hot in the daytime, can cause melting of sub-surface icy material a few centimetres deep. Supposing comets were seeded with microbes at the time of their formation from pre-solar material, there would be plenty of time for exponential amplification and evolution within the liquid interior and in the transient ponds or lakes formed as the outer layers are stripped away via sublimation.

Keywords

cometsexobiologyliquid waterpanspermiaradioactive heat sources
Type
Research Article
Information
International Journal of Astrobiology , Volume 8 , Issue 4 , October 2009 , pp. 281 - 290
Copyright
Copyright © Cambridge University Press 2009

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