Abstract On Titan, the largest satellite of Saturn, several of the organic molecules of terrestrial prebiotic importance are formed in its reduced nitrogen-methane atmosphere poor in hydrogen. However, because of the cold temperatures of Titan's environment, liquid water is absent from its surface, likely to be covered by an ocean of liquid ethane and methane. In addition, most of the atmospheric organics must condense in the low stratosphere, giving clouds of organic aerosols. Microphysical modeling of these processes shows that in the low atmosphere the aerosols would be constituted of a nucleus of several 10 microns mean diameter, mainly composed of nitriles, and covered by a thick layer of propane, ethane and methane. After precipitation of these aerosols down to the surface, a fraction of their organic material must dissolve in Titan's ocean. Thermodynamic modeling of the ocean indicates that this low temperature liquid milieu should include high concentrations of various organics. Thus, prebiotic chemistry on Titan appears to be governed by atmospheric processes in an atmosphere free of oxygen-containing organics, and by organic processes in a cryogenic apolar solvent. It must have followed a way very different from the terrestrial one.
Prebiotic-like organic syntheses in extraterrestrial environments: The case of titan
Advances in Space Research ; 9 , 6 ; 35-47
1989-01-01
13 pages
Article (Journal)
Electronic Resource
English
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