Enceladus is perhaps the most interesting astrobiology target in the outer solar system. This small satellite of Saturn has jets of water ice particles emanating from its South Pole. In addition to water ice, the jets include methane, propane, acetylene, and nitrogen gas or carbon monoxide. The likely source of Enceladus' jets is a pressurized subsurface liquid reservoir. If nitrogen is present it may reflect thermal decomposition of ammonia associated with the subsurface liquid reservoir and may imply that the water is in contact with hot rocks - providing a source of heat as well as mineral surfaces for catalyzing reactions. If this scenario proves correct, then all the ingredients are present on Enceladus for the origin of life by chemoauto-trophic pathways - a generally held model for the origin of life on Earth in deep-sea vents. In this case, the Enceladus South Polar jets would include the waste products of such an ecosystem - that is, its biomarkers.
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