NASA Astrobiologists --"Life On Saturn's Enceladus and Alien Bodies May Have Exotic Molecular Structures"

NASA astrobiologists say that we must recognize that life on Enceladus or other alien bodies may have originated by a process very different from the process by which life emerged on Earth. Alternatively, alien life may have originated in the same way as terran life but did not evolve as fast or as far as the terran biosphere. For example, if we accept the “RNA world” as part of a model for natural history on Earth, visits to the terran biosphere on early Earth would not have found encoded proteins, and possibly not straight-chain fatty acids.