We are used to thinking of life based upon the distinctive properties of carbon and water. It does not have to be like that, according to astrobiologists. Life probably requires solvents, and a way for complex molecules to be built up: a prerequisite for self-replication that is one of life’s essential features. However, out on Titan (a moon of Saturn) there is liquid methane in which life could arise and whole new biochemical pathways could be imagined. A National Research Council report concludes: “If life is an intrinsic property of chemical reactivity, life should exist on Titan.” ut why stop there? On Triton (a moon of Neptune), where temperatures are so low that gases liquefy, a metabolism based on strange silica compounds and liquid nitrogen has been posited. Or again, astrobiologists have proposed life in the clouds surrounding Venus, and based on sulfuric acid. Why not life around red dwarfs if one tweaks the elements in a different fashion?
more from Richard Fortey at the NY Times here.