Extraterrestrial life detection based on oxygen isotope exchange reactions.

A method is described for detecting extraterrestrial life, based on catalysis of isotopic oxygen exchange between water and oxygen-containing anions such as phosphate, nitrate, or sulfate. This catalytic activity appears to be unique to living systems. Its applicability requires very few assumptions concerning the chemical nature of "life." Data obtained so far indicate that the experiment is sound and technically feasible.