Researchers who are searching for evidence of water and organic compounds on Mars need to know how to recognize Martian life forms if Mars rocks are eventually brought back to Earth. Peter Buseck and Martha McCartney, of the NASA Astrobiology Institute, decided that clues can be found in bacteria here on Earth.
They were hired by NASA to develop reliable criteria for identifying traces of life, or ?biomarkers,? for use during future astrobiology missions. They decided that the study of organisms from Earth is the best way to start. Buseck says, ?If you find something in extraterrestrial samples that resembles life on Earth then it?s reasonable to think that you have found traces of life? on other planets.