title: Life as a planetary phenomenon:  the colonization of Mars.
abstract: Life is a planet-wide phenomenon in which its components incessantly move and interact. Life imperatively recycles its parts at the surface of the Earth in a chemical transformation and physical transport that depends utterly on the energy from a recent star, the Sun. Humanity, entirely dependent on other beings, plays a recent and relatively small part in the great phenomenon of life that transports and transforms the surface of the Earth. Our species accelerates but does not dominate the metabolism of the Earth system. Ironically, during the Apollo days of the sixties, fears were rampant that Martian or other extraterrestrial "germs" might "contaminate" our planet. After Viking, such fears are seen as the manifestation of cultural paranoia. The Viking missions complemented ground-based astronomical observation and yielded definitive evidence for the lack of life on the red planet. The Gaia hypothesis states that the surface temperature, composition of the reactive gases, oxidation state, alkalinity-acidity on today's Earth are kept homeorrhetically at values set by the sum of the activities of the current biota. Life, in other words, not only produces and maintains its immediate environment, but appears on Earth only as a planetary phenomenon. Since the natural tendency of all life is to grow exponentially to fill proximal volume, the question now "can life ecopoietically expand to Mars?" is entirely equivalent to the query of "can Gaia reproduce?"
authors.affiliation: Department of Biology, University of Massachusetts, Amherst, USA. pbi@bio.umass.edu
authors.forename: L
authors.initials: L
authors.lastname: Margulis
authors.forename: R
authors.initials: R
authors.lastname: Guerrero
mesh_terms: D018534:Earth, Planet; D017753:Ecosystem; D018559:Exobiology; D005118:Extraterrestrial Environment; D019369:Life; D018535:Mars; D008903:Minerals / Q000378:metabolism; D000069497:Origin of Life; D010802:Phylogeny; D018536:Venus
chemical_list: D008903:Minerals