HR: 16:00h
AN: P42C-01 INVITED     [PDF]
TI: Challenges to Life on Mars --- Ecological Perspective
AU: * Sun, H
EM: henry.j.sun@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, MS 183-301, Pasadena, CA 91109 United States
AU: McKay, C
EM: cmckay@arc.nasa.gov
AF: Ames Research Center, Space Science Division, 245-3, Moffett Field, CA 94035 United States
AU: Friedmann, I
EM: ifriedmann@mail.arc.nasa.gov
AF: Ames Research Center, Space Science Division, 245-3, Moffett Field, CA 94035 United States
AU: McDonald, G
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, MS 183-301, Pasadena, CA 91109 United States
AB: This talk will address the habitability of Mars by considering major environmental challenges against the tolerance limits of microorganisms from extreme terrestrial environments including the Antarctic desert and permafrost. At the planet surface, the combination of low atmospheric pressure (below the triple point of water), high fluxes of ultraviolet radiation, and one or more powerful oxidants are likely to create sterilizing conditions that will be a barrier to the colonization and dispersal of microorganisms. In the subsurface below, long-term survival is dependent upon the frequency and duration of warm, metabolically active periods that are needed to repair cellular damages. Low temperature itself does little harm to microorganisms, but a long dormant period will accrue lethal dosages of ionizing radiation and amino acid racemization. It is probable that within the depth range of current sampling technologies, there are no conditions for extant life, leaving organic or inorganic fossils as the only legitimate target in the search for life on Mars.
DE: 0400 Biogeosciences
DE: 1615 Biogeochemical processes (4805)
DE: 4840 Microbiology
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting