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Abstracts from the Second Astrobiology Science Conference International Journal of Astrobiology 1 (2): 87–176 (2002) Printed in the United Kingdom 87 DOI: 10.1017\S147355040200112X # 2002 Cambridge University Press Abstracts from the Second Astrobiology Science Conference NASA Ames Research Center, Moffett Field, California, USA 7–11 April 2002 Keynote presentations Digital organisms for experimental evolution Life beneath glacial ice – Earth! Mars? Europa? C. Adam $ Digital Life Laboratory; Jet Propulsion Laboratory; Carlton C. Allen $ NASA Johnson Space Center, Stephen. E. Grasby $ California Institute of Technology Geological Survey of Canada, Teresa G. Longazo $ Hernandez Experiments in evolution are difficult for all the obvious reasons: the Engineering, John T. Lisle $ United States Geological Survey, Benoit process is slow (such that macroevolutionary events occur only on a Beauchamp $ Geological Survey of Canada time scale of thousands to millions of years), and controlled conditions We are investigating a set of cold springs that deposit sulfur and are hard to establish. As a consequence, evolution has, in the past, been carbonate minerals on the surface of a Canadian arctic glacier. The mostly an observational and theoretical science, with little quantitative spring waters and mineral deposits contain microorganisms, as well as support. This has changed over the last decade, as more and more clear evidence that biological processes mediate subglacial chemistry, evolution experiments using microorganisms with short generational mineralogy, and isotope fractionation. The formation of native sulphur time have been conducted and their evolutionary dynamics studied in and associated deposits are related to bacterially mediated reduction controlled conditions. and oxidation of sulphur below the glacier. A non-volcanic, topography- Digital organisms are a new form of life that is adapted to life in the driven geothermal system, harboring a microbiological community, computer.1,2 Because of its simplicity, it is ideal for experimental operates in an extremely cold environment and discharges through solid evolution, even though (and perhaps because) digital life does not share ice. any ancestry with biochemical life on Earth. Digital organisms are self- Microbial life can thus exist in isolated geothermal refuges despite replicating computer programs that thrive in the memory of specially long-term subfreezing surface conditions. Earth history includes several prepared computers. They adapt to a virtual world, and grow in periods of essentially total glaciation. Ice in the near subsurface of Mars complexity. Their main use is as an experimental organism, to test and may have discharged liquid water in the recent past. Cracks in the ice study evolutionary theories and hypotheses. While several experiments crust of Europa have apparently allowed the release of water to the have been conducted that mirror classic experiments performed with surface. Chemolithotrophic bacteria, such as those in the Canadian microorganisms, recently new evolutionary dynamics have been springs, could have survived beneath the ice of ‘‘Snowball Earth,’’ and observed3 in digitals that await confirmation with ‘‘biochemicals.’’ life forms with similar characteristics might exist beneath the ice of References Mars or Europa. Discharges of water from such refuges may have 1 Adami, C. (1998). Introduction to Artificial Life (Springer Verlag, NY). brought to the surface living microbes, as well as long-lasting chemical, 2 Harvey, I. (1999). Creatures from another world. Nature 400, 618–619. mineralogical, and isotopic indications of subsurface life. 3 Wilke, C.O., Wang, J.L., Ofria, C., Lenski, R.E. & Adami, C. (2001). Evolution of digital organisms at high mutation rate leads to survival of A culture-independent survey of the bacterial the flattest. Nature, 412, 331–333. community in a radon hot spring in the Flinders Ranges of South Australia From interstellar polycyclic aromatic hydrocarbons Roberto Anitori $ Macquarie University, Australia, Cherida Trott $ and ice to astrobiology University of Auckland, David J. Saul $ University of Auckland, Peter Louis Allamandola $ NASA Ames Research Center L. Bergquist $ University of Auckland Medical School, New Zealand, The first part of this talk will describe how infrared studies of interstellar Malcolm Walter $ Macquarie University, Australia space, combined with laboratory simulations, have revealed the com- Studies of the microbial biota inhabiting active and ancient terrestrial position of interstellar ices (the building blocks of comets) and the hot springs is relevant to the analysis of similar Martian sites. For nature of interstellar polycyclic aromatic hydrocarbons (PAHs). instance, such research permits the development and refinement of The remainder of the presentation will focus on the photochemical appropriate methodologies (e.g. lipid biomarker analysis) for detecting evolution of these materials and astrobiology. Within a dense molecular evidence of present or past life on Mars. Paralana hot spring is located cloud, the birthplace of stars and planets, the materials frozen into the in the Mt Painter province of South Australia’s Flinders Ranges. This ices are energetically processed by ultraviolet light and cosmic rays, region is highly mineralised as the result of ancient and current producing complex organic molecules. Since these interstellar materials (Paralana) hydrothermal activity, with uranium and radium minerals are thought to be the building blocks of comets and related to the predominating. Consequently, radon gas is released into the Paralana organics in meteorites and micrometeorites, they are likely to have been hot spring (" 0n1–0n8 µCi\L) [Grant, 1938. Trans. Roy. Soc. S.A. 62, important sources of complex materials on the early Earth. Thus, their 357–365]. We have performed culture-independent 16S rRNA analyses composition may have played a role in the origin of life. (using bacteria-specific primers) of the microbial assemblages in nine Paralana samples. Water temperatures ranged from 48 to 63 mC, and pH was neutral. Database searches and phylogenetic analyses conducted using Paralana 16S sequences indicated the presence of a diverse microbial community. Representatives of at least eight bacterial divisions were identified, including members of the cyanobacteria, green sulfur bacteria, nitrospira, the proteobacteria, and candidate division Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.8, on 26 Sep 2021 at 09:48:23, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S147355040200112X 88 Abstracts from the Second Astrobiology Science Conference OP8. Interestingly, with the exception of one 16S sequence, there was no massive stars. In these environments, proto-planetary disks are exposed evidence of previously described radiation-resistant microorganisms. to the dynamical effects of dense proto-clusters or multiple star systems, harsh radiation fields, and powerful winds. As a result, disks may be Student research in astrobiology short lived. Indeed, in one of the nearest regions of star formation, the Jodi Asbel-Clarke $ TERC, Jeff Lockwood $ TERC, Dan Barstow $ Orion Nebula, the Hubble Space Telescope has provided direct evidence TERC for rapid disk destruction. The observed constraints imply that either Building on experience in several successful scientist–student research planets form very rapidly, or that planetary systems will be relatively partnership programs, the Center for Earth and Space Science Edu- rare. I will review our current understanding of star and planet formation cation (CESSE) at TERC is developing authentic research experiences with an emphasis on observational results and on the processes that for high school students and teachers in astrobiology. To enrich student may affect the prospects for the eventual evolution of life. learning in their early high-school integrated science astrobiology curriculum (to be published 2002–2003 by It’s About Time), CESSE has created Habitable Worlds, an interactive online research tool for students. Habitable Worlds provides a student-friendly user interface- Mars soil formation and properties: the ‘‘acid fog’’ called an Exploration Portal to access image data from Pathfinder and hypothesis in view of recent evidence other probes to enable students to pursue their own investigations about Amos Banin $ Hebrew University; NRC; NASA Ames Research Center Earth, Mars, and other worlds. We have proposed and tested experimentally a model that attributes the As the next step, CESSE is beginning development on student– peculiar nature of Mars soil to it being a relatively ‘‘young’’ weathering scientist partnerships in astrobiology following models used by other product. The model suggests that Mars soil components formed at the TERC projects. CESSE will develop tools and user interfaces for microscopic rock–atmosphere interface during recent periods by a databases so that large numbers of students and teachers can engage in process involving chemical neutralization of acidic volcanic aerosols authentic research, while minimizing the time needed from scientists. containing soluble S and Cl species. This ‘‘Acid Fog’’ formation scenario With initial input from scientists and teachers, CESSE will develop seeks to reconcile conflicting evidence for the presence of very soluble, protocols and instructions (with a background curriculum) so that water-transported sulfate and chloride salt minerals (‘‘evaporites’’)
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