Assessment of Planetary Protection Requirements for Mars Sample Return Missions (2009) / Chapter Skim
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4 The Potential for Finding Biosignatures in Returned Martian Samples
4 The Potential for Finding Biosignatures in Returned Martian Samples
Pages 37-44
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From page 37... ...
, which will be used to guide subsampling for biohazard testing and to inform decisions about sample allocations for further testing, or release from containment, will require understanding of the nature and origin of any organic matter present, whether derived from inorganic sources, from living or dormant life forms, or from fossils. For these reasons, it is prudent to briefly review some of the studies of biosignature capture and preservation that have been carried out in relevant terrestrial environments over the past decade.
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From page 38... ...
.23 Microbial biosignatures are not restricted to surface deposits but have also been described from mineralized subsurface fractures and other void spaces in subsurface volcanic rocks.24,25 Finally, glacial ice and permafrost have been shown to harbor a broad range of extant and dormant life forms, as well as their cryopreserved fossil remains within water and brine-filled voids. 26,27 The recent discovery of sulfate-rich evaporite deposits by the Opportunity rover (see Figure 2.2)
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From page 39... ...
. 38 Equally interesting from the standpoint of Special Regions are recently discovered evaporite deposits on Mars,39,40 including possible halite salts, which are the current record holders on Earth for the prolonged preservation of entombed, viable microorganisms.41,42 Finally, biosignature studies of martian analog environments and materials on Earth have also stimulated the development of new instrument and payload concepts to support future life detection missions on Mars.43,44,45 FIGURE 4.2 Photomicrograph of a thin section of a siliceous hot spring (sinter)
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From page 40... ...
, Copyright Elsevier, 2007. Many of the same challenges faced in the search for fossil biosignatures in ancient rocks on Earth are directly relevant to the exploration for a fossil record on Mars.46 Debates over the interpretation of biosignatures preserved in the earliest Precambrian fossil records on Earth47,48,49,50,51,52,53,54 and putative biosignatures in martian meteorite ALH 8400155 have stimulated new approaches to fossil biosignature analysis56,57,58 and directly influenced approaches to Mars exploration.59 Investigations of Earth's ancient geological record have also provided access to a geological record of ancient environments that were likely similar to early, potentially habitable, martian environments.
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From page 41... ...
Frias-Lopez, "Partitioning of Bacterial Communities Between . Travertine Depositional Facies at Mammoth Hot Springs, Yellowstone National Park, U.S.A.," Canadian Journal of Earth Sciences 40:1531-1548, 2003.
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From page 42... ...
Rosenzweig, "Paleobrine Temperatures, Chemistries, . and Paleoenvironments of Silurian Salina Formation f-1 Salt, Michigan Basin, USA, from Petrography and Fluid Inclusions in Halite," Journal of Sedimentary Research 75:534-546, 2005.
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From page 43... ...
See Mars Exploration Program Analysis Group (MEPAG) , "Findings of the Mars Special Regions Science Analysis Group," MEPAG SR-SAG, unpublished white paper, posted June 2006, available at http://mepag.jpl.nasa.gov/reports/ index.html.
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From page 44... ...
and N Zare, "Search for Past Life on Mars: Possible Relict Biogenic Activity in Martian Meteorite ALH 84001," Science 273:924-930, 1996.
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