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Executive Summary

Future exploration for life on Mars and icy bodies in the outer region of our solar system necessitates rapid development of innovative instruments and techniques for life-detection that can be field tested in analogue environments on Earth. With this goal in mind, IPTAI scientists are leading a highly collaborative effort to core, sample and characterize the microbial ecosystems present within regions of persistent permafrost in northern Canada. We intend to core a sequence of bore holes using aseptic procedures and starting from lichen-encrusted rocks at the ground surface (Figure 1), extending through hundreds of meters of rocky permafrost, and penetrating into deep sub-permafrost brines contained in fractured bedrock. We seek direct evidence of microbial biomass and activity, as well as indirect evidence of microbial metabolism in the form of distinctive chemical and isotopic anomalies in gases, aqueous species and minerals. Instrumental and assay techniques that prove to be effective for detecting biosignatures in permafrost will be modified for flight deployment on future orbiting and roving Mars missions.

Figure 1. Lichen covered rocks blanketing the landscape in northern Canada at Wolfden’s Ulu gold mine.

A research site has been established at Kinross/Echo Bay Lupin gold mine, Nunavat Territory of Canada by collaborating scientists from the Geological Survey of Finland and the University of Waterloo in Canada. At this site the permafrost rock is 500 m thick. During 2001 and 2002, the Finnish/Canadian Lupin Project drilled a borehole array, which is accessible at a depth of 880 and 1130 meters. Packers and valves were installed in the boreholes, allowing for multi-year monitoring of biogeochemical reactions (Figure 2). IPTAI scientists from Princeton University, Indiana University and the University of Toronto have analyzed chemical and isotopic compositions of numerous water and gas samples from the Lupin borehole array. Funding is being pursued aggressively to drill a second borehole array at a gold mine located to the north of Lupin mine. Parallel proposals for funding the second array are being submitted to Canadian and Finnish funding agencies as part of an unusual collaboration involving universities, research institutions, regulatory agencies, and commercial mines. Biological, chemical, and physical study of core samples from permafrost will provide crucial scientific insights and engineering constraints for future exploration drilling on Mars. In addition to conventional drilling, IPTAI scientists at University of Tennessee and Oak Ridge National Laboratory are preparing to conduct laboratory drilling tests using N₂ and CO₂ as drilling fluids. Laboratory results will be used to refine technologies that are best suited for acquisition of rock, ice, water and gas samples from regolith-covered permafrost terrains on Mars and from ice-covered terrains on Mars and other planetary bodies. Future drilling tests in the laboratory and field will target strategies for removing rock material from boreholes, stabilizing borehole walls and managing changes in fluid pressures during intersection of fractures or cavities.

Figure 2. Tullis Onstott from Princeton University and Monique Hobbs from Ontario Power and Light measure rates of gas discharge from a brine intersection at a depth of 1130 meters below the surface in the Lupin gold mine, Nunavat Territories Canada.

Three geomicrobiological field campaigns have been successfully conducted at the Lupin gold mine by IPTAI scientists. Microbial diversity at Lupin is being assessed and rates of microbial reactions are being measured in subsurface settings extending from about 200 to 1500 m below the surface. Laboratory investigations of psychrophilic (cold loving) and psycho-tolerant microbial communities recovered from water intersections at Lupin are strengthened by collaboration with astrobiologists at Michigan State University, University of Rhode Island, and Woods Hole Oceanographic Institutes. Culturing of both aerobic and anaerobic microbes from sub-permafrost brines at Lupin has been successful. Cell counts in the range of 350 to 97,000 cells/ml have been determined for Lupin bines (see details in Annual Report Year 7 from the University of Rhode Island). Harvesting deep-subsurface microbes (Figure 3) by filtering thousands of liters of sub-permafrost brine has yielded sufficient DNA for amplification and phylogenetic classification of ribosomal gene sequences. These environmental DNA samples will also be analyzed using the ribosomal gene microarray technology at Lawrence Berkeley National Laboratory and large-insert genomic sequencing using the high throughput sequencing capabilities at Diversa Corporation.

C and H stable isotopic analyses of the light C_1-4 hydrocarbons) and H₂ are being determined at the University of Toronto for the purpose of constraining estimates of in situ microbial activity in the deep subsurface. Isotopic study of carbon and hydrogen are a priority because of the recent discovery of CH₄ in the Martian atmosphere. Inferring biotic versus abiotic origins and mapping distributions of natural gases in deep permafrost and sub-permafrost brine systems is a long-term goal of IPTAI research at sites in northern Canada. Development of instruments capable of C and H isotopic analyses on trace-level methane in surface seeps or in bore holes is being pursued at Princeton University. A series of box experiments will be deployed on the ground surface above cryopegs and other types of permafrost fractures in order to identify CH₄ and other gases emanating from the subsurface. These field tests will allow IPTAI scientists and collaborators to determine which gases are readily detectable and which are reliable indicators of subsurface microbial activity.

Passage of ionizing radiation through water or ice produces a complex mixture of short-lived ions, free radicals, and electronically excited molecules that can participate in a wide range of chemical reactions involving solutes and solids. Reactions between radiolytically produced radicals and aqueous or solid media can accelerate water-rock interaction in ways that mimic groundwater in contact with atmospheric O₂. If radiolytically generated oxidants react with sulfide minerals or elemental sulfur then partially to fully oxidized sulfur species could be available for microbial metabolism in unexpected subsurface environments. Almost no data are available to assess the role of naturally occurring radionuclides on oxidation of sulfide minerals and subsequent formation of sulfate plumes in groundwater. Fractionation of sulfur isotopes has not been determined during radiolysis of water coupled to oxidation of sulfides or elemental sulfur. Consequently, IPTAI scientists at Indiana University have analyzed gaseous, aqueous, and solid products of abiotic pyrite oxidation in millimolar solutions of hydrogen peroxide (H₂O₂) as an analogue for oxidizing molecular products formed during the radiolysis of liquid water. Small amounts of O₂ can form during radiolysis but at the salinities representative of subpermafrost brines, the O₂ is probably insignificant. Mineralogical, chemical, and stable isotopic data are used to infer multiple pathways for pyrite oxidation during reaction with H₂O₂. These types of laboratory experiments will lead to technology for exploration of Mars where H₂O₂ is expected to be a catalytic species in the atmosphere and a significant oxidant in regolith.

Figure 3. Intact prokaryotic cells recovered by filtration of ground water at a depth of 1130 meters below the surface in the Lupin gold mine, Nunavat Territories Canada. Cells occur in clumps and exhibit diverse morphologies. Cells were enumerated using a green fluorescent dye.