Challenges for Coring Deep Permafrost on Earth and Mars
| Autor: | Eric W. Chan, Corien Bakermans, Adam P. Johnson, Timo Ruskeeniemi, Tullis C. Onstott, Randy L. Stotler, S. A. Difurio, Susan M. Pfiffner, Shaun K. Frape, Tommy J. Phelps, M. Le Puil, Jon Telling, B. Zerbin, I. Neill, B. Sherwood Lollar, Lisa M. Pratt, M. Talikka, D. McGown |
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| Rok vydání: | 2008 |
| Předmět: |
Extraterrestrial Environment
Earth Planet Borehole Geochemistry Mars Fresh Water Permafrost Astrobiology Chlorides Isotopes Ice Cover Phospholipids Fluorocarbons Bacteria Moisture Scientific drilling Sodium Water Drilling Heterotrophic Processes Satellite Communications Saline water Agricultural and Biological Sciences (miscellaneous) Coring Aerobiosis Microspheres Space and Planetary Science Autoradiography Calcium Geology Water vapor |
| Zdroj: | Astrobiology. 8:623-638 |
| ISSN: | 1557-8070 1531-1074 |
| DOI: | 10.1089/ast.2007.0159 |
| Popis: | A scientific drilling expedition to the High Lake region of Nunavut, Canada, was recently completed with the goals of collecting samples and delineating gradients in salinity, gas composition, pH, pe, and microbial abundance in a 400 m thick permafrost zone and accessing the underlying pristine subpermafrost brine. With a triple-barrel wireline tool and the use of stringent quality assurance and quality control (QA/QC) protocols, 200 m of frozen, Archean, mafic volcanic rock was collected from the lower boundary that separates the permafrost layer and subpermafrost saline water. Hot water was used to remove cuttings and prevent the drill rods from freezing in place. No cryopegs were detected during penetration through the permafrost. Coring stopped at the 535 m depth, and the drill water was bailed from the hole while saline water replaced it. Within 24 hours, the borehole iced closed at 125 m depth due to vapor condensation from atmospheric moisture and, initially, warm water leaking through the casing, which blocked further access. Preliminary data suggest that the recovered cores contain viable anaerobic microorganisms that are not contaminants even though isotopic analyses of the saline borehole water suggests that it is a residue of the drilling brine used to remove the ice from the upper, older portion of the borehole. Any proposed coring mission to Mars that seeks to access subpermafrost brine will not only require borehole stability but also a means by which to generate substantial heating along the borehole string to prevent closure of the borehole from condensation of water vapor generated by drilling. |
| Databáze: | OpenAIRE |
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