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Dark Life and DUSEL: 

Dark Life and DUSEL Dark Life – what is it and why is it important? Why DUSEL?

Deep Subsurface (> 1 km): 

Deep Subsurface (> 1 km) Biomass – extremely low - diminishes with depth to < 103 cells/ml Biodiversity diminishes with depth Respiratory rates – extremely low – nM/yr Space is limited (on Earth 1 – 5% at this depth) Heterogeneity is the rule – oases among vast deserts Fluid flow rates - ~ 1 mm/yr


Cells/ml or Cells/g Depth (m) 108 107 106 105 104 103 102 101 0 1000 2000 3000 4000

Deep Subsurface (> 1 km): 

Deep Subsurface (> 1 km) Biomass – extremely low - diminishes with depth to < 103 cells/ml Biodiversity diminishes with depth Respiratory rates – extremely low – nM/yr Fluid flow rates - ~ 1 mm/yr Space is limited (on Earth 1 – 5% at this depth) Heterogeneity is the rule – oases among vast deserts


A. B. C. D.

Dark Life: 

Dark Life nM/yr => ng C/L-yr => 103-4 cells/L-yr For 106 cells/L => 100 – 1000 year lifetimes Dosage rate – ~10 Grays/L-year nM/yr = mM/Myr. => 100 mg minerals/L – yr = 100 ml minerals/L-yr = 1% porosity fill

Still in the dark about dark life: 

Still in the dark about dark life What is the upper temperature limit ? Can subsurface life subsist completely without photosynthetically generated organic compounds? Can life originate in the subsurface? How can life evolve in the subsurface given the glacially slow metabolic rates and withering irradiation? Just how quickly does life migrate through impermeable formations? Why should we care if these creatures hardly do anything?

Why is it important?: 

Why is it important? Methane and recent volcanism (< 2 myr.) have been discovered on Mars. By 2011 rovers will be scraping the surface for organic signatures of ancient life. By 2015 - 2018 the drilling into Martian subsurface habitats may provide the first evidence of exobiology. Sample return may bring the first "martians" back to Earth.


Unless some significant discovery by telescopic observations, JIMO to Europa may be out of reach because of its cost. As for Titan, everything depends upon Huygens probe. Experimentation with self-replicating vesicles and RNA replicase has brought us closer to understanding the origin of terrestrial life. (e.g. Szostak's lab) By 2015, life may have been "created" in the lab and from this we may learn whether life can be created in the subsurface of a planet.


Dark life may dominate life in the universe and may be the means by which life is transported between solar systems.

Nothing good lasts forever: 

Nothing good lasts forever By 2015, terrestrial planet finder will be launched. Capable of spectrometric analyses of atmospheric gases, detecting oceans and possibly vegetation for stellar systems within 10 parsecs. By 2020, attention and resources could (and should) be directed to these Terra Novae. 10-15 year lifetime for major discoveries in Dark Life with increasingly difficult justification beyond that.

Why DUSEL?: 

Why DUSEL? NSF supports ODP for high profile investigations into marine subsurface life (e.g. Ridge). NSF also supports science investigations associated with ICDP. Coring from surface and operating mines provide access to 100's kg of rock per year and in some cases formation fluid. Environments accessed include everything from permafrost, salt beds to high temperature fault zones and plenty of extremophiles. Piggyback operations on extensive existing well fields provide infrastructure for field experiments. DOE supports subsurface experiments directly relevant to environmental management.

Why DUSEL?: 

Why DUSEL? Deep subsurface life processes are slow – any experiment designed to examine these processes require a high spatial sampling density and long sampling time span. Petroleum companies and mines don't care about subsurface life (unless it affects their bottom line). Boreholes with 1 meter spacing cannot be drilled at 2 km depth from the surface. Some geophysical characterization techniques (e.g. GPR) are limited to shallow boreholes, purging and sterility for km long boreholes is problematic, etc. etc.


Bio-geophysics Core and instrument active fault zone at 3.7 kmbls. in S. African mine Mining induced 3-4 M event within 2 years Monitor gaseous, aqueous and biological temporal response.


Stage 3 - Long-Term SAFOD Monitoring: 2005-2007 prototype 2007 long-term deployment Formaldehyde added to borehole fluid to prevent microbial corrosion of metal tubing and instrumentation CMC used in drilling fluid remains in borehole Monitoring Instrumentation Deployment Stage 3: Long-Term Monitoring After coring is completed, plug 3 out of 4 core holes with cement, leaving 1 open for fluid pressure monitoring. Deploy retrievable seismic, pore pressure, deformation and temperature monitoring array inside pipe via pipe or coiled tubing.

DUSEL Experiments: 

DUSEL Experiments Experiment must be unique and virtually impossible for perform by surface coring. The quality, quantity and meaningfulness of the anticipated data must be higher than can be obtained by surface mesoscale facilities or deep well fields. Multi-user, multi-experiment facilities with multi-year plan would be most appealing. User base and experiments/year and thus annual maintenance costs needs definition. Then DUSEL can provide long term access to dedicated rock volume for that experiment. For truly "dark life" experiments, pristine environments with "old" groundwater and with strict adherence to aseptic procedures and connection to NASA Mars exploration are all prerequisites. Connections with low background-counting facility (for use of radiotracers) needs clarification.

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