Summary of the Mars Hydrosphere Drilling Workshop
Los Alamos National Laboratory
12/13 May 1998
Purpose of the Workshop
- Review models of martian crustal water and environment (e.g. Clifford)
- Reassess rationale for acquisition of samples from martian hydrosphere
- Habitability potential of environment below cryosphere
- Requirements for sample acquisition (science and engineering)
- Requirements for associated environmental measurements (e.g. T, P, H2O, etc.)
- Assess technology options for gaining access to martian hydrosphere
- Assess potential for interAgency program of technology and science
- Prepare for Astrobiology Workshop 20-22 July 1998
Clifford model of martian crustal water and environment
Astrobiology rationale for acquisition of samples from martian hydrosphere
- Based on the most current model of the physical state, depth, volatile content and history of the martian megaregolith, it is plausible that a deep hydrosphere will be discovered to underlie kilometers-thick, near-surface ground ice within the cryosphere (region permanently below the freezing point of water)
- Distance between base of cryosphere and local water table may vary from zero to several kilometers in areas of low elevation
- Hydrothermal convection in response to local geothermal gradient will result in steady-state circulation of ascending vapor and descending condensate, resulting in increase in crustal pore saturation with proximity to water table
- Such an environment may be habitable to terrestrial lithoautotrophic micro-organisms and, therefore, is an attractive environment in which to seek evidence of extant martian life
- If low elevation regions are found with enhanced local heat flow, then such areas would be yet more hospitable to life and would require lesser depth penetration to reach a habitable environment
- Samples acquired at intervals within the uppermost regolith, within the ground ice and from beneath the ground ice will may be expected to provide our most comprehensive data set concerning:
- Whether life originated on Mars in the past
- Process leading to Origin of Life
- Size of Solar System's habitable zone
- Life in other solar systems
- Whether life is extant on Mars
- Comparison of terrestrial and martian life
- Is life on Mars monophyletic with life on Earth
- Possible cross contamination of terrestrial and martian life
- Processes leading to origin of life in the universe
- Fundamental constraints on biochemistry
Geologic and climate history of Mars
- Access to liquid water may determine ultimate human habitability
- Fuel
- Life Support
- Electrical Power Generation
Habitability Potential of the Martian Hydrosphere
- Lithoautotrophic life on Earth is apparently sustained at depth by processing
- Inorganic carbon
- Hydrogen (from chemical interaction of water and basalt)
- Products from metabolism of such bacterial life include
- methane
- minerals such as magnetite, gregite, Mg oxides etc.
Microbial communities in samples returned from depth in the Columbia River Basalts are many orders of magnitude fewer in number per unit volume in comparison to near-surface populations of heterotrophic microbes
- a comprehensive model of the environmental limitations to lithoautotrophic populations remains to be developed
- when such a model is developed it might be applied to the martian case recognising that we presently have no measure of e.g. the availability of nitrogen in the martian regolith
Anticipated Project Phases
- Site Selection
- Geophysical Survey to include some combination of
- Elevation Measurement (MGS will be definitive)
- Thermal Anomalies (MGS may suffice)
- E-M Sounding (Mars Express may suffice)
- Ground Ice near surface
- Brines at multi-kilometer depth
- Seismic Sounding
- Penetration to shallow depth (~200-300m) by Discovery-class mission at site determined to have near-surface ground ice
- Characterization of the physical properties of the uppermost regolith and ground ice
- Provide data to improve Clifford model
- In situ sample analysis (not Sample Return) to test bioassay approach
- Penetration to depth of ~4000m by autonomous or teleoperated facility accompanying early human mission
- Sample analysis laboratory near base
- Many planetary protection issues to be examined
Requirements for Sample Acquisition for Biological (Extant and Fossil) Assay and Characterization
- Sample must be in the form of a core rather than cuttings or chips
- For biological assay the core must be sub-sampled to avoid forward contamination
- Sample should have been collected at close to the ambient (unheated) temperature of the environment at possible to aboid mineralogical changes and loss of water content
- Sample should be collected in an inert environment to maintain mineralogy
- Sample should be returned to surface at original ambient temperature and pressure to preserve viability (requires containment -- note: some doubt feasibility and necessity)
- Positive steps (tracers) must be taken to ensure that the degree of forward contamination of the sample can be determined e.g. immuno assay for E. coli as well as chemical tracers
- Cross-contamination between different sampling depths must be avoided
- The sampling process must avoid back contamination
Requirements for Environmental Measurements as a Function of Depth
(by combination of core/cutting analysis and logging)
- Oxidant Gradient
- Biomarkers
- Water
- Chemical composition
- Mineralogical composition
- Physical Properties
- Porosity, Permeability, Density, El & Th Conductivity, T & P
Evolved Gases
- Age Dating
Technology Issues
- Mass of penetration system
- Stabilization of open bore hole
- Transportation of excavated materials
- Adaptivity to encoundtered conditions (of porosity etc.)
- Power
- Wear
- Reliability
- Automation
- Management of pressurized fluids within formations
- Mass of coring system
- Acquisition of sample from beyond zone of thermal contamination
- Containment of sample during transport to surface
- Planetary protection measures
- Logging system
- Sample analysis at surface
Some Key Considerations
- Diameter of bore hole
- Mass of penetration system is function of square of diameter
- hole support/lining
- power
- Diameter needed for Mars drilling is determined by coring requirements
- Time taken to penetrate to a given depth
- In commercial endeavours time is money
- For Mars application time is lesser consideration
- provides area of potential relief in determining power requirement
One Attractive Approach: Penetration by Melting
- Electrically heated probe melts rock and (under force from above additional to gravity) moves downward
- Borehole is lined with glass created by resolidified rock melt
- obviates need for lining hole (i.e. no casing is needed)
- thermal alteration to ~3 hole diameters
- makes down hole logging of physical properties and mineralogy difficult
- Excess excavated material is extruded through probe, collected as solid shards and periodically lifted to surface
- obviates need for fluids or gas in contact with rock
- Probe is attached to umbilical cable to probide power and to allow periodic retrieval
- Shape of bore hole need not be circular
- Core samples are acquired at intervals at bottom of hole
- Core must gain access beyond zone of thermal alteration
- Proven Russian lunar coring techniques may be adaptable to purpose
Interagency and Industrial Partnership Potential
- Workshop attendance included representation from:
- NASA and DoE (Los Alamos National Laboratory, Oak Ridge National Laboratory, Sandia National Laboratory)
- National Advanced Drilling Technology Institute (whose function is to facilitate interAgency technology development)
- Industry (national and international)
- Energy (Shell Intern)
- Drilling (Schlumberger, Tempress Technology, Halliburton Energy Services)
- Academia (Texas A&M, Princeton, Oklahoma, New Mexico Tech)
- International (Russian planetary drilling)
- Interest in science and technology is uniformly high
- Basis for Government-Industry-Academia Partnership appears excellent
A Strawman Cooperative Approach
- Divide effort into components and assign lead roles (including funding) for each:
- Technology Development toward creating a mobile (trailerable) facility for sampling/mapping the Earth's subterranean biosphere
- Penetration System
- Coring and Sample Containment System
- NASA lead, NADET facilitation?
- Autonomy
- Logging
- Industry lead, NADET facilitation?
- Facility System Integration
- Science Program Development
- NASA, DoE and NSF
- Support facility operations and science community use (sampling and analysis)
- Mars Exploration
Next Steps
- Create web page at LANL- This is it!
- Post workshop papers
- Post this summary for comment
- When July Astrobiology Program Workshop agenda is available, negotiate assignments to participate and present proposal
- LANL provide technology option assessment in form of written report with recommended technology roadmap (content including space component, schedule, cost estimate)
- Rocco Mancinelli develop/post planetary protection roadmap
- Biologists/astrobiologists led by Chris McKay, develop/post parallel science program roadmap (content, schedule, cost)
- Assuming Astrobiology Program Workshop endorses direction of effort:
- Reassemble team to integrate roadmaps, estimate/negotiate division of labor/funding, develop implementation plan for 1999 and on