(5) Group Reports


Each of the five working groups was tasked with developing scientific goals for a program, justifying the program, developing a strategy and time-line to accomplish the goals, and justifying why Lake Vostok is the preferred study site.

 

 

GEOCHEMISTRY WORKING GROUP CONCLUSIONS
Group Members: Mahlon C. Kennicutt II (archivist), Todd Sowers, Berry Lyons, Jean Robert Petit

 

JUSTIFICATION FOR LAKE VOSTOK STUDIES
Due to the remote location and the complexity and cost of the logistics to mount a study of subglacial lakes, it is imperative that the scientific return from such a study be justified in light of the resources needed to accomplish the program. In particular, it is important to elucidate what it is that makes subglacial lakes a high priority for study, and in particular why Lake Vostok is the preferred site amongst all other possible sites.

 

On the first issue, the “extreme” environment under which the lakes exist suggests that fundamental questions related to an array of scientific issues could be addressed by an interdisciplinary study of subglacial lakes. Life at the extremes is justified in the context of the ongoing LExEn program. From a geochemical standpoint, the subglacial lake systems represent an unique and unparalleled combination of physical and chemical environments.

 

The lakes are unique in the low temperatures and high pressures encountered, the total darkness, the origins of the water in the system (suspected to be fresh), the overlying thickness of ice, and their isolation from the atmosphere for long periods of time. It is hypothesized that this combination of attributes will lead to an unique geochemical system that is duplicated under few, if any other, circumstances world-wide.

 

While individual attributes can be found in various locations (dark, cold, and high pressure in the deep sea) the combination of traits described above is only found in subglacial lakes.


Amongst subglacial lakes, the most obvious characteristic of Lake Vostok that differentiates it from the 60 to 80 other known lakes, is its size. Lake Vostok is believed to be the largest subglacial lake on the Antarctic continent. The size of the lake imparts attributes that make it well-suited for an initial study of subglacial lakes.

 

The size of the lake suggests that Lake Vostok is the most likely site for a fully developed subglacial lake system that might be precluded in other smaller lakes. The varying water depths, the varying and substantial sediment accumulations, the varying thickness of the overlying ice sheet, and the sheer size of the lake suggests that the likelihood of physical and chemical gradients within the lake is high.

 

The physical setting suggests that circulation, stratification, and compartmentalization within the lake is likely. This setting is believed to be the most favorable for supporting a fully developed subglacial lake system and provides the greatest likelihood that biological systems have inoculated and developed within the lake.

 


GOALS FOR GEOCHEMICAL INVESTIGATIONS

1) The first and foremost goal of any geochemical investigations would be to characterize the structure of the lake’s water column. Due to the low temperatures and high pressures it is believed that hydrates of various gases will play an important role in determining the distribution of the lake’s geochemical properties. Stratification of the lake in very unusual ways may occur due to density differences between various gas hydrates, some heavier than water and some lighter, and the suspected cycles of thawing and freezing that appear to characterize different regions of the lake. In a more standard sense, initial studies of the lake would establish the limnological characteristics of the lake both vertically and horizontally including, for example, the distributions of salinity, temperature, major ions, and nutrients.


2) As a follow on to the discussion of hydrates, the gaseous constituents of the lake would also be a high priority for investigation. The physical occurrence of gaseous constituents and the partitioning between free, dissolved and hydrate phases will be important to establish. The origins of these gases should also be explored through the use of stable isotopic analysis of various key elements. It would also be important early in the study of the lakes to determine the distribution of those geochemical properties most directly affected by the presence of biota, in particular microbiota. These properties include, but are not limited to: redox potential, pH, sulfate reduction, methanogenesis, metal and nutrient concentrations.


3) Due to the emphasis on the theme of life in extreme environments, the carbon cycle would be an area of special emphasis for geochemical investigations. The system is expected to be unique in that cold water carbonates and hydrates of hydrocarbon gases may be important reservoirs of carbon. The carbonic acid system may also be unusual at the ambient high pressures and low temperatures. The origins and cycling of organic carbon in the lakes will also be of special interest. The distribution between dissolved and particulate organic carbon and the portions of the pools that are biologically available will be important considerations. The reservoir of carbon in sediments may also be important for sustaining any extant biological systems.


4) Finally, the interaction between the geochemical properties of the lake and the circulation within the lake will be important to characterize. Redistribution of chemicals in the lake and the development and location of physical and chemical gradients may be important in developing and sustaining biological systems.


JUSTIFICATION FOR GEOCHEMICAL INVESTIGATIONS

Geochemical investigations of subglacial lakes are critical to interdisciplinary studies to determine the origins and functioning of subglacial lake systems. Geochemical properties are widely recognized as evidence of the presence of life in systems. It can be argued that some of the more easily measured attributes of a system that provides evidence of biological processes are geochemical distributions and patterns.

 

Biological processes are known to produce and consume various compounds in the process of living and surviving in aquatic systems. The water and the sediments of the lake are also a repository of chemicals derived from various interactions over the lifetime of the lake. As such, geochemical distributions and patterns are keys to understanding the origins of various lake constituents.

 

As previously mentioned, subglacial lakes also represent geochemistry at the extremes of temperature, pressure, light, and isolation suggesting that the study of these lakes will provide insight into geochemical systems in general. Areas of particular interest where geochemical investigations will be key in providing information are the age of the lake and the origin of the water.


The sedimentary record is an important repository of evidence of the history and evolution of the lake. Organic and inorganic geochemical markers of the lake’s history may be deposited and preserved in the sedimentary record. Geochemical investigations are fundamental to addressing a wide range of interdisciplinary questions related to the evolution and history of subglacial lakes as well as documenting the functioning of these unique systems.

 


STRATEGY TO MEET GEOCHEMICAL GOALS

Most of the investigations that are important for the geochemistry component of an interdisciplinary study of subglacial lakes rely on standard and proven technologies. However, if it is proposed that the first entry into the lake will be in a non-sample retrieval mode, appropriate sensors for measuring geochemical attributes of the water column need to be developed.

 

As mentioned above, inferences related to the presence of life can be obtained by measuring specific geochemical characteristics of the lake. Initial establishment of the water column structure and heterogeneity will require real-time in situ detection of geochemical properties.


Once the investigations have proceeded to sample retrieval, the methods to be used are readily available and proven. In order to optimize the information return from geochemical investigations, water column profiles at multiple locations will be necessary. Time series measurements will also be important to determine if the lake is static or dynamic on short timeframes (< 1 yr).

 

A range of technologies including continuous measuring sensors left in place, profiling sensors, and discrete samples will be required to address the goals of the geochemical investigations.

 


TIMEFRAME

Geochemical investigations will be key to an interdisciplinary study of subglacial lakes. A range of characterization activities would be an initial goal including water column structure, the distribution and occurrence of gaseous components, the reservoirs and cycling of carbon, and the biogeochemical processes operating in the lake.

 

The vertical and horizontal distribution of essential chemicals in the lake will reflect interactions with lake circulation and the alteration of these patterns by organisms. Geochemical measurements will be key in determining the age, the origins of various constituents, the history, and the evolution of the lake.

 

Most technologies are currently available but development of remote sensors of geochemical properties will be needed. It is estimated that one to three years will be needed to develop these new technologies.


BIODIVERSITY WORKING GROUP CONCLUSIONS
Group Members: Cynan Ellis-Evans (archivist), José de la Torre, Dave Emerson, Paul Olsen, Roger Kern, Diane McKnight

 

JUSTIFICATION FOR LAKE VOSTOK STUDIES

The compelling science justification for undertaking research at Lake Vostok is:

1)the unique nature of the environment - permanently cold, dark, high pressure freshwater environment


2)this lake may lie within a rift valley of as yet undetermined age or activity - this offers the potential for geothermal processes comparable to the hydrothermal vents of the ocean abyss


3)the spatial scale of the environment - the lake is amongst the top 10 largest lakes worldwide and offers an opportunity to research large scale processes


4)the temporal scale of the environment - the possibility exists that the lake overlies sediments of an earlier rift valley lake, providing a vertical chronology


5)information on possible inoculum is available - it is likely to be representative of other sub-glacial lakes but the Vostok ice core has a detailed record for the overlying ice sheet of biota present within that ice sheet


6)the first opportunity to sample a microbial community isolated from the atmosphere for
perhaps a million years or more - possibly uncovering novel micro-organisms or
processes, notably the microbiology of gas clathrates (hydrates) in a water column


7)possible data on evolution of global biota - data gathered could potentially contribute to the current debate regarding the evolution of global biota.

 

GOAL FOR BIODIVERSITY STUDIES
Extreme environments have proved a rich source of novel physiological processes and biodiversity. The estimated age of this lake and its isolation from the atmosphere for possibly a million years, may allow the identification and study of novel micro-organisms or processes, notably the microbiology of gas clathrates (hydrates) in a water column. The goal of the biodiversity studies should be to establish the structure and functional diversity of Lake Vostok biota.

 


JUSTIFICATION FOR BIODIVERSITY STUDIES

Microorganisms are a substantial component of all environments and their significant role in key food web processes is recognized increasingly. The main lineages of life are dominated by microbial forms, and comparative analyses of molecular sequences indicate that all life belongs to one of three domains, Bacteria, Archaea and Eukarya.

 

Microbes are ubiquitous in extreme environments. Recent deep ocean hydrothermal vent studies suggest that such environments may have been sites for the origin of life. Novel environments, such as sub-glacial lakes, may likewise contain unique biota.

 


 STRATEGY FOR BIODIVERSITY STUDIES

At least four biodiversity scenarios exist for the lake:

1)The lake is geologically inactive and only contains till, glacially derived sediments with low organic carbon. No geothermal hot spots exist, and the low organic carbon till, substantially dilutes any input of ice sheet biota. Gas clathrates present in the lake are a potential target for microbial activity.
2)The lake is geologically inactive with old lake sediments buried under recent till. The clathrates are still a target, but retrieval of old lake sediments is a further goal.
3)The lake is geologically active without old lake sediments. The sites of geothermal activity would be a major focus requiring several coring sites.
4)The lake is geologically active and old lake sediments are present. This would be the best case scenario, offering a range of research topics, requiring long cores and possibly multiple sampling sites.

In the absence of detailed data on the lake characteristics this group suggests that the initial starting point for sampling the lake should be in the melting zone of the lake and not the accretion zone. The melt zone will be where the clathrates and ice sheet microflora enter the lake.

 

Both the ice/water interface region and the sediments offer the best opportunity for initially looking for microbes, but it was recognized that clathrates may be distributed through the water column. The accretion zone will not be a source for microbial or clathrate input to the lake.


In light of these four scenarios, the strategy for studying biodiversity in Lake Vostok would involve (a) preliminary activities prior to any field sampling (zero-order activities) to establish the nature of the environment, possible microfloral inputs and relevant technologies and (b) field sampling of Lake Vostok and post-sampling analysis:

(a) ZERO-ORDER ACTIVITIES -(no field campaign needed)

1 - Physical characterization of the lake (non-invasive)
2 - Technological developments for in situ micro- and macro- scale probes, sample retrieval, non-contamination of lake and data relay from within lake. Remote operated vehicle (ROV) to increase the area of lake studied
3 - Development of biogeochemical and ecosystem models
4 - Characterization of the ice sheet microflora using existing cores if possible and both molecular and cultural methodologies

(B) MAIN SAMPLING ACTIVITIES -(Field campaign needed)

1 - Obtain vertical profiles of physical and chemical parameters from the ice/water interface through to sediments. Microscale profiles within surface sediments

2 - Leave monitoring observatories in place with both physical/chemical monitoring and a bio-sensing capability, for detecting life in dilute environments needing long incubation times

3 - Sample retrieval (for chemical and biological purposes) from the ice/water interface, from the water body (may need to filter large volumes to concentrate biota) and from sediments - A suite of molecular, microscopical and activity measurements (see earlier overview by Jim Tiedje) will be required to analyze potential biota. Anti-contamination protocols will feature significantly here (see earlier overview by White/Kern).

4 - May need to consider repeat sampling or further sites, notably if there are geothermal hot spots. Also need to take into account possible heterogeneity, particularly in sediments. An ROV may offer an ability to sample heterogeneity more cheaply than numerous drill holes.


TIME FRAME FOR BIODIVERSITY STUDIES

  • Zero order activities - 2-3 years in advance of lake penetration, but continuing afterwards, notably with modeling studies

  • Year 1 - Vertical profiling and establishment of long term in situ “observatories”

  • Years 2 and 3 - Sample retrieval activities at one or more sites

  • Year 4 - Sample analysis ongoing and further planning

  • Year 5 and 6 - New research initiatives building on data collected to date - could include tackling issues of heterogeneity or perhaps novel biogeochemical processes

*Note 1: The merits of sampling another lake in the vicinity of Lake Vostok need to be considered.

*Note 2: The Year 1 work might be best undertaken with the NASA strategy of using both a hot water drill* and a modified Philberth probe** to penetrate the lake, deployment of hydrobots beneath the ice and at the sediments and establishment of observatories in the lake. Subsequent years could potentially use alternative drilling technologies to facilitate sample retrieval, once contamination issues have been addressed.


*A hot water drill pushes hot water down a hole to melt the ice.
**A Philberth probe is an instrumented cylindrical shaped device that has an electrical heater at its tip. The melting of ice ahead of the probe allows it to drop down through the ice under its own weight paying out cable to the surface as it goes. A device such as this is being proposed as a means of getting through the last 100 m or so of overlying ice sheet. (For more information on this please refer to Appendix (1) “Why Lake Vostok?” write up by Stephen Platt pg. 45.)
 

SEDIMENTS WORKING GROUP CONCLUSIONS
Group Members: Peter T. Doran (archivist), Mary Voytek, David Karl, Luanne Becker, Jim Tiedje, Kate Moran
 

JUSTIFICATION FOR LAKE VOSTOK STUDIES

The existing ice core from Lake Vostok can provide us with unique background information on the Lake which is not available to us from any other subglacial lakes in Antarctica. The size and estimated age of the lake offers the best potential for a long continuous sedimentary record.

 


 GOALS FOR SEDIMENT STUDIES

The sediments of Antarctic subglacial lakes have the potential to be significant for the following reasons:

1. Extant microbial communities. Microbial communities often favor interfaces as habitats, so that the ice/water and sediment/water interfaces will be prime targets in the search for life. Along with sediment deposition at the bottom of the lake, chemical energy required by the microbes may be focused on the bottom, i.e., if geothermal energy flux is significant in this habitat.

 

Therefore, the search for extant life in Lake Vostok should not end at the sediment/water interface, but should extend into the sediment column. Measurements of chemical profiles (including dissolved, particulate and gas phases) in the sediment can also be used for life detection (past and present) and for mapping of metabolic processes.


2. Storehouse of paleoenvironmental information. The sediment column in Lake Vostok has been estimated to be ~300 m. This thickness of sediment could contain an unparalleled record of Antarctic paleoenvironmental information, extending beyond the limit of ice core records. The record contained in the sediments may reveal information on past geochemical processes, microbial communities, and paleoclimate. Interpretation of this record will require a thorough understanding of the modern lake depositional environment.


The gas geochemistry in Lake Vostok has the potential to be unique, with hydrated gas layers accumulating in the water column based on density stratification. In particular, CO2 hydrates are expected to sink upon entering the water column and collect in the bottom sediments, potentially creating a continuous record of atmospheric CO2 in the lake sediments.


3. Direct measurement of geothermal heat flow. Any sediment borehole created can be used to determine geothermal heat flux through direct temperature measurements. This information will contribute to models of the lake’s origin, possible circulation and maintenance.

 

4. Extraterrestrial material capture. The lake sediments undoubtedly contain a large number of meteorites, micrometeorites and cosmic dust (e.g. interplanetary dust particles and cometary debris) given that all “coarse” material that moves into the lake and melts out of the ice will be focused in the sediments. In this way the sediments offer an extraordinary opportunity to measure extraterrestrial flux over possibly several million years.

 

The flux of extraterrestrial material can be monitored by measuring helium-3 in very small grains (<50 µm) in bulk sediments. In fact, it has been suggested that periodic changes in the accretion rate of extraterrestrial material is due to a previously unrecognized 100,000 yr periodicity in the Earth’s orbital inclination which may account for the prominence of this frequency in the climate record over the past million years. Measurements of the extraterrestrial flux of material to the Vostok sedimentary record coupled with the possible presence of CO2 clathrates may provide a record of climate change that could only be preserved in this unique setting.
 

JUSTIFICATION FOR SEDIMENT STUDIES
The sedimentary analysis of Lake Vostok is of particular interest among Antarctic subglacial lakes by virtue of its size, thickness of sediments, and because of the background information already available. The ice core record collected at Vostok Station will be valuable in conjunction with the historical sediment record for reconstruction of the paleoenvironment of the lake.

 

This is particularly true for the accretion zone at the base of the ice core. Furthermore, Lake Vostok’s size makes it the best candidate for the existence of a stable microbial community and a long, continuous sediment record.

 


 SEDIMENT SAMPLING STRATEGY

Information that can be gained by in situ measurements at the sediment/water interface will be limited. Therefore, its strongly encouraged that a strategy based on sample return be pursued. Initial survey measurements can be accomplished remotely and by in situ instruments, but in order to fully implement the science plan, return of samples to the surface will be essential.

 

The largest technological obstacle to the collection and return of 300 m of sediment core will be creating and maintaining an access hole through the deep ice. The Ocean Drilling Program (ODP) has already developed many of the techniques necessary for collecting and sampling cores of this length, and from this depth (in the ocean).

 

Some technology development would be required to utilize lake water as drilling fluid to minimize lake contamination. A suite of ODP standard procedures currently used could be applied to Lake Vostok sediments including: acquisition 300+ m of sediment core in pressurized ten (10) meter sections for sampling; sampling of gas hydrate formations; pore water sampling; down-hole logging; establishment of long-term benthic monitoring observatories; casing of the bore-hole for later re-entry if desired; and established sampling and repository protocol.


It is recommended that methodology for investigating the lake sediments proceed as follows:

1. remote site survey (e.g. thickness of sediments, stratigraphy, etc.)
2. in situ sediment/water interface survey (use of resistivity probes, video, sonar, particulate sampling)
3. surface sample “video grab” and return to the surface
4. establishment of long-term in situ sediment-water interface experiments
5. collection of long cores
6. down-hole logging (e.g. geothermal heat flux, fluid flow)
7. cap hole for future re-entry if desired


 CONTAMINATION ISSUES

Disturbance of the lake and contamination of the lake and samples can be kept to a minimum through a number of initiatives:

1. sterilization of all equipment entering the lake to greatest degree possible;
2. collection of the cores in sealed canisters so that there is no loss of sediment on removal or contact of the sample with upper strata as it is being raise through the water column; and 3. use of benthic lake water as drilling fluid to reduce introduction of foreign fluids.
 

NUMERICAL MODELING FOCUS GROUP CONCLUSIONS
Group Members: Christina L Hulbe (archivist) and David Holland
 

JUSTIFICATION FOR LAKE VOSTOK STUDIES

Lake Vostok is an unique physical environment which offers the opportunity for new development of information, and a better understanding of subglacial lakes. The study of closed lake circulation is new and therefore allows us to test and refine existing models, and develop new models and theories. Furthermore, available information suggests that Lake Vostok may be an analogue for ice-covered planetary bodies.

 


 NUMERICAL MODELING GOALS

Numerical modeling of ice sheet and lake behavior should begin early in a Lake Vostok initiative and form a close collaboration with other research communities before and after the direct exploration of the lake. Models will provide the best a priori characterization of the lake environment, offer advice for drilling site selection, and constrain the interpretation of observations made within the lake.

 

Existing ice sheet/ice shelf models need little modification to meet the requirements for such studies. However, the exploration of Lake Vostok poses a new challenge for modelers of lake circulation. The lake has no free boundaries, a unique physical environment on Earth that may be an analogue for ice-covered oceans on other planetary bodies.


The primary goal of an ice sheet flow/lake circulation modeling effort is characterization of the lake environment. Simulations of the modern ice sheet can provide three-dimensional views of temperature in the ice and lake sediments, and of ice velocity. Those results can then be used to predict the thermal environment of the lake and the pathways and delivery rates of sediments through the ice sheet into the lake.

 

Because basal melting is widespread under the thick East Antarctic Ice Sheet, the lake probably receives water and bedrock-derived sediments from the surrounding area. The flow of water and sediments at the ice/bed interface, both to and from the lake, should also be modeled. Another important use of the results of ice sheet simulations will be in the prescription of boundary conditions for lake circulation models.

 

Lake circulation will be influenced by gradients in ice temperature and overburden pressure (due to gradients in ice thickness), and by meltwater flow into and out of the lake along the ice/bed interface. The pattern of ice melting and freezing predicted by a lake circulation model will in turn be used to refine modeled ice flow over the lake.

 

Lake circulation models will resolve the patterns of water temperature, salinity, and clathrate (gas hydrate) distribution. Together, the simulations will define the habitats in which lake biota exist and can also be used to evaluate the constancy of those habitats over time.


Because the present state of the lake depends in part on past events, it will be important to conduct full climate-cycle ice sheet simulations. A coupled grounded ice/floating ice model that incorporates basal water and sediment balance can estimate past changes in lake water and sediment volume, including the possibility of periodic sediment fill-and-flush cycles.

 

The proximity of the Vostok ice core climate record makes Lake Vostok an ideal setting for such experiments. Investigating the full range of time since the lake first closed to the atmosphere is more challenging and may best be accomplished by a series of sensitivity studies, in which lake volume and melt water flow are predicted for extreme changes in ice sheet geometry, sea level, and geothermal heat flux.

 

Sensitivity experiments can also be used to speculate about the likelihood of modern hotspot activity, given what is known about lake extent and volume. Perspectives on past lake environments may be used to determine the best sites for lake sediment coring and will aid in understanding present-day lake habitats and biota.


NUMERICAL MODELING JUSTIFICATION
Numerical modeling of Lake Vostok will be interactive with the other areas of research undertaken at Lake Vostok, and will provide valuable support information for these research objectives. The modeling will provide valuable information on lake circulation characterization/ ice sheet flow, the role of past events such as changes in lake water and sediment volume, and the possibility of periodic sediment fill-and -flush cycles.

 


NUMERICAL MODELING STRATEGY
The first stage in meeting the modeling objectives for the exploration of Lake Vostok should be model development. Models of whole ice-sheet systems must be constructed to properly characterize ice flowing into the Vostok region. Nested models should be used to provide the high resolution needed for detailed studies of flow in the region. Existing models of grounded ice sheet and floating ice shelf flow are sufficient for those tasks, provided grounding-line flow transitions can be accommodated.

 

Basal water and sediment balance models should be coupled to the ice flow model. Full climate-cycle simulations should incorporate bedrock isostasy accurately but in a computationally practical manner. New lake circulation models must be developed to meet the challenge of Lake Vostok’s unique physical setting, in which there is no free boundary and clathrates (hydrates) are likely to be present in the water column.

 

New equations of state, that account for the lake’s low-temperature, high-pressure, low-salinity setting, must be developed. The optimal model will be three-dimensional, nonhydrostatic, resolving both vertical motions and convection, and must be of fine enough resolution to capture details of what is likely to be a complicated circulation pattern.

 

Biological and chemical models that use the products of ice sheet and lake circulation models to simulate the lake’s biogeochemical cycles should also be developed, although the final nature of such models cannot be determined until lake waters are sampled (for example, does the lake have a carbon cycle?).


The second stage of a Lake Vostok modeling effort should be the integration of new data sets into the models. Regional topography, especially lake bathymetry, will be essential for the fine resolution needed to fully characterize the lake environment.

 

Radar profiling of ice internal layers would promote studies of grounding line dynamics. Simulations of the present-day system can make use of existing ice sheet Digital Elevation Models and measurements of surface climate. The Vostok ice core climate record is ideal for driving longer-time simulations of ice sheet and lake behavior. Improved knowledge of regional geology will be important, both rock type—for model studies of lake sedimentation—and geothermal heat flux—for ice thermodynamics.

 

Such regional data sets should be developed before the drilling program begins, to give modelers ample time to describe the lake environment, discuss preliminary results with other project scientists, refine the models, and finally aid in drill site selection. Lake circulation models, in particular the development of an appropriate equation of state, will benefit from the products of drilling and lake water sampling. Interaction between modelers, biologists, limnologists, and the borehole site selection group will be vital as models are developed and tested.


In a final stage, the fully-developed and tested models can be used to link together observations made at discrete locations and to develop a robust history of lake evolution. The unique physical setting of the lake and its remoteness for observation demand an interdisciplinary approach to this stage of the modeling effort, including theoretical, numerical, and observational components.

 


NUMERICAL MODELING TIMEFRAME
Any time schedule proposed for a Lake Vostok initiative must accommodate time in the predrilling phase for model development, analysis, and interaction with other project scientists. That development can proceed in tandem with preliminary geophysical surveys of the Vostok region.

Model simulations should be analyzed, in conjunction with geophysical surveys, prior to drilling site selection in order to identify areas of special interest (for example, likely sites of thick sediment deposits). Once sampling has begun, lake circulation models can be tested and improved and biogeochemical models can be developed. Finally, modelers can work with biologists, geochemists, and limnologists to develop a comprehensive understanding of the lake’s unique physical and ecological systems.


SITE SURVEY GROUP CONCLUSIONS
Group members: Brent Turrin (archivist), Ron Kwok, Martin Siegert, Robin Bell
 

JUSTIFICATION FOR LAKE VOSTOK STUDIES
Lake Vostok provides a rare opportunity for an interdisciplinary study of an extremely cold, dark, high pressure aqueous environment. The chance to study the synergy between geologic/ geochemical processes and biologic/biochemical processes that define this distinct aqueous system may lead to new fundamental understandings.

 


SITE SURVEY GOALS
The primary goal of a site characterization study at Lake Vostok is to acquire the critical regional information both across Lake Vostok and the surrounding area to constrain the flux of material across and into the Lake, and to provide insights into the geologic framework for the Lake. These improved datasets will provide critical insights into selecting sites for installing observatories and acquiring samples.

 

Site selection would best be facilitated by generation of a high-resolution 3-D geophysical image of the ice-sheet, water body, the lake sediment package, and bedrock. This 3-D image would address ice-sheet thickness and structure as well as dynamics; water-depth and aerial extent; lake sediment thickness and distribution; and bedrock topography, structure, and lake bathymetry.

 

These data sets will also provide input for ice sheet and water circulation models.

 


SITE SURVEY JUSTIFICATION
Lake Vostok is the largest subglacial lake yet discovered. Because of its size, Lake Vostok will have a greater influence on ice dynamics than a smaller subglacial lake. Therefore, it provides a superior natural laboratory for studying the phenomena of ice dynamics such as grounding/ungrounding and the associated stress/strain regime and mass balance considerations, in both the transition and upstream-downstream environs.


In addition to providing an occasion to study ice dynamics, the drilling of Lake Vostok will also provide an opportunity to sample a distinct extreme (cold, dark, high pressure) aqueous environment. Biologic and biochemical sampling of Lake Vostok could lead to the discovery of new organisms and enzymes with potentially invaluable societal relevance.


Geologic, geochemical and geophysical studies will lead to a better understanding of (1) the geology of Antarctica and (2) how geologic/geochemical processes interact with biologic and biochemical processes that define this distinct aqueous system

 


SITE SURVEY STRATEGY
The site survey strategy is broken down into two components: airborne studies; and ground-based studies. The airborne studies consist of collecting aerogravity data, aeromagnetic data and coherent radar data. These data sets would be enhanced by ground-based seismic studies, and by the installation of a passive seismic and Global Positioning Satellite (GPS) network around Lake Vostok.

 

The seismic studies should be further broken down into two phases. First, a preliminary pilot study, where data collection is concentrated mostly in the Lake Vostok area proper, and second, a high-resolution seismic study in which the seismic lines are tied into the existing regional seismic data.

 


SITE SURVEY TIME FRAME
The group feels that the necessary data can be collected and evaluated in two years/field seasons. In year one four separate teams would be needed. Team one, would be responsible for the airborne geophysical studies; gravity, magnetics, and radar. Team two, would conduct the pilot seismic study. The third team would install the passive seismic and GPS nets. The fourth team will conduct radar 3-D imaging studies on and around Lake Vostok.


Year two, would be devoted mostly to a collaborative international project collecting high-resolution seismic data, tied to existing regional data.


TECHNOLOGY DEVELOPMENT WORKING GROUP CONCLUSIONS
Group members: Frank Carsey (archivist), Steve Platt, David White, Mark Lupisella, Frank Rack, Eddy Carmack
 

JUSTIFICATION FOR LAKE VOSTOK STUDIES
Why should we study Lake Vostok? The lake is unique and interesting because of its immense size, isolation, high pressure, low temperature, estimated age, water thermodynamics, contamination concerns, habitat, biota, sediments, geological setting and possible planetary analogue.

 


TECHNOLOGY GOALS
The broad goal of Lake Vostok exploration is to access the lake water and sediments in a noncontaminating fashion, obtain certain physical, chemical and biological measurements, as well as retrieve water and sediment samples for study in the laboratory. Numerous aspects of this program have never been done and have no documented approaches.

 

The areas which require technologic development are detailed below.

1. Site Selection. The lake is large. Presently the satellite altimeter and limited airborne radar data point to the presence of numerous, varied interesting sites but rigorous site selection requires improved regional data. Well-planned airborne geophysics and seismic programs are necessary to complete the specification of the lake, its ice cover, and its sediments. In this regard, ice penetrating radar is a key means of observing the ice, providing estimates of ice ablation and accretion over and near the lake. The technology of sounding radar has developed rapidly in recent years. To generate accurate data on ablation and accretion as it varies in the lake environs, optimized radar configurations should be employed in the site survey.

 

2. Entry Means. The emerging scientific goal requires robotic, observatory installation and sample-return programs. These approaches necessitate different means of obtaining access to the lake water, ice surface, lakefloor, and sediment. None of these approaches has ever been demonstrated through 3700 m of ice or within a lake of this pressure-depth.

 

3. Contamination Prevention. Access to the lake, activities within the lake, withdrawal from the lake, any equipment abandoned in the lake, and possible unplanned experimental difficulties in the course of studying the lake must be proven to be safe with respect to contamination by living microbes.


4. Sampling Requirements. Preliminary scientific goals point to physical, chemical, and biological observations of the ice above the lake, the lake water, the lakefloor, and the sediments, at several sites. To understand the three dimensional system within the Lake several in situ robotic, observatory installations and sample-return efforts will be necessary. On the whole, these campaigns require accessing the lake in at least two different ways, one way for robotic vehicles and observatory installations and another for coring operations.

Contamination issues are significant for both approaches. In addition, some means of sampling within the lake is required, e.g. something simple such as a vertical profile to the lake floor from the entry point, or something more complex such as an autonomous submersible vehicle.

 

The sediments must be sampled; it is probable that in situ sampling of the pore water and structure of the upper sediment layers will precede sample return of sediment cores.

 

The lake floor itself should be observed, both the sediment and basement rock areas, for paleoenvironmental and sedimentation studies. Finally, the water, ice, and sediment must be observed and analyzed in situ for composition, microbial populations, stratification, particulate burden and nature, circulation, and related characterizations.


In situ Observations and Robotics. In the past few years the capability for robotic activity and in situ measurements with micro-instrumentation has grown immensely; in coastal oceanography it has significantly changed spatial data gathering, and the Ocean Drilling Program is now interested in this kind of data acquisition at depth.

 

Also, NASA has undertaken a significant program of in situ development for solar system exploration. The goals of Lake Vostok exploration have much in common with those of oceanographic and planetary work, and this overlap of interests provides an avenue for economy and creative collaboration which the Lake Vostok exploration can utilize.

 


TECHNOLOGY JUSTIFICATION
Technology development is a resource investment, and an appropriate question in a discussion of it concerns its inherent value, i.e., the importance of its immediate use and its applicability to other uses.
To address the first issue, the question “Why Lake Vostok?” is posed.

 

Lake Vostok is scientifically unique and interesting because it is large and deep, essentially isolated, at high pressure and low temperature, old, fresh (as nearly as can be determined), the site of interesting water thermodynamics and dynamics, underlain by deep sediments of biological and geological promise, in an interesting geological setting, characterized by several unusual sorts of habitats, strongly influenced by the overlying ice sheet, and analogous to interesting planetary sites.

 

Taken together, the pressure and temperature regimes and the ice sheet processes give rise to another interesting aspect; they indicate that the gases present will be in clathrate (gas hydrate) form, and this provides a key biological question regarding the ability of microbes to utilize gas clathrates.


The second category addresses whether the technologies of Lake Vostok exploration are of use in other pursuits. Clearly they are. The tools and techniques needed for Lake Vostok site survey and in situ campaigns are applicable to ice sheet and permafrost studies, in situ water and sediment composition analysis, device miniaturization, sterilization and sterile methods development, biological assessments, seafloor characterization, radar surveys in other sites and even other planets, and similar problems.

 


TECHNOLOGY STRATEGY
The pathway of activity to lead from this workshop to the actual initiation of Lake Vostok campaigns is complex, with some elements that can, in principle, be conducted in parallel.


Technology development precedes field deployments; thus, with the exception of procedural and legal issues related to contamination control, the technology will come first and determine the earliest date that performance data or testing results can be available. Clearly, the technology time frame is of crucial importance; what controls it?

 

The following approximate high-level sequence of activities is suggested.

1. Interagency International Interest Group. The science and technology of Lake Vostok, and similar sites, is relevant to several agencies and a number of national Antarctic programs, and possibly industrial supporting partners. A group representing interested agencies should be formed to outline possible lines of support.


2. Science Working Team. Before any implementation can begin, a working team of scientists, engineers, and logistics experts must be appointed to establish science requirements for the first campaign, and a general sequence for future campaigns.


3. Site Survey and Selection Team. A working group on site selection issues and information needs, should meet immediately to set forth what data should be sought.

 

4. Observation and Sampling Strategy. A strategy of measurement and sampling needs can be constructed as project scenarios, flexible enough to adapt to varying success rates for the development activities.


5. Technology Plan. A plan is needed for technology development and testing, including subsystem level functional units as well as integrated systems and including contamination prevention procedures and validation at each step. This will include documentation of requirements, priorities, constraints, information system roles, and phasing of deployment and integration. The plan should be viewed as a roadmap and a living document, and its architecture is not specified here as there may be effective web-based methods for its implementation.

 

6. Technology Implementation. Development of implementation teams to obtain funding and perform the functional unit development. Selection and recruitment of these specialists groups are key tasks. Actual development of technologies will follow, and coordination of developments is needed.


7. Testing. The subsystems, the integrated systems, and the contamination prevention techniques all require realistic testing. These testing regiments are demanding and can be expensive, but they are not as expensive as failure during a campaign. The testing of a given subsystem, e.g. an instrument to obtain chemical data from the lake water, may well call for deployment in an analogous environment, e.g. an ice-covered lake, and this deployment could be costly unless it is collaborative with other investigations of ice-covered lakes. To optimize the testing process, planning, coordination and collaboration are essential.


TECHNOLOGY TIMEFRAME

1. Summary of Actions. From above, the actions required for a Lake Vostok program include interagency communications, science and engineering team definition work, development of technology requirements and project scenarios, system definition, subsystem development (including integration and test), system level test, the first Lake Vostok entry, and the subsequent review of status to determine future directions.


2. Crucial Technologies. While much of the technical work required for a successful Lake Vostok exploration is challenging, most of the technologies are seen to be within reach, and many of the tasks have several candidate approaches. An exception is contamination control; this technology is challenging in both development and validation, and it should be developed and proved before any in situ examination of the lake can be addressed. Apparently, this work has begun within NASA, and at the earliest opportunity an estimate of the time required for its completion should be requested.


3. Other Timetable Considerations. In assessing the technology timeframe it is necessary to understand the overall schedule constraints, e.g. contamination prevention, development of consensus on scientific objectives and requirements, logistical resources and commitments, site surveys, international participation, etc. From an initial assessment, it appears that site surveys may be addressable as early as in the 00-01 field year (but maybe later), and this seems to be the schedule driver. From the perspective of participating scientists, the field work could begin in the field season of the year following the site survey, assuming that site survey data can be made widely available.

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