Science Projects - RAGES
RAGES: Robotic Access to Grounding-zones for Exploration and Science
As one of three components of WISSARD (Whillans Ice Stream Subglacial Access Research Drilling), RAGES (Robotic Access to Grounding-zones for Exploration and Science) research concentrates on the stability of the fast flowing Whillans Ice Stream in subglacial system between SLW and the ice stream grounding zone. A grounding zone is an area where the ice, ocean waters and sea floor interact; where the ice is being melted by or is freezing seawater, and where debris below and in the ice and streams flowing under the ice are released and discharge their loads. Based on our present limited data and modeling efforts, grounding zones can be influenced by: (i) internal ice stream dynamics, (ii) rates of subglacial sediment (till) supply to the grounding zone, (iii) increased melting by warming ocean waters, and/or (iv) filling/draining cycles of subglacial lakes. Grounding zones are seen as high priority targets to investigate because models indicate these are important areas that strongly influence ice sheet stability.
Science Problem: Can the Grounding Zone be an Effective Buttress for Protecting the Sensitive West Antarctic Ice Sheet?
Five of Antarctica's recognized geoscience researchers from four U.S. universities will lead RAGES through its planning years and field season in the austral summer of 2013-14. During the WISSARD project, the RAGES focus will be on the grounded ice side of the grounding line. Follow-up work is being planned for future studies of the sub-ice shelf cavity and the Ross Sea side of the grounding line. The RAGES field-sampling plan integrates surface geophysical surveys with borehole and subglacial sampling and measurements. The boreholes provide:
- Samples of subglacial water, sediments, and basal ice for biological, geochemical, sedimentological, micropaleontological, and glaciological analyses;
- Measurements of subglacial physical and chemical conditions; their variability within the cavity and through time;
- Data on sediment types, state and change of the subglacial water discharge, and basal ice at the grounding line.
These data will allow RAGES scientists to address three main goals, which are to assess: (i) how the grounding-zone controls stability of the West Antarctic Ice Sheet (WAIS), (ii) how WAIS dynamics have changed in the past based on information stored in the "library" of grounding-zone sediments; and (iii) how important microbial activity and subglacial weathering is in supplying nutrients to the ocean both under the Ross Ice Shelf and potentially through the highly productive Southern Ocean.
The RAGES project not only addresses scientific questions of direct societal relevance and significance, it also represents major advances in polar technology. Unique instruments are being custom-designed and built for use in RAGES and they will advance the level of sophistication in polar instrumentation and data collection. Examples of this instrumentation are: IPSIE (Instrumentation Packages for Sub-Ice Exploration) and a newly designed percussion corer for sediment sampling. More detailed descriptions of the instruments are available under the Technology tab.
Locations of Subglacial Lake Whillans study site for LISSARD (Fricker et al. 2007), the grounding zone wedge, study site for RAGES, and GBASE will sample both sites. Subglacial Lake Whillans drainage path is estimated from recent ICESat analysis and hydropotential maps (Fricker, pers. comm.). Background image is from MODIS Mosaic of Antarctica (MOA; Scambos et al. 2007).
Project Significance and Impacts:
Our biggest unknowns in trying to estimate the magnitude and rate of future global sea-level rise come from a poor understanding of ice sheet dynamics and ice sheet vulnerability to warming of oceans and atmosphere. Complete disappearance of the West Antarctic Ice Sheet alone would contribute 3-5m to global sea-level rise, making it a focus of scientific concern due to its possible susceptibility to internal or ocean-driven instability. Data from RAGES will contribute to a scientific community effort to develop more realistic ice-sheet models that can lessen our uncertainties about future ice sheet changes and sea level. Rages can provide data to more realistically constrain those ice sheet models by providing data about how the sediment and water at the bed, just up-stream from the grounding-line, can influence its dynamics and hence stability.