GeoPebbles: A network of wireless seismic and GPS nodes designed for Polar deployment

Properties at the base of Polar ice sheets and glaciers are of critical importance in understanding the current dynamics of the cryosphere. Ice slides over its base or deforms internally. The water content of the bed; whether that bed is of sedimentary or crystalline material; the roughness of the interface; all determine the speed of ice flow. Seismic reflection imaging is one of the best tools for measuring basal conditions. Current practice in the academic community is based on multi-conductor cables with geophones connected at intervals along the cable. This technique is best suited to linear arrays and twodimensional images along those lines. In an effort to provide new and improved geophysical sensing capabilities for the study of ice sheets in Antarctica and Greenland, or to study mountain glaciers, we have developed a network of wirelessly interconnected seismic and GPS sensor nodes (called ``geoPebbles''), with the primary objective of making such instruments more capable and cost effective. We describe our design methodology, which has enabled us to develop these state-of-the art sensors using commercial-off-the-shelf hardware combined with custom-designed hardware and software.