Impact Analysis and Design Development for Air-Dropped Antarctic Seismo-Geodetic Ice Penetrator

Abstract

Existing measurement tools for ice shelves and other glaciated regions have limited capability to measure dynamic events in remote areas. The Seismo-Geodetic Ice Penetrator (SGIP) offers a method for rapid deployment of a broadband seismometer and Global Navigation Satellite System (GNSS) positioning system designed to sense ice shelf resonant forcings caused by ocean gravity waves and atmospheric waves. Additionally, SGIP will track seismic indications of calving and rifting, facilitating better estimates of sea level rise. During operation, SGIP is dropped from an aerial vehicle, reaching a terminal velocity of 42 ms⁻¹; during impact with the snowpack surface SGIP experiences an average acceleration of approximately 500 ms⁻². Upon impact, a fore-body section separates from the upper aft-body "flare" section and continues several meters into the ice shelf, while the aft-body remains at the surface with a set of communications antennas. The SGIP platform is compared to previously envisioned and tested penetrator systems. Impact modeling of SGIP into glacial firn is detailed, with a focus on fast simulation run-times for design exploration. Designs of snow spikes and a rigid antenna mast are detailed, analyzed and tested. Results from a full-scale prototype hardware test in Juneau, Alaska are discussed.