A Design Concept for Spaceborne Imaging of the Base of Terrestrial Ice Sheets and Icy Bodies in the Outer Solar

Glaciers and ice sheets modulate global sea level by storing water deposited as snow on the surface and discharging water back into the ocean through melting and via icebergs. Only recently have we recognized, primarily from satellite observations, that the size of this frozen reservoir can change as demonstrated by the rapid thinning of Jacobshavn Glacier in Greenland [1], the Pine Island and Thwaites Glaciers in Antarctica [2] and the demise of the Larsen Ice Shelf followed by thinning of interior Antarctic Peninsula Glaciers. Yet none of these events are captured by current glaciological models suggesting that there are critical gaps in observations and theory about the dynamics of large ice sheets. Missing from the constellation of satellites currently observing the polar regions, is a sensor capable of probing the volume of the ice sheet and measuring the topography and properties of the glacier bed. While much work has been done to measure ice thickness from aircraft, gaps in coverage remain especially over part of Antarctica [3]. Very little information is available about variations in properties of the subglacial bed where we believe critical changes in the control on ice sheet flow takes place. Here, we present a concept for a new sensor to probe, systematically and comprehensively, the base of the polar ice sheets. We ultimately seek to perform pole-to-pole measurements of glacier and ice sheet thickness, basal topography, and physical properties of the glacier bed that will help to answer two fundamental questions: What is the impact of changing ice sheets on global sea level rise?; Can we predict changes in ice sheet volume and hence changes in global sea level as global climate changes? Our technology concept addresses an approach for obtaining spaceborne estimates of the mass of the polar ice sheets with an ultimate goal of providing essential information to modelers estimating the mass balance of the polar ice sheets and estimating the response of ice sheets to changing climate. The science goals driving our concept are: 1) determine total global ice sheet volume by mapping surface and basal topography; 2) determine basal boundary conditions from radar reflectivity; and 3) understand the phenomenology of radar sounding of ice for applications to planetary studies. Our concept is built around a VHF and P-band, multi-phase-center radar for measuring the surface and bottom topographies of polar ice sheets. Our approach, which relies on a combination of radar interferometry and …