Detection of Near-Surface Frozen Brines at Europa: Radar Investigation of a Canadian Arctic Analog
Abstract
Refrozen meltwater in porous snow and firn can serve as a terrestrial analog for hypothesized refrozen brines in Europa's porous ice regolith. Understanding near-surface (i.e. depth of meters to tens of meters) melt or brine mobilization on Europa is crucial for understanding shallow subsurface exchange mechanisms important to habitability of this icy moon. The Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) instrument on the Europa Clipper mission is capable of detecting near-surface melt. Reflectometry measurements can be used to constrain the fate and evolution of melt through porous ice. We leverage Devon Ice Cap, Canadian Arctic, as a terrestrial analog to improve interpretation of radar signatures associated with percolated, refrozen meltwater in snow/firn.
The Radar Statistical Reconnaissance (RSR) method has been used to characterize terrestrial and planetary surfaces, by separating the coherent (specular) and incoherent (scattered) energy from radar returns. The incoherent component has been previously shown to correlate well with firn zones containing heterogeneous ice layers from refrozen surface melt. Here, we apply the RSR method to data collected over Devon Ice Cap with the University of Texas Institute for Geophysics High Capability Radar Sounder (HiCARS2). HiCARS2 is an airborne radar sounder operating at a 60 MHz center frequency and 15 MHz bandwidth (i.e. near-surface depth of 5 to 10 meters), similar to REASON. We compare the RSR results to firn cores and ground-penetrating radar data to understand the contribution of the near-surface structure (e.g. ice lens thickness and depth) to the coherent component. The coherent component is mainly sensitive to the permittivity, which can be related to the composition and deterministic structure of the reflecting interface. This study can augment the interpretation of radar sounding data for planetary exploration by detecting and characterizing near-surface environments with past melt/brine migration. It can also provide quantitative constraints on meltwater stored within the firn of ice masses affected by significant surface melt, which can benefit future surface mass balance studies.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.P23A3471C
- Keywords:
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- 5215 Origin of life;
- PLANETARY SCIENCES: ASTROBIOLOGY;
- 6024 Interiors;
- PLANETARY SCIENCES: COMETS AND SMALL BODIES;
- 6218 Jovian satellites;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 6280 Saturnian satellites;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS