Radar Scattering from Titan and Saturn’s Icy Satellites Using the Cassini Spacecraft

Abstract

Titan is the largest moon of Saturn and the second largest moon in the solar system. It has a thick atmosphere rich in nitrogen and hydrocarbons, analogous to the atmosphere of early, prebiotic Earth. This atmosphere inhibits observations of the surface using traditional optical methods. The Cassini-Huygens spacecraft (a joint endeavor of NASA/ESA/ASI) began orbiting Saturn in 2004, with a flyby of Titan nearly every month. Its RADAR instrument, with a 2.2 cm wavelength, penetrates the hazy atmosphere to detect the surface. RADAR operates near closest approach on roughly half of the Titan flybys. As of July 2011, the RADAR instrument has observed the surface on 41 of the 77 Titan flybys. The RADAR instrument operates in several modes. It calculates surface height profiles, measures the emissivity, and also maps the surface at resolutions as fine as 300 m. The high-resolution maps reveal a surprisingly Earth-like physical surface, complete with icy mountains, dune fields, cryovolcanoes, flowing liquids, and hydrocarbon lakes. Another operation of the instrument, called scatterometer mode, measures the real aperture (beam-averaged) backscatter reflectivity as a function of incidence angle. The shape of this backscatter curve reveals much about the surface, such as material composition and roughness structure. We develop a real aperture processor to reduce the scatterometer data, and also extend this reduction to the other active modes of the RADAR instrument. We calibrate the different modes in order to combine the data sets globally. We correct the measured backscatter for incidence angle effects to produce a global backscatter map (99.9% surface coverage) with real-aperture resolutions between 10 and 250 km.

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Cite this paper

@inproceedings{Wye2011RadarSF, title={Radar Scattering from Titan and Saturn’s Icy Satellites Using the Cassini Spacecraft}, author={Lauren C. Wye and Howard A. Zebker and Ivan R. Linscott}, year={2011} }