New Results for Scattering from Buried Craters and Refractive Lenses: Implications for Remote Sensing of Icy Surfaces

Details New Results for Scattering from Buried Craters and Refractive Lenses: Implications for Remote Sensing of Icy Surfaces New Results for Scattering from Buried Craters and Refractive Lenses: Implications for Remote Sensing of Icy Surfaces

Sep 1998

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998baas...30.1087b&link_type=abstract

American Astronomical Society, DPS meeting #30, #38.P13; Bulletin of the American Astronomical Society, Vol. 30, p.1087

Physics

Optics

Scientific paper

Several scattering models have been proposed to explain the unusual radar properties of the icy Galilean satellites and certain other icy surfaces. Among these models are the coherent backscatter effect (Hapke 1990, Icarus 88, 407--417), retrorefractive permittivity gradients or ``lenses'' (Hagfors 1985, Nature 315, 637--640), and radar glory from buried craters (Eshleman 1986, Science 234, 755--757), the latter two of which have been analyzed in the geometric optics limit for large scatterers. Radar data currently available are insufficient to distinguish among the models. In this paper we use numerical methods to calculate scattering in both monostatic and bistatic geometries from wavelength-scale refractive lenses and buried craters, which---if they exist---are more likely to be found in large numbers at sizes for which geometric optics may not apply. We model single scattering from hemispherical craters and spherical refractive lenses with effective size parameters as large as ka ~ 16. For the lenses we choose a refractivity profile corresponding to that of an Eaton-Lippman lens, or ``cat's eye.'' The (hemi)spherical shapes are chosen for convenience, but can inhibit the same-sense circular (SC) or orthogonal linear (OL) responses due to coherent cancellations from annular apertures. We introduce randomly-distributed, sub-wavelength-scale dielectric inhomogeneities (corresponding to rocky debris, ice, or air pockets) into the background crater/lens model as a means of simulating irregularities within the scatterering centers. We do not observe any unusual backscatter enhancements in the circular polarization ratio, muC = sigmaSC / sigmaOC, or the linear polarization ratio, muL = sigmaOL / sigmaSL, for small buried craters. We have assumed that small craters are bowl-shaped, but deviations from spherical symmetry could act as an additional depolarizing mechanism. The bistatic angle at which sigmaSC exceeds sigmaOC ranges from 10(deg) to 20(deg) for ka ~ 16. Refractive lenses have stronger depolarized backscatter responses. For example, a lens with ~ 15% of its volume filled with rocky debris gives an average muC ~ 1.6 and muL ~ 0.8, slightly higher than values measured for the Galilean satellites (Ostro et al./ 1992, JGR Planets 97, 18227--18244).

Affiliated with

Also associated with

No associations

Rating

New Results for Scattering from Buried Craters and Refractive Lenses: Implications for Remote Sensing of Icy Surfaces does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with New Results for Scattering from Buried Craters and Refractive Lenses: Implications for Remote Sensing of Icy Surfaces, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and New Results for Scattering from Buried Craters and Refractive Lenses: Implications for Remote Sensing of Icy Surfaces will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-813562