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Science 31 October 1986:
Vol. 234. no. 4776, pp. 587 - 590
DOI: 10.1126/science.234.4776.587
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Articles

Radar Glory from Buried Craters on Icy Moons

VON R. ESHLEMAN 1

1 Department of Electrical Engineering and Center for Radar Astronomy, Stanford University, Stanford, CA 94305.

Three ice-covered moons of Jupiter, in comparison with rocky planets and Earth's moon, produce radar echoes of astounding strengths and bizarre polarizations. Scattering from buried craters can explain these and other anomalous properties of the echoes. The role of such craters is analogous to that of the water droplets that create the apparition known as "the glory," the optically bright region surrounding an observer's shadow on a cloud. Both situations involve the electromagnetic phenomenon of total internal reflection at a dielectric interface, operating in a geometry that strongly favors exact backscattering. Dim surface craters are transformed into bright glory holes by being buried under somewhat denser material, thereby increasing the intensity of their echoes by factors of hundreds. The dielectric interface thus formed at the crater walls nicely accounts for the unusual polarizations of the echoes.

Submitted on May 12, 1986
Accepted on August 25, 1986


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Radar Reflectivity of Titan.
D. O. Muhleman, D. O. Muhleman, A. W. Grossman, B. J. Butler, and M. A. Slade (1990)
Science 248, 975-980
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