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Radar measurements of Mercury’s north pole at 70 cm wavelength |
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| Authors: | GJ Black DB Campbell |
| Institution: | a Department of Astronomy, University of Virginia, PO Box 400325, Charlottesville, VA 22904-4325, United States b Department of Astronomy, Cornell University, 528 Space Sciences Bldg., Ithaca, NY 14853, United States c Arecibo Observatory, HC03 Box 53995, Arecibo, PR 00612, United States |
| Abstract: | We present radar imaging of Mercury using the Arecibo Observatory’s 70-cm wavelength radar system during the inferior conjunction of July 1999. At that time the sub-Earth latitude was ∼11°N and the highly reflective region at Mercury’s north pole that was first identified in radar images at the shorter wavelengths of 3.6 cm Slade, M.A., Butler, B.J., Muhleman, D.O., 1992. Science 258, 635-640] and 13 cm Harmon, J.K., Slade, M.A., 1992. Science 258, 640-643] was again clearly detected. The reflectivity averaged over a 75,000 km2 region including the pole is similar to that measured at the other wavelengths over a comparable area, and the 70 cm circular polarization ratio of μC∼0.87 is possibly slightly lower. If this strong backscattering results from volume scattering in low absorption layers, the persistence of this effect over more than an order of magnitude change in wavelength scale has implications for the depth and thickness of the deposits responsible. The resolution of the radar maps at this wavelength is not sufficient to resolve individual craters, nor to discern features at other latitudes, but the planet’s total reflectivity is consistent with previous work and the scattering function suggests a surface roughness at this wavelength similar to the lunar highlands. |
| Keywords: | Mercury Radar observations Ices |
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