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Published October 23, 1992 | public
Journal Article

Mercury Radar Imaging: Evidence for Polar Ice

Abstract

The first unambiguous full-disk radar mapping of Mercury at 3.5-centimeter wavelength, with the Goldstone 70-meter antenna transmitting and 26 antennas of the Very Large Array receiving, has provided evidence for the presence of polar ice. The radar experiments, conducted on 8 and 23 August 1991, were designed to image the half of Mercury not photographed by Mariner 10. The orbital geometry allowed viewing beyond the north pole of Mercury; a highly reflective region was clearly visible on the north pole during both experiments. This polar region has areas in which the circular polarization ratio (pt) was 1.0 to 1.4; values <∼0.1 are typical for terrestrial planets. Such high values of have hitherto been observed in radar observations only from icy regions of Mars and icy outer planet satellites.

Additional Information

© 1992 American Association for the Advancement of Science. 3 June 1992; accepted 4 August 1992. We thank all the observing staff at the VLA and the Radio Astronomy and Radar Group at Goldstone for the attention and care in performing the experiments. In particular we thank K. Sowinski and W. M. Gross for their help in various aspects of these experiments. R. F. Jurgens, E. M. Standish, Jr., and D. K. Yeomans provided assistance with radar operations and ephemerides. We also thank D. A. Paige, S. E. Wood, A. R. Vasavada, and J. K. Harmon for discussions of their results before publication. Part of the research described above was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. The Caltech work was supported under NASA grant NAGW 1499. Contribution number 5158 from the Division of Geological and Planetary Sciences, Caltech.

Additional details

Created:
August 22, 2023
Modified:
October 19, 2023