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Published on: September 8, 2023
Mercury radar imaging: evidence for polar ice
Science (New York, N.Y.)
|October 23, 1992
Summary
Radar mapping of Mercury revealed a highly reflective polar region, suggesting the presence of ice. This finding, observed using advanced radar technology, offers new insights into Mercury's surface composition.
Area of Science:
- Planetary Science
- Radio Astronomy
- Geophysics
Background:
- Mercury's surface composition remains incompletely understood, particularly regions not mapped by previous missions.
- Radar observations offer a unique method for probing planetary surfaces, including composition and topography.
Purpose of the Study:
- To conduct the first unambiguous full-disk radar mapping of Mercury.
- To investigate the unphotographed hemisphere of Mercury using radar.
- To search for evidence of surface volatiles, such as ice, at Mercury's poles.
Main Methods:
- Utilized the Goldstone 70-meter antenna for transmitting and the Very Large Array (26 antennas) for receiving radar signals.
- Conducted radar mapping experiments at a 3.5-centimeter wavelength on August 8 and 23, 1991.
- Analyzed radar echo characteristics, including the circular polarization ratio (pt), to infer surface properties.
Main Results:
- Successfully mapped a significant portion of Mercury's surface, including areas beyond the north pole.
- Identified a highly reflective region at Mercury's north pole.
- Observed exceptionally high circular polarization ratios (pt) ranging from 1.0 to 1.4 in the polar region, values atypical for terrestrial planets.
Conclusions:
- The observed high circular polarization ratio strongly suggests the presence of surface ice at Mercury's north pole.
- These findings are comparable to radar signatures of icy regions on Mars and outer planet satellites.
- This study provides the first unambiguous radar evidence for polar ice on Mercury.
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