Ground-Penetrating Radar
Investigations of Terrestrial Analogs to the
Martian Crust for 2011 Mars Scout
Mission, 20-9470
Principal Investigator
Cynthia Dinwiddie
Inclusive Dates: 04/04/04 - Current
Background - The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) aboard the European Space Agency's Mars Express spacecraft will acquire the first global data set of Martian subsurface radar properties, including, perhaps, inferred depth to water. Because only limited ground-penetrating radar investigations of the Earth have been made within the low-frequency range of MARSIS, an accurate interpretation of its forthcoming data is uncertain. Terrestrial analogs to Mars provide the opportunity to collect low-frequency radar data from well-known, well-characterized sites so that uncertainties may be minimized when interpreting Mars radar data.
Approach - A team of geoscientists and geophysicists from SwRI and the Lunar and Planetary Institute in Houston is conducting transient electromagnetic and low-frequency ground-penetrating radar investigations of terrestrial analog sites in the western United States at frequencies similar to those proposed for Mars studies. Study sites include the Volcanic Tableland, Bishop, California, and Craters of the Moon National Monument, Idaho. Transient electromagnetic soundings were performed to measure ground conductivity and estimate absorptive losses.
Accomplishments - Inversion models of transient electromagnetic data from the Volcanic Tableland suggest a very resistive near-surface layer overlying a conductive region. The conductive region is easily interpreted from site data as the saturated zone. Electrical ground conductivity results from the Volcanic Tableland are, thus, very promising for radar work, which is to commence in the immediate future. Radar results from Craters of the Moon indicate ground-penetrating radar penetration depths of 50 and 150 m were achieved with the 100- and 16-MHz antennas. These depths of investigation may be attributed to the high porosity of the subsurface, which lowered electrical losses, thus favoring a relatively deep penetration of the radar wave. This project is providing SwRI with the capability to develop benchmarks against which planetary scientists can interpret low-frequency MARSIS radar data and the capability to study synergisms between multiple geophysical techniques. Results from this project also will support the submission of future proposals to secure funding for MARSIS data analysis and development of next-generation planetary geophysical instruments.
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USGS Side-Looking Airborne Radar Image of the Volcanic Tablelands overlaid with roads, TEM sounding locations (red), and surface water measurement site locations (blue). |
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Project staff conducts transient electromagnetic soundings. |
