Radar Remote Sensing
Subsurface radar Remote Sensing of Earth from Space in Interests of National Economy and Ecology
Tech Area / Field
- ENV-MIN/Monitoring and Instrumentation/Environment
- PHY-RAW/Radiofrequency Waves/Physics
3 Approved without Funding
Moscow Scientific Res. Institute of Instrument Engineering, Russia, Moscow
Project summaryThe aim of the proposed project is to provide a scientific and engineering stock required for subsequent development of a space-borne synthetic aperture radar (SAR) for surveying natural formations and other objects below the vegetation cover and/or under the soil surface layer of the Earth in the interests of national economy and ecology.
Space-borne SAR's designed for remote sensing of the Earth operates nowadays in the microwave (centimeter and decimeter) waveband. They prove to be ineffective when used to survey natural formations and other objects located below the vegetation cover and/of under the Earth surface soil layer.
A SAR that could allow to solve these problems should operate in the VHP (meter) band since the penetrability of VHP waves through the vegetation cover and the Earth surface soil layer is much higher, while the masking effect of Earth surface backscatter is much lower than those in the microwave band.
However, there are substantial difficulties in the development of such a SAR. They involve the problem of providing a high resolution in the VHP band that is required to drastically bring down the masking effect of the backscatter from terrain covers.
The above difficulties are caused by the destructive effect of signal distortions in the ionosphere on the resolution of a VHP space-borne SAR along both coordinates. The effect consists in dispersion of the signal and fluctuations of its phase in the course of its passage through the ionosphere. It is the inability to solve this problem that has made it impossible up to now to design a VHP space-borne SAR for efficient subsurface sensing of the Earth.
A preliminary theoretical analysis of the problem, the results of which were presented at the European conference EUSAR'96 (Konigswinter, Germany, March, 1996) by the major participants of the project, has proved that the problem can be solved in principle.
In the present project this work is to be continued and made more profound. The first stage (duration is one year) involves the development and analysis of concrete methods to reduce the above-mentioned destructive effect of the ionosphere on the performance of a VHP space-borne SAR.
Theoretical studies and computer simulation are planned with the use of real data obtained by a VHP air-borne SAR in flight as well as records of actual signal phase fluctuations in the ionosphere. In addition, a quantitative assessment will be made of the effect produced by the wavelength and other factors on the penetrability of such a SAR. On optimum wavelength will also be selected. Technical requirements for inpidual SAR's subsystems will be worked out.
Methods to reduce the interference caused by ground based communications radio sets will also be suggested and simulated.
The second stage (duration is also one year) involves the development of a general design and possible major characteristics of the space-borne SAR for subsurface sensing, the selection of rational ways of designing its major subsystems (antenna, transmitter, receiver, signal processor, etc.) and the provisions for mating the SAR with the spacecraft.
The fulfillment of the project will provide a scientific and engineering stock allowing passing over to the design, development and space tests of a VHP space-borne SAR that will effectively solve new problems in the interests of national economy and ecology. Nowadays these problems are beyond the possibilities of modern space assets for remote sensing, e.g.:
- locating geologic structures (cracks, fractures) hidden by vegetation or snow covers as well as those below loose sedimentary rocks, the structures indicating possible deposits of mineral resources;
- locating objects below the Earth soil layer (pipelines, archeological objects, etc.);
- carrying out hydrological surveys, in particular, locating aquifers and subsurface water deposits, etc.;
- locating polluted subsurface layers.
The aim of the project as stated above has not been achieved anywhere till now. Hence, one can presume that the project will attract potential collaborators and investors from abroad (first of all those who are interested in its commercial aspects).
After the proposed project has been carried out there are possibilities to continue cooperation in the development of a SAR prototype.
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