RADAR TECHNIQUES APPLIED TO SUBSURFACE STUDIES IN SOLAR SYSTEM STUDIES IN SOLAR SYSTEM EXPLORATION

摘要

Over the past decades,a number of different Synthetic Aperture Radar(SAR)techniques were developed for mapping the surface of the planets either from Earth or from orbiting spacecrafts.However,the idea to use radar to study the subsurface started to develop during the last 15 years.The ability of the radio waves to penetrate the ice,permafrost and arid surface was at the origins of the development of the Ground Penetrating Radars(GPR).GPRs have been widely applied on Earth with a large number of the scientific and industrial applications.The application of GPR to the space exploration relies on the same operation principle but requires the development of low power and low mass equipments.In this paper,we start by discussing the general electromagnetic behavior of the materials which determines the principal characteristics of the GPR instrument.Then we describe the GPR instrument that was developed for the Mars 1998 mission(unfortunately cancelled).Then,we discuss a general GPR design that can be implemented on future rover missions. rnThe measurements from the surface cannot replace the global mapping from orbit using orbital radar sounders. MARSIS radar is an example of these orbital radar sounders that is now in Mars orbit on the Mars Express spacecraft.Another example of an orbital radar sounder design was presented in the Surprise proposal for the Mars Express mission.These radars work essentially in the altimeter mode even if some Doppler treatment is implemented and is used in the data analysis. rnAnother major milestone in planetary radar application will be achieved once the radar doing the tomography of the interior of the small objects is implemented.We conclude this paper by the discussion of its principle, implementation and show its tentative definition.