WE PROPOSE TO USE WELL ESTABLISHED THREE DIMENSIONAL (3D) IMAGING TECHNIQUES DEVELOPED AND USED FOR TERRESTRIAL SEISMIC DATA TO FULLY AND ACCURATELY 3D IMAGE THE POLAR REGIONS OF MARS KNOWN AS PLANUM AUSTRALE (PA) AND PLANUM BOREUM (PB) USING SETS OF SUBSURFACE OBSERVATIONS ACQUIRED BY MARS ADVANCED RADAR FOR SUBSURFACE AND IONOSPHERE SOUNDING (MARSIS) ON THE MARS EXPRESS (MEX) ORBITER. WE FURTHER PROPOSE TO ANALYZE AND INTERPRET THE RESULTING 3D MARSIS IMAGES TO REFINE OUR UNDERSTANDING OF PRIOR AND SEARCH FOR NEW SCIENTIFICALLY IMPORTANT PA AND PB FEATURES SUCH AS ACCUMULATIONS OF LIQUID WATER AND BURIED CRATERS WITHIN OR BENEATH THE POLAR LAYERED DEPOSITS (PLD).