<h2>AAS  96-156</h2><h2>IMPROVEMENTS IN MARS GRAVITY FIELD DETERMINATION USING RIDGE-TYPE ESTIMATION METHODS</h2><h4>C. F. Minter and D. A. Cicci, Auburn University</h4><h2> Abstract </h2>The objective of this research was to improve the accuracy of the latest gravity field of Mars, labeled Mars50c as developed by NASA's Jet Propulsion Laboratory, through the use of ridge-type estimation methods.  These advanced parameter estimation techniques were applied to the calculation of a (50x50) field of harmonic coefficients which represent the graviational potential of Mars.  Data used in this analysis were derived from Viking and Mariner 9 doppler tracking data.<br><br>