MARS DYNAMICS FROM EARTH-BASED TRACKING OF THE MARS PATHFINDER LANDER

Measurements of Mars' rotational variations can be conducted via Earth -based radio tracking observations of the Mars Pathfinder lander durin g an extended mission. Two-way range measurements between an Earth tra cking station and the lander will enable precise monitoring of the pla net's orientation, allowing details of Mars' internal structure and gl obal surface/atmosphere interactions to be determined. An analysis has been performed to investigate the accuracy with which key physical pa rameters of Mars can be determined using the Earth-based radio trackin g measurements. Acquisition of such measurements over one Martian year should enable determination of Mars' polar moment of inertia to 1% or better, providing a strong constraint on radial density profiles (and hence on the iron content of the core and mantle) and on long-term va riations of the obliquity, which influences the climate. Variations in Mars length of day and polar motion should also be detectable, and wi ll yield information on the seasonal cycling of carbon dioxide between the atmosphere and the surface.