The Solar Test of the Equivalence Principle

The Earth, Mars, Sun, Jupiter system allows for a sensitive test of the strong equivalence principle (SEP) which is qualitatively different from that provided by Lunar Laser Ranging. Using analytic and numerical methods we demonstrate that Earth-Mars ranging can provide a useful estimate of the SEP parameter $eta$. Two estimates of the predicted accuracy are derived and quoted, one based on conventional covariance analysis, and another (called ``modified worst case'' analysis) which assumes that systematic errors dominate the experiment. If future Mars missions provide ranging measurements with an accuracy of $sigma$ meters, after ten years of ranging the expected accuracy for the SEP parameter $eta$ will be of order $(1-12) imes 10^{-4}sigma$. These ranging measurements will also provide the most accurate determination of the mass of Jupiter, independent of the SEP effect test.Comment: 10 pages; LaTeX; three figures upon reques