A Trajectory Analysis of the Galileo Flyby at Asteroid 243 Ida.

Abstract

On August 28, 1993 the Galileo spacecraft encountered the asteroid 243 Ida on its way to Jupiter. The flyby resulted in a shift of the Doppler data of 0,1mm/s due to Idas gravitational deflection, that was, however, not observable from ground-based S-Band Doppler data with a typical data noise of about 2 mm/s. Therefore the Galileo trajectory relative to Ida within the encounter regime may well be approximated based on its heliocentric Keplerian motion. It is shown that the expansion of the heliocentric trajectory of Ida and Galileo in time series leads to a simple description of Galileos motion with respect to Ida, that may be applied for the propagation of the trajectory and the partial derivative computation in the vicinity of Ida.