AAS 95-381
Navigation Strategy for the Galileo Jupiter Encounter and Orbital Tour
L. A. D'Amario, D. V. Byrnes, W. E. Kirhofer, F. T. Nicholson and M. G. Wilson, Jet Propulsion Laboratory, Pasadena, CA
Abstract
At Jupiter arrival on December 7, 1995, the Galileo Orbiter will have a close Io flyby (1000 km target altitude), record up to 75 min of science data transmitted from the atmospheric Probe, and then perform a large (~650 m/s) Jupiter Orbit Insertion maneuver. The ensuing two-year "orbital tour" includes 10 close satellite flybys at altitudes between 250 and 3100 km. Four Jupiter-approach maneuvers and three maneuvers per orbit are planned to achieve accurate delivery of the Orbiter at each satellite encounter. Precise orbit determination is accomplished with S-band Doppler data and optical navigation pictures as the primary data types. At each orbit trim maneuver, the remaining orbital tour trajectory will be re-optimized to minimize total V by varying satellite aimpoints within allowable bounds. Satellite delivery errors for the orbital tour are generally less than about 40 km (B-plane) and 2 sec (closest approach time). The V required to navigate the orbital tour is about 70 m/s, and the end-of-mission propellant margin is 27 kg (both 90% probability values).