<h2>AAS 95-381</h2><h2>Navigation Strategy for the Galileo Jupiter Encounter and Orbital Tour</h2><h4>L.  A. D'Amario,  D. V. Byrnes, W. E. Kirhofer, F. T. Nicholson and M. G. Wilson, Jet Propulsion Laboratory, Pasadena, CA</h4><h2> Abstract </h2>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).<br><br>