ORBIT DETERMINATION STUDIES FOR A LOW-ALTITUDE EUROPA ORBITER

摘要

Orbit simulations were conducted for a 30-day Europa mission with a 100-km, near-polar orbit. The reconstructed orbit accuracy was approximately 50 m, 60 m, and 30 m (3-sigma) for the radial, crosstrack, and alongtrack components respectively and was dominated by the relatively large level of a priori gravity error, with secondary effects due to maneuver execution errors. A critical assumption was that prior to entering the primary science orbit phase the gravity field error was reduced by a strategy comparable to providing two-weeks of tracking data during orbit conditions similar to the science orbit. Given the reconstruction capability, orbit error predictability in the presence of no tracking data was dominated by 1-rev perturbations for the crosstrack and radial components with little change in overall amplitude while the alongtrack error increased at a nearly secular rate of ～5 m/day (3-sigma).