IDEAL FRAMES AND REGULARIZATION IN NUMERICAL ORBIT COMPUTATION

Centimeter accuracy over one hundred revolutions of a satellite is req uired in some missions. The quest for higher efficiency in numerical c omputation of perturbed Keplerian orbits, lead us to develop new formu lations using ideal (Hansen) frames and quaternions for rotations. Fur thermore, a regularization and a rescaling of the force linearizing th e equations of motion and allowing the use of the true anomaly as a ti me-like variable resulting in the consideration of a constant step-siz e in the numerical integration has been performed. Several tests show that formulations using ideal frames and quaternions improve the class ical integration in Cartesian coordinates and that a regularized formu lation is very adequate for high eccentricity orbits and gives equival ent results for low eccentricities.