High-accuracy simulation of orbital dynamics: An object-oriented approach

The use of Keplerian or Equinoctial parameters instead of Cartesian coordinates as state variables in object-oriented spacecraft models is introduced in this paper. The rigid body model of the standard MultiBody library is extended by adding transformation equations from Keplerian or Equinoctial parameters to Cartesian coordinates, and by setting the former as preferred states, instead of the latter. The remaining parts of the model are left untouched, thus ensuring maximum re-usability of the model itself. The results shown in the paper demonstrate the superior accuracy and speed of computation both in the case of a point-mass gravity field, and in the case of more accurate gravity field models.