Accurate orbit propagation in the presence of planetary close encounters
Abstract
We present an efficient strategy for the numerical propagation of small Solar system objects undergoing close encounters with massive bodies. The trajectory is split into several phases, each of them being the solution of a perturbed twobody problem. Formulations regularized with respect to different primaries are employed in two subsequent phases. In particular, we consider the KustaanheimoStiefel regularization and a novel set of nonsingular orbital elements pertaining to the Dromo family. In order to test the proposed strategy, we perform ensemble propagations in the EarthSun Circular Restricted 3Body Problem (CR3BP) using a variable step size and order multistep integrator and an improved version of Everhart's radau solver of 15th order. By combining the trajectory splitting with regularized equations of motion in shortterm propagations (1 year), we gain up to six orders of magnitude in accuracy with respect to the classical Cowell's method for the same computational cost. Moreover, in the propagation of asteroid (99942) Apophis through its 2029 Earth encounter, the position error stays within 100 metres after 100 years. In general, as to improve the performance of regularized formulations, the trajectory must be split between 1.2 and 3 Hill radii from the Earth. We also devise a robust iterative algorithm to stop the integration of regularized equations of motion at a prescribed physical time. The results rigorously hold in the CR3BP, and similar considerations may apply when considering more complex models. The methods and algorithms are implemented in the naples fortran 2003 code, which is available online as a GitHub repository.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 September 2017
 DOI:
 10.1093/mnras/stx1254
 Bibcode:
 2017MNRAS.470.2079A
 Keywords:

 methods: numerical;
 celestial mechanics;
 minor planets;
 asteroids: general