This package provides the interface for force models that will be used by the {@link org.orekit.propagation.numerical.NumericalPropagator} and the {@link org.orekit.propagation.numerical.NumericalPropagatorWithJacobians}, as well as some classical spacecraft models for surface forces (spherical, box and solar array ...). @author Luc Maisonobe @author Pascal Parraud