This pull request introduces the Einstein-Infeld-Hoffmann (EIH) equations into Tudat, which are a first-order post-Newtonian expansion of the relativistic acceleration acting on a set of interaction point masses. This model is typically used in the dynamics of the solar system (e.g. ephemerides). The code includes a complete analytical formulation of the acceleration partials for the EIH accelerations.
As one of the unit tests, position observables for Venus are generated from INPOP, and we then fit a dynamical model to them using (i) EIH and (ii) Newtonian point-mass interactions for a period of 25 years gives:
Difference of > factor 10 for postfit position residuals (9 m for EIH, 150 m for Newtonian)
Difference of > factor 40 for required change in initial position and velocity to fit INPOP
Difference of factor > factor 5000 for required change in Sun's gravitational parameter to fit INPOP
This pull request introduces the Einstein-Infeld-Hoffmann (EIH) equations into Tudat, which are a first-order post-Newtonian expansion of the relativistic acceleration acting on a set of interaction point masses. This model is typically used in the dynamics of the solar system (e.g. ephemerides). The code includes a complete analytical formulation of the acceleration partials for the EIH accelerations.
As one of the unit tests, position observables for Venus are generated from INPOP, and we then fit a dynamical model to them using (i) EIH and (ii) Newtonian point-mass interactions for a period of 25 years gives: