Multiple orbits from single KeplerianOrbit

Orekit usage
1

Hello,
This is a basic usage question, please forgive my ignorance, I am still very new to Orbital mechanics.

I have an array of three PVCordinates objects that I would like to propagate. I create KeplerianOrbit objects and store them in a list.

List<KeplerianOrbit> svs = new ArrayList<>();

 // Create orbit list
for (int i = 0; i < 3; i++) {
  PVCoordinates sv_new = new PVCoordinates(rs[i], vs[i]);
  // Orbits are immutable, so we create a new orbit with the new state vector.
  KeplerianOrbit orbit_new = new KeplerianOrbit(
       sv_new, 
       inertialFrame, 
       t_new, 
       Constants.EGM96_EARTH_MU);
  svs.add(orbit_new);
}

I then pass the List to a method for propagation.

public boolean validate_propagation(List<KeplerianOrbit> states,KeplerianOrbit orb, int targetTime, int searchTime) {
        // propagate at the targetTime
        KeplerianPropagator propagator0 = new KeplerianPropagator(states.get(0));
        KeplerianPropagator propagator1 = new KeplerianPropagator(states.get(1));
        KeplerianPropagator propagator2 = new KeplerianPropagator(states.get(2));

        double step = 1.0;
        AbsoluteDate targetDate = orb.getDate().shiftedBy(targetTime);
        SpacecraftState state = propagator0.propagate(targetDate);

Do I have to create an instance of a KeplerianOrbit for every unique position and velocity pair? If the same initial conditions apply to each object I am trying to propagate, can’t I use the same KeplerianOrbit object for all three propagations? I think the answer is yet, but can’t see why.

Thank you so much.
sg

2

Hi there,

You can use resetInitialState instead of recreating a KeplerianPropagator. You’ll need to wrap your Orbit with a SpacecraftState first.

Cheers,
Romain.