DSST6X0OrbitalState.java

  1. /* Copyright 2020-2024 Exotrail
  2.  * Licensed to CS GROUP (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.propagation.conversion.averaging;

  18. import org.orekit.forces.gravity.potential.UnnormalizedSphericalHarmonicsProvider;
  19. import org.orekit.frames.Frame;
  20. import org.orekit.orbits.EquinoctialOrbit;
  21. import org.orekit.orbits.Orbit;
  22. import org.orekit.orbits.OrbitType;
  23. import org.orekit.orbits.PositionAngleType;
  24. import org.orekit.propagation.SpacecraftState;
  25. import org.orekit.propagation.semianalytical.dsst.DSSTPropagator;
  26. import org.orekit.propagation.semianalytical.dsst.forces.DSSTForceModel;
  27. import org.orekit.propagation.semianalytical.dsst.forces.DSSTZonal;
  28. import org.orekit.time.AbsoluteDate;
  29. import org.orekit.propagation.conversion.averaging.elements.AveragedEquinoctialWithMeanAngle;

  30. import java.util.ArrayList;
  31. import java.util.Collection;
  32. import java.util.List;

  33. /**
  34.  * Class representing an averaged orbital state as in the DSST theory using only the first 6 zonal
  35.  * harmonics as perturbations.
  36.  *
  37.  * @author Romain Serra
  38.  * @see AveragedOrbitalState
  39.  * @see DSSTPropagator
  40.  * @see DSSTZonal
  41.  * @since 12.1
  42.  */
  43. public class DSST6X0OrbitalState extends AbstractHarmonicsBasedOrbitalState {

  44.     /** Averaged equinoctial elements. */
  45.     private final AveragedEquinoctialWithMeanAngle averagedElements;

  46.     /**
  47.      * Constructor.
  48.      * @param date epoch
  49.      * @param elements averaged orbital elements
  50.      * @param frame reference frame
  51.      * @param harmonicsProvider spherical harmonics provider
  52.      */
  53.     public DSST6X0OrbitalState(final AbsoluteDate date,
  54.                                final AveragedEquinoctialWithMeanAngle elements,
  55.                                final Frame frame,
  56.                                final UnnormalizedSphericalHarmonicsProvider harmonicsProvider) {
  57.         super(date, frame, harmonicsProvider);
  58.         this.averagedElements = elements;
  59.     }

  60.     /**
  61.      * Create collection of fist 6 zonal DSST forces.
  62.      * @param provider spherical harmonics provider
  63.      * @return six first zonal forces
  64.      */
  65.     public static Collection<DSSTForceModel> createForces(final UnnormalizedSphericalHarmonicsProvider provider) {
  66.         final List<DSSTForceModel> forceModels = new ArrayList<>();
  67.         final DSSTZonal zonal = new DSSTZonal(provider);
  68.         forceModels.add(zonal);
  69.         return forceModels;
  70.     }

  71.     /** {@inheritDoc} */
  72.     @Override
  73.     public OrbitType getOrbitType() {
  74.         return OrbitType.EQUINOCTIAL;
  75.     }

  76.     /** {@inheritDoc} */
  77.     @Override
  78.     public PositionAngleType getPositionAngleType() {
  79.         return PositionAngleType.MEAN;
  80.     }

  81.     /** {@inheritDoc} */
  82.     @Override
  83.     public AveragedEquinoctialWithMeanAngle getAveragedElements() {
  84.         return averagedElements;
  85.     }

  86.     /** {@inheritDoc} */
  87.     @Override
  88.     public Orbit toOsculatingOrbit() {
  89.         final EquinoctialOrbit orekitOrbit = createOrekitOrbit();
  90.         final Collection<DSSTForceModel> forceModels = createForces(getHarmonicsProvider());
  91.         final SpacecraftState osculatingState = DSSTPropagator.computeOsculatingState(
  92.                 new SpacecraftState(orekitOrbit), null, forceModels);
  93.         return osculatingState.getOrbit();
  94.     }

  95.     /**
  96.      * Create equinoctial orbit representation of averaged state.
  97.      * @return equinoctial orbit
  98.      */
  99.     private EquinoctialOrbit createOrekitOrbit() {
  100.         return new EquinoctialOrbit(averagedElements.getAveragedSemiMajorAxis(),
  101.                 averagedElements.getAveragedEquinoctialEx(),
  102.                 averagedElements.getAveragedEquinoctialEy(),
  103.                 averagedElements.getAveragedHx(), averagedElements.getAveragedHy(),
  104.                 averagedElements.getAveragedMeanLongitudeArgument(),
  105.                 getPositionAngleType(), getFrame(), getDate(), getMu());
  106.     }

  107. }