EcksteinHechlerTheory.java
- /* Copyright 2002-2025 CS GROUP
- * Licensed to CS GROUP (CS) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * CS licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package org.orekit.propagation.conversion.osc2mean;
- import org.hipparchus.CalculusFieldElement;
- import org.orekit.forces.gravity.potential.GravityFieldFactory;
- import org.orekit.forces.gravity.potential.TideSystem;
- import org.orekit.forces.gravity.potential.UnnormalizedSphericalHarmonicsProvider;
- import org.orekit.orbits.FieldOrbit;
- import org.orekit.orbits.Orbit;
- import org.orekit.orbits.OrbitType;
- import org.orekit.propagation.PropagationType;
- import org.orekit.propagation.analytical.EcksteinHechlerPropagator;
- import org.orekit.propagation.analytical.FieldEcksteinHechlerPropagator;
- /**
- * Eckstein-Hechler theory for osculating to mean orbit conversion.
- *
- * @author Pascal Parraud
- * @since 13.0
- */
- public class EcksteinHechlerTheory implements MeanTheory {
- /** Theory used for converting from osculating to mean orbit. */
- public static final String THEORY = "Eckstein-Hechler";
- /** Unnormalized spherical harmonics provider. */
- private final UnnormalizedSphericalHarmonicsProvider provider;
- /**
- * Constructor.
- * @param provider unnormalized spherical harmonics provider
- */
- public EcksteinHechlerTheory(final UnnormalizedSphericalHarmonicsProvider provider) {
- this.provider = provider;
- }
- /**
- * Constructor.
- * @param referenceRadius reference radius of the Earth for the potential model (m)
- * @param mu central attraction coefficient (m³/s²)
- * @param c20 un-normalized zonal coefficient (about -1.08e-3 for Earth)
- * @param c30 un-normalized zonal coefficient (about +2.53e-6 for Earth)
- * @param c40 un-normalized zonal coefficient (about +1.62e-6 for Earth)
- * @param c50 un-normalized zonal coefficient (about +2.28e-7 for Earth)
- * @param c60 un-normalized zonal coefficient (about -5.41e-7 for Earth)
- */
- public EcksteinHechlerTheory(final double referenceRadius,
- final double mu,
- final double c20,
- final double c30,
- final double c40,
- final double c50,
- final double c60) {
- this(GravityFieldFactory.getUnnormalizedProvider(referenceRadius, mu,
- TideSystem.UNKNOWN,
- new double[][] { { 0 }, { 0 }, { c20 }, { c30 }, { c40 }, { c50 }, { c60 } },
- new double[][] { { 0 }, { 0 }, { 0 }, { 0 }, { 0 }, { 0 }, { 0 } }));
- }
- /** {@inheritDoc} */
- @Override
- public String getTheoryName() {
- return THEORY;
- }
- /** {@inheritDoc} */
- @Override
- public double getReferenceRadius() {
- return provider.getAe();
- };
- /** {@inheritDoc} */
- @Override
- public Orbit meanToOsculating(final Orbit mean) {
- final EcksteinHechlerPropagator propagator =
- new EcksteinHechlerPropagator(mean, provider, PropagationType.MEAN);
- return propagator.getOsculatingCircularOrbit(mean.getDate());
- }
- /** {@inheritDoc} */
- @Override
- public <T extends CalculusFieldElement<T>> FieldOrbit<T> meanToOsculating(final FieldOrbit<T> mean) {
- final FieldEcksteinHechlerPropagator<T> propagator =
- new FieldEcksteinHechlerPropagator<>(mean, provider, PropagationType.MEAN);
- return propagator.getOsculatingCircularOrbit(mean.getDate());
- }
- /** Post-treatment of the converted mean orbit.
- * <p>The mean orbit returned is circular.</p>
- * @param osculating the osculating orbit to be converted
- * @param mean the converted mean orbit
- * @return postprocessed mean orbit
- */
- @Override
- public Orbit postprocessing(final Orbit osculating, final Orbit mean) {
- return OrbitType.CIRCULAR.convertType(mean);
- }
- /** Post-treatment of the converted mean orbit.
- * <p>The mean orbit returned is circular.</p>
- * @param <T> type of the field elements
- * @param osculating the osculating orbit to be converted
- * @param mean the converted mean orbit
- * @return postprocessed mean orbit
- */
- @Override
- public <T extends CalculusFieldElement<T>> FieldOrbit<T> postprocessing(final FieldOrbit<T> osculating,
- final FieldOrbit<T> mean) {
- return OrbitType.CIRCULAR.convertType(mean);
- }
- }