DSSTAtmosphericDrag.java
- /* Copyright 2002-2024 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.semianalytical.dsst.forces;
- import java.util.List;
- import java.util.stream.Stream;
- import org.hipparchus.CalculusFieldElement;
- import org.hipparchus.Field;
- import org.hipparchus.util.FastMath;
- import org.hipparchus.util.MathArrays;
- import org.hipparchus.util.MathUtils;
- import org.orekit.forces.drag.DragForce;
- import org.orekit.forces.drag.DragSensitive;
- import org.orekit.forces.drag.IsotropicDrag;
- import org.orekit.models.earth.atmosphere.Atmosphere;
- import org.orekit.propagation.FieldSpacecraftState;
- import org.orekit.propagation.SpacecraftState;
- import org.orekit.propagation.events.EventDetector;
- import org.orekit.propagation.events.FieldEventDetector;
- import org.orekit.propagation.semianalytical.dsst.utilities.AuxiliaryElements;
- import org.orekit.propagation.semianalytical.dsst.utilities.FieldAuxiliaryElements;
- import org.orekit.utils.Constants;
- import org.orekit.utils.ParameterDriver;
- /** Atmospheric drag contribution to the
- * {@link org.orekit.propagation.semianalytical.dsst.DSSTPropagator DSSTPropagator}.
- * <p>
- * The drag acceleration is computed through the acceleration model of
- * {@link org.orekit.forces.drag.DragForce DragForce}.
- * </p>
- *
- * @author Pascal Parraud
- */
- public class DSSTAtmosphericDrag extends AbstractGaussianContribution {
- /** Threshold for the choice of the Gauss quadrature order. */
- private static final double GAUSS_THRESHOLD = 6.0e-10;
- /** Default upper limit for atmospheric drag (m) . */
- private static final double DEFAULT_MAX_ATMOSPHERE_ALTITUDE = 1000000.;
- /** Atmospheric drag force model. */
- private final DragForce drag;
- /** Critical distance from the center of the central body for
- * entering/leaving the atmosphere, i.e. upper limit of atmosphere.
- */
- private double rbar;
- /** Simple constructor with custom force.
- * @param force atmospheric drag force model
- * @param mu central attraction coefficient
- */
- public DSSTAtmosphericDrag(final DragForce force, final double mu) {
- //Call to the constructor from superclass using the numerical drag model as ForceModel
- super("DSST-drag-", GAUSS_THRESHOLD, force, mu);
- this.drag = force;
- this.rbar = DEFAULT_MAX_ATMOSPHERE_ALTITUDE + Constants.WGS84_EARTH_EQUATORIAL_RADIUS;
- }
- /** Simple constructor assuming spherical spacecraft.
- * @param atmosphere atmospheric model
- * @param cd drag coefficient
- * @param area cross sectionnal area of satellite
- * @param mu central attraction coefficient
- */
- public DSSTAtmosphericDrag(final Atmosphere atmosphere, final double cd,
- final double area, final double mu) {
- this(atmosphere, new IsotropicDrag(area, cd), mu);
- }
- /** Simple constructor with custom spacecraft.
- * @param atmosphere atmospheric model
- * @param spacecraft spacecraft model
- * @param mu central attraction coefficient
- */
- public DSSTAtmosphericDrag(final Atmosphere atmosphere, final DragSensitive spacecraft, final double mu) {
- //Call to the constructor from superclass using the numerical drag model as ForceModel
- this(new DragForce(atmosphere, spacecraft), mu);
- }
- /** Get the atmospheric model.
- * @return atmosphere model
- */
- public Atmosphere getAtmosphere() {
- return drag.getAtmosphere();
- }
- /** Get the critical distance.
- * <p>
- * The critical distance from the center of the central body aims at
- * defining the atmosphere entry/exit.
- * </p>
- * @return the critical distance from the center of the central body (m)
- */
- public double getRbar() {
- return rbar;
- }
- /** Set the critical distance from the center of the central body at which
- * the atmosphere is considered to end, i.e. beyond this distance
- * atmospheric drag is not considered.
- *
- * @param rbar the critical distance from the center of the central body (m)
- */
- public void setRbar(final double rbar) {
- this.rbar = rbar;
- }
- /** {@inheritDoc} */
- public Stream<EventDetector> getEventDetectors() {
- return drag.getEventDetectors();
- }
- /** {@inheritDoc} */
- @Override
- public <T extends CalculusFieldElement<T>> Stream<FieldEventDetector<T>> getFieldEventDetectors(final Field<T> field) {
- return drag.getFieldEventDetectors(field);
- }
- /** {@inheritDoc} */
- protected double[] getLLimits(final SpacecraftState state, final AuxiliaryElements auxiliaryElements) {
- final double perigee = auxiliaryElements.getSma() * (1. - auxiliaryElements.getEcc());
- // Trajectory entirely out of the atmosphere
- if (perigee > rbar) {
- return new double[2];
- }
- final double apogee = auxiliaryElements.getSma() * (1. + auxiliaryElements.getEcc());
- // Trajectory entirely within of the atmosphere
- if (apogee < rbar) {
- return new double[] { -FastMath.PI + MathUtils.normalizeAngle(state.getLv(), 0),
- FastMath.PI + MathUtils.normalizeAngle(state.getLv(), 0) };
- }
- // Else, trajectory partialy within of the atmosphere
- final double fb = FastMath.acos(((auxiliaryElements.getSma() * (1. - auxiliaryElements.getEcc() * auxiliaryElements.getEcc()) / rbar) - 1.) / auxiliaryElements.getEcc());
- final double wW = FastMath.atan2(auxiliaryElements.getH(), auxiliaryElements.getK());
- return new double[] {wW - fb, wW + fb};
- }
- /** {@inheritDoc} */
- protected <T extends CalculusFieldElement<T>> T[] getLLimits(final FieldSpacecraftState<T> state,
- final FieldAuxiliaryElements<T> auxiliaryElements) {
- final Field<T> field = state.getDate().getField();
- final T[] tab = MathArrays.buildArray(field, 2);
- final T perigee = auxiliaryElements.getSma().multiply(auxiliaryElements.getEcc().negate().add(1.));
- // Trajectory entirely out of the atmosphere
- if (perigee.getReal() > rbar) {
- return tab;
- }
- final T apogee = auxiliaryElements.getSma().multiply(auxiliaryElements.getEcc().add(1.));
- // Trajectory entirely within of the atmosphere
- if (apogee.getReal() < rbar) {
- final T zero = field.getZero();
- final T pi = zero.getPi();
- tab[0] = MathUtils.normalizeAngle(state.getLv(), zero).subtract(pi);
- tab[1] = MathUtils.normalizeAngle(state.getLv(), zero).add(pi);
- return tab;
- }
- // Else, trajectory partialy within of the atmosphere
- final T fb = FastMath.acos(((auxiliaryElements.getSma().multiply(auxiliaryElements.getEcc().multiply(auxiliaryElements.getEcc()).negate().add(1.)).divide(rbar)).subtract(1.)).divide(auxiliaryElements.getEcc()));
- final T wW = FastMath.atan2(auxiliaryElements.getH(), auxiliaryElements.getK());
- tab[0] = wW.subtract(fb);
- tab[1] = wW.add(fb);
- return tab;
- }
- /** {@inheritDoc} */
- @Override
- protected List<ParameterDriver> getParametersDriversWithoutMu() {
- return drag.getParametersDrivers();
- }
- /** Get spacecraft shape.
- *
- * @return spacecraft shape
- */
- public DragSensitive getSpacecraft() {
- return drag.getSpacecraft();
- }
- /** Get drag force.
- *
- * @return drag force
- */
- public DragForce getDrag() {
- return drag;
- }
- }