IsotropicRadiationClassicalConvention.java
/* Copyright 2002-2024 CS GROUP
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* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
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*
* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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package org.orekit.forces.radiation;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.hipparchus.CalculusFieldElement;
import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.hipparchus.util.FastMath;
import org.orekit.propagation.FieldSpacecraftState;
import org.orekit.propagation.SpacecraftState;
import org.orekit.utils.ParameterDriver;
/** This class represents the features of a simplified spacecraft.
* <p>This model uses the classical thermo-optical coefficients
* Ca for absorption, Cs for specular reflection and Cd for diffuse
* reflection. The equation Ca + Cs + Cd = 1 always holds.
* </p>
* <p>
* A less standard set of coefficients α = Ca for absorption and
* τ = Cs/(1-Ca) for specular reflection is implemented in the sister
* class {@link IsotropicRadiationCNES95Convention}.
* </p>
*
* @see org.orekit.forces.BoxAndSolarArraySpacecraft
* @see org.orekit.forces.drag.IsotropicDrag
* @see IsotropicRadiationCNES95Convention
* @author Luc Maisonobe
* @since 7.1
*/
public class IsotropicRadiationClassicalConvention implements RadiationSensitive {
/** Parameters scaling factor.
* <p>
* We use a power of 2 to avoid numeric noise introduction
* in the multiplications/divisions sequences.
* </p>
*/
private final double SCALE = FastMath.scalb(1.0, -3);
/** Drivers for absorption and reflection coefficients. */
private final List<ParameterDriver> parameterDrivers;
/** Cross section (m²). */
private final double crossSection;
/** Simple constructor.
* @param crossSection Surface (m²)
* @param ca absorption coefficient Ca between 0.0 an 1.0
* @param cs specular reflection coefficient Cs between 0.0 an 1.0
*/
public IsotropicRadiationClassicalConvention(final double crossSection, final double ca, final double cs) {
this.parameterDrivers = new ArrayList<>(3);
parameterDrivers.add(new ParameterDriver(RadiationSensitive.GLOBAL_RADIATION_FACTOR, 1.0, SCALE, 0.0, Double.POSITIVE_INFINITY));
parameterDrivers.add(new ParameterDriver(RadiationSensitive.ABSORPTION_COEFFICIENT, ca, SCALE, 0.0, 1.0));
parameterDrivers.add(new ParameterDriver(RadiationSensitive.REFLECTION_COEFFICIENT, cs, SCALE, 0.0, 1.0));
this.crossSection = crossSection;
}
/** {@inheritDoc} */
@Override
public List<ParameterDriver> getRadiationParametersDrivers() {
return Collections.unmodifiableList(parameterDrivers);
}
/** {@inheritDoc} */
@Override
public Vector3D radiationPressureAcceleration(final SpacecraftState state, final Vector3D flux,
final double[] parameters) {
final double ca = parameters[1];
final double cs = parameters[2];
final double kP = parameters[0] * crossSection * (1 + 4 * (1.0 - ca - cs) / 9.0);
return new Vector3D(kP / state.getMass(), flux);
}
/** {@inheritDoc} */
@Override
public <T extends CalculusFieldElement<T>> FieldVector3D<T>
radiationPressureAcceleration(final FieldSpacecraftState<T> state,
final FieldVector3D<T> flux,
final T[] parameters) {
final T ca = parameters[1];
final T cs = parameters[2];
final T kP = ca.add(cs).negate().add(1).multiply(4.0 / 9.0).add(1).
multiply(parameters[0]).multiply(crossSection);
return new FieldVector3D<>(state.getMass().reciprocal().multiply(kP), flux);
}
}