1   /* Copyright 2002-2025 CS GROUP
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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
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9    *   http://www.apache.org/licenses/LICENSE-2.0
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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
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16   */
17  package org.orekit.forces.radiation;
18  
19  import java.util.ArrayList;
20  import java.util.Collections;
21  import java.util.List;
22  
23  import org.hipparchus.CalculusFieldElement;
24  import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
25  import org.hipparchus.geometry.euclidean.threed.Vector3D;
26  import org.hipparchus.util.FastMath;
27  import org.orekit.propagation.FieldSpacecraftState;
28  import org.orekit.propagation.SpacecraftState;
29  import org.orekit.utils.ParameterDriver;
30  
31  /** This class represents the features of a simplified spacecraft.
32   * <p>This model uses a single coefficient cr, considered to be
33   * a {@link RadiationSensitive#REFLECTION_COEFFICIENT}.
34   * </p>
35   *
36   * @see org.orekit.forces.BoxAndSolarArraySpacecraft
37   * @see org.orekit.forces.drag.IsotropicDrag
38   * @see IsotropicRadiationCNES95Convention
39   * @author Luc Maisonobe
40   * @since 7.1
41   */
42  public class IsotropicRadiationSingleCoefficient implements RadiationSensitive {
43  
44      /** Parameters scaling factor.
45       * <p>
46       * We use a power of 2 to avoid numeric noise introduction
47       * in the multiplications/divisions sequences.
48       * </p>
49       */
50      private final double SCALE = FastMath.scalb(1.0, -3);
51  
52      /** Drivers for radiation coefficient. */
53      private final List<ParameterDriver> radiationParametersDrivers;
54  
55      /** Cross section (m²). */
56      private final double crossSection;
57  
58      /** Constructor with reflection coefficient min/max set to ±∞.
59       * @param crossSection Surface (m²)
60       * @param cr reflection coefficient
61       */
62      public IsotropicRadiationSingleCoefficient(final double crossSection, final double cr) {
63          this(crossSection, cr, Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY);
64      }
65  
66      /** Constructor with reflection coefficient min/max set by user.
67      * @param crossSection Surface (m²)
68      * @param cr reflection coefficient
69      * @param crMin Minimum value of reflection coefficient
70      * @param crMax Maximum value of reflection coefficient
71      */
72      public IsotropicRadiationSingleCoefficient(final double crossSection, final double cr,
73                                                 final double crMin, final double crMax) {
74          // in some corner cases (unknown spacecraft, fuel leaks, active piloting ...)
75          // the single coefficient may be arbitrary, and even negative
76          // the REFLECTION_COEFFICIENT parameter should be sufficient, but GLOBAL_RADIATION_FACTOR
77          // was added as of 12.0 for consistency with BoxAndSolarArraySpacecraft
78          // that only has a global multiplicatof factor, hence allowing this name
79          // to be used for both models
80          this.radiationParametersDrivers = new ArrayList<>(2);
81          radiationParametersDrivers.add(new ParameterDriver(RadiationSensitive.GLOBAL_RADIATION_FACTOR,
82                                                             1.0, SCALE,
83                                                             0.0, Double.POSITIVE_INFINITY));
84          radiationParametersDrivers.add(new ParameterDriver(RadiationSensitive.REFLECTION_COEFFICIENT,
85                                                             cr, SCALE,
86                                                             crMin, crMax));
87  
88          this.crossSection = crossSection;
89  
90      }
91  
92      /** {@inheritDoc} */
93      @Override
94      public List<ParameterDriver> getRadiationParametersDrivers() {
95          return Collections.unmodifiableList(radiationParametersDrivers);
96      }
97  
98      /** {@inheritDoc} */
99      @Override
100     public Vector3D radiationPressureAcceleration(final SpacecraftState state, final Vector3D flux,
101                                                   final double[] parameters) {
102         final double cr = parameters[1];
103         return new Vector3D(parameters[0] * crossSection * cr / state.getMass(), flux);
104     }
105 
106     /** {@inheritDoc} */
107     @Override
108     public <T extends CalculusFieldElement<T>> FieldVector3D<T>
109         radiationPressureAcceleration(final FieldSpacecraftState<T> state,
110                                       final FieldVector3D<T> flux,
111                                       final T[] parameters) {
112         final T cr = parameters[1];
113         return new FieldVector3D<>(state.getMass().reciprocal().multiply(parameters[0]).multiply(crossSection).multiply(cr),
114                                    flux);
115 
116     }
117 }