1   /* Copyright 2002-2024 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
6    * (the "License"); you may not use this file except in compliance with
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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
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16   */
17  package org.orekit.propagation.analytical.tle;
18  
19  import java.util.List;
20  
21  import org.hipparchus.analysis.differentiation.Gradient;
22  import org.orekit.attitudes.AttitudeProvider;
23  import org.orekit.frames.Frame;
24  import org.orekit.propagation.FieldSpacecraftState;
25  import org.orekit.propagation.analytical.AbstractAnalyticalGradientConverter;
26  import org.orekit.time.TimeScale;
27  import org.orekit.utils.ParameterDriver;
28  import org.orekit.utils.ParameterDriversProvider;
29  
30  /** Converter for TLE propagator.
31   * @author Luc Maisonobe
32   * @author Bryan Cazabonne
33   * @author Thomas Paulet
34   * @since 11.0
35   */
36  class TLEGradientConverter extends AbstractAnalyticalGradientConverter implements ParameterDriversProvider {
37  
38      /** Fixed dimension of the state. */
39      public static final int FREE_STATE_PARAMETERS = 6;
40  
41      /** Current TLE. */
42      private final TLE tle;
43  
44      /** UTC time scale. */
45      private final TimeScale utc;
46  
47      /** TEME frame. */
48      private final Frame teme;
49  
50      /** Attitude provider. */
51      private final AttitudeProvider provider;
52  
53      /** Simple constructor.
54       * @param propagator TLE propagator used to access initial orbit
55       */
56      TLEGradientConverter(final TLEPropagator propagator) {
57          super(propagator, TLEConstants.MU, FREE_STATE_PARAMETERS);
58          // TLE and related parameters
59          this.tle      = propagator.getTLE();
60          this.teme     = propagator.getFrame();
61          this.utc      = tle.getUtc();
62          this.provider = propagator.getAttitudeProvider();
63      }
64  
65      /** {@inheritDoc} */
66      @Override
67      public FieldTLEPropagator<Gradient> getPropagator(final FieldSpacecraftState<Gradient> state,
68                                                        final Gradient[] parameters) {
69  
70          // Zero
71          final Gradient zero = state.getA().getField().getZero();
72  
73          // Template TLE
74          final int satelliteNumber         = tle.getSatelliteNumber();
75          final char classification         = tle.getClassification();
76          final int launchYear              = tle.getLaunchYear();
77          final int launchNumber            = tle.getLaunchNumber();
78          final String launchPiece          = tle.getLaunchPiece();
79          final int ephemerisType           = tle.getEphemerisType();
80          final int elementNumber           = tle.getElementNumber();
81          final int revolutionNumberAtEpoch = tle.getRevolutionNumberAtEpoch();
82          final double bStar                = tle.getBStar(state.getDate().toAbsoluteDate());
83  
84          // Initialize the new TLE
85          final FieldTLE<Gradient> templateTLE = new FieldTLE<>(satelliteNumber, classification,
86                          launchYear, launchNumber, launchPiece, ephemerisType, elementNumber, state.getDate(),
87                          zero, zero, zero, zero, zero, zero, zero, zero,
88                          revolutionNumberAtEpoch, bStar, utc);
89  
90          // TLE
91          final FieldTLE<Gradient> gTLE = TLEPropagator.getDefaultTleGenerationAlgorithm(utc, teme).generate(state, templateTLE);
92  
93          // Return the "Field" propagator
94          return FieldTLEPropagator.selectExtrapolator(gTLE, provider, state.getMass(), teme, parameters);
95  
96      }
97  
98      /** {@inheritDoc} */
99      @Override
100     public List<ParameterDriver> getParametersDrivers() {
101         return tle.getParametersDrivers();
102     }
103 
104 }