1   /* Copyright 2002-2025 CS GROUP
2    * Licensed to CS GROUP (CS) under one or more
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
7    * the License.  You may obtain a copy of the License at
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
15   * limitations under the License.
16   */
17  package org.orekit.orbits;
18  
19  import org.orekit.bodies.CR3BPSystem;
20  import org.orekit.utils.PVCoordinates;
21  
22  /** Class calculating different parameters of a Halo Orbit.
23   * @author Vincent Mouraux
24   * @since 10.2
25   */
26  public class HaloOrbit extends LibrationOrbit {
27  
28      /**
29       * Simple Constructor.
30       * <p>
31       * This constructor can be used if the user wants to use a first guess from
32       * any other sources or if he has the initial conditions of a well defined Halo Orbit.
33       * In that case, it is assumed that the user knows the
34       * characteristics of the Halo Orbit leading to this first guess/point. Also, the
35       * orbital period of this Halo Orbit has to be specified for further
36       * computation.
37       * </p>
38       * @param syst CR3BP System considered
39       * @param pv PVCoordinates of the initial point or of the first guess
40       * @param orbitalPeriod Normalized orbital period linked to the given Halo Orbit first guess
41       */
42      public HaloOrbit(final CR3BPSystem syst,
43                       final PVCoordinates pv, final double orbitalPeriod) {
44          super(syst, pv, orbitalPeriod);
45      }
46  
47      /**
48       * Simple Constructor.
49       * <p>
50       * Standard constructor, the first guess will be computed with both start
51       * time and phase equal to zero.
52       * </p>
53       * @param richardson third-Order Richardson Expansion
54       * @param az z-axis Amplitude of the required Halo Orbit, meters
55       * @param type type of the Halo Orbit (Northern or Southern)
56       */
57      public HaloOrbit(final RichardsonExpansion richardson,
58                       final double az, final LibrationOrbitFamily type) {
59          super(richardson.getCr3bpSystem(),
60                richardson.computeHaloFirstGuess(az, type, 0.0, 0.0),
61                richardson.getHaloOrbitalPeriod(az));
62      }
63  
64      /** {@inheritDoc} */
65      @Override
66      protected PVCoordinates applyCorrectionOnPV(final CR3BPDifferentialCorrection diff) {
67          return diff.compute(LibrationOrbitType.HALO);
68      }
69  
70  }
71