/* Copyright 2002-2017 CS Systèmes d'Information
* Licensed to CS Systèmes d'Information (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,
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package org.orekit.forces.gravity;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.hipparchus.ode.AbstractIntegrator;
import org.hipparchus.ode.nonstiff.DormandPrince853Integrator;
import org.hipparchus.util.FastMath;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.orekit.Utils;
import org.orekit.bodies.CelestialBodyFactory;
import org.orekit.errors.OrekitException;
import org.orekit.forces.ForceModel;
import org.orekit.forces.gravity.potential.GravityFieldFactory;
import org.orekit.forces.gravity.potential.NormalizedSphericalHarmonicsProvider;
import org.orekit.frames.Frame;
import org.orekit.frames.FramesFactory;
import org.orekit.orbits.KeplerianOrbit;
import org.orekit.orbits.Orbit;
import org.orekit.orbits.OrbitType;
import org.orekit.orbits.PositionAngle;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.numerical.NumericalPropagator;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.TimeScale;
import org.orekit.time.TimeScalesFactory;
import org.orekit.time.UT1Scale;
import org.orekit.utils.Constants;
import org.orekit.utils.IERSConventions;
public class SolidTidesTest {
@Test
public void testDefaultInterpolation() throws OrekitException {
IERSConventions conventions = IERSConventions.IERS_2010;
Frame eme2000 = FramesFactory.getEME2000();
Frame itrf = FramesFactory.getITRF(conventions, true);
TimeScale utc = TimeScalesFactory.getUTC();
UT1Scale ut1 = TimeScalesFactory.getUT1(conventions, true);
NormalizedSphericalHarmonicsProvider gravityField =
GravityFieldFactory.getConstantNormalizedProvider(5, 5);
// initialization
AbsoluteDate date = new AbsoluteDate(1970, 07, 01, 13, 59, 27.816, utc);
Orbit orbit = new KeplerianOrbit(7201009.7124401, 1e-3, FastMath.toRadians(98.7),
FastMath.toRadians(93.0), FastMath.toRadians(15.0 * 22.5),
0, PositionAngle.MEAN, eme2000, date,
gravityField.getMu());
AbsoluteDate target = date.shiftedBy(7 * Constants.JULIAN_DAY);
ForceModel hf = new HolmesFeatherstoneAttractionModel(itrf, gravityField);
SpacecraftState raw = propagate(orbit, target, hf,
new SolidTides(itrf, gravityField.getAe(), gravityField.getMu(),
gravityField.getTideSystem(), true, Double.NaN, -1,
conventions, ut1,
CelestialBodyFactory.getSun(),
CelestialBodyFactory.getMoon()));
SpacecraftState interpolated = propagate(orbit, target, hf,
new SolidTides(itrf, gravityField.getAe(), gravityField.getMu(),
gravityField.getTideSystem(),
conventions, ut1,
CelestialBodyFactory.getSun(),
CelestialBodyFactory.getMoon()));
Assert.assertEquals(0.0,
Vector3D.distance(raw.getPVCoordinates().getPosition(),
interpolated.getPVCoordinates().getPosition()),
2.0e-5); // threshold would be 1.2e-3 for 30 days propagation
}
@Test
public void testTideEffect1996() throws OrekitException {
Frame eme2000 = FramesFactory.getEME2000();
TimeScale utc = TimeScalesFactory.getUTC();
AbsoluteDate date = new AbsoluteDate(2003, 07, 01, 13, 59, 27.816, utc);
Orbit orbit = new KeplerianOrbit(7201009.7124401, 1e-3, FastMath.toRadians(98.7),
FastMath.toRadians(93.0), FastMath.toRadians(15.0 * 22.5),
0, PositionAngle.MEAN, eme2000, date,
Constants.EIGEN5C_EARTH_MU);
doTestTideEffect(orbit, IERSConventions.IERS_1996, 44.09481, 0.00000);
}
@Test
public void testTideEffect2003WithinAnnualPoleRange() throws OrekitException {
Frame eme2000 = FramesFactory.getEME2000();
TimeScale utc = TimeScalesFactory.getUTC();
AbsoluteDate date = new AbsoluteDate(1969, 07, 01, 13, 59, 27.816, utc);
Orbit orbit = new KeplerianOrbit(7201009.7124401, 1e-3, FastMath.toRadians(98.7),
FastMath.toRadians(93.0), FastMath.toRadians(15.0 * 22.5),
0, PositionAngle.MEAN, eme2000, date,
Constants.EIGEN5C_EARTH_MU);
doTestTideEffect(orbit, IERSConventions.IERS_2003, 73.14011, 0.87360);
}
@Test
public void testTideEffect2003AfterAnnualPoleRange() throws OrekitException {
Frame eme2000 = FramesFactory.getEME2000();
TimeScale utc = TimeScalesFactory.getUTC();
AbsoluteDate date = new AbsoluteDate(2003, 07, 01, 13, 59, 27.816, utc);
Orbit orbit = new KeplerianOrbit(7201009.7124401, 1e-3, FastMath.toRadians(98.7),
FastMath.toRadians(93.0), FastMath.toRadians(15.0 * 22.5),
0, PositionAngle.MEAN, eme2000, date,
Constants.EIGEN5C_EARTH_MU);
doTestTideEffect(orbit, IERSConventions.IERS_2003, 44.24999, 0.61752);
}
@Test
public void testTideEffect2010BeforePoleModelChange() throws OrekitException {
Frame eme2000 = FramesFactory.getEME2000();
TimeScale utc = TimeScalesFactory.getUTC();
AbsoluteDate date = new AbsoluteDate(2003, 07, 01, 13, 59, 27.816, utc);
Orbit orbit = new KeplerianOrbit(7201009.7124401, 1e-3, FastMath.toRadians(98.7),
FastMath.toRadians(93.0), FastMath.toRadians(15.0 * 22.5),
0, PositionAngle.MEAN, eme2000, date,
Constants.EIGEN5C_EARTH_MU);
doTestTideEffect(orbit, IERSConventions.IERS_2010, 44.25001, 0.70710);
}
@Test
public void testTideEffect2010AfterModelChange() throws OrekitException {
Frame eme2000 = FramesFactory.getEME2000();
TimeScale utc = TimeScalesFactory.getUTC();
AbsoluteDate date = new AbsoluteDate(2964, 8, 12, 11, 30, 00.000, utc);
Orbit orbit = new KeplerianOrbit(7201009.7124401, 1e-3, FastMath.toRadians(98.7),
FastMath.toRadians(93.0), FastMath.toRadians(15.0 * 22.5),
0, PositionAngle.MEAN, eme2000, date,
Constants.EIGEN5C_EARTH_MU);
doTestTideEffect(orbit, IERSConventions.IERS_2010, 24.02815, 30.92816);
}
private void doTestTideEffect(Orbit orbit, IERSConventions conventions, double delta1, double delta2)
throws OrekitException {
Frame itrf = FramesFactory.getITRF(conventions, true);
UT1Scale ut1 = TimeScalesFactory.getUT1(conventions, true);
NormalizedSphericalHarmonicsProvider gravityField =
GravityFieldFactory.getConstantNormalizedProvider(5, 5);
// initialization
AbsoluteDate target = orbit.getDate().shiftedBy(7 * Constants.JULIAN_DAY);
ForceModel hf = new HolmesFeatherstoneAttractionModel(itrf, gravityField);
SpacecraftState noTides = propagate(orbit, target, hf);
SpacecraftState solidTidesNoPoleTide = propagate(orbit, target, hf,
new SolidTides(itrf, gravityField.getAe(), gravityField.getMu(),
gravityField.getTideSystem(), false,
SolidTides.DEFAULT_STEP, SolidTides.DEFAULT_POINTS,
conventions, ut1,
CelestialBodyFactory.getSun(),
CelestialBodyFactory.getMoon()));
SpacecraftState solidTidesPoleTide = propagate(orbit, target, hf,
new SolidTides(itrf, gravityField.getAe(), gravityField.getMu(),
gravityField.getTideSystem(), true,
SolidTides.DEFAULT_STEP, SolidTides.DEFAULT_POINTS,
conventions, ut1,
CelestialBodyFactory.getSun(),
CelestialBodyFactory.getMoon()));
Assert.assertEquals(delta1,
Vector3D.distance(noTides.getPVCoordinates().getPosition(),
solidTidesNoPoleTide.getPVCoordinates().getPosition()),
0.01);
Assert.assertEquals(delta2,
Vector3D.distance(solidTidesNoPoleTide.getPVCoordinates().getPosition(),
solidTidesPoleTide.getPVCoordinates().getPosition()),
0.01);
}
private SpacecraftState propagate(Orbit orbit, AbsoluteDate target, ForceModel... forceModels)
throws OrekitException {
double[][] tolerances = NumericalPropagator.tolerances(10, orbit, OrbitType.KEPLERIAN);
AbstractIntegrator integrator = new DormandPrince853Integrator(1.0e-3, 300, tolerances[0], tolerances[1]);
NumericalPropagator propagator = new NumericalPropagator(integrator);
for (ForceModel forceModel : forceModels) {
propagator.addForceModel(forceModel);
}
propagator.setInitialState(new SpacecraftState(orbit));
return propagator.propagate(target);
}
@Before
public void setUp() {
Utils.setDataRoot("regular-data:potential/icgem-format");
}
}