Examples with CelestialBody org.orekit.bodies.CelestialBody used on opensource projects

Example 21 with CelestialBody

use of org.orekit.bodies.CelestialBody in project Orekit by CS-SI.

the class SolidTidesField method onDate.

/**
 * {@inheritDoc}
 */
@Override
public NormalizedSphericalHarmonics onDate(final AbsoluteDate date) throws OrekitException {
    // computed Cnm and Snm coefficients
    final double[][] cnm = buildTriangularArray(5, true);
    final double[][] snm = buildTriangularArray(5, true);
    // work array to hold Legendre coefficients
    final double[][] pnm = buildTriangularArray(5, true);
    // equations 6.6 (for degrees 2 and 3) and 6.7 (for degree 4) in IERS conventions 2010
    for (final CelestialBody body : bodies) {
        // compute tide generating body state
        final Vector3D position = body.getPVCoordinates(date, centralBodyFrame).getPosition();
        // compute polar coordinates
        final double x = position.getX();
        final double y = position.getY();
        final double z = position.getZ();
        final double x2 = x * x;
        final double y2 = y * y;
        final double z2 = z * z;
        final double r2 = x2 + y2 + z2;
        final double r = FastMath.sqrt(r2);
        final double rho2 = x2 + y2;
        final double rho = FastMath.sqrt(rho2);
        // evaluate Pnm
        evaluateLegendre(z / r, rho / r, pnm);
        // update spherical harmonic coefficients
        frequencyIndependentPart(r, body.getGM(), x / rho, y / rho, pnm, cnm, snm);
    }
    // step 2: frequency dependent corrections
    frequencyDependentPart(date, cnm, snm);
    if (centralTideSystem == TideSystem.ZERO_TIDE) {
        // step 3: remove permanent tide which is already considered
        // in the central body gravity field
        removePermanentTide(cnm);
    }
    if (poleTideFunction != null) {
        // add pole tide
        poleTide(date, cnm, snm);
    }
    return new TideHarmonics(date, cnm, snm);
}

Example 22 with CelestialBody

use of org.orekit.bodies.CelestialBody in project Orekit by CS-SI.

the class KalmanOrbitDeterminationTest method createPropagatorBuilder.

/**
 * Create a propagator builder from input parameters
 * @param parser input file parser
 * @param conventions IERS conventions to use
 * @param gravityField gravity field
 * @param body central body
 * @param orbit first orbit estimate
 * @return propagator builder
 * @throws NoSuchElementException if input parameters are missing
 * @throws OrekitException if body frame cannot be created
 */
private NumericalPropagatorBuilder createPropagatorBuilder(final KeyValueFileParser<ParameterKey> parser, final IERSConventions conventions, final NormalizedSphericalHarmonicsProvider gravityField, final OneAxisEllipsoid body, final Orbit orbit) throws NoSuchElementException, OrekitException {
    final double minStep;
    if (!parser.containsKey(ParameterKey.PROPAGATOR_MIN_STEP)) {
        minStep = 0.001;
    } else {
        minStep = parser.getDouble(ParameterKey.PROPAGATOR_MIN_STEP);
    }
    final double maxStep;
    if (!parser.containsKey(ParameterKey.PROPAGATOR_MAX_STEP)) {
        maxStep = 300;
    } else {
        maxStep = parser.getDouble(ParameterKey.PROPAGATOR_MAX_STEP);
    }
    final double dP;
    if (!parser.containsKey(ParameterKey.PROPAGATOR_POSITION_ERROR)) {
        dP = 10.0;
    } else {
        dP = parser.getDouble(ParameterKey.PROPAGATOR_POSITION_ERROR);
    }
    final double positionScale;
    if (!parser.containsKey(ParameterKey.ESTIMATOR_ORBITAL_PARAMETERS_POSITION_SCALE)) {
        positionScale = dP;
    } else {
        positionScale = parser.getDouble(ParameterKey.ESTIMATOR_ORBITAL_PARAMETERS_POSITION_SCALE);
    }
    final NumericalPropagatorBuilder propagatorBuilder = new NumericalPropagatorBuilder(orbit, new DormandPrince853IntegratorBuilder(minStep, maxStep, dP), PositionAngle.MEAN, positionScale);
    // initial mass
    final double mass;
    if (!parser.containsKey(ParameterKey.MASS)) {
        mass = 1000.0;
    } else {
        mass = parser.getDouble(ParameterKey.MASS);
    }
    propagatorBuilder.setMass(mass);
    // gravity field force model
    propagatorBuilder.addForceModel(new HolmesFeatherstoneAttractionModel(body.getBodyFrame(), gravityField));
    // ocean tides force model
    if (parser.containsKey(ParameterKey.OCEAN_TIDES_DEGREE) && parser.containsKey(ParameterKey.OCEAN_TIDES_ORDER)) {
        final int degree = parser.getInt(ParameterKey.OCEAN_TIDES_DEGREE);
        final int order = parser.getInt(ParameterKey.OCEAN_TIDES_ORDER);
        if (degree > 0 && order > 0) {
            propagatorBuilder.addForceModel(new OceanTides(body.getBodyFrame(), gravityField.getAe(), gravityField.getMu(), degree, order, conventions, TimeScalesFactory.getUT1(conventions, true)));
        }
    }
    // solid tides force model
    List<CelestialBody> solidTidesBodies = new ArrayList<CelestialBody>();
    if (parser.containsKey(ParameterKey.SOLID_TIDES_SUN) && parser.getBoolean(ParameterKey.SOLID_TIDES_SUN)) {
        solidTidesBodies.add(CelestialBodyFactory.getSun());
    }
    if (parser.containsKey(ParameterKey.SOLID_TIDES_MOON) && parser.getBoolean(ParameterKey.SOLID_TIDES_MOON)) {
        solidTidesBodies.add(CelestialBodyFactory.getMoon());
    }
    if (!solidTidesBodies.isEmpty()) {
        propagatorBuilder.addForceModel(new SolidTides(body.getBodyFrame(), gravityField.getAe(), gravityField.getMu(), gravityField.getTideSystem(), conventions, TimeScalesFactory.getUT1(conventions, true), solidTidesBodies.toArray(new CelestialBody[solidTidesBodies.size()])));
    }
    // third body attraction
    if (parser.containsKey(ParameterKey.THIRD_BODY_SUN) && parser.getBoolean(ParameterKey.THIRD_BODY_SUN)) {
        propagatorBuilder.addForceModel(new ThirdBodyAttraction(CelestialBodyFactory.getSun()));
    }
    if (parser.containsKey(ParameterKey.THIRD_BODY_MOON) && parser.getBoolean(ParameterKey.THIRD_BODY_MOON)) {
        propagatorBuilder.addForceModel(new ThirdBodyAttraction(CelestialBodyFactory.getMoon()));
    }
    // drag
    if (parser.containsKey(ParameterKey.DRAG) && parser.getBoolean(ParameterKey.DRAG)) {
        final double cd = parser.getDouble(ParameterKey.DRAG_CD);
        final double area = parser.getDouble(ParameterKey.DRAG_AREA);
        final boolean cdEstimated = parser.getBoolean(ParameterKey.DRAG_CD_ESTIMATED);
        MarshallSolarActivityFutureEstimation msafe = new MarshallSolarActivityFutureEstimation("(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\\p{Digit}\\p{Digit}\\p{Digit}\\p{Digit}F10\\.(?:txt|TXT)", MarshallSolarActivityFutureEstimation.StrengthLevel.AVERAGE);
        DataProvidersManager manager = DataProvidersManager.getInstance();
        manager.feed(msafe.getSupportedNames(), msafe);
        Atmosphere atmosphere = new DTM2000(msafe, CelestialBodyFactory.getSun(), body);
        propagatorBuilder.addForceModel(new DragForce(atmosphere, new IsotropicDrag(area, cd)));
        if (cdEstimated) {
            for (final ParameterDriver driver : propagatorBuilder.getPropagationParametersDrivers().getDrivers()) {
                if (driver.getName().equals(DragSensitive.DRAG_COEFFICIENT)) {
                    driver.setSelected(true);
                }
            }
        }
    }
    // solar radiation pressure
    if (parser.containsKey(ParameterKey.SOLAR_RADIATION_PRESSURE) && parser.getBoolean(ParameterKey.SOLAR_RADIATION_PRESSURE)) {
        final double cr = parser.getDouble(ParameterKey.SOLAR_RADIATION_PRESSURE_CR);
        final double area = parser.getDouble(ParameterKey.SOLAR_RADIATION_PRESSURE_AREA);
        final boolean cREstimated = parser.getBoolean(ParameterKey.SOLAR_RADIATION_PRESSURE_CR_ESTIMATED);
        propagatorBuilder.addForceModel(new SolarRadiationPressure(CelestialBodyFactory.getSun(), body.getEquatorialRadius(), new IsotropicRadiationSingleCoefficient(area, cr)));
        if (cREstimated) {
            for (final ParameterDriver driver : propagatorBuilder.getPropagationParametersDrivers().getDrivers()) {
                if (driver.getName().equals(RadiationSensitive.REFLECTION_COEFFICIENT)) {
                    driver.setSelected(true);
                }
            }
        }
    }
    // post-Newtonian correction force due to general relativity
    if (parser.containsKey(ParameterKey.GENERAL_RELATIVITY) && parser.getBoolean(ParameterKey.GENERAL_RELATIVITY)) {
        propagatorBuilder.addForceModel(new Relativity(gravityField.getMu()));
    }
    // extra polynomial accelerations
    if (parser.containsKey(ParameterKey.POLYNOMIAL_ACCELERATION_NAME)) {
        final String[] names = parser.getStringArray(ParameterKey.POLYNOMIAL_ACCELERATION_NAME);
        final Vector3D[] directions = parser.getVectorArray(ParameterKey.POLYNOMIAL_ACCELERATION_DIRECTION_X, ParameterKey.POLYNOMIAL_ACCELERATION_DIRECTION_Y, ParameterKey.POLYNOMIAL_ACCELERATION_DIRECTION_Z);
        final List<String>[] coefficients = parser.getStringsListArray(ParameterKey.POLYNOMIAL_ACCELERATION_COEFFICIENTS, ',');
        final boolean[] estimated = parser.getBooleanArray(ParameterKey.POLYNOMIAL_ACCELERATION_ESTIMATED);
        for (int i = 0; i < names.length; ++i) {
            final PolynomialParametricAcceleration ppa = new PolynomialParametricAcceleration(directions[i], true, names[i], null, coefficients[i].size() - 1);
            for (int k = 0; k < coefficients[i].size(); ++k) {
                final ParameterDriver driver = ppa.getParameterDriver(names[i] + "[" + k + "]");
                driver.setValue(Double.parseDouble(coefficients[i].get(k)));
                driver.setSelected(estimated[i]);
            }
            propagatorBuilder.addForceModel(ppa);
        }
    }
    return propagatorBuilder;
}

Example 23 with CelestialBody

use of org.orekit.bodies.CelestialBody in project Orekit by CS-SI.

the class OEMParserTest method testParseOemMissingOptionalData.

@Test
public void testParseOemMissingOptionalData() throws OrekitException, IOException {
    final String ex = "/ccsds/OEMExample6.txt";
    final InputStream inEntry = getClass().getResourceAsStream(ex);
    final OEMParser parser = new OEMParser().withMu(CelestialBodyFactory.getEarth().getGM()).withConventions(IERSConventions.IERS_2010);
    final OEMFile file = parser.parse(inEntry);
    Assert.assertEquals(CcsdsTimeScale.UTC, file.getEphemeridesBlocks().get(0).getMetaData().getTimeSystem());
    Assert.assertEquals("MARS GLOBAL SURVEYOR", file.getEphemeridesBlocks().get(0).getMetaData().getObjectName());
    Assert.assertEquals("1996-062A", file.getEphemeridesBlocks().get(0).getMetaData().getObjectID());
    Assert.assertEquals(1, file.getSatellites().size());
    Assert.assertEquals(true, file.getSatellites().containsKey("1996-062A"));
    Assert.assertEquals(false, file.getSatellites().containsKey("MARS GLOBAL SURVEYOR"));
    Assert.assertEquals(1, file.getSatellites().size());
    Assert.assertEquals("1996-062A", file.getSatellites().values().iterator().next().getId());
    Assert.assertEquals(new AbsoluteDate("2002-12-18T12:00:00.331", TimeScalesFactory.getUTC()), file.getEphemeridesBlocks().get(0).getStartTime());
    OemSatelliteEphemeris satellite = file.getSatellites().get("1996-062A");
    Assert.assertEquals(satellite.getId(), "1996-062A");
    Assert.assertEquals(satellite.getMu(), file.getMuUsed(), 0);
    EphemeridesBlock actualBlock = satellite.getSegments().get(0);
    Assert.assertEquals(actualBlock.getMu(), file.getMuUsed(), 0);
    FactoryManagedFrame eme2000 = FramesFactory.getEME2000();
    Frame actualFrame = actualBlock.getFrame();
    AbsoluteDate actualStart = satellite.getStart();
    Transform actualTransform = eme2000.getTransformTo(actualFrame, actualStart);
    CelestialBody mars = CelestialBodyFactory.getMars();
    TimeStampedPVCoordinates marsPV = mars.getPVCoordinates(actualStart, eme2000);
    Assert.assertEquals(actualTransform.getTranslation(), marsPV.getPosition());
    Assert.assertEquals(actualTransform.getVelocity(), marsPV.getVelocity());
    Assert.assertEquals(actualTransform.getAcceleration(), marsPV.getAcceleration());
    Assert.assertEquals(Rotation.distance(actualTransform.getRotation(), Rotation.IDENTITY), 0.0, 0.0);
    Assert.assertEquals(actualTransform.getRotationRate(), Vector3D.ZERO);
    Assert.assertEquals(actualTransform.getRotationAcceleration(), Vector3D.ZERO);
    Assert.assertEquals(actualFrame.getName(), "Mars/EME2000");
    Assert.assertEquals(actualBlock.getFrameString(), "EME2000");
    Assert.assertEquals(actualBlock.getTimeScaleString(), "UTC");
    Assert.assertEquals(actualBlock.getTimeScale(), TimeScalesFactory.getUTC());
    Assert.assertEquals(actualBlock.getAvailableDerivatives(), CartesianDerivativesFilter.USE_PV);
    Assert.assertEquals(satellite.getSegments().get(0).getStartTime(), actualStart);
    Assert.assertEquals(satellite.getSegments().get(2).getStopTime(), satellite.getStop());
    final BoundedPropagator propagator = satellite.getPropagator();
    Assert.assertEquals(propagator.getMinDate(), satellite.getStart());
    Assert.assertEquals(propagator.getMinDate(), satellite.getSegments().get(0).getStart());
    Assert.assertEquals(propagator.getMaxDate(), satellite.getStop());
    Assert.assertEquals(propagator.getMaxDate(), satellite.getSegments().get(2).getStop());
    final List<TimeStampedPVCoordinates> dataLines = new ArrayList<>();
    for (EphemeridesBlock block : file.getEphemeridesBlocks()) {
        for (TimeStampedPVCoordinates dataLine : block.getEphemeridesDataLines()) {
            if (dataLine.getDate().compareTo(satellite.getStart()) >= 0) {
                dataLines.add(dataLine);
            }
        }
    }
    final int ulps = 12;
    for (TimeStampedPVCoordinates coord : dataLines) {
        Assert.assertThat(propagator.getPVCoordinates(coord.getDate(), actualFrame), OrekitMatchers.pvCloseTo(coord, ulps));
        Assert.assertThat(propagator.propagate(coord.getDate()).getPVCoordinates(), OrekitMatchers.pvCloseTo(coord, ulps));
    }
}

Example 24 with CelestialBody

use of org.orekit.bodies.CelestialBody in project Orekit by CS-SI.

the class OrbitDeterminationTest method createPropagatorBuilder.

/**
 * Create a propagator builder from input parameters
 * @param parser input file parser
 * @param conventions IERS conventions to use
 * @param gravityField gravity field
 * @param body central body
 * @param orbit first orbit estimate
 * @return propagator builder
 * @throws NoSuchElementException if input parameters are missing
 * @throws OrekitException if body frame cannot be created
 */
private NumericalPropagatorBuilder createPropagatorBuilder(final KeyValueFileParser<ParameterKey> parser, final IERSConventions conventions, final NormalizedSphericalHarmonicsProvider gravityField, final OneAxisEllipsoid body, final Orbit orbit) throws NoSuchElementException, OrekitException {
    final double minStep;
    if (!parser.containsKey(ParameterKey.PROPAGATOR_MIN_STEP)) {
        minStep = 0.001;
    } else {
        minStep = parser.getDouble(ParameterKey.PROPAGATOR_MIN_STEP);
    }
    final double maxStep;
    if (!parser.containsKey(ParameterKey.PROPAGATOR_MAX_STEP)) {
        maxStep = 300;
    } else {
        maxStep = parser.getDouble(ParameterKey.PROPAGATOR_MAX_STEP);
    }
    final double dP;
    if (!parser.containsKey(ParameterKey.PROPAGATOR_POSITION_ERROR)) {
        dP = 10.0;
    } else {
        dP = parser.getDouble(ParameterKey.PROPAGATOR_POSITION_ERROR);
    }
    final double positionScale;
    if (!parser.containsKey(ParameterKey.ESTIMATOR_ORBITAL_PARAMETERS_POSITION_SCALE)) {
        positionScale = dP;
    } else {
        positionScale = parser.getDouble(ParameterKey.ESTIMATOR_ORBITAL_PARAMETERS_POSITION_SCALE);
    }
    final NumericalPropagatorBuilder propagatorBuilder = new NumericalPropagatorBuilder(orbit, new DormandPrince853IntegratorBuilder(minStep, maxStep, dP), PositionAngle.MEAN, positionScale);
    // initial mass
    final double mass;
    if (!parser.containsKey(ParameterKey.MASS)) {
        mass = 1000.0;
    } else {
        mass = parser.getDouble(ParameterKey.MASS);
    }
    propagatorBuilder.setMass(mass);
    // gravity field force model
    propagatorBuilder.addForceModel(new HolmesFeatherstoneAttractionModel(body.getBodyFrame(), gravityField));
    // ocean tides force model
    if (parser.containsKey(ParameterKey.OCEAN_TIDES_DEGREE) && parser.containsKey(ParameterKey.OCEAN_TIDES_ORDER)) {
        final int degree = parser.getInt(ParameterKey.OCEAN_TIDES_DEGREE);
        final int order = parser.getInt(ParameterKey.OCEAN_TIDES_ORDER);
        if (degree > 0 && order > 0) {
            propagatorBuilder.addForceModel(new OceanTides(body.getBodyFrame(), gravityField.getAe(), gravityField.getMu(), degree, order, conventions, TimeScalesFactory.getUT1(conventions, true)));
        }
    }
    // solid tides force model
    List<CelestialBody> solidTidesBodies = new ArrayList<CelestialBody>();
    if (parser.containsKey(ParameterKey.SOLID_TIDES_SUN) && parser.getBoolean(ParameterKey.SOLID_TIDES_SUN)) {
        solidTidesBodies.add(CelestialBodyFactory.getSun());
    }
    if (parser.containsKey(ParameterKey.SOLID_TIDES_MOON) && parser.getBoolean(ParameterKey.SOLID_TIDES_MOON)) {
        solidTidesBodies.add(CelestialBodyFactory.getMoon());
    }
    if (!solidTidesBodies.isEmpty()) {
        propagatorBuilder.addForceModel(new SolidTides(body.getBodyFrame(), gravityField.getAe(), gravityField.getMu(), gravityField.getTideSystem(), conventions, TimeScalesFactory.getUT1(conventions, true), solidTidesBodies.toArray(new CelestialBody[solidTidesBodies.size()])));
    }
    // third body attraction
    if (parser.containsKey(ParameterKey.THIRD_BODY_SUN) && parser.getBoolean(ParameterKey.THIRD_BODY_SUN)) {
        propagatorBuilder.addForceModel(new ThirdBodyAttraction(CelestialBodyFactory.getSun()));
    }
    if (parser.containsKey(ParameterKey.THIRD_BODY_MOON) && parser.getBoolean(ParameterKey.THIRD_BODY_MOON)) {
        propagatorBuilder.addForceModel(new ThirdBodyAttraction(CelestialBodyFactory.getMoon()));
    }
    // drag
    if (parser.containsKey(ParameterKey.DRAG) && parser.getBoolean(ParameterKey.DRAG)) {
        final double cd = parser.getDouble(ParameterKey.DRAG_CD);
        final double area = parser.getDouble(ParameterKey.DRAG_AREA);
        final boolean cdEstimated = parser.getBoolean(ParameterKey.DRAG_CD_ESTIMATED);
        MarshallSolarActivityFutureEstimation msafe = new MarshallSolarActivityFutureEstimation("(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\\p{Digit}\\p{Digit}\\p{Digit}\\p{Digit}F10\\.(?:txt|TXT)", MarshallSolarActivityFutureEstimation.StrengthLevel.AVERAGE);
        DataProvidersManager manager = DataProvidersManager.getInstance();
        manager.feed(msafe.getSupportedNames(), msafe);
        Atmosphere atmosphere = new DTM2000(msafe, CelestialBodyFactory.getSun(), body);
        propagatorBuilder.addForceModel(new DragForce(atmosphere, new IsotropicDrag(area, cd)));
        if (cdEstimated) {
            for (final ParameterDriver driver : propagatorBuilder.getPropagationParametersDrivers().getDrivers()) {
                if (driver.getName().equals(DragSensitive.DRAG_COEFFICIENT)) {
                    driver.setSelected(true);
                }
            }
        }
    }
    // solar radiation pressure
    if (parser.containsKey(ParameterKey.SOLAR_RADIATION_PRESSURE) && parser.getBoolean(ParameterKey.SOLAR_RADIATION_PRESSURE)) {
        final double cr = parser.getDouble(ParameterKey.SOLAR_RADIATION_PRESSURE_CR);
        final double area = parser.getDouble(ParameterKey.SOLAR_RADIATION_PRESSURE_AREA);
        final boolean cREstimated = parser.getBoolean(ParameterKey.SOLAR_RADIATION_PRESSURE_CR_ESTIMATED);
        propagatorBuilder.addForceModel(new SolarRadiationPressure(CelestialBodyFactory.getSun(), body.getEquatorialRadius(), new IsotropicRadiationSingleCoefficient(area, cr)));
        if (cREstimated) {
            for (final ParameterDriver driver : propagatorBuilder.getPropagationParametersDrivers().getDrivers()) {
                if (driver.getName().equals(RadiationSensitive.REFLECTION_COEFFICIENT)) {
                    driver.setSelected(true);
                }
            }
        }
    }
    // post-Newtonian correction force due to general relativity
    if (parser.containsKey(ParameterKey.GENERAL_RELATIVITY) && parser.getBoolean(ParameterKey.GENERAL_RELATIVITY)) {
        propagatorBuilder.addForceModel(new Relativity(gravityField.getMu()));
    }
    // extra polynomial accelerations
    if (parser.containsKey(ParameterKey.POLYNOMIAL_ACCELERATION_NAME)) {
        final String[] names = parser.getStringArray(ParameterKey.POLYNOMIAL_ACCELERATION_NAME);
        final Vector3D[] directions = parser.getVectorArray(ParameterKey.POLYNOMIAL_ACCELERATION_DIRECTION_X, ParameterKey.POLYNOMIAL_ACCELERATION_DIRECTION_Y, ParameterKey.POLYNOMIAL_ACCELERATION_DIRECTION_Z);
        final List<String>[] coefficients = parser.getStringsListArray(ParameterKey.POLYNOMIAL_ACCELERATION_COEFFICIENTS, ',');
        final boolean[] estimated = parser.getBooleanArray(ParameterKey.POLYNOMIAL_ACCELERATION_ESTIMATED);
        for (int i = 0; i < names.length; ++i) {
            final PolynomialParametricAcceleration ppa = new PolynomialParametricAcceleration(directions[i], true, names[i], null, coefficients[i].size() - 1);
            for (int k = 0; k < coefficients[i].size(); ++k) {
                final ParameterDriver driver = ppa.getParameterDriver(names[i] + "[" + k + "]");
                driver.setValue(Double.parseDouble(coefficients[i].get(k)));
                driver.setSelected(estimated[i]);
            }
            propagatorBuilder.addForceModel(ppa);
        }
    }
    return propagatorBuilder;
}

Example 25 with CelestialBody

use of org.orekit.bodies.CelestialBody in project Orekit by CS-SI.

the class BoxAndSolarArraySpacecraftTest method testBestPointing.

@Test
public void testBestPointing() throws OrekitException {
    AbsoluteDate initialDate = propagator.getInitialState().getDate();
    CelestialBody sun = CelestialBodyFactory.getSun();
    BoxAndSolarArraySpacecraft s = new BoxAndSolarArraySpacecraft(1.5, 3.5, 2.5, sun, 20.0, Vector3D.PLUS_J, 0.0, 0.0, 0.0);
    for (double dt = 0; dt < 4000; dt += 60) {
        SpacecraftState state = propagator.propagate(initialDate.shiftedBy(dt));
        Vector3D sunInert = sun.getPVCoordinates(initialDate, state.getFrame()).getPosition();
        Vector3D momentum = state.getPVCoordinates().getMomentum();
        double sunElevation = FastMath.PI / 2 - Vector3D.angle(sunInert, momentum);
        Assert.assertEquals(15.1, FastMath.toDegrees(sunElevation), 0.1);
        Vector3D n = s.getNormal(state.getDate(), state.getFrame(), state.getPVCoordinates().getPosition(), state.getAttitude().getRotation());
        Assert.assertEquals(0.0, n.getY(), 1.0e-10);
        // normal misalignment should be entirely due to sun being out of orbital plane
        Vector3D sunSat = state.getAttitude().getRotation().applyTo(sunInert);
        double misAlignment = Vector3D.angle(sunSat, n);
        Assert.assertEquals(sunElevation, misAlignment, 1.0e-3);
    }
}