@Test
public void testEphemerisDatesBackward() throws OrekitException {
// setup
TimeScale tai = TimeScalesFactory.getTAI();
AbsoluteDate initialDate = new AbsoluteDate("2015-07-05", tai);
AbsoluteDate startDate = new AbsoluteDate("2015-07-03", tai).shiftedBy(-0.1);
AbsoluteDate endDate = new AbsoluteDate("2015-07-04", tai);
Frame eci = FramesFactory.getGCRF();
KeplerianOrbit orbit =
new KeplerianOrbit(
600e3 + Constants.WGS84_EARTH_EQUATORIAL_RADIUS,
0,
0,
0,
0,
0,
PositionAngle.TRUE,
eci,
initialDate,
mu);
double[][] tol = NumericalPropagator.tolerances(1, orbit, OrbitType.CARTESIAN);
Propagator prop =
new NumericalPropagator(new DormandPrince853Integrator(0.1, 500, tol[0], tol[1]));
prop.resetInitialState(new SpacecraftState(new CartesianOrbit(orbit)));
// action
prop.setEphemerisMode();
prop.propagate(endDate, startDate);
BoundedPropagator ephemeris = prop.getGeneratedEphemeris();
// verify
TimeStampedPVCoordinates actualPV = ephemeris.getPVCoordinates(startDate, eci);
TimeStampedPVCoordinates expectedPV = orbit.getPVCoordinates(startDate, eci);
MatcherAssert.assertThat(
actualPV.getPosition(), OrekitMatchers.vectorCloseTo(expectedPV.getPosition(), 1.0));
MatcherAssert.assertThat(
actualPV.getVelocity(), OrekitMatchers.vectorCloseTo(expectedPV.getVelocity(), 1.0));
MatcherAssert.assertThat(
ephemeris.getMinDate().durationFrom(startDate), OrekitMatchers.closeTo(0, 0));
MatcherAssert.assertThat(
ephemeris.getMaxDate().durationFrom(endDate), OrekitMatchers.closeTo(0, 0));
// test date
AbsoluteDate date = endDate.shiftedBy(-0.11);
Assert.assertEquals(ephemeris.propagate(date).getDate().durationFrom(date), 0, 0);
}
