Ephemeris.java
/* Copyright 2002-2023 CS GROUP
* Licensed to CS GROUP (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.propagation.analytical;
import org.hipparchus.exception.LocalizedCoreFormats;
import org.hipparchus.exception.MathIllegalArgumentException;
import org.hipparchus.linear.RealMatrix;
import org.orekit.attitudes.Attitude;
import org.orekit.attitudes.AttitudeProvider;
import org.orekit.attitudes.FrameAlignedProvider;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitIllegalArgumentException;
import org.orekit.errors.OrekitIllegalStateException;
import org.orekit.errors.OrekitMessages;
import org.orekit.frames.Frame;
import org.orekit.orbits.Orbit;
import org.orekit.propagation.AbstractMatricesHarvester;
import org.orekit.propagation.BoundedPropagator;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.SpacecraftStateInterpolator;
import org.orekit.propagation.StateCovariance;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.AbstractTimeInterpolator;
import org.orekit.time.TimeInterpolator;
import org.orekit.time.TimeStampedPair;
import org.orekit.utils.DoubleArrayDictionary;
import org.orekit.utils.ImmutableTimeStampedCache;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
/**
* This class is designed to accept and handle tabulated orbital entries. Tabulated entries are classified and then
* extrapolated in way to obtain continuous output, with accuracy and computation methods configured by the user.
*
* @author Fabien Maussion
* @author Véronique Pommier-Maurussane
* @author Luc Maisonobe
* @author Vincent Cucchietti
*/
public class Ephemeris extends AbstractAnalyticalPropagator implements BoundedPropagator {
/** First date in range. */
private final AbsoluteDate minDate;
/** Last date in range. */
private final AbsoluteDate maxDate;
/** Reference frame. */
private final Frame frame;
/** Names of the additional states. */
private final String[] additional;
/** List of spacecraft states. */
private final transient ImmutableTimeStampedCache<SpacecraftState> statesCache;
/** List of covariances. **/
private final transient ImmutableTimeStampedCache<StateCovariance> covariancesCache;
/** Spacecraft state interpolator. */
private final transient TimeInterpolator<SpacecraftState> stateInterpolator;
/** State covariance interpolator. */
private final transient TimeInterpolator<TimeStampedPair<Orbit, StateCovariance>> covarianceInterpolator;
/** Flag defining if states are defined using an orbit or an absolute position-velocity-acceleration. */
private final transient boolean statesAreOrbitDefined;
/**
* Legacy constructor with tabulated states and default Hermite interpolation.
* <p>
* As this implementation of interpolation is polynomial, it should be used only with small samples (about 10-20 points)
* in order to avoid <a href="http://en.wikipedia.org/wiki/Runge%27s_phenomenon">Runge's phenomenon</a> and numerical
* problems (including NaN appearing).
*
* @param states list of spacecraft states
* @param interpolationPoints number of points to use in interpolation
*
* @throws MathIllegalArgumentException if the number of states is smaller than the number of points to use in
* interpolation
* @throws OrekitIllegalArgumentException if states are not defined the same way (orbit or absolute
* position-velocity-acceleration)
* @see #Ephemeris(List, TimeInterpolator, List, TimeInterpolator)
* @see SpacecraftStateInterpolator
*/
public Ephemeris(final List<SpacecraftState> states, final int interpolationPoints)
throws MathIllegalArgumentException {
// If states is empty an exception will be thrown in the other constructor
this(states, new SpacecraftStateInterpolator(interpolationPoints,
states.get(0).getFrame(),
states.get(0).getFrame()),
new ArrayList<>(), null);
}
/**
* Constructor with tabulated states.
*
* @param states list of spacecraft states
* @param stateInterpolator spacecraft state interpolator
*
* @throws MathIllegalArgumentException if the number of states is smaller than the number of points to use in
* interpolation
* @throws OrekitIllegalArgumentException if states are not defined the same way (orbit or absolute
* position-velocity-acceleration)
* @see #Ephemeris(List, TimeInterpolator, List, TimeInterpolator)
*/
public Ephemeris(final List<SpacecraftState> states, final TimeInterpolator<SpacecraftState> stateInterpolator)
throws MathIllegalArgumentException {
this(states, stateInterpolator, new ArrayList<>(), null);
}
/**
* Constructor with tabulated states.
*
* @param states list of spacecraft states
* @param stateInterpolator spacecraft state interpolator
* @param attitudeProvider attitude law to use, null by default
*
* @throws MathIllegalArgumentException if the number of states is smaller than the number of points to use in
* interpolation
* @throws OrekitIllegalArgumentException if states are not defined the same way (orbit or absolute
* position-velocity-acceleration)
* @see #Ephemeris(List, TimeInterpolator, List, TimeInterpolator)
*/
public Ephemeris(final List<SpacecraftState> states, final TimeInterpolator<SpacecraftState> stateInterpolator,
final AttitudeProvider attitudeProvider)
throws MathIllegalArgumentException {
this(states, stateInterpolator, new ArrayList<>(), null, attitudeProvider);
}
/**
* Constructor with tabulated states and associated covariances.
*
* @param states list of spacecraft states
* @param stateInterpolator spacecraft state interpolator
* @param covariances tabulated covariances associated to tabulated states ephemeris bounds to be doing extrapolation
* @param covarianceInterpolator covariance interpolator
*
* @throws MathIllegalArgumentException if the number of states is smaller than the number of points to use in
* interpolation
* @throws OrekitIllegalArgumentException if states are not defined the same way (orbit or absolute
* position-velocity-acceleration)
* @throws OrekitIllegalArgumentException if number of states is different from the number of covariances
* @throws OrekitIllegalStateException if dates between states and associated covariances are different
* @see #Ephemeris(List, TimeInterpolator, List, TimeInterpolator, AttitudeProvider)
* @since 9.0
*/
public Ephemeris(final List<SpacecraftState> states,
final TimeInterpolator<SpacecraftState> stateInterpolator,
final List<StateCovariance> covariances,
final TimeInterpolator<TimeStampedPair<Orbit, StateCovariance>> covarianceInterpolator)
throws MathIllegalArgumentException {
this(states, stateInterpolator, covariances, covarianceInterpolator,
// if states is empty an exception will be thrown in the other constructor
states.isEmpty() ? null : FrameAlignedProvider.of(states.get(0).getFrame()));
}
/**
* Constructor with tabulated states and associated covariances.
* <p>
* The user is expected to explicitly define an attitude provider if they want to use one. Otherwise, it is null by
* default
*
* @param states list of spacecraft states
* @param stateInterpolator spacecraft state interpolator
* @param covariances tabulated covariances associated to tabulated states
* @param covarianceInterpolator covariance interpolator
* @param attitudeProvider attitude law to use, null by default
*
* @throws MathIllegalArgumentException if the number of states is smaller than the number of points to use in
* interpolation
* @throws OrekitIllegalArgumentException if states are not defined the same way (orbit or absolute
* position-velocity-acceleration)
* @throws OrekitIllegalArgumentException if number of states is different from the number of covariances
* @throws OrekitIllegalStateException if dates between states and associated covariances are different
* @since 10.1
*/
public Ephemeris(final List<SpacecraftState> states,
final TimeInterpolator<SpacecraftState> stateInterpolator,
final List<StateCovariance> covariances,
final TimeInterpolator<TimeStampedPair<Orbit, StateCovariance>> covarianceInterpolator,
final AttitudeProvider attitudeProvider)
throws MathIllegalArgumentException {
super(attitudeProvider);
// Check input consistency
checkInputConsistency(states, stateInterpolator, covariances, covarianceInterpolator);
// Initialize variables
final SpacecraftState s0 = states.get(0);
minDate = s0.getDate();
maxDate = states.get(states.size() - 1).getDate();
frame = s0.getFrame();
final List<DoubleArrayDictionary.Entry> as = s0.getAdditionalStatesValues().getData();
additional = new String[as.size()];
for (int i = 0; i < additional.length; ++i) {
additional[i] = as.get(i).getKey();
}
this.statesCache = new ImmutableTimeStampedCache<>(stateInterpolator.getNbInterpolationPoints(), states);
this.stateInterpolator = stateInterpolator;
this.covarianceInterpolator = covarianceInterpolator;
if (covarianceInterpolator != null) {
this.covariancesCache = new ImmutableTimeStampedCache<>(covarianceInterpolator.getNbInterpolationPoints(),
covariances);
} else {
this.covariancesCache = null;
}
this.statesAreOrbitDefined = s0.isOrbitDefined();
// Initialize initial state
super.resetInitialState(getInitialState());
}
/**
* Check input consistency between states, covariances and their associated interpolators.
*
* @param states spacecraft states sample
* @param stateInterpolator spacecraft state interpolator
* @param covariances covariances sample
* @param covarianceInterpolator covariance interpolator
*/
public static void checkInputConsistency(final List<SpacecraftState> states,
final TimeInterpolator<SpacecraftState> stateInterpolator,
final List<StateCovariance> covariances,
final TimeInterpolator<TimeStampedPair<Orbit, StateCovariance>> covarianceInterpolator) {
// Checks to perform is states are provided
if (!states.isEmpty()) {
// Check given that given states definition are consistent
// (all defined by either orbits or absolute position-velocity-acceleration coordinates)
SpacecraftStateInterpolator.checkStatesDefinitionsConsistency(states);
// Check that every interpolator used in the state interpolator are compatible with the sample size
AbstractTimeInterpolator.checkInterpolatorCompatibilityWithSampleSize(stateInterpolator, states.size());
// Additional checks if covariances are provided
if (!covariances.isEmpty()) {
// Check that every interpolator used in the state covariance interpolator are compatible with the sample size
AbstractTimeInterpolator.checkInterpolatorCompatibilityWithSampleSize(covarianceInterpolator,
covariances.size());
// Check states and covariances consistency
checkStatesAndCovariancesConsistency(states, covariances);
}
}
else {
throw new OrekitIllegalArgumentException(OrekitMessages.NOT_ENOUGH_DATA, 0);
}
}
/**
* Check that given states and covariances are consistent.
*
* @param states tabulates states to check
* @param covariances tabulated covariances associated to tabulated states to check
*/
public static void checkStatesAndCovariancesConsistency(final List<SpacecraftState> states,
final List<StateCovariance> covariances) {
final int nbStates = states.size();
// Check that we have an equal number of states and covariances
if (nbStates != covariances.size()) {
throw new OrekitIllegalArgumentException(LocalizedCoreFormats.DIMENSIONS_MISMATCH,
states.size(),
covariances.size());
}
// Check that states and covariance are defined at the same date
for (int i = 0; i < nbStates; i++) {
if (!states.get(i).getDate().isCloseTo(covariances.get(i).getDate(),
TimeStampedPair.DEFAULT_DATE_EQUALITY_THRESHOLD)) {
throw new OrekitIllegalStateException(OrekitMessages.STATE_AND_COVARIANCE_DATES_MISMATCH,
states.get(i).getDate(), covariances.get(i).getDate());
}
}
}
/**
* Get the first date of the range.
*
* @return the first date of the range
*/
public AbsoluteDate getMinDate() {
return minDate;
}
/**
* Get the last date of the range.
*
* @return the last date of the range
*/
public AbsoluteDate getMaxDate() {
return maxDate;
}
/** {@inheritDoc} */
@Override
public Frame getFrame() {
return frame;
}
/**
* Get the covariance at given date.
* <p>
* BEWARE : If this instance has been created without sample of covariances and/or with spacecraft states defined with
* absolute position-velocity-acceleration, it will return an empty {@link Optional}.
*
* @param date date at which the covariance is desired
*
* @return covariance at given date
*
* @see Optional
*/
public Optional<StateCovariance> getCovariance(final AbsoluteDate date) {
if (covarianceInterpolator != null && covariancesCache != null && statesAreOrbitDefined) {
// Build list of time stamped pair of orbits and their associated covariances
final List<TimeStampedPair<Orbit, StateCovariance>> sample = buildOrbitAndCovarianceSample();
// Interpolate
final TimeStampedPair<Orbit, StateCovariance> interpolatedOrbitAndCovariance =
covarianceInterpolator.interpolate(date, sample);
return Optional.of(interpolatedOrbitAndCovariance.getSecond());
}
else {
return Optional.empty();
}
}
/** @return sample of orbits and their associated covariances */
private List<TimeStampedPair<Orbit, StateCovariance>> buildOrbitAndCovarianceSample() {
final List<TimeStampedPair<Orbit, StateCovariance>> sample = new ArrayList<>();
final List<SpacecraftState> states = statesCache.getAll();
final List<StateCovariance> covariances = covariancesCache.getAll();
for (int i = 0; i < states.size(); i++) {
sample.add(new TimeStampedPair<>(states.get(i).getOrbit(), covariances.get(i)));
}
return sample;
}
/** {@inheritDoc} */
@Override
public SpacecraftState basicPropagate(final AbsoluteDate date) {
final AbsoluteDate centralDate =
AbstractTimeInterpolator.getCentralDate(date, statesCache, stateInterpolator.getExtrapolationThreshold());
final SpacecraftState evaluatedState = stateInterpolator.interpolate(date, statesCache.getNeighbors(centralDate));
final AttitudeProvider attitudeProvider = getAttitudeProvider();
if (attitudeProvider == null) {
return evaluatedState;
}
else {
final Attitude calculatedAttitude;
// Verify if orbit is defined
if (evaluatedState.isOrbitDefined()) {
calculatedAttitude =
attitudeProvider.getAttitude(evaluatedState.getOrbit(), date, evaluatedState.getFrame());
return new SpacecraftState(evaluatedState.getOrbit(), calculatedAttitude, evaluatedState.getMass(),
evaluatedState.getAdditionalStatesValues(),
evaluatedState.getAdditionalStatesDerivatives());
}
else {
calculatedAttitude =
attitudeProvider.getAttitude(evaluatedState.getAbsPVA(), date, evaluatedState.getFrame());
return new SpacecraftState(evaluatedState.getAbsPVA(), calculatedAttitude, evaluatedState.getMass(),
evaluatedState.getAdditionalStatesValues(),
evaluatedState.getAdditionalStatesDerivatives());
}
}
}
/** {@inheritDoc} */
protected Orbit propagateOrbit(final AbsoluteDate date) {
return basicPropagate(date).getOrbit();
}
/** {@inheritDoc} */
protected double getMass(final AbsoluteDate date) {
return basicPropagate(date).getMass();
}
/**
* Try (and fail) to reset the initial state.
* <p>
* This method always throws an exception, as ephemerides cannot be reset.
* </p>
*
* @param state new initial state to consider
*/
public void resetInitialState(final SpacecraftState state) {
throw new OrekitException(OrekitMessages.NON_RESETABLE_STATE);
}
/** {@inheritDoc} */
protected void resetIntermediateState(final SpacecraftState state, final boolean forward) {
throw new OrekitException(OrekitMessages.NON_RESETABLE_STATE);
}
/** {@inheritDoc} */
public SpacecraftState getInitialState() {
return basicPropagate(getMinDate());
}
/** {@inheritDoc} */
@Override
public boolean isAdditionalStateManaged(final String name) {
// the additional state may be managed by a specific provider in the base class
if (super.isAdditionalStateManaged(name)) {
return true;
}
// the additional state may be managed in the states sample
for (final String a : additional) {
if (a.equals(name)) {
return true;
}
}
return false;
}
/** {@inheritDoc} */
@Override
public String[] getManagedAdditionalStates() {
final String[] upperManaged = super.getManagedAdditionalStates();
final String[] managed = new String[upperManaged.length + additional.length];
System.arraycopy(upperManaged, 0, managed, 0, upperManaged.length);
System.arraycopy(additional, 0, managed, upperManaged.length, additional.length);
return managed;
}
/** {@inheritDoc} */
@Override
protected AbstractMatricesHarvester createHarvester(final String stmName, final RealMatrix initialStm,
final DoubleArrayDictionary initialJacobianColumns) {
// In order to not throw an Orekit exception during ephemeris based orbit determination
// The default behavior of the method is overridden to return a null parameter
return null;
}
/** Get state interpolator.
* @return state interpolator
*/
public TimeInterpolator<SpacecraftState> getStateInterpolator() {
return stateInterpolator;
}
/** Get covariance interpolator.
* @return optional covariance interpolator
* @see Optional
*/
public Optional<TimeInterpolator<TimeStampedPair<Orbit, StateCovariance>>> getCovarianceInterpolator() {
return Optional.ofNullable(covarianceInterpolator);
}
}