org.orekit.propagation.analytical

Class Ephemeris

java.lang.Object

org.orekit.propagation.AbstractPropagator

org.orekit.propagation.analytical.AbstractAnalyticalPropagator

org.orekit.propagation.analytical.Ephemeris

All Implemented Interfaces:

BoundedPropagator, Propagator, PVCoordinatesProvider

public class Ephemeris
extends AbstractAnalyticalPropagator
implements BoundedPropagator

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, Véronique Pommier-Maurussane, Luc Maisonobe

Field Summary

Fields

Modifier and Type	Field and Description
static double	DEFAULT_EXTRAPOLATION_THRESHOLD_SEC Default extrapolation time threshold: 1ms.

Fields inherited from interface org.orekit.propagation.Propagator

DEFAULT_MASS

Constructor Summary

Constructors

Constructor and Description
Ephemeris(List<SpacecraftState> states, int interpolationPoints) Constructor with tabulated states.
Ephemeris(List<SpacecraftState> states, int interpolationPoints, double extrapolationThreshold) Constructor with tabulated states.
Ephemeris(List<SpacecraftState> states, int interpolationPoints, double extrapolationThreshold, AttitudeProvider attitudeProvider) Constructor with tabulated states.

Method Summary

Modifier and Type	Method and Description
SpacecraftState	basicPropagate(AbsoluteDate date) Propagate an orbit without any fancy features.
protected AbstractMatricesHarvester	createHarvester(String stmName, RealMatrix initialStm, DoubleArrayDictionary initialJacobianColumns) Create the harvester suitable for propagator.
double	getExtrapolationThreshold() Get the maximum timespan outside of the stored ephemeris that is allowed for extrapolation.
Frame	getFrame() Get the frame in which the orbit is propagated.
SpacecraftState	getInitialState() Get the propagator initial state.
String[]	getManagedAdditionalStates() Get all the names of all managed states.
protected double	getMass(AbsoluteDate date) Get the mass.
AbsoluteDate	getMaxDate() Get the last date of the range.
AbsoluteDate	getMinDate() Get the first date of the range.
TimeStampedPVCoordinates	getPVCoordinates(AbsoluteDate date, Frame f) Get the PVCoordinates of the body in the selected frame.
boolean	isAdditionalStateManaged(String name) Check if an additional state is managed.
protected Orbit	propagateOrbit(AbsoluteDate date) Extrapolate an orbit up to a specific target date.
void	resetInitialState(SpacecraftState state) Try (and fail) to reset the initial state.
protected void	resetIntermediateState(SpacecraftState state, boolean forward) Reset an intermediate state.

Methods inherited from class org.orekit.propagation.analytical.AbstractAnalyticalPropagator

acceptStep, addEventDetector, clearEventsDetectors, getEphemerisGenerator, getEventsDetectors, getJacobiansColumnsNames, getPvProvider, propagate

Methods inherited from class org.orekit.propagation.AbstractPropagator

addAdditionalStateProvider, getAdditionalStateProviders, getAttitudeProvider, getHarvester, getMultiplexer, getStartDate, initializeAdditionalStates, initializePropagation, propagate, setAttitudeProvider, setStartDate, setupMatricesComputation, stateChanged, updateAdditionalStates, updateUnmanagedStates

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.orekit.propagation.Propagator

addAdditionalStateProvider, addEventDetector, clearEventsDetectors, clearStepHandlers, getAdditionalStateProviders, getAttitudeProvider, getDefaultLaw, getEphemerisGenerator, getEventsDetectors, getMultiplexer, propagate, propagate, setAttitudeProvider, setStepHandler, setStepHandler, setupMatricesComputation

Field Detail

DEFAULT_EXTRAPOLATION_THRESHOLD_SEC

public static final double DEFAULT_EXTRAPOLATION_THRESHOLD_SEC

Default extrapolation time threshold: 1ms.

Since:

9.0

See Also:

Constant Field Values

Constructor Detail

Ephemeris

public Ephemeris(List<SpacecraftState> states,
                 int interpolationPoints)
          throws MathIllegalArgumentException

Constructor with tabulated states.

This constructor allows extrapolating outside of the states time span by up to the 1ms default extrapolation threshold.

Parameters:

states - tabulates states

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

See Also:

Ephemeris(List, int, double), Ephemeris(List, int, double, AttitudeProvider)

Ephemeris

public Ephemeris(List<SpacecraftState> states,
                 int interpolationPoints,
                 double extrapolationThreshold)
          throws MathIllegalArgumentException

Constructor with tabulated states.

Parameters:

states - tabulates states

interpolationPoints - number of points to use in interpolation

extrapolationThreshold - the largest time difference in seconds between the start or stop boundary of the ephemeris bounds to be doing extrapolation

Throws:

MathIllegalArgumentException - if the number of states is smaller than the number of points to use in interpolation

Since:

9.0

See Also:

Ephemeris(List, int, double, AttitudeProvider)

Ephemeris

public Ephemeris(List<SpacecraftState> states,
                 int interpolationPoints,
                 double extrapolationThreshold,
                 AttitudeProvider attitudeProvider)
          throws MathIllegalArgumentException

Constructor with tabulated states.

Parameters:

states - tabulates states

interpolationPoints - number of points to use in interpolation

extrapolationThreshold - the largest time difference in seconds between the start or stop boundary of the ephemeris bounds to be doing extrapolation

attitudeProvider - attitude law to use.

Throws:

MathIllegalArgumentException - if the number of states is smaller than the number of points to use in interpolation

Since:

10.1

Method Detail

getMinDate

public AbsoluteDate getMinDate()

Get the first date of the range.

Specified by:

getMinDate in interface BoundedPropagator

Returns:

the first date of the range

getMaxDate

public AbsoluteDate getMaxDate()

Get the last date of the range.

Specified by:

getMaxDate in interface BoundedPropagator

Returns:

the last date of the range

getExtrapolationThreshold

public double getExtrapolationThreshold()

Get the maximum timespan outside of the stored ephemeris that is allowed for extrapolation.

Returns:

the extrapolation threshold in seconds

getFrame

public Frame getFrame()

Description copied from class: AbstractPropagator

Get the frame in which the orbit is propagated.

The propagation frame is the definition frame of the initial state, so this method should be called after this state has been set, otherwise it may return null.

Specified by:

getFrame in interface Propagator

Overrides:

getFrame in class AbstractPropagator

Returns:

frame in which the orbit is propagated

See Also:

Propagator.resetInitialState(SpacecraftState)

basicPropagate

public SpacecraftState basicPropagate(AbsoluteDate date)

Description copied from class: AbstractAnalyticalPropagator

Propagate an orbit without any fancy features.

This method is similar in spirit to the AbstractAnalyticalPropagator.propagate(org.orekit.time.AbsoluteDate, org.orekit.time.AbsoluteDate) method, except that it does not call any handler during propagation, nor any discrete events, not additional states. It always stop exactly at the specified date.

Overrides:

basicPropagate in class AbstractAnalyticalPropagator

Parameters:

date - target date for propagation

Returns:

state at specified date

propagateOrbit

protected Orbit propagateOrbit(AbsoluteDate date)

Extrapolate an orbit up to a specific target date.

Specified by:

propagateOrbit in class AbstractAnalyticalPropagator

Parameters:

date - target date for the orbit

Returns:

extrapolated parameters

getMass

protected double getMass(AbsoluteDate date)

Get the mass.

Specified by:

getMass in class AbstractAnalyticalPropagator

Parameters:

date - target date for the orbit

Returns:

mass mass

getPVCoordinates

public TimeStampedPVCoordinates getPVCoordinates(AbsoluteDate date,
                                                 Frame f)

Get the PVCoordinates of the body in the selected frame.

Specified by:

getPVCoordinates in interface PVCoordinatesProvider

Overrides:

getPVCoordinates in class AbstractPropagator

Parameters:

date - current date

f - the frame where to define the position

Returns:

time-stamped position/velocity of the body (m and m/s)

resetInitialState

public void resetInitialState(SpacecraftState state)

Try (and fail) to reset the initial state.

This method always throws an exception, as ephemerides cannot be reset.

Specified by:

resetInitialState in interface Propagator

Overrides:

resetInitialState in class AbstractPropagator

Parameters:

state - new initial state to consider

resetIntermediateState

protected void resetIntermediateState(SpacecraftState state,
                                      boolean forward)

Reset an intermediate state.

Specified by:

resetIntermediateState in class AbstractAnalyticalPropagator

Parameters:

state - new intermediate state to consider

forward - if true, the intermediate state is valid for propagations after itself

getInitialState

public SpacecraftState getInitialState()

Get the propagator initial state.

Specified by:

getInitialState in interface Propagator

Overrides:

getInitialState in class AbstractPropagator

Returns:

initial state

isAdditionalStateManaged

public boolean isAdditionalStateManaged(String name)

Check if an additional state is managed.

Managed states are states for which the propagators know how to compute its evolution. They correspond to additional states for which a provider has been registered by calling the addAdditionalStateProvider method.

Additional states that are present in the initial state but have no evolution method registered are not considered as managed states. These unmanaged additional states are not lost during propagation, though. Their value are piecewise constant between state resets that may change them if some event handler resetState method is called at an event occurrence and happens to change the unmanaged additional state.

Specified by:

isAdditionalStateManaged in interface Propagator

Overrides:

isAdditionalStateManaged in class AbstractPropagator

Parameters:

name - name of the additional state

Returns:

true if the additional state is managed

getManagedAdditionalStates

public String[] getManagedAdditionalStates()

Get all the names of all managed states.

Specified by:

getManagedAdditionalStates in interface Propagator

Overrides:

getManagedAdditionalStates in class AbstractPropagator

Returns:

names of all managed states

createHarvester

protected AbstractMatricesHarvester createHarvester(String stmName,
                                                    RealMatrix initialStm,
                                                    DoubleArrayDictionary initialJacobianColumns)

Create the harvester suitable for propagator.

Overrides:

createHarvester in class AbstractPropagator

Parameters:

stmName - State Transition Matrix state name

initialStm - initial State Transition Matrix ∂Y/∂Y₀, if null (which is the most frequent case), assumed to be 6x6 identity

initialJacobianColumns - initial columns of the Jacobians matrix with respect to parameters, if null or if some selected parameters are missing from the dictionary, the corresponding initial column is assumed to be 0

Returns:

harvester to retrieve computed matrices during and after propagation