org.orekit.propagation.analytical

Class AdapterPropagator

java.lang.Object

org.orekit.propagation.AbstractPropagator

org.orekit.propagation.analytical.AbstractAnalyticalPropagator

org.orekit.propagation.analytical.AdapterPropagator

All Implemented Interfaces:

Propagator, PVCoordinatesProvider

public class AdapterPropagator
extends AbstractAnalyticalPropagator

Orbit propagator that adapts an underlying propagator, adding differential effects.

This propagator is used when a reference propagator does not handle some effects that we need. A typical example would be an ephemeris that was computed for a reference orbit, and we want to compute a station-keeping maneuver on top of this ephemeris, changing its final state. The principal is to add one or more small maneuvers analytical models to it and use it as a new propagator, which takes the maneuvers into account.

From a space flight dynamics point of view, this is a differential correction approach. From a computer science point of view, this is a use of the decorator design pattern.

Author:

Luc Maisonobe

See Also:

Propagator, SmallManeuverAnalyticalModel

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	AdapterPropagator.DifferentialEffect Interface for orbit differential effects.

Field Summary

Fields inherited from interface org.orekit.propagation.Propagator

DEFAULT_LAW, DEFAULT_MASS, EPHEMERIS_GENERATION_MODE, MASTER_MODE, SLAVE_MODE

Constructor Summary

Constructors

Constructor and Description
AdapterPropagator(Propagator reference) Build a propagator from an underlying reference propagator.

Method Summary

Modifier and Type	Method and Description
void	addEffect(AdapterPropagator.DifferentialEffect effect) Add a differential effect.
protected SpacecraftState	basicPropagate(AbsoluteDate date) Propagate an orbit without any fancy features.
List<AdapterPropagator.DifferentialEffect>	getEffects() Get the differential effects.
SpacecraftState	getInitialState() Get the propagator initial state.
protected double	getMass(AbsoluteDate date) Get the mass.
Propagator	getPropagator() Get the reference propagator.
protected Orbit	propagateOrbit(AbsoluteDate date) Extrapolate an orbit up to a specific target date.
void	resetInitialState(SpacecraftState state) Reset the propagator 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, getEventsDetectors, getGeneratedEphemeris, getPvProvider, propagate

Methods inherited from class org.orekit.propagation.AbstractPropagator

addAdditionalStateProvider, getAdditionalStateProviders, getAttitudeProvider, getFixedStepSize, getFrame, getManagedAdditionalStates, getMode, getPVCoordinates, getStartDate, getStepHandler, isAdditionalStateManaged, propagate, setAttitudeProvider, setEphemerisMode, setEphemerisMode, setMasterMode, setMasterMode, setSlaveMode, setStartDate, updateAdditionalStates

Methods inherited from class java.lang.Object

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

Constructor Detail

AdapterPropagator

public AdapterPropagator(Propagator reference)

Build a propagator from an underlying reference propagator.

The reference propagator can be almost anything, numerical, analytical, and even an ephemeris. It may already take some maneuvers into account.

Parameters:

reference - reference propagator

Method Detail

addEffect

public void addEffect(AdapterPropagator.DifferentialEffect effect)

Add a differential effect.

Parameters:

effect - differential effect

getPropagator

public Propagator getPropagator()

Get the reference propagator.

Returns:

reference propagator

getEffects

public List<AdapterPropagator.DifferentialEffect> getEffects()

Get the differential effects.

Returns:

differential effects models, as an unmodifiable list

getInitialState

public SpacecraftState getInitialState()
                                throws OrekitException

Get the propagator initial state.

Specified by:

getInitialState in interface Propagator

Overrides:

getInitialState in class AbstractPropagator

Returns:

initial state

Throws:

OrekitException - if state cannot be retrieved

resetInitialState

public void resetInitialState(SpacecraftState state)
                       throws OrekitException

Reset the propagator initial state.

Specified by:

resetInitialState in interface Propagator

Overrides:

resetInitialState in class AbstractPropagator

Parameters:

state - new initial state to consider

Throws:

OrekitException - if initial state cannot be reset

resetIntermediateState

protected void resetIntermediateState(SpacecraftState state,
                                      boolean forward)
                               throws OrekitException

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

Throws:

OrekitException - if initial state cannot be reset

basicPropagate

protected SpacecraftState basicPropagate(AbsoluteDate date)
                                  throws OrekitException

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

Throws:

OrekitException - if propagation cannot reach specified date

propagateOrbit

protected Orbit propagateOrbit(AbsoluteDate date)
                        throws OrekitException

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

Throws:

OrekitException - if some parameters are out of bounds

getMass

protected double getMass(AbsoluteDate date)
                  throws OrekitException

Get the mass.

Specified by:

getMass in class AbstractAnalyticalPropagator

Parameters:

date - target date for the orbit

Returns:

mass mass

Throws:

OrekitException - if some parameters are out of bounds