org.orekit.propagation
Interface Propagator

All Superinterfaces:

PVCoordinatesProvider, Serializable

All Known Subinterfaces:

BoundedPropagator

All Known Implementing Classes:

AbstractEphemeris, AbstractLyddanePropagator, AbstractPropagator, AdapterPropagator, Analytical2DPropagator, AnalyticalIntegratedEphemeris, EcksteinHechlerPropagator, Ephemeris, HermiteEphemeris, IntegratedEphemeris, J2SecularPropagator, KeplerianPropagator, LagrangeEphemeris, LyddaneLongPeriodPropagator, LyddaneSecularPropagator, MultiIntegratedEphemeris, NumericalPropagator, PVCoordinatePropagator, StelaAbstractPropagator, StelaGTOPropagator, TLEPropagator

public interface Propagator
extends PVCoordinatesProvider, Serializable

This interface provides a way to propagate an orbit at any time.

This interface is the top-level abstraction for orbit propagation. It only allows propagation to a predefined date. It is implemented by analytical models which have no time limit, by orbit readers based on external data files, by numerical integrators using rich force models and by continuous models built after numerical integration has been completed and dense output data as been gathered.

Author:

Luc Maisonobe, Véronique Pommier-Maurussane

Field Summary

static int	EPHEMERIS_GENERATION_MODE Indicator for ephemeris generation mode.
static int	MASTER_MODE Indicator for master mode.
static int	SLAVE_MODE Indicator for slave mode.

Method Summary

void	addEventDetector(EventDetector detector) Add an event detector.
void	clearEventsDetectors() Remove all events detectors.
AttitudeProvider	getAttitudeProvider() Get attitude provider.
AttitudeProvider	getAttitudeProviderEvents() Get attitude provider for events computation.
AttitudeProvider	getAttitudeProviderForces() Get attitude provider for forces computation.
Collection<EventDetector>	getEventsDetectors() Get all the events detectors that have been added.
Frame	getFrame() Get the frame in which the orbit is propagated.
BoundedPropagator	getGeneratedEphemeris() Get the ephemeris generated during propagation.
SpacecraftState	getInitialState() Get the propagator initial state.
int	getMode() Get the current operating mode of the propagator.
SpacecraftState	propagate(AbsoluteDate target) Propagate towards a target date.
SpacecraftState	propagate(AbsoluteDate start, AbsoluteDate target) Propagate from a start date towards a target date.
void	resetInitialState(SpacecraftState state) Reset the propagator initial state.
void	setAttitudeProvider(AttitudeProvider attitudeProvider) Set attitude provider for forces and events computation.
void	setAttitudeProviderEvents(AttitudeProvider attitudeProviderEvents) Set attitude provider for events computation.
void	setAttitudeProviderForces(AttitudeProvider attitudeProviderForces) Set attitude provider for forces computation.
void	setEphemerisMode() Set the propagator to ephemeris generation mode.
void	setMasterMode(double h, OrekitFixedStepHandler handler) Set the propagator to master mode with fixed steps.
void	setMasterMode(OrekitStepHandler handler) Set the propagator to master mode with variable steps.
void	setOrbitFrame(Frame frame) Set propagation frame.
void	setSlaveMode() Set the propagator to slave mode.

Methods inherited from interface org.orekit.utils.PVCoordinatesProvider

getPVCoordinates

Field Detail

SLAVE_MODE

static final int SLAVE_MODE

Indicator for slave mode.

See Also:

Constant Field Values

MASTER_MODE

static final int MASTER_MODE

Indicator for master mode.

See Also:

Constant Field Values

EPHEMERIS_GENERATION_MODE

static final int EPHEMERIS_GENERATION_MODE

Indicator for ephemeris generation mode.

See Also:

Constant Field Values

Method Detail

getMode

int getMode()

Get the current operating mode of the propagator.

Returns:

one of SLAVE_MODE, MASTER_MODE, EPHEMERIS_GENERATION_MODE

See Also:

setSlaveMode(), setMasterMode(double, OrekitFixedStepHandler), setMasterMode(OrekitStepHandler), setEphemerisMode()

setSlaveMode

void setSlaveMode()

Set the propagator to slave mode.

This mode is used when the user needs only the final orbit at the target time. The (slave) propagator computes this result and return it to the calling (master) application, without any intermediate feedback.

This is the default mode.

See Also:

setMasterMode(double, OrekitFixedStepHandler), setMasterMode(OrekitStepHandler), setEphemerisMode(), getMode(), SLAVE_MODE

setMasterMode

void setMasterMode(double h,
                   OrekitFixedStepHandler handler)

Set the propagator to master mode with fixed steps.

This mode is used when the user needs to have some custom function called at the end of each finalized step during integration. The (master) propagator integration loop calls the (slave) application callback methods at each finalized step.

Parameters:

h - fixed stepsize (s)

handler - handler called at the end of each finalized step

See Also:

setSlaveMode(), setMasterMode(OrekitStepHandler), setEphemerisMode(), getMode(), MASTER_MODE

setMasterMode

void setMasterMode(OrekitStepHandler handler)

Set the propagator to master mode with variable steps.

This mode is used when the user needs to have some custom function called at the end of each finalized step during integration. The (master) propagator integration loop calls the (slave) application callback methods at each finalized step.

Parameters:

handler - handler called at the end of each finalized step

See Also:

setSlaveMode(), setMasterMode(double, OrekitFixedStepHandler), setEphemerisMode(), getMode(), MASTER_MODE

setEphemerisMode

void setEphemerisMode()

Set the propagator to ephemeris generation mode.

This mode is used when the user needs random access to the orbit state at any time between the initial and target times, and in no sequential order. A typical example is the implementation of search and iterative algorithms that may navigate forward and backward inside the propagation range before finding their result.

Beware that since this mode stores all intermediate results, it may be memory intensive for long integration ranges and high precision/short time steps.

See Also:

getGeneratedEphemeris(), setSlaveMode(), setMasterMode(double, OrekitFixedStepHandler), setMasterMode(OrekitStepHandler), getMode(), EPHEMERIS_GENERATION_MODE

setOrbitFrame

void setOrbitFrame(Frame frame)
                   throws OrekitException

Set propagation frame.

Parameters:

frame - the frame to use. This frame must be inertial or pseudo-inertial, otherwise an exception is raised.

Throws:

OrekitException - if frame is not inertial or pseudo-inertial

getGeneratedEphemeris

BoundedPropagator getGeneratedEphemeris()
                                        throws IllegalStateException

Get the ephemeris generated during propagation.

Returns:

generated ephemeris

Throws:

IllegalStateException - if the propagator was not set in ephemeris generation mode before propagation

See Also:

setEphemerisMode()

getInitialState

SpacecraftState getInitialState()
                                throws OrekitException

Get the propagator initial state.

Returns:

initial state

Throws:

OrekitException - if state cannot be retrieved

resetInitialState

void resetInitialState(SpacecraftState state)
                       throws PropagationException

Reset the propagator initial state.

Parameters:

state - new initial state to consider

Throws:

PropagationException - if initial state cannot be reset

addEventDetector

void addEventDetector(EventDetector detector)

Add an event detector.

Parameters:

detector - event detector to add

See Also:

clearEventsDetectors(), getEventsDetectors()

getEventsDetectors

Collection<EventDetector> getEventsDetectors()

Get all the events detectors that have been added.

Returns:

an unmodifiable collection of the added detectors

See Also:

addEventDetector(EventDetector), clearEventsDetectors()

clearEventsDetectors

void clearEventsDetectors()

Remove all events detectors.

See Also:

addEventDetector(EventDetector), getEventsDetectors()

getAttitudeProvider

AttitudeProvider getAttitudeProvider()

Get attitude provider.

Returns:

attitude provider for forces computation (by default)

getAttitudeProviderForces

AttitudeProvider getAttitudeProviderForces()

Get attitude provider for forces computation.

Returns:

attitude provider for forces computation

getAttitudeProviderEvents

AttitudeProvider getAttitudeProviderEvents()

Get attitude provider for events computation.

Returns:

attitude provider for events computation

setAttitudeProvider

void setAttitudeProvider(AttitudeProvider attitudeProvider)

Set attitude provider for forces and events computation. A default attitude provider is available in ConstantAttitudeLaw.

Parameters:

attitudeProvider - attitude provider

setAttitudeProviderForces

void setAttitudeProviderForces(AttitudeProvider attitudeProviderForces)

Set attitude provider for forces computation. A default attitude provider is available in ConstantAttitudeLaw.

Parameters:

attitudeProviderForces - attitude provider for forces computation

setAttitudeProviderEvents

void setAttitudeProviderEvents(AttitudeProvider attitudeProviderEvents)

Set attitude provider for events computation. A default attitude provider is available in ConstantAttitudeLaw.

Parameters:

attitudeProviderEvents - attitude provider for events computation

getFrame

Frame getFrame()

Get the frame in which the orbit is propagated.

4 cases are possible:

• The propagation frame has been defined (using setOrbitFrame(Frame)): it is returned.
• The propagation frame has not been defined and the initial state has been provided and is expressed in a pseudo-inertial frame: the initial state frame is returned.
• The propagation frame has not been defined and the initial state has been provided and is not expressed in a pseudo-inertial frame: null is returned.
• The propagation frame has not been defined and the initial state has not been provided: null is returned.

Returns:

frame in which the orbit is propagated

propagate

SpacecraftState propagate(AbsoluteDate target)
                          throws PropagationException

Propagate towards a target date.

Simple propagators use only the target date as the specification for computing the propagated state. More feature rich propagators can consider other information and provide different operating modes or G-stop facilities to stop at pinpointed events occurrences. In these cases, the target date is only a hint, not a mandatory objective.

Parameters:

target - target date towards which orbit state should be propagated

Returns:

propagated state

Throws:

PropagationException - if state cannot be propagated

propagate

SpacecraftState propagate(AbsoluteDate start,
                          AbsoluteDate target)
                          throws PropagationException

Propagate from a start date towards a target date.

Those propagators use a start date and a target date to compute the propagated state. For propagators using event detection mechanism, if the provided start date is different from the initial state date, a first, simple propagation is performed, without processing any event computation. Then complete propagation is performed from start date to target date.

Parameters:

start - start date from which orbit state should be propagated

target - target date to which orbit state should be propagated

Returns:

propagated state

Throws:

PropagationException - if state cannot be propagated