org.orekit.forces.gravity

Class SingleBodyAbsoluteAttraction

java.lang.Object

org.orekit.forces.AbstractForceModel

org.orekit.forces.gravity.SingleBodyAbsoluteAttraction

All Implemented Interfaces:

ForceModel

public class SingleBodyAbsoluteAttraction
extends AbstractForceModel

Body attraction force model computed as absolute acceleration towards a body.

This force model represents the same physical principles as NewtonianAttraction, but has several major differences:

• the attracting body can be away from the integration frame center,
• several instances of this force model can be added when several bodies are involved,
• this force model is never automatically added by the numerical propagator

The possibility for the attracting body to be away from the frame center allows to use this force model when integrating for example an interplanetary trajectory propagated in an Earth centered frame (in which case an instance of InertialForces must also be added to take into account the coupling effect of relative frames motion).

The possibility to add several instances allows to use this in interplanetary trajectories or in trajectories about Lagrangian points

The fact this force model is never automatically added by the numerical propagator differs from NewtonianAttraction as NewtonianAttraction may be added automatically when propagating a trajectory represented as an Orbit, which must always refer to a central body, if user did not add the NewtonianAttraction or set the central attraction coefficient by himself.

Author:

Luc Maisonobe, Julio Hernanz

See Also:

InertialForces

Field Summary

Fields

Modifier and Type	Field and Description
static String	ATTRACTION_COEFFICIENT_SUFFIX Suffix for parameter name for attraction coefficient enabling Jacobian processing.

Constructor Summary

Constructors

Constructor and Description
SingleBodyAbsoluteAttraction(CelestialBody body) Simple constructor.

Method Summary

Modifier and Type	Method and Description
<T extends CalculusFieldElement<T>> FieldVector3D<T>	acceleration(FieldSpacecraftState<T> s, T[] parameters) Compute acceleration.
Vector3D	acceleration(SpacecraftState s, double[] parameters) Compute acceleration.
boolean	dependsOnPositionOnly() Check if force models depends on position only.
Stream<EventDetector>	getEventsDetectors() Get the discrete events related to the model.
<T extends CalculusFieldElement<T>> Stream<FieldEventDetector<T>>	getFieldEventsDetectors(Field<T> field) Get the discrete events related to the model.
List<ParameterDriver>	getParametersDrivers() Get the drivers for force model parameters.

Methods inherited from class org.orekit.forces.AbstractForceModel

complainIfNotSupported, getParameterDriver, isSupported

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.orekit.forces.ForceModel

addContribution, addContribution, getParameters, getParameters, init, init

Field Detail

ATTRACTION_COEFFICIENT_SUFFIX

public static final String ATTRACTION_COEFFICIENT_SUFFIX

Suffix for parameter name for attraction coefficient enabling Jacobian processing.

See Also:

Constant Field Values

Constructor Detail

SingleBodyAbsoluteAttraction

public SingleBodyAbsoluteAttraction(CelestialBody body)

Simple constructor.

Parameters:

body - the body to consider (ex: CelestialBodies.getSun() or CelestialBodies.getMoon())

Method Detail

dependsOnPositionOnly

public boolean dependsOnPositionOnly()

Check if force models depends on position only.

Returns:

true if force model depends on position only, false if it depends on velocity, either directly or due to a dependency on attitude

acceleration

public Vector3D acceleration(SpacecraftState s,
                             double[] parameters)

Compute acceleration.

Parameters:

s - current state information: date, kinematics, attitude

parameters - values of the force model parameters

Returns:

acceleration in same frame as state

acceleration

public <T extends CalculusFieldElement<T>> FieldVector3D<T> acceleration(FieldSpacecraftState<T> s,
                                                                         T[] parameters)

Compute acceleration.

Type Parameters:

T - type of the elements

Parameters:

s - current state information: date, kinematics, attitude

parameters - values of the force model parameters

Returns:

acceleration in same frame as state

getEventsDetectors

public Stream<EventDetector> getEventsDetectors()

Get the discrete events related to the model.

Returns:

stream of events detectors

getFieldEventsDetectors

public <T extends CalculusFieldElement<T>> Stream<FieldEventDetector<T>> getFieldEventsDetectors(Field<T> field)

Description copied from interface: ForceModel

Get the discrete events related to the model.

Type Parameters:

T - extends CalculusFieldElement<T>

Parameters:

field - field to which the state belongs

Returns:

stream of events detectors

getParametersDrivers

public List<ParameterDriver> getParametersDrivers()

Get the drivers for force model parameters.

Returns:

drivers for force model parameters