org.orekit.forces.gravity

Class Relativity

java.lang.Object

org.apache.commons.math3.ode.AbstractParameterizable

org.orekit.forces.gravity.Relativity

All Implemented Interfaces:

Parameterizable, ParameterizedODE, ForceModel

public class Relativity
extends AbstractParameterizable
implements ForceModel

Post-Newtonian correction force due to general relativity. The main effect is the precession of perigee by a few arcseconds per year.

Implemented from Montenbruck and Gill equation 3.146.

Author:

Evan Ward

See Also:

"Montenbruck, Oliver, and Gill, Eberhard. Satellite orbits : models, methods, and applications. Berlin New York: Springer, 2000."

Constructor Summary

Constructors

Constructor and Description
Relativity(double gm) Create a force model to add post-Newtonian acceleration corrections to an Earth orbit.

Method Summary

Methods

Modifier and Type	Method and Description
FieldVector3D<DerivativeStructure>	accelerationDerivatives(AbsoluteDate date, Frame frame, FieldVector3D<DerivativeStructure> position, FieldVector3D<DerivativeStructure> velocity, FieldRotation<DerivativeStructure> rotation, DerivativeStructure mass) Compute acceleration derivatives with respect to state parameters.
FieldVector3D<DerivativeStructure>	accelerationDerivatives(SpacecraftState s, String paramName) Compute acceleration derivatives with respect to additional parameters.
void	addContribution(SpacecraftState s, TimeDerivativesEquations adder) Compute the contribution of the force model to the perturbing acceleration.
EventDetector[]	getEventsDetectors() Get the discrete events related to the model.
double	getParameter(String name)
void	setParameter(String name, double value)

Methods inherited from class org.apache.commons.math3.ode.AbstractParameterizable

complainIfNotSupported, getParametersNames, isSupported

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.commons.math3.ode.Parameterizable

getParametersNames, isSupported

Constructor Detail

Relativity

public Relativity(double gm)

Create a force model to add post-Newtonian acceleration corrections to an Earth orbit.

Parameters:

gm - Earth's gravitational parameter.

Method Detail

addContribution

public void addContribution(SpacecraftState s,
                   TimeDerivativesEquations adder)
                     throws OrekitException

Description copied from interface: ForceModel

Compute the contribution of the force model to the perturbing acceleration.

Specified by:

addContribution in interface ForceModel

Parameters:

s - current state information: date, kinematics, attitude

adder - object where the contribution should be added

Throws:

OrekitException - if some specific error occurs

accelerationDerivatives

public FieldVector3D<DerivativeStructure> accelerationDerivatives(AbsoluteDate date,
                                                         Frame frame,
                                                         FieldVector3D<DerivativeStructure> position,
                                                         FieldVector3D<DerivativeStructure> velocity,
                                                         FieldRotation<DerivativeStructure> rotation,
                                                         DerivativeStructure mass)

Description copied from interface: ForceModel

Compute acceleration derivatives with respect to state parameters.

The derivatives should be computed with respect to position, velocity and optionnaly mass. The input parameters already take into account the free parameters (6 or 7 depending on derivation with respect to mass being considered or not) and order (always 1). Free parameters at indices 0, 1 and 2 correspond to derivatives with respect to position. Free parameters at indices 3, 4 and 5 correspond to derivatives with respect to velocity. Free parameter at index 6 (if present) corresponds to to derivatives with respect to mass.

Specified by:

accelerationDerivatives in interface ForceModel

Parameters:

date - current date

frame - inertial reference frame for state (both orbit and attitude)

position - position of spacecraft in reference frame

velocity - velocity of spacecraft in reference frame

rotation - orientation (attitude) of the spacecraft with respect to reference frame

mass - spacecraft mass

Returns:

acceleration with all derivatives specified by the input parameters own derivatives

accelerationDerivatives

public FieldVector3D<DerivativeStructure> accelerationDerivatives(SpacecraftState s,
                                                         String paramName)
                                                           throws OrekitException

Description copied from interface: ForceModel

Compute acceleration derivatives with respect to additional parameters.

Specified by:

accelerationDerivatives in interface ForceModel

Parameters:

s - spacecraft state

paramName - name of the parameter with respect to which derivatives are required

Returns:

acceleration with all derivatives specified by the input parameters own derivatives

Throws:

OrekitException - if derivatives cannot be computed

getEventsDetectors

public EventDetector[] getEventsDetectors()

Description copied from interface: ForceModel

Get the discrete events related to the model.

Specified by:

getEventsDetectors in interface ForceModel

Returns:

array of events detectors or null if the model is not related to any discrete events

getParameter

public double getParameter(String name)
                    throws UnknownParameterException

Specified by:

getParameter in interface ParameterizedODE

Throws:

UnknownParameterException

setParameter

public void setParameter(String name,
                double value)
                  throws UnknownParameterException

Specified by:

setParameter in interface ParameterizedODE

Throws:

UnknownParameterException