Package org.orekit.forces.radiation

Class KnockeRediffusedForceModel

java.lang.Object

org.orekit.forces.radiation.KnockeRediffusedForceModel

All Implemented Interfaces:

ForceModel, EventDetectorsProvider, ParameterDriversProvider

public class KnockeRediffusedForceModel
extends Object
implements ForceModel

The Knocke Earth Albedo and IR emission force model.

This model is based on "EARTH RADIATION PRESSURE EFFECTS ON SATELLITES", 1988, by P. C. Knocke, J. C. Ries, and B. D. Tapley.

This model represents the effects of radiation pressure coming from the Earth. It considers Solar radiation which has been reflected by Earth (albedo) and Earth infrared emissions. The planet is considered as a sphere and is divided into elementary areas. Each elementary area is considered as a plane and emits radiation according to Lambert's law. The flux the satellite receives is then equal to the sum of the elementary fluxes coming from Earth.

The radiative model of the satellite, and its ability to diffuse, reflect or absorb radiation is handled by a radiation sensitive model.

Caution: This model is only suitable for Earth. Using it with another central body is prone to error..

Since:

10.3

Author:

Thomas Paulet

Field Summary

Fields inherited from interface org.orekit.propagation.events.EventDetectorsProvider

DATATION_ACCURACY

Constructor Summary

Constructors

Constructor	Description
KnockeRediffusedForceModel(ExtendedPositionProvider sun, RadiationSensitive spacecraft, double equatorialRadius, double angularResolution)	Default Constructor.
KnockeRediffusedForceModel(ExtendedPositionProvider sun, RadiationSensitive spacecraft, double equatorialRadius, double angularResolution, TimeScale utc)	General constructor.

Method Summary

Modifier and Type	Method	Description
<T extends CalculusFieldElement<T>> FieldVector3D<T>	acceleration(FieldSpacecraftState<T> s, T[] parameters)	Compute acceleration.
Vector3D	acceleration(SpacecraftState s, double[] parameters)	Compute acceleration.
double	computeAlbedo(AbsoluteDate date, double phi)	Compute Earth albedo.
<T extends CalculusFieldElement<T>> T	computeAlbedo(FieldAbsoluteDate<T> date, T phi)	Compute Earth albedo.
<T extends CalculusFieldElement<T>> FieldVector3D<T>	computeElementaryFlux(FieldSpacecraftState<T> state, FieldVector3D<T> elementCenter, FieldVector3D<T> sunPosition, OneAxisEllipsoid earth, T elementArea)	Compute elementary rediffused flux on satellite.
Vector3D	computeElementaryFlux(SpacecraftState state, Vector3D elementCenter, Vector3D sunPosition, OneAxisEllipsoid earth, double elementArea)	Compute elementary rediffused flux on satellite.
double	computeEmissivity(AbsoluteDate date, double phi)	Compute Earth emisivity.
<T extends CalculusFieldElement<T>> T	computeEmissivity(FieldAbsoluteDate<T> date, T phi)	Compute Earth emisivity.
<T extends CalculusFieldElement<T>> T	computeSolarFlux(FieldVector3D<T> sunPosition)	Compute total solar flux impacting Earth.
double	computeSolarFlux(Vector3D sunPosition)	Compute total solar flux impacting Earth.
boolean	dependsOnPositionOnly()	Check if force model depends on position only at a given, fixed date.
List<ParameterDriver>	getParametersDrivers()	Get the drivers for parameters.

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.events.EventDetectorsProvider

getDateDetector, getEventDetectors, getFieldDateDetector, getFieldEventDetectors

Methods inherited from interface org.orekit.forces.ForceModel

addContribution, addContribution, dependsOnAttitudeRate, getEventDetectors, getFieldEventDetectors, init, init

Methods inherited from interface org.orekit.utils.ParameterDriversProvider

getNbParametersDriversValue, getParameterDriver, getParameters, getParameters, getParameters, getParameters, getParametersAllValues, getParametersAllValues, isSupported

Constructor Detail

KnockeRediffusedForceModel

@DefaultDataContext
public KnockeRediffusedForceModel(ExtendedPositionProvider sun,
                                  RadiationSensitive spacecraft,
                                  double equatorialRadius,
                                  double angularResolution)

Default Constructor.

This constructor uses the default data context

.

Parameters:

sun - Sun model

spacecraft - the object physical and geometrical information

equatorialRadius - the Earth equatorial radius in m

angularResolution - angular resolution in rad

KnockeRediffusedForceModel

public KnockeRediffusedForceModel(ExtendedPositionProvider sun,
                                  RadiationSensitive spacecraft,
                                  double equatorialRadius,
                                  double angularResolution,
                                  TimeScale utc)

General constructor.

Parameters:

sun - Sun model

spacecraft - the object physical and geometrical information

equatorialRadius - the Earth equatorial radius in m

angularResolution - angular resolution in rad

utc - the UTC time scale to define reference epoch

Method Detail

dependsOnPositionOnly

public boolean dependsOnPositionOnly()

Check if force model depends on position only at a given, fixed date.

Specified by:

dependsOnPositionOnly in interface ForceModel

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.

Specified by:

acceleration in interface ForceModel

Parameters:

s - current state information: date, kinematics, attitude

parameters - values of the force model parameters at state date, only 1 value for each parameterDriver

Returns:

acceleration in same frame as state

acceleration

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

Compute acceleration.

Specified by:

acceleration in interface ForceModel

Type Parameters:

T - type of the elements

Parameters:

s - current state information: date, kinematics, attitude

parameters - values of the force model parameters at state date, only 1 value for each parameterDriver

Returns:

acceleration in same frame as state

getParametersDrivers

public List<ParameterDriver> getParametersDrivers()

Get the drivers for parameters.

Specified by:

getParametersDrivers in interface ParameterDriversProvider

Returns:

drivers for parameters

computeAlbedo

public double computeAlbedo(AbsoluteDate date,
                            double phi)

Compute Earth albedo. Albedo value represents the fraction of solar radiative flux that is reflected by Earth. Its value is in [0;1].

Parameters:

date - the date

phi - the equatorial latitude in rad

Returns:

the albedo in [0;1]

computeAlbedo

public <T extends CalculusFieldElement<T>> T computeAlbedo(FieldAbsoluteDate<T> date,
                                                           T phi)

Compute Earth albedo. Albedo value represents the fraction of solar radiative flux that is reflected by Earth. Its value is in [0;1].

Type Parameters:

T - extends CalculusFieldElement

Parameters:

date - the date

phi - the equatorial latitude in rad

Returns:

the albedo in [0;1]

computeEmissivity

public double computeEmissivity(AbsoluteDate date,
                                double phi)

Compute Earth emisivity. Emissivity is used to compute the infrared flux that is emitted by Earth. Its value is in [0;1].

Parameters:

date - the date

phi - the equatorial latitude in rad

Returns:

the emissivity in [0;1]

computeEmissivity

public <T extends CalculusFieldElement<T>> T computeEmissivity(FieldAbsoluteDate<T> date,
                                                               T phi)

Compute Earth emisivity. Emissivity is used to compute the infrared flux that is emitted by Earth. Its value is in [0;1].

Type Parameters:

T - extends CalculusFieldElement

Parameters:

date - the date

phi - the equatorial latitude in rad

Returns:

the emissivity in [0;1]

computeSolarFlux

public double computeSolarFlux(Vector3D sunPosition)

Compute total solar flux impacting Earth.

Parameters:

sunPosition - the Sun position in an Earth centered frame

Returns:

the total solar flux impacting Earth in J/m^3

computeSolarFlux

public <T extends CalculusFieldElement<T>> T computeSolarFlux(FieldVector3D<T> sunPosition)

Compute total solar flux impacting Earth.

Type Parameters:

T - extends CalculusFieldElement

Parameters:

sunPosition - the Sun position in an Earth centered frame

Returns:

the total solar flux impacting Earth in J/m^3

computeElementaryFlux

public Vector3D computeElementaryFlux(SpacecraftState state,
                                      Vector3D elementCenter,
                                      Vector3D sunPosition,
                                      OneAxisEllipsoid earth,
                                      double elementArea)

Compute elementary rediffused flux on satellite.

Parameters:

state - the current spacecraft state

elementCenter - the position of the considered area center

sunPosition - the position of the Sun in the spacecraft frame

earth - the Earth model

elementArea - the area of the current element

Returns:

the rediffused flux from considered element on the spacecraft

computeElementaryFlux

public <T extends CalculusFieldElement<T>> FieldVector3D<T> computeElementaryFlux(FieldSpacecraftState<T> state,
                                                                                  FieldVector3D<T> elementCenter,
                                                                                  FieldVector3D<T> sunPosition,
                                                                                  OneAxisEllipsoid earth,
                                                                                  T elementArea)

Compute elementary rediffused flux on satellite.

Type Parameters:

T - extends CalculusFieldElement

Parameters:

state - the current spacecraft state

elementCenter - the position of the considered area center

sunPosition - the position of the Sun in the spacecraft frame

earth - the Earth model

elementArea - the area of the current element

Returns:

the rediffused flux from considered element on the spacecraft