Package org.orekit.forces.radiation

Class ECOM2

java.lang.Object

org.orekit.forces.radiation.AbstractRadiationForceModel

org.orekit.forces.radiation.ECOM2

All Implemented Interfaces:

ForceModel, RadiationForceModel, EventDetectorsProvider, ParameterDriversProvider

public class ECOM2
extends AbstractRadiationForceModel

The Empirical CODE Orbit Model 2 (ECOM2) of the Center for Orbit Determination in Europe (CODE).

The drag acceleration is computed as follows : γ = γ₀ + D(u)e_D + Y(u)e_Y + B(u)e_B

In the above equation, γ₀ is a selectable a priori model. Since 2013, no a priori model is used for CODE IGS contribution (i.e. γ₀ = 0). Moreover, u denotes the satellite's argument of latitude.

D(u), Y(u) and B(u) are three functions of the ECOM2 model that can be represented as Fourier series. The coefficients of the Fourier series are estimated during the estimation process. he ECOM2 model has user-defines upper limits nD and nB for the Fourier series (i.e. nD for D(u) and nB for B(u). Y(u) is defined as a constant value).

It exists several configurations to initialize nD and nB values. However, Arnold et al recommend to use D2B1 (i.e. nD = 1 and nB = 1) and D4B1 (i.e. nD = 2 an nB = 1) configurations. At the opposite, in Arnold paper, it is recommend to not use D2B0 (i.e. nD = 1 and nB = 0) configuration.

Since Orekit 11.0, it is possible to take into account the eclipses generated by Moon in the solar radiation pressure force model using the AbstractRadiationForceModel.addOccultingBody(ExtendedPositionProvider, double) method.
ECOM2 srp = new ECOM2(1, 1, 0.0, CelestialBodyFactory.getSun(), Constants.EIGEN5C_EARTH_EQUATORIAL_RADIUS);
srp.addOccultingBody(CelestialBodyFactory.getMoon(), Constants.MOON_EQUATORIAL_RADIUS);

Since:

10.2

Author:

David Soulard

See Also:

• "Arnold, Daniel, et al, CODE’s new solar radiation pressure model for GNSS orbit determination, Journal of geodesy 89.8 (2015): 775-791."
• "Tzu-Pang tseng and Michael Moore, Impact of solar radiation pressure mis-modeling on GNSS satellite orbit determination, IGS Worshop, Wuhan, China, 2018."

Field Summary

Fields

Modifier and Type	Field	Description
static final String	ECOM_COEFFICIENT	Parameter name for ECOM model coefficients enabling Jacobian processing.

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

DATATION_ACCURACY

Constructor Summary

Constructors

Constructor	Description
ECOM2(int nD, int nB, double value, ExtendedPositionProvider sun, double equatorialRadius)	Constructor.
ECOM2(int nD, int nB, double value, ExtendedPositionProvider sun, double equatorialRadius, Frames frames)	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.
List<ParameterDriver>	getParametersDrivers()	Get the drivers for parameters.

Methods inherited from class org.orekit.forces.radiation.AbstractRadiationForceModel

addOccultingBody, addOccultingBody, getDefaultEclipseDetectionSettings, getEventDetectors, getFieldEventDetectors, getGeneralEclipseAngles, getGeneralEclipseAngles, getOccultingBodies

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, getMassDerivative, getMassDerivative, init, init

Methods inherited from interface org.orekit.utils.ParameterDriversProvider

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

Methods inherited from interface org.orekit.forces.radiation.RadiationForceModel

dependsOnPositionOnly

Field Details

ECOM_COEFFICIENT

public static final String ECOM_COEFFICIENT

Parameter name for ECOM model coefficients enabling Jacobian processing.

See Also:

• Constant Field Values

Constructor Details

ECOM2

@DefaultDataContext
public ECOM2(int nD,
 int nB,
 double value,
 ExtendedPositionProvider sun,
 double equatorialRadius)

Constructor.

Parameters:

nD - truncation rank of Fourier series in D term.

nB - truncation rank of Fourier series in B term.

value - parameters initial value

sun - provide for Sun parameter

equatorialRadius - spherical shape model (for umbra/penumbra computation)

ECOM2

public ECOM2(int nD,
 int nB,
 double value,
 ExtendedPositionProvider sun,
 double equatorialRadius,
 Frames frames)

Constructor.

Parameters:

nD - truncation rank of Fourier series in D term.

nB - truncation rank of Fourier series in B term.

value - parameters initial value

sun - provide for Sun parameter

equatorialRadius - spherical shape model (for umbra/penumbra computation)

frames - list of frames with user-defined data context

Since:

13.1.1

Method Details

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 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.

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.

Returns:

drivers for parameters