AbstractGaussianContribution (ORbit Extrapolation KIT 9.0 API)

java.lang.Object
- org.orekit.propagation.semianalytical.dsst.forces.AbstractGaussianContribution

All Implemented Interfaces:

DSSTForceModel

Direct Known Subclasses:

DSSTAtmosphericDrag, DSSTSolarRadiationPressure
```
public abstract class AbstractGaussianContribution
extends Object
implements DSSTForceModel
```
Common handling of DSSTForceModel methods for Gaussian contributions to DSST propagation.
This abstract class allows to provide easily a subset of DSSTForceModel methods for specific Gaussian contributions.
This class implements the notion of numerical averaging of the DSST theory. Numerical averaging is mainly used for non-conservative disturbing forces such as atmospheric drag and solar radiation pressure.
Gaussian contributions can be expressed as: da_i/dt = δa_i/δv . q
where:
- a_i are the six equinoctial elements
- v is the velocity vector
- q is the perturbing acceleration due to the considered force
The averaging process and other considerations lead to integrate this contribution over the true longitude L possibly taking into account some limits.
To create a numerically averaged contribution, one needs only to provide a ForceModel and to implement in the derived class the method: getLLimits(SpacecraftState).
Author:

Pascal Parraud

Field Summary

Fields
Modifier and Type	Field and Description
`protected double`	`a` a.
`protected double`	`A` A = sqrt(μ * a).
`protected double`	`B` B = sqrt(1 - h² - k²).
`protected double`	`C` C = 1 + p² + q².
`protected double`	`co2AB` C / (2 * A * B) .
`protected double`	`ecc` Eccentricity.
`protected Vector3D`	`f` Equinoctial frame f vector.
`protected Vector3D`	`g` Equinoctial frame g vector.
`protected double`	`h` e_y.
`protected double`	`k` e_x.
`protected double`	`lm` Mean longitude.
`protected double`	`mu` μ .
`protected double`	`n` Kepler mean motion: n = sqrt(μ / a³).
`protected double`	`ooA` 1 / A .
`protected double`	`ooAB` 1 / (A * B) .
`protected double`	`ooBpo` 1 / (1 + B) .
`protected double`	`ooMu` 1 / μ .
`protected double`	`p` h_y.
`protected double`	`q` h_x.
`protected double`	`ton2a` 2 / (n² * a) .
`protected Vector3D`	`w` Equinoctial frame w vector.

Constructor Summary

Constructors
Modifier	Constructor and Description
`protected`	`AbstractGaussianContribution(String coefficientsKeyPrefix, double threshold, ForceModel contribution)` Build a new instance.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`protected abstract double[]`	`getLLimits(SpacecraftState state)` Compute the limits in L, the true longitude, for integration.
`double[]`	`getMeanElementRate(SpacecraftState state)` Computes the mean equinoctial elements rates da_i / dt.
`List<ShortPeriodTerms>`	`initialize(AuxiliaryElements aux, boolean meanOnly)` Performs initialization prior to propagation for the current force model.
`void`	`initializeStep(AuxiliaryElements aux)` Performs initialization at each integration step for the current force model.
`void`	`registerAttitudeProvider(AttitudeProvider provider)` Register an attitude provider.
`void`	`updateShortPeriodTerms(SpacecraftState... meanStates)` Update the short period terms.

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.semianalytical.dsst.forces.DSSTForceModel
getEventsDetectors

- Field Detail
  - a
```
protected double a
```
    a.
  - k
```
protected double k
```
    e_x.
  - h
```
protected double h
```
    e_y.
  - q
```
protected double q
```
    h_x.
  - p
```
protected double p
```
    h_y.
  - ecc
```
protected double ecc
```
    Eccentricity.
  - n
```
protected double n
```
    Kepler mean motion: n = sqrt(μ / a³).
  - lm
```
protected double lm
```
    Mean longitude.
  - f
```
protected Vector3D f
```
    Equinoctial frame f vector.
  - g
```
protected Vector3D g
```
    Equinoctial frame g vector.
  - w
```
protected Vector3D w
```
    Equinoctial frame w vector.
  - A
```
protected double A
```
    A = sqrt(μ * a).
  - B
```
protected double B
```
    B = sqrt(1 - h² - k²).
  - C
```
protected double C
```
    C = 1 + p² + q².
  - ton2a
```
protected double ton2a
```
    2 / (n² * a) .
  - ooA
```
protected double ooA
```
    1 / A .
  - ooAB
```
protected double ooAB
```
    1 / (A * B) .
  - co2AB
```
protected double co2AB
```
    C / (2 * A * B) .
  - ooBpo
```
protected double ooBpo
```
    1 / (1 + B) .
  - ooMu
```
protected double ooMu
```
    1 / μ .
  - mu
```
protected double mu
```
    μ .
- Constructor Detail
  - AbstractGaussianContribution
```
protected AbstractGaussianContribution(String coefficientsKeyPrefix,
                                       double threshold,
                                       ForceModel contribution)
```
    Build a new instance.
    
    Parameters:
    
    coefficientsKeyPrefix - prefix for coefficients keys
    
    threshold - tolerance for the choice of the Gauss quadrature order
    
    contribution - the ForceModel to be numerically averaged
- Method Detail
  - initialize
```
public List<ShortPeriodTerms> initialize(AuxiliaryElements aux,
                                         boolean meanOnly)
```
    Performs initialization prior to propagation for the current force model.
    This method aims at being called at the very beginning of a propagation.
    
    Specified by:
    
    initialize in interface DSSTForceModel
    
    Parameters:
    
    aux - auxiliary elements related to the current orbit
    
    meanOnly - only mean elements are used during the propagation
    
    Returns:
    
    a list of objects that will hold short period terms (the objects are also retained by the force model, which will update them during propagation)
  - initializeStep
```
public void initializeStep(AuxiliaryElements aux)
                    throws OrekitException
```
    Performs initialization at each integration step for the current force model.
    This method aims at being called before mean elements rates computation.
    
    Specified by:
    
    initializeStep in interface DSSTForceModel
    
    Parameters:
    
    aux - auxiliary elements related to the current orbit
    
    Throws:
    
    OrekitException - if some specific error occurs
  - getMeanElementRate
```
public double[] getMeanElementRate(SpacecraftState state)
                            throws OrekitException
```
    Computes the mean equinoctial elements rates da_i / dt.
    
    Specified by:
    
    getMeanElementRate in interface DSSTForceModel
    
    Parameters:
    
    state - current state information: date, kinematics, attitude
    
    Returns:
    
    the mean element rates dai/dt
    
    Throws:
    
    OrekitException - if some specific error occurs
  - getLLimits
```
protected abstract double[] getLLimits(SpacecraftState state)
                                throws OrekitException
```
    Compute the limits in L, the true longitude, for integration.
    
    Parameters:
    
    state - current state information: date, kinematics, attitude
    
    Returns:
    
    the integration limits in L
    
    Throws:
    
    OrekitException - if some specific error occurs
  - registerAttitudeProvider
```
public void registerAttitudeProvider(AttitudeProvider provider)
```
    Register an attitude provider.
    Register an attitude provider that can be used by the force model.
    
    Specified by:
    
    registerAttitudeProvider in interface DSSTForceModel
    
    Parameters:
    
    provider - the AttitudeProvider
  - updateShortPeriodTerms
```
public void updateShortPeriodTerms(SpacecraftState... meanStates)
                            throws OrekitException
```
    Update the short period terms.
    The short period terms that will be updated are the ones that were returned during the call to DSSTForceModel.initialize(AuxiliaryElements, boolean).
    
    Specified by:
    
    updateShortPeriodTerms in interface DSSTForceModel
    
    Parameters:
    
    meanStates - mean states information: date, kinematics, attitude
    
    Throws:
    
    OrekitException - if some specific error occurs

Class AbstractGaussianContribution

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface org.orekit.propagation.semianalytical.dsst.forces.DSSTForceModel

Field Detail

a

k

h

q

p

ecc

n

lm

f

g

w

A

B

C

ton2a

ooA

ooAB

co2AB

ooBpo

ooMu

mu

Constructor Detail

AbstractGaussianContribution

Method Detail

initialize

initializeStep

getMeanElementRate

getLLimits

registerAttitudeProvider

updateShortPeriodTerms