org.orekit.propagation.analytical

Class BrouwerLyddanePropagator

java.lang.Object

org.orekit.propagation.AbstractPropagator

org.orekit.propagation.analytical.AbstractAnalyticalPropagator

org.orekit.propagation.analytical.BrouwerLyddanePropagator

All Implemented Interfaces:

Propagator, PVCoordinatesProvider

public class BrouwerLyddanePropagator
extends AbstractAnalyticalPropagator

This class propagates a SpacecraftState using the analytical Brouwer-Lyddane model (from J2 to J5 zonal harmonics).

At the opposite of the EcksteinHechlerPropagator, the Brouwer-Lyddane model is suited for elliptical orbits, there is no problem having a rather small eccentricity or inclination (Lyddane helped to solve this issue with the Brouwer model). Singularity for the critical inclination i = 63.4° is avoided using the method developed in Warren Phipps' 1992 thesis.

By default, Brouwer-Lyddane model considers only the perturbations due to zonal harmonics. However, for low Earth orbits, the magnitude of the perturbative acceleration due to atmospheric drag can be significant. Warren Phipps' 1992 thesis considered the atmospheric drag by time derivatives of the mean mean anomaly using the catch-all coefficient M2Driver. Usually, M2 is adjusted during an orbit determination process and it represents the combination of all unmodeled secular along-track effects (i.e. not just the atmospheric drag). The behavior of M2 is close to the TLE.getBStar() parameter for the TLE. If the value of M2 is equal to 0.0, the along-track secular effects are not considered in the dynamical model. Typical values for M2 are not known. It depends on the orbit type. However, the value of M2 must be very small (e.g. between 1.0e-14 and 1.0e-15). The unit of M2 is rad/s². The along-track effects, represented by the secular rates of the mean semi-major axis and eccentricity, are computed following Eq. 2.38, 2.41, and 2.45 of Warren Phipps' thesis.

Since:

11.1

Author:

Melina Vanel, Bryan Cazabonne

See Also:

"Brouwer, Dirk. Solution of the problem of artificial satellite theory without drag. YALE UNIV NEW HAVEN CT NEW HAVEN United States, 1959.", "Lyddane, R. H. Small eccentricities or inclinations in the Brouwer theory of the artificial satellite. The Astronomical Journal 68 (1963): 555.", "Phipps Jr, Warren E. Parallelization of the Navy Space Surveillance Center (NAVSPASUR) Satellite Model. NAVAL POSTGRADUATE SCHOOL MONTEREY CA, 1992."

Field Summary

Fields

Modifier and Type	Field and Description
static double	M2 Default value for M2 coefficient.
static String	M2_NAME Parameter name for M2 coefficient.

Fields inherited from interface org.orekit.propagation.Propagator

DEFAULT_MASS

Constructor Summary

Constructors

Constructor and Description
BrouwerLyddanePropagator(Orbit initialOrbit, AttitudeProvider attitudeProv, double referenceRadius, double mu, double c20, double c30, double c40, double c50, double M2) Build a propagator from orbit, attitude provider and potential.
BrouwerLyddanePropagator(Orbit initialOrbit, AttitudeProvider attitudeProv, double mass, double referenceRadius, double mu, double c20, double c30, double c40, double c50, double M2) Build a propagator from orbit, attitude provider, mass and potential.
BrouwerLyddanePropagator(Orbit initialOrbit, AttitudeProvider attitudeProv, double mass, double referenceRadius, double mu, double c20, double c30, double c40, double c50, PropagationType initialType, double M2) Build a propagator from orbit, attitude provider, mass and potential.
BrouwerLyddanePropagator(Orbit initialOrbit, AttitudeProvider attitudeProv, double mass, double referenceRadius, double mu, double c20, double c30, double c40, double c50, PropagationType initialType, double M2, double epsilon, int maxIterations) Build a propagator from orbit, attitude provider, mass and potential.
BrouwerLyddanePropagator(Orbit initialOrbit, AttitudeProvider attitudeProv, double mass, UnnormalizedSphericalHarmonicsProvider provider, double M2) Build a propagator from orbit, attitude provider, mass and potential provider.
BrouwerLyddanePropagator(Orbit initialOrbit, AttitudeProvider attitudeProv, double mass, UnnormalizedSphericalHarmonicsProvider provider, PropagationType initialType, double M2) Build a propagator from orbit, attitude provider, mass and potential provider.
BrouwerLyddanePropagator(Orbit initialOrbit, AttitudeProvider attitude, double mass, UnnormalizedSphericalHarmonicsProvider provider, UnnormalizedSphericalHarmonicsProvider.UnnormalizedSphericalHarmonics harmonics, double M2) Private helper constructor.
BrouwerLyddanePropagator(Orbit initialOrbit, AttitudeProvider attitude, double mass, UnnormalizedSphericalHarmonicsProvider provider, UnnormalizedSphericalHarmonicsProvider.UnnormalizedSphericalHarmonics harmonics, PropagationType initialType, double M2) Private helper constructor.
BrouwerLyddanePropagator(Orbit initialOrbit, AttitudeProvider attitudeProv, UnnormalizedSphericalHarmonicsProvider provider, double M2) Build a propagator from orbit, attitude provider and potential provider.
BrouwerLyddanePropagator(Orbit initialOrbit, double referenceRadius, double mu, double c20, double c30, double c40, double c50, double M2) Build a propagator from orbit and potential.
BrouwerLyddanePropagator(Orbit initialOrbit, double mass, double referenceRadius, double mu, double c20, double c30, double c40, double c50, double M2) Build a propagator from orbit, mass and potential.
BrouwerLyddanePropagator(Orbit initialOrbit, double mass, UnnormalizedSphericalHarmonicsProvider provider, double M2) Build a propagator from orbit, mass and potential provider.
BrouwerLyddanePropagator(Orbit initialOrbit, UnnormalizedSphericalHarmonicsProvider provider, double M2) Build a propagator from orbit and potential provider.
BrouwerLyddanePropagator(Orbit initialOrbit, UnnormalizedSphericalHarmonicsProvider provider, PropagationType initialType, double M2) Build a propagator from orbit and potential provider.

Method Summary

Modifier and Type	Method and Description
static KeplerianOrbit	computeMeanOrbit(Orbit osculating, double referenceRadius, double mu, double c20, double c30, double c40, double c50, double M2Value, double epsilon, int maxIterations) Conversion from osculating to mean orbit.
static KeplerianOrbit	computeMeanOrbit(Orbit osculating, UnnormalizedSphericalHarmonicsProvider provider, UnnormalizedSphericalHarmonicsProvider.UnnormalizedSphericalHarmonics harmonics, double M2Value) Conversion from osculating to mean orbit.
static KeplerianOrbit	computeMeanOrbit(Orbit osculating, UnnormalizedSphericalHarmonicsProvider provider, UnnormalizedSphericalHarmonicsProvider.UnnormalizedSphericalHarmonics harmonics, double M2Value, double epsilon, int maxIterations) Conversion from osculating to mean orbit.
protected AbstractMatricesHarvester	createHarvester(String stmName, RealMatrix initialStm, DoubleArrayDictionary initialJacobianColumns) Create the harvester suitable for propagator.
double[]	getCk0() Get the un-normalized zonal coefficients.
protected List<String>	getJacobiansColumnsNames() Get the names of the parameters in the matrix returned by MatricesHarvester.getParametersJacobian(org.orekit.propagation.SpacecraftState).
double	getM2() Get the value of the M2 drag parameter.
protected double	getMass(AbsoluteDate date) Get the mass.
double	getMu() Get the central attraction coefficient μ.
List<ParameterDriver>	getParametersDrivers() Get the parameters driver for propagation model.
double	getReferenceRadius() Get the reference radius of the central body attraction model.
KeplerianOrbit	propagateOrbit(AbsoluteDate date) Extrapolate an orbit up to a specific target date.
void	resetInitialState(SpacecraftState state) Reset the propagator initial state.
void	resetInitialState(SpacecraftState state, PropagationType stateType) Reset the propagator initial state.
void	resetInitialState(SpacecraftState state, PropagationType stateType, double epsilon, int maxIterations) Reset the propagator initial state.
protected void	resetIntermediateState(SpacecraftState state, boolean forward) Reset an intermediate state.
protected void	resetIntermediateState(SpacecraftState state, boolean forward, double epsilon, int maxIterations) Reset an intermediate state.

Methods inherited from class org.orekit.propagation.analytical.AbstractAnalyticalPropagator

acceptStep, addEventDetector, basicPropagate, clearEventsDetectors, getEphemerisGenerator, getEventsDetectors, getPvProvider, propagate

Methods inherited from class org.orekit.propagation.AbstractPropagator

addAdditionalStateProvider, getAdditionalStateProviders, getAttitudeProvider, getFrame, getHarvester, getInitialState, getManagedAdditionalStates, getMultiplexer, getPVCoordinates, getStartDate, initializeAdditionalStates, initializePropagation, isAdditionalStateManaged, propagate, setAttitudeProvider, setStartDate, setupMatricesComputation, stateChanged, updateAdditionalStates, updateUnmanagedStates

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.Propagator

clearStepHandlers, getDefaultLaw, setStepHandler, setStepHandler

Field Detail

M2_NAME

public static final String M2_NAME

Parameter name for M2 coefficient.

See Also:

Constant Field Values

M2

public static final double M2

Default value for M2 coefficient.

See Also:

Constant Field Values

Constructor Detail

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                UnnormalizedSphericalHarmonicsProvider provider,
                                double M2)

Build a propagator from orbit and potential provider.

Mass and attitude provider are set to unspecified non-null arbitrary values.

Using this constructor, an initial osculating orbit is considered.

Parameters:

initialOrbit - initial orbit

provider - for un-normalized zonal coefficients

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

See Also:

BrouwerLyddanePropagator(Orbit, AttitudeProvider, UnnormalizedSphericalHarmonicsProvider, double), BrouwerLyddanePropagator(Orbit, UnnormalizedSphericalHarmonicsProvider, PropagationType, double)

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                AttitudeProvider attitude,
                                double mass,
                                UnnormalizedSphericalHarmonicsProvider provider,
                                UnnormalizedSphericalHarmonicsProvider.UnnormalizedSphericalHarmonics harmonics,
                                double M2)

Private helper constructor.

Using this constructor, an initial osculating orbit is considered.

Parameters:

initialOrbit - initial orbit

attitude - attitude provider

mass - spacecraft mass

provider - for un-normalized zonal coefficients

harmonics - provider.onDate(initialOrbit.getDate())

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

See Also:

BrouwerLyddanePropagator(Orbit, AttitudeProvider, double, UnnormalizedSphericalHarmonicsProvider, UnnormalizedSphericalHarmonicsProvider.UnnormalizedSphericalHarmonics, PropagationType, double)

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                double referenceRadius,
                                double mu,
                                double c20,
                                double c30,
                                double c40,
                                double c50,
                                double M2)

Build a propagator from orbit and potential.

Mass and attitude provider are set to unspecified non-null arbitrary values.

The C_n,0 coefficients are the denormalized zonal coefficients, they are related to both the normalized coefficients C_n,0 and the J_n one as follows:

C_n,0 = [(2-δ_0,m)(2n+1)(n-m)!/(n+m)!]^½ C_n,0

C_n,0 = -J_n

Using this constructor, an initial osculating orbit is considered.

Parameters:

initialOrbit - initial orbit

referenceRadius - reference radius of the Earth for the potential model (m)

mu - central attraction coefficient (m³/s²)

c20 - un-normalized zonal coefficient (about -1.08e-3 for Earth)

c30 - un-normalized zonal coefficient (about +2.53e-6 for Earth)

c40 - un-normalized zonal coefficient (about +1.62e-6 for Earth)

c50 - un-normalized zonal coefficient (about +2.28e-7 for Earth)

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

See Also:

Constants, BrouwerLyddanePropagator(Orbit, AttitudeProvider, double, double, double, double, double, double, double, double)

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                double mass,
                                UnnormalizedSphericalHarmonicsProvider provider,
                                double M2)

Build a propagator from orbit, mass and potential provider.

Attitude law is set to an unspecified non-null arbitrary value.

Using this constructor, an initial osculating orbit is considered.

Parameters:

initialOrbit - initial orbit

mass - spacecraft mass

provider - for un-normalized zonal coefficients

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

See Also:

BrouwerLyddanePropagator(Orbit, AttitudeProvider, double, UnnormalizedSphericalHarmonicsProvider, double)

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                double mass,
                                double referenceRadius,
                                double mu,
                                double c20,
                                double c30,
                                double c40,
                                double c50,
                                double M2)

Build a propagator from orbit, mass and potential.

Attitude law is set to an unspecified non-null arbitrary value.

The C_n,0 coefficients are the denormalized zonal coefficients, they are related to both the normalized coefficients C_n,0 and the J_n one as follows:

C_n,0 = [(2-δ_0,m)(2n+1)(n-m)!/(n+m)!]^½ C_n,0

C_n,0 = -J_n

Using this constructor, an initial osculating orbit is considered.

Parameters:

initialOrbit - initial orbit

mass - spacecraft mass

referenceRadius - reference radius of the Earth for the potential model (m)

mu - central attraction coefficient (m³/s²)

c20 - un-normalized zonal coefficient (about -1.08e-3 for Earth)

c30 - un-normalized zonal coefficient (about +2.53e-6 for Earth)

c40 - un-normalized zonal coefficient (about +1.62e-6 for Earth)

c50 - un-normalized zonal coefficient (about +2.28e-7 for Earth)

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

See Also:

BrouwerLyddanePropagator(Orbit, AttitudeProvider, double, double, double, double, double, double, double, double)

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                AttitudeProvider attitudeProv,
                                UnnormalizedSphericalHarmonicsProvider provider,
                                double M2)

Build a propagator from orbit, attitude provider and potential provider.

Mass is set to an unspecified non-null arbitrary value.

Using this constructor, an initial osculating orbit is considered.

Parameters:

initialOrbit - initial orbit

attitudeProv - attitude provider

provider - for un-normalized zonal coefficients

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                AttitudeProvider attitudeProv,
                                double referenceRadius,
                                double mu,
                                double c20,
                                double c30,
                                double c40,
                                double c50,
                                double M2)

Build a propagator from orbit, attitude provider and potential.

Mass is set to an unspecified non-null arbitrary value.

The C_n,0 coefficients are the denormalized zonal coefficients, they are related to both the normalized coefficients C_n,0 and the J_n one as follows:

C_n,0 = [(2-δ_0,m)(2n+1)(n-m)!/(n+m)!]^½ C_n,0

C_n,0 = -J_n

Using this constructor, an initial osculating orbit is considered.

Parameters:

initialOrbit - initial orbit

attitudeProv - attitude provider

referenceRadius - reference radius of the Earth for the potential model (m)

mu - central attraction coefficient (m³/s²)

c20 - un-normalized zonal coefficient (about -1.08e-3 for Earth)

c30 - un-normalized zonal coefficient (about +2.53e-6 for Earth)

c40 - un-normalized zonal coefficient (about +1.62e-6 for Earth)

c50 - un-normalized zonal coefficient (about +2.28e-7 for Earth)

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                AttitudeProvider attitudeProv,
                                double mass,
                                UnnormalizedSphericalHarmonicsProvider provider,
                                double M2)

Build a propagator from orbit, attitude provider, mass and potential provider.

Using this constructor, an initial osculating orbit is considered.

Parameters:

initialOrbit - initial orbit

attitudeProv - attitude provider

mass - spacecraft mass

provider - for un-normalized zonal coefficients

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

See Also:

BrouwerLyddanePropagator(Orbit, AttitudeProvider, double, UnnormalizedSphericalHarmonicsProvider, PropagationType, double)

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                AttitudeProvider attitudeProv,
                                double mass,
                                double referenceRadius,
                                double mu,
                                double c20,
                                double c30,
                                double c40,
                                double c50,
                                double M2)

Build a propagator from orbit, attitude provider, mass and potential.

The C_n,0 coefficients are the denormalized zonal coefficients, they are related to both the normalized coefficients C_n,0 and the J_n one as follows:

C_n,0 = [(2-δ_0,m)(2n+1)(n-m)!/(n+m)!]^½ C_n,0

C_n,0 = -J_n

Using this constructor, an initial osculating orbit is considered.

Parameters:

initialOrbit - initial orbit

attitudeProv - attitude provider

mass - spacecraft mass

referenceRadius - reference radius of the Earth for the potential model (m)

mu - central attraction coefficient (m³/s²)

c20 - un-normalized zonal coefficient (about -1.08e-3 for Earth)

c30 - un-normalized zonal coefficient (about +2.53e-6 for Earth)

c40 - un-normalized zonal coefficient (about +1.62e-6 for Earth)

c50 - un-normalized zonal coefficient (about +2.28e-7 for Earth)

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

See Also:

BrouwerLyddanePropagator(Orbit, AttitudeProvider, double, double, double, double, double, double, double, PropagationType, double)

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                UnnormalizedSphericalHarmonicsProvider provider,
                                PropagationType initialType,
                                double M2)

Build a propagator from orbit and potential provider.

Mass and attitude provider are set to unspecified non-null arbitrary values.

Using this constructor, it is possible to define the initial orbit as a mean Brouwer-Lyddane orbit or an osculating one.

Parameters:

initialOrbit - initial orbit

provider - for un-normalized zonal coefficients

initialType - initial orbit type (mean Brouwer-Lyddane orbit or osculating orbit)

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                AttitudeProvider attitudeProv,
                                double mass,
                                UnnormalizedSphericalHarmonicsProvider provider,
                                PropagationType initialType,
                                double M2)

Build a propagator from orbit, attitude provider, mass and potential provider.

Using this constructor, it is possible to define the initial orbit as a mean Brouwer-Lyddane orbit or an osculating one.

Parameters:

initialOrbit - initial orbit

attitudeProv - attitude provider

mass - spacecraft mass

provider - for un-normalized zonal coefficients

initialType - initial orbit type (mean Brouwer-Lyddane orbit or osculating orbit)

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                AttitudeProvider attitude,
                                double mass,
                                UnnormalizedSphericalHarmonicsProvider provider,
                                UnnormalizedSphericalHarmonicsProvider.UnnormalizedSphericalHarmonics harmonics,
                                PropagationType initialType,
                                double M2)

Private helper constructor.

Using this constructor, it is possible to define the initial orbit as a mean Brouwer-Lyddane orbit or an osculating one.

Parameters:

initialOrbit - initial orbit

attitude - attitude provider

mass - spacecraft mass

provider - for un-normalized zonal coefficients

harmonics - provider.onDate(initialOrbit.getDate())

initialType - initial orbit type (mean Brouwer-Lyddane orbit or osculating orbit)

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                AttitudeProvider attitudeProv,
                                double mass,
                                double referenceRadius,
                                double mu,
                                double c20,
                                double c30,
                                double c40,
                                double c50,
                                PropagationType initialType,
                                double M2)

Build a propagator from orbit, attitude provider, mass and potential.

The C_n,0 coefficients are the denormalized zonal coefficients, they are related to both the normalized coefficients C_n,0 and the J_n one as follows:

C_n,0 = [(2-δ_0,m)(2n+1)(n-m)!/(n+m)!]^½ C_n,0

C_n,0 = -J_n

Using this constructor, it is possible to define the initial orbit as a mean Brouwer-Lyddane orbit or an osculating one.

Parameters:

initialOrbit - initial orbit

attitudeProv - attitude provider

mass - spacecraft mass

referenceRadius - reference radius of the Earth for the potential model (m)

mu - central attraction coefficient (m³/s²)

c20 - un-normalized zonal coefficient (about -1.08e-3 for Earth)

c30 - un-normalized zonal coefficient (about +2.53e-6 for Earth)

c40 - un-normalized zonal coefficient (about +1.62e-6 for Earth)

c50 - un-normalized zonal coefficient (about +2.28e-7 for Earth)

initialType - initial orbit type (mean Brouwer-Lyddane orbit or osculating orbit)

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

BrouwerLyddanePropagator

public BrouwerLyddanePropagator(Orbit initialOrbit,
                                AttitudeProvider attitudeProv,
                                double mass,
                                double referenceRadius,
                                double mu,
                                double c20,
                                double c30,
                                double c40,
                                double c50,
                                PropagationType initialType,
                                double M2,
                                double epsilon,
                                int maxIterations)

Build a propagator from orbit, attitude provider, mass and potential.

The C_n,0 coefficients are the denormalized zonal coefficients, they are related to both the normalized coefficients C_n,0 and the J_n one as follows:

C_n,0 = [(2-δ_0,m)(2n+1)(n-m)!/(n+m)!]^½ C_n,0

C_n,0 = -J_n

Using this constructor, it is possible to define the initial orbit as a mean Brouwer-Lyddane orbit or an osculating one.

Parameters:

initialOrbit - initial orbit

attitudeProv - attitude provider

mass - spacecraft mass

referenceRadius - reference radius of the Earth for the potential model (m)

mu - central attraction coefficient (m³/s²)

c20 - un-normalized zonal coefficient (about -1.08e-3 for Earth)

c30 - un-normalized zonal coefficient (about +2.53e-6 for Earth)

c40 - un-normalized zonal coefficient (about +1.62e-6 for Earth)

c50 - un-normalized zonal coefficient (about +2.28e-7 for Earth)

initialType - initial orbit type (mean Brouwer-Lyddane orbit or osculating orbit)

M2 - value of empirical drag coefficient in rad/s². If equal to M2 drag is not computed

epsilon - convergence threshold for mean parameters conversion

maxIterations - maximum iterations for mean parameters conversion

Since:

11.2

Method Detail

computeMeanOrbit

public static KeplerianOrbit computeMeanOrbit(Orbit osculating,
                                              UnnormalizedSphericalHarmonicsProvider provider,
                                              UnnormalizedSphericalHarmonicsProvider.UnnormalizedSphericalHarmonics harmonics,
                                              double M2Value)

Conversion from osculating to mean orbit.

Compute mean orbit in a Brouwer-Lyddane sense, corresponding to the osculating SpacecraftState in input.

Since the osculating orbit is obtained with the computation of short-periodic variation, the resulting output will depend on both the gravity field parameterized in input and the atmospheric drag represented by the m2 parameter.

The computation is done through a fixed-point iteration process.

Parameters:

osculating - osculating orbit to convert

provider - for un-normalized zonal coefficients

harmonics - provider.onDate(osculating.getDate())

M2Value - value of empirical drag coefficient in rad/s². If equal to BrouwerLyddanePropagator.M2 drag is not considered

Returns:

mean orbit in a Brouwer-Lyddane sense

Since:

11.2

computeMeanOrbit

public static KeplerianOrbit computeMeanOrbit(Orbit osculating,
                                              UnnormalizedSphericalHarmonicsProvider provider,
                                              UnnormalizedSphericalHarmonicsProvider.UnnormalizedSphericalHarmonics harmonics,
                                              double M2Value,
                                              double epsilon,
                                              int maxIterations)

Conversion from osculating to mean orbit.

Compute mean orbit in a Brouwer-Lyddane sense, corresponding to the osculating SpacecraftState in input.

Since the osculating orbit is obtained with the computation of short-periodic variation, the resulting output will depend on both the gravity field parameterized in input and the atmospheric drag represented by the m2 parameter.

The computation is done through a fixed-point iteration process.

Parameters:

osculating - osculating orbit to convert

provider - for un-normalized zonal coefficients

harmonics - provider.onDate(osculating.getDate())

M2Value - value of empirical drag coefficient in rad/s². If equal to BrouwerLyddanePropagator.M2 drag is not considered

epsilon - convergence threshold for mean parameters conversion

maxIterations - maximum iterations for mean parameters conversion

Returns:

mean orbit in a Brouwer-Lyddane sense

Since:

11.2

computeMeanOrbit

public static KeplerianOrbit computeMeanOrbit(Orbit osculating,
                                              double referenceRadius,
                                              double mu,
                                              double c20,
                                              double c30,
                                              double c40,
                                              double c50,
                                              double M2Value,
                                              double epsilon,
                                              int maxIterations)

Conversion from osculating to mean orbit.

Compute mean orbit in a Brouwer-Lyddane sense, corresponding to the osculating SpacecraftState in input.

Since the osculating orbit is obtained with the computation of short-periodic variation, the resulting output will depend on both the gravity field parameterized in input and the atmospheric drag represented by the m2 parameter.

The computation is done through a fixed-point iteration process.

Parameters:

osculating - osculating orbit to convert

referenceRadius - reference radius of the Earth for the potential model (m)

mu - central attraction coefficient (m³/s²)

c20 - un-normalized zonal coefficient (about -1.08e-3 for Earth)

c30 - un-normalized zonal coefficient (about +2.53e-6 for Earth)

c40 - un-normalized zonal coefficient (about +1.62e-6 for Earth)

c50 - un-normalized zonal coefficient (about +2.28e-7 for Earth)

M2Value - value of empirical drag coefficient in rad/s². If equal to BrouwerLyddanePropagator.M2 drag is not considered

epsilon - convergence threshold for mean parameters conversion

maxIterations - maximum iterations for mean parameters conversion

Returns:

mean orbit in a Brouwer-Lyddane sense

Since:

11.2

resetInitialState

public void resetInitialState(SpacecraftState state)

Reset the propagator initial state.

The new initial state to consider must be defined with an osculating orbit.

Specified by:

resetInitialState in interface Propagator

Overrides:

resetInitialState in class AbstractPropagator

Parameters:

state - new initial state to consider

See Also:

resetInitialState(SpacecraftState, PropagationType)

resetInitialState

public void resetInitialState(SpacecraftState state,
                              PropagationType stateType)

Reset the propagator initial state.

Parameters:

state - new initial state to consider

stateType - mean Brouwer-Lyddane orbit or osculating orbit

resetInitialState

public void resetInitialState(SpacecraftState state,
                              PropagationType stateType,
                              double epsilon,
                              int maxIterations)

Reset the propagator initial state.

Parameters:

state - new initial state to consider

stateType - mean Brouwer-Lyddane orbit or osculating orbit

epsilon - convergence threshold for mean parameters conversion

maxIterations - maximum iterations for mean parameters conversion

Since:

11.2

resetIntermediateState

protected void resetIntermediateState(SpacecraftState state,
                                      boolean forward)

Reset an intermediate state.

Specified by:

resetIntermediateState in class AbstractAnalyticalPropagator

Parameters:

state - new intermediate state to consider

forward - if true, the intermediate state is valid for propagations after itself

resetIntermediateState

protected void resetIntermediateState(SpacecraftState state,
                                      boolean forward,
                                      double epsilon,
                                      int maxIterations)

Reset an intermediate state.

Parameters:

state - new intermediate state to consider

forward - if true, the intermediate state is valid for propagations after itself

epsilon - convergence threshold for mean parameters conversion

maxIterations - maximum iterations for mean parameters conversion

Since:

11.2

propagateOrbit

public KeplerianOrbit propagateOrbit(AbsoluteDate date)

Extrapolate an orbit up to a specific target date.

Specified by:

propagateOrbit in class AbstractAnalyticalPropagator

Parameters:

date - target date for the orbit

Returns:

extrapolated parameters

getM2

public double getM2()

Get the value of the M2 drag parameter.

Returns:

the value of the M2 drag parameter

getMu

public double getMu()

Get the central attraction coefficient μ.

Returns:

mu central attraction coefficient (m³/s²)

getCk0

public double[] getCk0()

Get the un-normalized zonal coefficients.

Returns:

the un-normalized zonal coefficients

getReferenceRadius

public double getReferenceRadius()

Get the reference radius of the central body attraction model.

Returns:

the reference radius in meters

getParametersDrivers

public List<ParameterDriver> getParametersDrivers()

Get the parameters driver for propagation model.

Returns:

drivers for propagation model

createHarvester

protected AbstractMatricesHarvester createHarvester(String stmName,
                                                    RealMatrix initialStm,
                                                    DoubleArrayDictionary initialJacobianColumns)

Create the harvester suitable for propagator.

Overrides:

createHarvester in class AbstractPropagator

Parameters:

stmName - State Transition Matrix state name

initialStm - initial State Transition Matrix ∂Y/∂Y₀, if null (which is the most frequent case), assumed to be 6x6 identity

initialJacobianColumns - initial columns of the Jacobians matrix with respect to parameters, if null or if some selected parameters are missing from the dictionary, the corresponding initial column is assumed to be 0

Returns:

harvester to retrieve computed matrices during and after propagation

getJacobiansColumnsNames

protected List<String> getJacobiansColumnsNames()

Get the names of the parameters in the matrix returned by MatricesHarvester.getParametersJacobian(org.orekit.propagation.SpacecraftState).

Overrides:

getJacobiansColumnsNames in class AbstractAnalyticalPropagator

Returns:

names of the parameters (i.e. columns) of the Jacobian matrix

getMass

protected double getMass(AbsoluteDate date)

Get the mass.

Specified by:

getMass in class AbstractAnalyticalPropagator

Parameters:

date - target date for the orbit

Returns:

mass mass