org.orekit.orbits
Class EquatorialOrbit

java.lang.Object
  org.orekit.orbits.Orbit
      org.orekit.orbits.EquatorialOrbit

All Implemented Interfaces:

Serializable, TimeInterpolable<Orbit>, TimeShiftable<Orbit>, TimeStamped, PVCoordinatesProvider

public final class EquatorialOrbit
extends Orbit

This class handles non circular equatorial orbital parameters.

The parameters used internally are the equatorial elements (see EquatorialParameters for more information.

The instance EquatorialOrbit is guaranteed to be immutable.

Since:

1.3

Version:

$Id: EquatorialOrbit.java 17602 2017-05-18 08:25:23Z bignon $

Author:

Denis Claude

See Also:

Orbit, CircularOrbit, CartesianOrbit, EquinoctialOrbit, Serialized Form

Concurrency :

immutable

Constructor Summary

EquatorialOrbit(double a, double e, double pomega, double ix, double iy, double anomaly, PositionAngle type, Frame frame, AbsoluteDate date, double mu)
Creates a new instance.

EquatorialOrbit(IOrbitalParameters parameters, Frame frame, AbsoluteDate date)
Creates a new instance.

EquatorialOrbit(Orbit op)
Constructor from any kind of orbital parameters.

EquatorialOrbit(PVCoordinates pvCoordinates, Frame frame, AbsoluteDate date, double mu)
Constructor from cartesian parameters.

Method Summary

protected double[][]	computeJacobianEccentricWrtCartesian() Compute the Jacobian of the orbital parameters with eccentric angle with respect to the Cartesian parameters.
protected double[][]	computeJacobianMeanWrtCartesian() Compute the Jacobian of the orbital parameters with mean angle with respect to the Cartesian parameters.
protected double[][]	computeJacobianTrueWrtCartesian() Compute the Jacobian of the orbital parameters with true angle with respect to the Cartesian parameters.
double	getA() Get the semi-major axis.
double	getAnomaly(PositionAngle type) Get the anomaly.
double	getE() Get the eccentricity.
double	getEccentricAnomaly() Get the eccentric anomaly.
EquatorialParameters	getEquatorialParameters() Getter for underlying equatorial parameters.
double	getEquinoctialEx() Get the first component of the eccentricity vector.
double	getEquinoctialEy() Get the second component of the eccentricity vector.
double	getHx() Get hx = ix / (2 * cos(i/2)), where ix is the first component of the inclination vector.
double	getHy() Get hy = iy / (2 * cos(i/2)), where iy is the second component of the inclination vector.
double	getI() Get the inclination angle.
double	getIx() Get the first component of the inclination vector.
double	getIy() Get the second component of the inclination vector.
double	getLE() Get the eccentric latitude argument.
double	getLM() Get the mean latitude argument.
double	getLv() Get the true latitude argument.
double	getMeanAnomaly() Get the mean anomaly.
IOrbitalParameters	getParameters() Get underlying orbital parameters.
double	getPomega() Get the longitude of the periapsis (ω + Ω).
double	getTrueAnomaly() Get the true anomaly.
OrbitType	getType() Get the orbit type.
protected PVCoordinates	initPVCoordinates() Compute the position/velocity coordinates from the canonical parameters.
EquatorialOrbit	interpolate(AbsoluteDate date, Collection<Orbit> sample) Get an interpolated instance.
protected void	orbitAddKeplerContribution(PositionAngle type, double gm, double[] pDot) Add the contribution of the Keplerian motion to parameters derivatives
protected EquatorialOrbit	orbitShiftedBy(double dt) Get a time-shifted orbit.
String	toString() Returns a string representation of this non circular equatorial orbital parameters object.

Methods inherited from class org.orekit.orbits.Orbit

addKeplerContribution, createInverseJacobian, fillHalfRow, fillHalfRow, fillHalfRow, fillHalfRow, fillHalfRow, fillHalfRow, getDate, getFrame, getJacobian, getJacobianWrtCartesian, getJacobianWrtParameters, getJacobianWrtParametersEccentric, getJacobianWrtParametersMean, getJacobianWrtParametersTrue, getKeplerianMeanMotion, getKeplerianPeriod, getKeplerianTransitionMatrix, getMu, getPVCoordinates, getPVCoordinates, getPVCoordinates, isPositiveDefinite, setJacobianWrtParametersEccentric, setJacobianWrtParametersMean, setJacobianWrtParametersTrue, shiftedBy

Methods inherited from class java.lang.Object

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

Constructor Detail

EquatorialOrbit

public EquatorialOrbit(IOrbitalParameters parameters,
                       Frame frame,
                       AbsoluteDate date)

Creates a new instance.

Parameters:

parameters - orbital parameters

frame - the frame in which the parameters are defined (must be a pseudo-inertial frame)

date - date of the orbital parameters

EquatorialOrbit

public EquatorialOrbit(double a,
                       double e,
                       double pomega,
                       double ix,
                       double iy,
                       double anomaly,
                       PositionAngle type,
                       Frame frame,
                       AbsoluteDate date,
                       double mu)
                throws IllegalArgumentException

Creates a new instance.

Parameters:

a - semi-major axis (m)

e - eccentricity

pomega - ω + Ω (rad)

ix - 2 sin(i/2) cos(Ω), first component of inclination vector

iy - 2 sin(i/2) sin(Ω), second component of inclination vector

anomaly - (M or E or v) = anomaly mean, eccentric or true anomaly (rad)

type - type of anomaly

frame - the frame in which the parameters are defined

date - date of the orbital parameters

mu - central attraction coefficient (m³/s²)

Throws:

IllegalArgumentException - if orbit is hyperbolic

IllegalArgumentException - if orbit mismatch with conic type

IllegalArgumentException - if inclination vector is not valid, meaning ix^2 + iy^2 > 4

EquatorialOrbit

public EquatorialOrbit(PVCoordinates pvCoordinates,
                       Frame frame,
                       AbsoluteDate date,
                       double mu)
                throws IllegalArgumentException

Constructor from cartesian parameters.

Parameters:

pvCoordinates - the PVCoordinates of the satellite

frame - the frame in which are defined the PVCoordinates

date - date of the orbital parameters

mu - central attraction coefficient (m³/s²)

Throws:

IllegalArgumentException - if orbit is hyperbolic

EquatorialOrbit

public EquatorialOrbit(Orbit op)

Constructor from any kind of orbital parameters.

Parameters:

op - orbital parameters to copy

Method Detail

getParameters

public IOrbitalParameters getParameters()

Get underlying orbital parameters.

Specified by:

getParameters in class Orbit

Returns:

orbital parameters

getEquatorialParameters

public EquatorialParameters getEquatorialParameters()

Getter for underlying equatorial parameters.

Returns:

equatorial parameters

getType

public OrbitType getType()

Get the orbit type.

Specified by:

getType in class Orbit

Returns:

orbit type

getA

public double getA()

Get the semi-major axis.

Specified by:

getA in class Orbit

Returns:

semi-major axis (m)

getE

public double getE()

Get the eccentricity.

Specified by:

getE in class Orbit

Returns:

eccentricity

getI

public double getI()

Get the inclination angle.

Specified by:

getI in class Orbit

Returns:

inclination (rad)

getAnomaly

public double getAnomaly(PositionAngle type)

Get the anomaly.

Parameters:

type - type of the angle

Returns:

anomaly (rad)

getPomega

public double getPomega()

Get the longitude of the periapsis (ω + Ω).

Returns:

longitude of the periapsis (rad)

getTrueAnomaly

public double getTrueAnomaly()

Get the true anomaly.

Returns:

true anomaly (rad)

getEccentricAnomaly

public double getEccentricAnomaly()

Get the eccentric anomaly.

Returns:

eccentric anomaly (rad)

getMeanAnomaly

public double getMeanAnomaly()

Get the mean anomaly.

Returns:

mean anomaly (rad)

getEquinoctialEx

public double getEquinoctialEx()

Get the first component of the eccentricity vector.

Specified by:

getEquinoctialEx in class Orbit

Returns:

first component of the eccentricity vector

getEquinoctialEy

public double getEquinoctialEy()

Get the second component of the eccentricity vector.

Specified by:

getEquinoctialEy in class Orbit

Returns:

second component of the eccentricity vector

getIx

public double getIx()

Get the first component of the inclination vector. ix = 2 sin(i/2) cos(Ω)

Returns:

first component of the inclination vector.

getIy

public double getIy()

Get the second component of the inclination vector. iy = 2 sin(i/2) sin(Ω)

Returns:

second component of the inclination vector.

getHx

public double getHx()

Get hx = ix / (2 * cos(i/2)), where ix is the first component of the inclination vector. Another formulation is hx = tan(i/2) cos(Ω)

Specified by:

getHx in class Orbit

Returns:

hx

getHy

public double getHy()

Get hy = iy / (2 * cos(i/2)), where iy is the second component of the inclination vector. Another formulation is hy = tan(i/2) sin(Ω)

Specified by:

getHy in class Orbit

Returns:

hy

getLv

public double getLv()

Get the true latitude argument.

Specified by:

getLv in class Orbit

Returns:

true latitude argument (rad)

getLE

public double getLE()

Get the eccentric latitude argument.

Specified by:

getLE in class Orbit

Returns:

eccentric latitude argument.(rad)

getLM

public double getLM()

Get the mean latitude argument.

Specified by:

getLM in class Orbit

Returns:

mean latitude argument.(rad)

initPVCoordinates

protected PVCoordinates initPVCoordinates()

Compute the position/velocity coordinates from the canonical parameters.

Specified by:

initPVCoordinates in class Orbit

Returns:

computed position/velocity coordinates

orbitShiftedBy

protected EquatorialOrbit orbitShiftedBy(double dt)

Get a time-shifted orbit.

The orbit can be slightly shifted to close dates. This shift is based on a simple keplerian model. It is not intended as a replacement for proper orbit and attitude propagation but should be sufficient for small time shifts or coarse accuracy.

Specified by:

orbitShiftedBy in class Orbit

Parameters:

dt - time shift in seconds

Returns:

a new orbit, shifted with respect to the instance (which is immutable)

interpolate

public EquatorialOrbit interpolate(AbsoluteDate date,
                                   Collection<Orbit> sample)

Get an interpolated instance.

Note that the state of the current instance may not be used in the interpolation process, only its type and non interpolable fields are used (for example central attraction coefficient or frame when interpolating orbits). The interpolable fields taken into account are taken only from the states of the sample points. So if the state of the instance must be used, the instance should be included in the sample points.

The interpolated instance is created by polynomial Hermite interpolation on Keplerian elements, without derivatives (which means the interpolation falls back to Lagrange interpolation only).

Parameters:

date - interpolation date

sample - sample points on which interpolation should be done

Returns:

a new instance, interpolated at specified date

computeJacobianMeanWrtCartesian

protected double[][] computeJacobianMeanWrtCartesian()

Compute the Jacobian of the orbital parameters with mean angle with respect to the Cartesian parameters.

Element jacobian[i][j] is the derivative of parameter i of the orbit with respect to Cartesian coordinate j. This means each row correspond to one orbital parameter whereas columns 0 to 5 correspond to the Cartesian coordinates x, y, z, xDot, yDot and zDot.

Specified by:

computeJacobianMeanWrtCartesian in class Orbit

Returns:

6x6 Jacobian matrix

See Also:

Orbit.computeJacobianEccentricWrtCartesian(), Orbit.computeJacobianTrueWrtCartesian()

computeJacobianEccentricWrtCartesian

protected double[][] computeJacobianEccentricWrtCartesian()

Compute the Jacobian of the orbital parameters with eccentric angle with respect to the Cartesian parameters.

Element jacobian[i][j] is the derivative of parameter i of the orbit with respect to Cartesian coordinate j. This means each row correspond to one orbital parameter whereas columns 0 to 5 correspond to the Cartesian coordinates x, y, z, xDot, yDot and zDot.

Specified by:

computeJacobianEccentricWrtCartesian in class Orbit

Returns:

6x6 Jacobian matrix

See Also:

Orbit.computeJacobianMeanWrtCartesian(), Orbit.computeJacobianTrueWrtCartesian()

computeJacobianTrueWrtCartesian

protected double[][] computeJacobianTrueWrtCartesian()

Compute the Jacobian of the orbital parameters with true angle with respect to the Cartesian parameters.

Element jacobian[i][j] is the derivative of parameter i of the orbit with respect to Cartesian coordinate j. This means each row correspond to one orbital parameter whereas columns 0 to 5 correspond to the Cartesian coordinates x, y, z, xDot, yDot and zDot.

Specified by:

computeJacobianTrueWrtCartesian in class Orbit

Returns:

6x6 Jacobian matrix

See Also:

Orbit.computeJacobianMeanWrtCartesian(), Orbit.computeJacobianEccentricWrtCartesian()

orbitAddKeplerContribution

protected void orbitAddKeplerContribution(PositionAngle type,
                                          double gm,
                                          double[] pDot)

Add the contribution of the Keplerian motion to parameters derivatives

This method is used by numerical propagators to evaluate the part of Keplerrian motion to evolution of the orbital state.

Specified by:

orbitAddKeplerContribution in class Orbit

Parameters:

type - type of the position angle in the state

gm - attraction coefficient to use

pDot - array containing orbital state derivatives to update (the Keplerian part must be added to the array components, as the array may already contain some non-zero elements corresponding to non-Keplerian parts)

toString

public String toString()

Returns a string representation of this non circular equatorial orbital parameters object.

Overrides:

toString in class Object

Returns:

a string representation of this object