org.orekit.orbits

## Class CartesianOrbit

• ### Constructor Summary

Constructors
Constructor and Description
CartesianOrbit(Orbit op)
Constructor from any kind of orbital parameters.
CartesianOrbit(PVCoordinates pvaCoordinates, Frame frame, AbsoluteDate date, double mu)
Constructor from Cartesian parameters.
CartesianOrbit(TimeStampedPVCoordinates pvaCoordinates, Frame frame, double mu)
Constructor from Cartesian parameters.
• ### Method Summary

All Methods
Modifier and Type Method and Description
void addKeplerContribution(PositionAngle type, double gm, double[] pDot)
Add the contribution of the Keplerian motion to parameters derivatives
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 getADot()
Get the semi-major axis derivative.
double getE()
Get the eccentricity.
double getEDot()
Get the eccentricity derivative.
double getEquinoctialEx()
Get the first component of the equinoctial eccentricity vector derivative.
double getEquinoctialExDot()
Get the first component of the equinoctial eccentricity vector.
double getEquinoctialEy()
Get the second component of the equinoctial eccentricity vector derivative.
double getEquinoctialEyDot()
Get the second component of the equinoctial eccentricity vector.
double getHx()
Get the first component of the inclination vector.
double getHxDot()
Get the first component of the inclination vector derivative.
double getHy()
Get the second component of the inclination vector.
double getHyDot()
Get the second component of the inclination vector derivative.
double getI()
Get the inclination.
double getIDot()
Get the inclination derivative.
double getLE()
Get the eccentric longitude argument.
double getLEDot()
Get the eccentric longitude argument derivative.
double getLM()
Get the mean longitude argument.
double getLMDot()
Get the mean longitude argument derivative.
double getLv()
Get the true longitude argument.
double getLvDot()
Get the true longitude argument derivative.
OrbitType getType()
Get the orbit type.
boolean hasDerivatives()
Check if orbit includes derivatives.
protected Vector3D initPosition()
Compute the position coordinates from the canonical parameters.
protected TimeStampedPVCoordinates initPVCoordinates()
Compute the position/velocity coordinates from the canonical parameters.
CartesianOrbit interpolate(AbsoluteDate date, Stream<Orbit> sample)
Get an interpolated instance.
CartesianOrbit shiftedBy(double dt)
Get a time-shifted orbit.
String toString()
Returns a string representation of this Orbit object.
• ### Methods inherited from class org.orekit.orbits.Orbit

fillHalfRow, fillHalfRow, fillHalfRow, fillHalfRow, fillHalfRow, fillHalfRow, getDate, getFrame, getJacobianWrtCartesian, getJacobianWrtParameters, getKeplerianMeanMotion, getKeplerianPeriod, getMu, getPosition, getPosition, getPVCoordinates, getPVCoordinates, getPVCoordinates, hasNonKeplerianAcceleration
• ### Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
• ### Methods inherited from interface org.orekit.time.TimeInterpolable

interpolate
• ### Methods inherited from interface org.orekit.utils.PVCoordinatesProvider

getPosition
• ### Method Detail

• #### 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.

Note that the semi-major axis is considered negative for hyperbolic orbits.

Specified by:
getA in class Orbit
Returns:
semi-major axis (m)

public double getADot()
Get the semi-major axis derivative.

Note that the semi-major axis is considered negative for hyperbolic orbits.

If the orbit was created without derivatives, the value returned is Double.NaN.

Specified by:
getADot in class Orbit
Returns:
semi-major axis derivative (m/s)
Orbit.hasDerivatives()
• #### getE

public double getE()
Get the eccentricity.
Specified by:
getE in class Orbit
Returns:
eccentricity
• #### getEDot

public double getEDot()
Get the eccentricity derivative.

If the orbit was created without derivatives, the value returned is Double.NaN.

Specified by:
getEDot in class Orbit
Returns:
eccentricity derivative
Orbit.hasDerivatives()
• #### getI

public double getI()
Get the inclination.
Specified by:
getI in class Orbit
Returns:
• #### getIDot

public double getIDot()
Get the inclination derivative.

If the orbit was created without derivatives, the value returned is Double.NaN.

Specified by:
getIDot in class Orbit
Returns:
Orbit.hasDerivatives()
• #### getEquinoctialEx

public double getEquinoctialEx()
Get the first component of the equinoctial eccentricity vector derivative.
Specified by:
getEquinoctialEx in class Orbit
Returns:
first component of the equinoctial eccentricity vector derivative
• #### getEquinoctialExDot

public double getEquinoctialExDot()
Get the first component of the equinoctial eccentricity vector.

If the orbit was created without derivatives, the value returned is Double.NaN.

Specified by:
getEquinoctialExDot in class Orbit
Returns:
first component of the equinoctial eccentricity vector
Orbit.hasDerivatives()
• #### getEquinoctialEy

public double getEquinoctialEy()
Get the second component of the equinoctial eccentricity vector derivative.
Specified by:
getEquinoctialEy in class Orbit
Returns:
second component of the equinoctial eccentricity vector derivative
• #### getEquinoctialEyDot

public double getEquinoctialEyDot()
Get the second component of the equinoctial eccentricity vector.

If the orbit was created without derivatives, the value returned is Double.NaN.

Specified by:
getEquinoctialEyDot in class Orbit
Returns:
second component of the equinoctial eccentricity vector
Orbit.hasDerivatives()
• #### getHx

public double getHx()
Get the first component of the inclination vector.
Specified by:
getHx in class Orbit
Returns:
first component of the inclination vector
• #### getHxDot

public double getHxDot()
Get the first component of the inclination vector derivative.

If the orbit was created without derivatives, the value returned is Double.NaN.

Specified by:
getHxDot in class Orbit
Returns:
first component of the inclination vector derivative
Orbit.hasDerivatives()
• #### getHy

public double getHy()
Get the second component of the inclination vector.
Specified by:
getHy in class Orbit
Returns:
second component of the inclination vector
• #### getHyDot

public double getHyDot()
Get the second component of the inclination vector derivative.

If the orbit was created without derivatives, the value returned is Double.NaN.

Specified by:
getHyDot in class Orbit
Returns:
second component of the inclination vector derivative
Orbit.hasDerivatives()
• #### getLv

public double getLv()
Get the true longitude argument.
Specified by:
getLv in class Orbit
Returns:
v + ω + Ω true longitude argument (rad)
• #### getLvDot

public double getLvDot()
Get the true longitude argument derivative.

If the orbit was created without derivatives, the value returned is Double.NaN.

Specified by:
getLvDot in class Orbit
Returns:
d(v + ω + Ω)/dt true longitude argument derivative (rad/s)
Orbit.hasDerivatives()
• #### getLE

public double getLE()
Get the eccentric longitude argument.
Specified by:
getLE in class Orbit
Returns:
E + ω + Ω eccentric longitude argument (rad)
• #### getLEDot

public double getLEDot()
Get the eccentric longitude argument derivative.

If the orbit was created without derivatives, the value returned is Double.NaN.

Specified by:
getLEDot in class Orbit
Returns:
d(E + ω + Ω)/dt eccentric longitude argument derivative (rad/s)
Orbit.hasDerivatives()
• #### getLM

public double getLM()
Get the mean longitude argument.
Specified by:
getLM in class Orbit
Returns:
M + ω + Ω mean longitude argument (rad)
• #### getLMDot

public double getLMDot()
Get the mean longitude argument derivative.

If the orbit was created without derivatives, the value returned is Double.NaN.

Specified by:
getLMDot in class Orbit
Returns:
d(M + ω + Ω)/dt mean longitude argument derivative (rad/s)
Orbit.hasDerivatives()
• #### initPosition

protected Vector3D initPosition()
Compute the position coordinates from the canonical parameters.
Specified by:
initPosition in class Orbit
Returns:
computed position coordinates
• #### initPVCoordinates

protected TimeStampedPVCoordinates initPVCoordinates()
Compute the position/velocity coordinates from the canonical parameters.
Specified by:
initPVCoordinates in class Orbit
Returns:
computed position/velocity coordinates
• #### shiftedBy

public CartesianOrbit shiftedBy(double dt)
Get a time-shifted orbit.

The orbit can be slightly shifted to close dates. The shifting model is a Keplerian one if no derivatives are available in the orbit, or Keplerian plus quadratic effect of the non-Keplerian acceleration if derivatives are available. Shifting is not intended as a replacement for proper orbit propagation but should be sufficient for small time shifts or coarse accuracy.

Specified by:
shiftedBy in interface TimeShiftable<Orbit>
Specified by:
shiftedBy in class Orbit
Parameters:
dt - time shift in seconds
Returns:
a new orbit, shifted with respect to the instance (which is immutable)
• #### interpolate

public CartesianOrbit interpolate(AbsoluteDate date,
Stream<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.

Note that this method is designed for small samples only (say up to about 10-20 points) so it can be implemented using polynomial interpolation (typically Hermite interpolation). Using too much points may induce Runge's phenomenon and numerical problems (including NaN appearing).

The interpolated instance is created by polynomial Hermite interpolation ensuring velocity remains the exact derivative of position.

As this implementation of interpolation is polynomial, it should be used only with small samples (about 10-20 points) in order to avoid Runge's phenomenon and numerical problems (including NaN appearing).

If orbit interpolation on large samples is needed, using the Ephemeris class is a better way than using this low-level interpolation. The Ephemeris class automatically handles selection of a neighboring sub-sample with a predefined number of point from a large global sample in a thread-safe way.

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()
Description copied from class: Orbit
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
Orbit.computeJacobianEccentricWrtCartesian(), Orbit.computeJacobianTrueWrtCartesian()
• #### computeJacobianEccentricWrtCartesian

protected double[][] computeJacobianEccentricWrtCartesian()
Description copied from class: Orbit
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
Orbit.computeJacobianMeanWrtCartesian(), Orbit.computeJacobianTrueWrtCartesian()
• #### computeJacobianTrueWrtCartesian

protected double[][] computeJacobianTrueWrtCartesian()
Description copied from class: Orbit
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
Orbit.computeJacobianMeanWrtCartesian(), Orbit.computeJacobianEccentricWrtCartesian()

public void addKeplerContribution(PositionAngle type,
double gm,
double[] pDot)
Add the contribution of the Keplerian motion to parameters derivatives

This method is used by integration-based propagators to evaluate the part of Keplerian motion to evolution of the orbital state.

Specified by:
addKeplerContribution 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 Orbit object.
Overrides:
toString in class Object
Returns:
a string representation of this object