Package org.orekit.propagation

Class FieldSpacecraftState<T extends org.hipparchus.RealFieldElement<T>>

  • All Implemented Interfaces:
    FieldTimeInterpolable<FieldSpacecraftState<T>,​T>, FieldTimeShiftable<FieldSpacecraftState<T>,​T>, FieldTimeStamped<T>
    public class FieldSpacecraftState<T extends org.hipparchus.RealFieldElement<T>>
extends Object
implements FieldTimeStamped<T>, FieldTimeShiftable<FieldSpacecraftState<T>,​T>, FieldTimeInterpolable<FieldSpacecraftState<T>,​T>
    This class is the representation of a complete state holding orbit, attitude and mass information at a given date.

    It contains an orbital state at a current FieldAbsoluteDate both handled by an FieldOrbit, plus the current mass and attitude. FieldOrbitand state are guaranteed to be consistent in terms of date and reference frame. The spacecraft state may also contain additional states, which are simply named double arrays which can hold any user-defined data.

    The state can be slightly shifted to close dates. This shift is based on a simple Keplerian model for orbit, a linear extrapolation for attitude taking the spin rate into account and no mass change. It is not intended as a replacement for proper orbit and attitude propagation but should be sufficient for either small time shifts or coarse accuracy.

    The instance FieldSpacecraftState is guaranteed to be immutable.

    Author:
    Fabien Maussion, Véronique Pommier-Maurussane, Luc Maisonobe
    See Also:
    NumericalPropagator

    • Constructor Detail

      • FieldSpacecraftState

        public FieldSpacecraftState​(FieldOrbit<T> orbit)
        Build a spacecraft state from orbit only.

        FieldAttitude and mass are set to unspecified non-null arbitrary values.

        Parameters:
        orbit - the orbit

      • FieldSpacecraftState

        public FieldSpacecraftState​(FieldOrbit<T> orbit,
                            FieldAttitude<T> attitude)
                     throws IllegalArgumentException
        Build a spacecraft state from orbit and attitude provider.

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

        Parameters:
        orbit - the orbit
        attitude - attitude
        Throws:
        IllegalArgumentException - if orbit and attitude dates or frames are not equal

      • FieldSpacecraftState

        public FieldSpacecraftState​(FieldOrbit<T> orbit,
                            T mass)
        Create a new instance from orbit and mass.

        FieldAttitude law is set to an unspecified default attitude.

        Parameters:
        orbit - the orbit
        mass - the mass (kg)

      • FieldSpacecraftState

        public FieldSpacecraftState​(FieldOrbit<T> orbit,
                            Map<String,​T[]> additional)
        Build a spacecraft state from orbit only.

        FieldAttitude and mass are set to unspecified non-null arbitrary values.

        Parameters:
        orbit - the orbit
        additional - additional states

      • FieldSpacecraftState

        public FieldSpacecraftState​(FieldOrbit<T> orbit,
                            FieldAttitude<T> attitude,
                            Map<String,​T[]> additional)
                     throws IllegalArgumentException
        Build a spacecraft state from orbit and attitude provider.

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

        Parameters:
        orbit - the orbit
        attitude - attitude
        additional - additional states
        Throws:
        IllegalArgumentException - if orbit and attitude dates or frames are not equal

      • FieldSpacecraftState

        public FieldSpacecraftState​(FieldOrbit<T> orbit,
                            T mass,
                            Map<String,​T[]> additional)
        Create a new instance from orbit and mass.

        FieldAttitude law is set to an unspecified default attitude.

        Parameters:
        orbit - the orbit
        mass - the mass (kg)
        additional - additional states

      • FieldSpacecraftState

        public FieldSpacecraftState​(FieldOrbit<T> orbit,
                            FieldAttitude<T> attitude,
                            T mass,
                            Map<String,​T[]> additional)
                     throws IllegalArgumentException
        Build a spacecraft state from orbit, attitude provider and mass.
        Parameters:
        orbit - the orbit
        attitude - attitude
        mass - the mass (kg)
        additional - additional states (may be null if no additional states are available)
        Throws:
        IllegalArgumentException - if orbit and attitude dates or frames are not equal

      • FieldSpacecraftState

        public FieldSpacecraftState​(org.hipparchus.Field<T> field,
                            SpacecraftState state)
        Convert a SpacecraftState.
        Parameters:
        field - field to which the elements belong
        state - state to convert

    • Method Detail

      • addAdditionalState

        @SafeVarargs
public final FieldSpacecraftState<T> addAdditionalState​(String name,
                                                        T... value)
        Add an additional state.

        SpacecraftState instances are immutable, so this method does not change the instance, but rather creates a new instance, which has the same orbit, attitude, mass and additional states as the original instance, except it also has the specified state. If the original instance already had an additional state with the same name, it will be overridden. If it did not have any additional state with that name, the new instance will have one more additional state than the original instance.

        Parameters:
        name - name of the additional state
        value - value of the additional state
        Returns:
        a new instance, with the additional state added
        See Also:
        hasAdditionalState(String), getAdditionalState(String), getAdditionalStates()

      • shiftedBy

        public FieldSpacecraftState<T> shiftedBy​(double dt)
        Get a time-shifted state.

        The state can be slightly shifted to close dates. This shift is based on a simple Keplerian model for orbit, a linear extrapolation for attitude taking the spin rate into account and neither mass nor additional states changes. It is not intended as a replacement for proper orbit and attitude propagation but should be sufficient for small time shifts or coarse accuracy.

        As a rough order of magnitude, the following table shows the extrapolation errors obtained between this simple shift method and an numerical propagator for a low Earth Sun Synchronous Orbit, with a 20x20 gravity field, Sun and Moon third bodies attractions, drag and solar radiation pressure. Beware that these results will be different for other orbits.

        Extrapolation Error
        interpolation time (s) position error without derivatives (m)position error with derivatives (m)
        60 18 1.1
        120 72 9.1
        300 447 140
        60016011067
        90031413307
        Specified by:
        shiftedBy in interface FieldTimeShiftable<FieldSpacecraftState<T extends org.hipparchus.RealFieldElement<T>>,​T extends org.hipparchus.RealFieldElement<T>>
        Parameters:
        dt - time shift in seconds
        Returns:
        a new state, shifted with respect to the instance (which is immutable) except for the mass which stay unchanged

      • shiftedBy

        public FieldSpacecraftState<T> shiftedBy​(T dt)
        Get a time-shifted state.

        The state can be slightly shifted to close dates. This shift is based on a simple Keplerian model for orbit, a linear extrapolation for attitude taking the spin rate into account and neither mass nor additional states changes. It is not intended as a replacement for proper orbit and attitude propagation but should be sufficient for small time shifts or coarse accuracy.

        As a rough order of magnitude, the following table shows the extrapolation errors obtained between this simple shift method and an numerical propagator for a low Earth Sun Synchronous Orbit, with a 20x20 gravity field, Sun and Moon third bodies attractions, drag and solar radiation pressure. Beware that these results will be different for other orbits.

        Extrapolation Error
        interpolation time (s) position error without derivatives (m)position error with derivatives (m)
        60 18 1.1
        120 72 9.1
        300 447 140
        60016011067
        90031413307
        Specified by:
        shiftedBy in interface FieldTimeShiftable<FieldSpacecraftState<T extends org.hipparchus.RealFieldElement<T>>,​T extends org.hipparchus.RealFieldElement<T>>
        Parameters:
        dt - time shift in seconds
        Returns:
        a new state, shifted with respect to the instance (which is immutable) except for the mass which stay unchanged

      • interpolate

        public FieldSpacecraftState<T> interpolate​(FieldAbsoluteDate<T> date,
                                           Stream<FieldSpacecraftState<T>> sample)
        Get an interpolated instance.

        The additional states that are interpolated are the ones already present in the instance. The sample instances must therefore have at least the same additional states has the instance. They may have more additional states, but the extra ones will be ignored.

        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).

        Specified by:
        interpolate in interface FieldTimeInterpolable<FieldSpacecraftState<T extends org.hipparchus.RealFieldElement<T>>,​T extends org.hipparchus.RealFieldElement<T>>
        Parameters:
        date - interpolation date
        sample - sample points on which interpolation should be done
        Returns:
        a new instance, interpolated at specified date

      • getOrbit

        public FieldOrbit<T> getOrbit()
        Gets the current orbit.
        Returns:
        the orbit

      • getFrame

        public Frame getFrame()
        Get the inertial frame.
        Returns:
        the frame

      • ensureCompatibleAdditionalStates

        public void ensureCompatibleAdditionalStates​(FieldSpacecraftState<T> state)
                                      throws org.hipparchus.exception.MathIllegalArgumentException
        Check if two instances have the same set of additional states available.

        Only the names and dimensions of the additional states are compared, not their values.

        Parameters:
        state - state to compare to instance
        Throws:
        org.hipparchus.exception.MathIllegalArgumentException - if an additional state does not have the same dimension in both states

      • toTransform

        public FieldTransform<T> toTransform()
        Compute the transform from orbite/attitude reference frame to spacecraft frame.

        The spacecraft frame origin is at the point defined by the orbit, and its orientation is defined by the attitude.

        Returns:
        transform from specified frame to current spacecraft frame

      • getMu

        public double getMu()
        Get the central attraction coefficient.
        Returns:
        mu central attraction coefficient (m^3/s^2)

      • getKeplerianPeriod

        public T getKeplerianPeriod()
        Get the Keplerian period.

        The Keplerian period is computed directly from semi major axis and central acceleration constant.

        Returns:
        Keplerian period in seconds

      • getKeplerianMeanMotion

        public T getKeplerianMeanMotion()
        Get the Keplerian mean motion.

        The Keplerian mean motion is computed directly from semi major axis and central acceleration constant.

        Returns:
        Keplerian mean motion in radians per second

      • getA

        public T getA()
        Get the semi-major axis.
        Returns:
        semi-major axis (m)

      • getEquinoctialEx

        public T getEquinoctialEx()
        Get the first component of the eccentricity vector (as per equinoctial parameters).
        Returns:
        e cos(ω + Ω), first component of eccentricity vector
        See Also:
        getE()

      • getEquinoctialEy

        public T getEquinoctialEy()
        Get the second component of the eccentricity vector (as per equinoctial parameters).
        Returns:
        e sin(ω + Ω), second component of the eccentricity vector
        See Also:
        getE()

      • getHx

        public T getHx()
        Get the first component of the inclination vector (as per equinoctial parameters).
        Returns:
        tan(i/2) cos(Ω), first component of the inclination vector
        See Also:
        getI()

      • getHy

        public T getHy()
        Get the second component of the inclination vector (as per equinoctial parameters).
        Returns:
        tan(i/2) sin(Ω), second component of the inclination vector
        See Also:
        getI()

      • getLv

        public T getLv()
        Get the true latitude argument (as per equinoctial parameters).
        Returns:
        v + ω + Ω true latitude argument (rad)
        See Also:
        getLE(), getLM()

      • getLE

        public T getLE()
        Get the eccentric latitude argument (as per equinoctial parameters).
        Returns:
        E + ω + Ω eccentric latitude argument (rad)
        See Also:
        getLv(), getLM()

      • getLM

        public T getLM()
        Get the mean latitude argument (as per equinoctial parameters).
        Returns:
        M + ω + Ω mean latitude argument (rad)
        See Also:
        getLv(), getLE()

      • getI

        public T getI()
        Get the inclination.
        Returns:
        inclination (rad)
        See Also:
        getHx(), getHy()

      • getPVCoordinates

        public TimeStampedFieldPVCoordinates<T> getPVCoordinates​(Frame outputFrame)
        Get the TimeStampedFieldPVCoordinates in given output frame. Compute the position and velocity of the satellite. This method caches its results, and recompute them only when the method is called with a new value for mu. The result is provided as a reference to the internally cached TimeStampedFieldPVCoordinates, so the caller is responsible to copy it in a separate TimeStampedFieldPVCoordinates if it needs to keep the value for a while.
        Parameters:
        outputFrame - frame in which coordinates should be defined
        Returns:
        pvCoordinates in orbit definition frame

      • getAttitude

        public FieldAttitude<T> getAttitude()
        Get the attitude.
        Returns:
        the attitude.

      • getMass

        public T getMass()
        Gets the current mass.
        Returns:
        the mass (kg)

      • toSpacecraftState

        public SpacecraftState toSpacecraftState()
        To convert a FieldSpacecraftState instance into a SpacecraftState instance.
        Returns:
        SpacecraftState instance with the same properties