Package org.orekit.ssa.collision.shorttermencounter.probability.twod

Class Chan1997

  • All Implemented Interfaces:
    ShortTermEncounter2DPOCMethod
    public class Chan1997
extends AbstractShortTermEncounter2DPOCMethod
    Compute the probability of collision using the method described in :
    "Chan, K. “Collision Probability Analyses for Earth Orbiting Satellites.” In Space Cooperation into the 21st Century: 7th AAS/JRS/CSA Symposium, International Space Conference of Pacific-Basin Societies (ISCOPS; formerly PISSTA) (July 15-18, 1997, Nagasaki, Japan), edited by Peter M. Bainum, et al., 1033-1048. Advances in the Astronautical Sciences Series 96. San Diego, California: Univelt, 1997. (Zeroth order analytical expression).

    This method is also described in depth in : "CHAN, F. Kenneth, et al. Spacecraft collision probability. El Segundo, CA : Aerospace Press, 2008."

    It assumes :

    • Short encounter leading to a linear relative motion.
    • Spherical collision object.
    • Uncorrelated positional covariance.
    • Gaussian distribution of the position uncertainties.
    • Deterministic velocity i.e. no velocity uncertainties.
    • Approximate ellipse by a disk
    Since:
    12.0
    Author:
    Vincent Cucchietti

    • Constructor Detail

      • Chan1997

        public Chan1997()
        Empty constructor.

    • Method Detail

      • compute

        public ProbabilityOfCollision compute​(double xm,
                                      double ym,
                                      double sigmaX,
                                      double sigmaY,
                                      double radius)
        Compute the probability of collision using arguments specific to the rotated encounter frame.

        The rotated encounter frame is define by the initial encounter frame (defined in ShortTermEncounter2DDefinition) rotated by the rotation matrix which is used to diagonalize the combined covariance matrix.

        Specified by:
        compute in interface ShortTermEncounter2DPOCMethod
        Specified by:
        compute in class AbstractShortTermEncounter2DPOCMethod
        Parameters:
        xm - other collision object projected position onto the collision plane in the rotated encounter frame x-axis (m)
        ym - other collision object projected position onto the collision plane in the rotated encounter frame y-axis (m)
        sigmaX - square root of the x-axis eigen value of the diagonalized combined covariance matrix projected onto the collision plane (m)
        sigmaY - square root of the y-axis eigen value of the diagonalized combined covariance matrix projected onto the collision plane (m)
        radius - sum of primary and secondary collision object equivalent sphere radii (m)
        Returns:
        probability of collision

      • compute

        public <T extends CalculusFieldElement<T>> FieldProbabilityOfCollision<T> compute​(T xm,
                                                                                  T ym,
                                                                                  T sigmaX,
                                                                                  T sigmaY,
                                                                                  T radius)
        Compute the probability of collision using arguments specific to the rotated encounter frame.

        The rotated encounter frame is define by the initial encounter frame (defined in ShortTermEncounter2DDefinition) rotated by the rotation matrix which is used to diagonalize the combined covariance matrix.

        Specified by:
        compute in interface ShortTermEncounter2DPOCMethod
        Specified by:
        compute in class AbstractShortTermEncounter2DPOCMethod
        Type Parameters:
        T - type of the field elements
        Parameters:
        xm - other collision object projected position onto the collision plane in the rotated encounter frame x-axis (m)
        ym - other collision object projected position onto the collision plane in the rotated encounter frame y-axis (m)
        sigmaX - square root of the x-axis eigen value of the diagonalized combined covariance matrix projected onto the collision plane (m)
        sigmaY - square root of the y-axis eigen value of the diagonalized combined covariance matrix projected onto the collision plane (m)
        radius - sum of primary and secondary collision object equivalent sphere radii (m)
        Returns:
        probability of collision