Procedure

     PARTOF ( Parabolic time of flight )

     SUBROUTINE PARTOF ( MA, D )

Abstract

     Solve the time of flight equation MA = D + (D**3) / 3
     for the parabolic eccentric anomaly D, given mean anomaly.

Required_Reading

     None.

Keywords

     CONIC

Declarations

     IMPLICIT NONE

     DOUBLE PRECISION      MA
     DOUBLE PRECISION      D

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     MA         I   Mean anomaly at epoch.
     D          O   Parabolic eccentric anomaly.

Detailed_Input

     MA       is the parabolic mean anomaly of an orbiting body at
              some epoch t,

                                   3  1/2
                 MA = (t-T) (mu/(2q ))

              where T is the time of periapsis passage, mu is
              the gravitational parameter of the primary body,
              and q is the perifocal distance.

Detailed_Output

     D        is the corresponding parabolic anomaly. This is the
              solution to the time of flight equation

                           3
                 MA = D + D / 3

Parameters

     None.

Exceptions

     Error free.

Files

     None.

Particulars

     Iterate to solve

                         3
        f(D,MA,p) = D + D / 3 - MA = 0

Examples

     ELLTOF, HYPTOF, and PARTOF are used by CONICS.

Restrictions

     None.

Literature_References

     [1]  R. Bate, D. Mueller, and J. White, "Fundamentals of
          Astrodynamics," Dover Publications Inc., 1971.

Author_and_Institution

     J. Diaz del Rio    (ODC Space)
     W.L. Taber         (JPL)
     I.M. Underwood     (JPL)

Version

    SPICELIB Version 2.1.0, 14-APR-2021 (JDR)

        Added IMPLICIT NONE statement.

        Edited the header to comply with NAIF standard. Removed
        unnecessary $Revisions section.

    SPICELIB Version 2.0.1, 10-MAR-1992 (WLT)

        Comment section for permuted index source lines was added
        following the header.

    SPICELIB Version 2.0.0, 19-APR-1991 (WLT)

        A write statement left over from debugging days was removed.

    SPICELIB Version 1.0.0, 31-JAN-1990 (IMU)