ijk2keplerian

Keplerian orbit elements using position and velocity vectors

Syntax

[a,ecc,incl,RAAN,argp,nu,truelon,arglat,lonper] = ijk2keplerian(r_ijk, v_ijk)

Description

[a,ecc,incl,RAAN,argp,nu,truelon,arglat,lonper] = ijk2keplerian(r_ijk, v_ijk) calculates Keplerian orbit elements for given position and velocity vectors in the geocentric equatorial coordinate system.

Examples

Convert IJK Position and Velocity

This example shows how to convert the geocentric equatorial coordinate system (IJK) position and velocity to Keplerian orbital elements.

r_ijk = [-2981784 5207055 3161595];
v_ijk = [-3384 -4887 4843];
[a, ecc, incl, RAAN, argp, nu, truelon, arglat, lonper] =...
ijk2keplerian(r_ijk, v_ijk)

a = 
6.7845e+06

ecc = 
9.1950e-04

incl = 
51.7528

RAAN = 
95.2570

argp = 
106.4005

nu = 
290.0096

truelon = 
NaN

arglat = 
NaN

lonper = 
NaN

Input Arguments

r_ijk — Position component

0 (default) | 3-by-1 array

Geocentric equatorial position components, specified as a 3-by-1 array, in meters.

Data Types: double

v_ijk — Velocity component

0 (default) | 3-by-1 array

Geocentric equatorial velocity components, specified as a 3-by-1 array, in m/s.

Data Types: double

Output Arguments

a — Semi-major axis

scalar

Semimajor axis (half of the longest diameter) of the orbit, returned as a scalar, in meters.

Data Types: double

ecc — Orbit eccentricity

scalar value greater than or equal to 0

Orbit eccentricity (deviation of orbital curve from circular), returned as a scalar.

Data Types: double

incl — Inclination

scalar value from 0 to 180

Inclination (tilt angle) of the orbit, in degrees.

Data Types: double

RAAN — Right ascension of ascending node

scalar value from 0 to 360

Angle in the equatorial plane from the x-axis to the location of the ascending node (point at which the satellite crosses the equator from south to north), in degrees.

Data Types: double

argp — Angle between CubeSat ascending node and periapsis

scalar value from 0 to 360

Angle between the CubeSat ascending node and periapsis (closest point of orbit to Earth), in degrees.

Data Types: double

nu — Angle between periapsis and current position of CubeSat

scalar value from 0 to 360

Angle between periapsis and current position of CubeSat, in degrees.

Data Types: double

truelon — Angle between x-axis and CubeSat position vector

scalar value from 0 to 360

Angle between the x-axis and CubeSat position vector, in degrees.

Data Types: double

arglat — Angle between ascending node and CubeSat position vector

scalar value from 0 to 360

Angle between the ascending node and the CubeSat position vector, in degrees.

Data Types: double

lonper — Angle between x-axis and eccentricity vector

scalar value from 0 to 360

Angle between the x-axis and the eccentricity vector, in degrees.

Data Types: double

References

[1] Vallado, D. A. Fundamentals of Astrodynamics and Applications. alg. 5. McGraw-Hill, 1997.

Version History

Introduced in R2019a