$LastChangedDate: 27-Juil-2011 $

# CL_op_driftJ2

Drift of orbital elements due to J2

## Calling Sequence

       [drift_pom,drift_gom,drift_M[,dpomdaei[,dgomdaei[,dMdaei]]]] = CL_op_driftJ2(sma,ecc,inc[,er[,mu[,j2]]])

## Description

- Computes:

  - the secular drifts (drift_pom=d(pom)/dt, drift_gom=d(gom)/dt, drift_M=dM/dt) on the keplerian elements, where pom=argument of periapsis, gom=right ascension of ascending node,M=mean anomaly, considering the effect of the first zonal harmonic J2,

  - the partial derivatives of these drifts with respect to semi major axis, eccentricity and inclination.

  (See the formulas, where: R = equatorial radius, n = keplerian mean motion

## Parameters

sma:

  Semi-major axis [m] (1x1 or 1xN)

ecc:

  Eccentricity (1x1 or 1xN)

inc:

  Inclination [rad] (1x1 or 1xN)

er:

  (optional) Equatorial radius [m] (default is %CL_eqRad)

mu:

  (optional) Gravitational constant [m^3/s^2] (default value is %CL_mu)

j2:

  (optional) Second zonal harmonic) (default is %CL_j2)

drift_pom:

  drift of the argument of periapsis [rad/s] (1xN)

drift_gom:

  drift of the right ascension of ascending node [rad/s] (1xN)

drift_M:

  drift of the mean anomaly [rad/s] (1xN)

dpomdaei:

  partial derivative of drift_pom with respect to sma, ecc and inc (3xN)

dgomdaei:

  partial derivative of drift_gom with respect to sma, ecc and inc (3xN)

dMdaei:

  partial derivative of drift_M with respect to sma, ecc and inc (3xN)

## Bibliography

- 1) CNES - MSLIB FORTRAN 90, Volume E (me_deriv_secul_J2)

## Authors

- CNES - DCT/SB

## Examples

    sma=[%CL_eqRad+350000,%CL_eqRad+700000];
    ecc=[0.001,0.001];
    inc=CL_deg2rad([51.6,51.6]);
    [drift_pom,drift_gom,drift_M]=CL_op_driftJ2(sma,ecc,inc)