CL_stela_deriv

Description

• Computes the orbital time derivatives due to various perturbations using STELA.

  The results are described by res:

  - "m": Derivatives of mean orbital elements (6xN)

  - "i": Information data (structure)

  The input orbital elements are internally converted to the adequate type and frame before the call to STELA. The results are then converted to the same type and frame.

• Warning:

  The dynamic motion (that is the apparent acceleration) of the chosen reference frame with respect to CIRS (which is the frame in which STELA integrates the motion) is not included in the derivatives. The results must then be used with caution if the chosen frame is not ECI. This may change in future versions.

• Notes:

  - The integration time step parameter (in the "params" structure) is not used but must exist.

• See the STELA page for more details.

Parameters

type_oe:

(string) Type of orbital elements: "kep", "cir", "cireq", "equin", "pv".

cjd:

Reference dates (CJD, time scale: TREF) (1xN)

mean_oe:

Mean orbital elements for the reference orbit (6xN)

params:

(structure) Propagation model parameters.

res:

(string) Wanted results: "m", "i".

frame:

(string, optional) Input/output frame. Default is "ECI"

ut1_tref:

(optional) UT1-TREF [seconds]. Default is %CL_UT1_TREF (1x1)

tt_tref:

(optional) TT-TREF [seconds]. Default is %CL_TT_TREF (1x1)

result1, ...:

Time derivatives or information data

Authors

• CNES - DCT/SB/MS

Examples

// Generate reference orbit (Sun-synchronous, MLTAN=14h, frame: ECI) kep0 = [7.e6; 1.136e-3; 1.7085241; %pi/2; 0; 0]; cjd0 = 20000; cjd = cjd0 + (0:365); // days, time scale: TREF kep = CL_ex_propagate("eckhech", "kep", cjd0, kep0, cjd, "m"); // STELA model parameters (default values) params = CL_stela_params(); // Time derivatives [dkepdt, info] = CL_stela_deriv("kep", cjd, kep, params, ["m", "i"]); // Plot inclination derivative (deg/year) scf(); plot(cjd, dkepdt(3,:) * (180/%pi) * 86400 * 365.25);