Name

CL_kp_characteristics — Various Keplerian characteristics

Calling Sequence

   kep = CL_kp_characteristics(sma,ecc,v[,er[,mu]])
   
   

Description

  • This function computes many keplerian parameters for elliptic or hyperbolic orbits (parabolic orbits are not handled):

    - orbit parameters: semi major axis, eccentricity, apoapsis radius, periapsis radius, apoapsis altitude, periapsis altitude, apoapsis velocity, periapsis velocity, energy, area law constant, period, semi minor axis, conic's p parameter, conic's c parameter (kinetic moment), mean motion, velocity at infinity on an hyperbola, distance from asymptote to focus for an hyperbola, apoapsis liberation velocity, periapsis liberation velocity, apoapsis liberation delta-v, periapsis liberation delta-v.

    - position on orbit parameters: true anomaly, mean anomaly, eccentric anomaly, time from periapsis, radius, x cartesian coordinate, y cartesian coordinate, velocity slope, velocity modulus.

    Parameters with no sense are given the value 0 (example: kep.period is 0 for hyperbolic orbits)

    All this parameters are given as output in the kep variable, which is a tlist. kep is defined as follows:

    --> kep.orb_type: type of orbit (1->elliptic, 2->hyperbolic)

    --> kep.sma: semi major axis [m]

    --> kep.ecc: eccentricity

    --> kep.ra: apoapsis radius [m]

    --> kep.rp: periapsis radius [m]

    --> kep.ha: apoapsis altitude (kep.ra - planet radius) [m]

    --> kep.hp: periapsis altitude (kep.rp - planet radius) [m]

    --> kep.va: apoapsis velocity modulus [m/s]

    --> kep.vp: periapsis velocity modulus [m/s]

    --> kep.vinf: velocity at infinity for an hyperbolic orbit (0 if elliptic orbit) [m/s]

    --> kep.period: orbit's period [s]

    --> kep.mm: orbit's mean motion [rad/s]

    --> kep.k: orbit's energy [J]

    --> kep.C_area: C constant for the areas law [m^2/s]

    --> kep.l_con: conic's l parameter (semi latus rectum)

    --> kep.c_con: conic's c parameter (linear eccentricity) [m]

    --> kep.smb: semi minor axis [m]

    --> kep.d_foy: distance asymptote-focus for an hyperbolic orbit (0 if elliptic orbit) [m]

    --> kep.vlp: periapsis liberation velocity modulus [m/s]

    --> kep.vla: apoapsis liberation velocity modulus [m/s]

    --> kep.dvp: delta-v for liberation at periapsis [m/s]

    --> kep.dva: delta-v for liberation at apoapsis [m/s]

    --> kep.v: true anomaly [rad]

    --> kep.M: mean anomaly [rad]

    --> kep.E: eccentric anomaly [rad]

    --> kep.anvinf: true anomaly at infinity (only for hyperbolic orbits, 0 if elliptic) [rad]

    --> kep.date: time from periapsis [s]

    --> kep.R: modulus of radius vector [m]

    --> kep.x: x cartesian coordinate [m]

    --> kep.y: y cartesian coordinate [m]

    --> kep.v_slope: velocity slope [rad]

    --> kep.vel: velocity modulus [m/s]

    NOTE: the linear eccentricity (kep.c_con) is the distance between the center and the focus (or one of the two foci). The latus rectum is the chord parallel to the directrix and passing through the focus (or one of the two foci). The semi latus rectum (kep.l_con) is half of the latus rectum.

  • Last update : 5/3/2008

Parameters

sma:

semi major axis [m] (1xN)

ecc:

eccentricity (1xN)

v:

true anomaly [rad] (1xN)

mu:

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

er:

(optional) astral radius [m] (default is earth radius %CL_eqRad)

kep:

tlist containing computed keplerian parameters. See description for units. Each field is (1xN)

See also

CL_kp_params, CL_kp_E2v, CL_kp_v2E, CL_kp_E2M, CL_kp_M2E, CL_op_rarp2ae, CL_op_rava2ae, CL_op_rpvinf2ae, CL_op_rpvp2ae

Authors

CNES - DCT/SB

Examples

sma = 7078.e3;
ecc = 0.0001;
v = %pi/4;
kep = CL_kp_characteristics(sma,ecc,v)