CL_ip_flybyVectors

Description

• Given two vectors characterizing a fly-by, computes other ones.

  The argument type_in describes the nature of the input vectors:

  - pv: Position and velocity on the hyperbola (pos and vel) - any anomaly

  - pvinfa: Arrival impact and excess velocity vectors (pinfva and vinfva)

  - pvinfd: Departure impact and excess velocity vectors (pinfvd and vinfvd)

  - vvinf: Arrival and departure excess velocity vectors (vinfva and vinfvd)

  The quantities that can be computed are given in output and can be:

  - posp: Position vector at periapsis

  - velp: Velocity vector at periapsis

  - vinfva: Arrival excess velocity vector

  - vinfvd: Departure excess velocity vector

  - pinfva: Arrival impact vector (perpendicular to excess velocity vector)

  - pinfvd: Departure impact vector (perpendicular to excess velocity vector)

  The output vectors are given in the same frame as the input vectors.

  Notes:

  1) Input impact vector (case type_in = pvinf):

  The impact vector pinfva does not need to be perpendicular to the excess velocity vector (vinfva). pinfva can be any vector from the body center to a point M on the arrival aymptote.

  2) Input departure excess velocity vector (case type_in = vvinf):

  It is not checked whether the norm of vinfva is identical to the norm of the departure excess velocity vector (vinfvd). The norm of vinfvd is actually not used.

Parameters

type_in:

(string) Nature of input vectors: "pv", "pvinf" or "vvinf". (1x1)

pos, vel:

Position [m] and velocity [m/s] vectors. (3xN or 3x1)

pinfva, vinfva:

Arrival impact [m] and excess velocity [m/s] vectors. (3xN or 3x1)

pinfvd, vinfvd:

Departure impact [m] and excess velocity [m/s] vectors. (3xN or 3x1)

vinfva, vindvd:

Arrival and departure excess velocity vectors [m/s]. (3xN or 3x1)

output:

(string) Name of outputs: "posp", "velp", "vinfva", "vinfvd", "pinfva" or "pinfvd". (1xP)

mu:

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

par_out1, par_out2, ...:

Output vectors [m, m/s]. (3xN)

Authors

• CNES - DCT/SB

See also

• CL_ip_flybyParams

Examples

// Earth fly-by - Arrival impact and excess velocity vectors (m and m/s) // Note: the vectors are chosen perpendicular to each other. pinfva = [15000.e3; 0; 0]; vinfva = [0; 6.e3; 3.e3]; // Position and velocity vectors at periapsis (m and m/s) [posp, velp] = CL_ip_flybyVectors("pvinfa", pinfva, vinfva, ["posp", "velp"]) // Departure excess velocity vector from position/velocity vectors (m/s) [vinfvd] = CL_ip_flybyVectors("pv", posp, velp, ["vinfvd"]) // Impact vector from excess velocity vectors // Note: computed perpendicular to excess velocity vector CL_ip_flybyVectors("vvinf", vinfva, vinfvd, ["pinfva"]) - pinfva // => 0