CL_fo_srpPanelAcc

Description

• Acceleration due to solar radiation pressure (SRP) for a flat plate.

  The SRP coefficient coefp is defined by:

  coefp = [Ka; Kd; Ks] * a / M

  With:

  - Ka: proportion (between 0 and 1) of absorbed radiation,

  - Kd: proportion (between 0 and 1) of diffuse radiation.

  - Ks: proportion (between 0 and 1) of radiation that is reflected specularly,

  - a / M is the area to mass ratio (a: area of the flat plate, M: total mass of the object subjected to the force).

  Note: Ka + Kd + Ks is equal to 1.

  nsides specifies if only the side oriented by normal is considered or if both sides are. If nsides is 1, the acceleration is 0 if the normal does not point at the Sun. If nsides is 2, either +normal or -normal is considered depending on which one points at the Sun.

  Eclipses can be taken into account or not. If they are, the acceleration is multiplied by a factor equal to 1 out of the eclipse region and less than 1 otherwise.

• Notes:

  - The coordinates frame can be any frame. The origin of the frame does not matter, except if eclipses are taken into account, in which case the origin of the frame must be the center of the eclipsing body (usually the same as the central body).

  - The normal vector may not be a unit vector.

  - The calculation of eclipses uses the radius of the eclipsing body (er) and the radius of the Sun (ersun). If ersun is empty ([]), an internal value is used.

  - p0 is the solar pressure at 1 AU. If p0 is empty ([]), an internal value is used, equal to the total solar irradiance divided by the speed of light.

  - Remark:

  > CL_fo_srpAcc(pos, pos_sun, coefp)

  is equivalent to:

  > CL_fo_srpPanelAcc(pos, pos_sun, [coefp; 0; 0], pos_sun-pos, 1)

• See Force models for more details.

Parameters

pos:

Position vector [m]. (3xN or 3x1)

pos_sun:

Sun position vector [m]. (3xN or 3x1)

normal:

Normal vector to the flat plate (3xN or 3x1)

coefp:

SRP coefficients: [Ka; Kd; Ks] * area/mass [m^2/kg]. (3xN or 3x1)

nsides:

(integer) Number of sides to be considered: 1 or 2 (1xN or 1x1)

ecl:

(optional, boolean) %t if eclipses are taken into account; %f otherwise. Default is %t. (1x1)

er:

(optional) Equatorial radius of eclipsing body. Default is %CL_eqRad. [m] (1x1)

ersun:

(optional) Equatorial radius of the Sun. Default is [] (internal value used). [m] (1x1)

p0:

(optional) Solar radiation pressure at 1 AU. Default is [] (internal value used). [N/m^2] (1x1)

acc:

Acceleration [m/s^2]. (3xN)

Authors

• CNES - DCT/SB

See also

• CL_fo_srpAcc

• CL_gm_eclipseCheck

Examples

pos = [1;0;0] * 1.e7; pos_sun = CL_dataGet("au") * [1; 0; 0]; normal = [1; 1; 0]; // [Ka; Kd; Ks] * 1 m^2 / 100 kg // 50% absorbed, 50% specular coefp = [0.5; 0; 0.5] * 1.e-2; CL_fo_srpPanelAcc(pos, pos_sun, coefp, normal, 1) CL_fo_srpPanelAcc(pos, pos_sun, coefp, -normal, 1) CL_fo_srpPanelAcc(pos, pos_sun, coefp, -normal, 2)