sc_environs.h File Reference

Environmental functions. More...

Go to the source code of this file.

Classes
struct	mag_data_s
	Structure for storing magnetic field data. More...

Typedefs
typedef struct mag_data_s	mag_data_t
	Structure for storing magnetic field data.

Enumerations
enum	{   kMercury , kVenus , kEarth , kMars ,   kJupiter , kSaturn , kUranus , kNeptune ,   kPluto , kMoon , kPhobos , kDeimos ,   kSun }
	Planet IDs.

Functions
Atmosphere and gas functions
double	mol_wt_to_R (double mol_wt)
	Compute gas constant R given the molecular weight. More...
double	atm_dens_exp (double h, int planet=kEarth)
	Atmospheric density using an exponential model. More...
double	atm_dens_scale (double h)
	Atmospheric density using scale heights. More...
Radiation
double	earth_radiation_total (const ml_matrix &pos, const ml_matrix &u_sun)
	Computes the total earth radiation including albedo. More...
double	earth_radiation (const ml_matrix &pos)
	Computes the earth radiation. More...
Magnetic field functions
ml_matrix	b_dipole (const ml_matrix &pos, double jd)
	Computes the magnetic field based on a tilted dipole model. More...
ml_matrix	mag_field (const ml_matrix &position, double jd, int nMax, const mag_data_s &mag_data)
	Planetary magnetic field at a given position. More...
ml_matrix	schmidt (int nMax, int mMax)
	Schmidt normalization. More...
double	albedo_flux (const ml_matrix &r, const ml_matrix &rPlanet, const ml_matrix &rSun, double radius=RADIUS_EARTH, double albedo=0.34)
	Albedo flux. More...

Variables
const double	SOLAR_FLUX = 1367.0
	Value of solar flux at 1 AU, in W/m2.

Detailed Description

Environmental functions.

Atmosphere, magnetic field, and radiation models.

Function Documentation

mol_wt_to_R()

double mol_wt_to_R

(

double

mol_wt

)

Compute gas constant R given the molecular weight.

Compute gas constant R given the molecular weight.

Parameters

mol_wt

The molecular weight.

Returns

Gas constant

References GAS_R.

atm_dens_exp()

double atm_dens_exp	(	double	h,
		int	planet
	)

Atmospheric density using an exponential model.

Atmospheric density using an exponential model.

The earth model has an additional scaling coefficient in the exponent.

Parameters

h	Altitude (km)
planet	Planetary ID

Returns

rho The density of the atmosphere in kg/m3.

atm_dens_scale()

double atm_dens_scale

(

double

h

)

Atmospheric density using scale heights.

Atmospheric density using scale heights.

Valid from 0 to 1000 km. Ref: Wertz, J.R., Spacecraft Attitude Determination and Control, Kluwer, 1976, p. 820.

Parameters

h	Altitude (km)

Returns

rho Atmospheric density (km/m3)

earth_radiation_total()

double earth_radiation_total	(	const ml_matrix &	pos,
		const ml_matrix &	u_sun
	)

Computes the total earth radiation including albedo.

Computes the total earth radiation including albedo.

Assumes a fixed albedo fraction.

Parameters

pos	Position vector relative to the Earth (km)
u_sun	Sun unit vector

Returns

Combined earth and albedo radiation flux

References earth_radiation(), RADIUS_EARTH, and SOLAR_FLUX.

earth_radiation()

double earth_radiation

(

const ml_matrix &

pos

)

Computes the earth radiation.

Parameters

pos	Position vector relative to the Earth (km)

Returns

Combined earth and albedo radiation flux

References earth_radiation(), and RADIUS_EARTH.

Referenced by earth_radiation(), and earth_radiation_total().

b_dipole()

ml_matrix b_dipole	(	const ml_matrix &	pos,
		double	jd
	)

Computes the magnetic field based on a tilted dipole model.

Computes the magnetic field based on a tilted dipole model.

Parameters

pos	(3,1) position vector in ECI frame.
jd	Julian date.

Returns

Magnetic field vector (T).

References earth_rot(), and jd_to_jcent().

mag_field()

ml_matrix mag_field	(	const ml_matrix &	position,
		double	jd,
		int	nMax,
		const mag_data_t &	mag_data
	)

Planetary magnetic field at a given position.

Planetary magnetic field at a given position.

Ref: Wertz, J., Spacecraft Attitude Determination and Control, Kluwer, 1976, pp. 779-781. Jursa, Adolph S., ed., Handbook of Geophysics and the Space Environment, Air Force Geophysics Laboratory, 1985, p. 4-28.

Parameters

position	(3,1) Position in planet-centered frame (km)
jd	Julian date
nMax	Maximum number of terms used
mag_data	Structure containing magnetic field data

Returns

b Magnetic field at position

References cart_to_sph(), mag_data_s::dateOfModel, earth_rot(), mag_data_s::g, mag_data_s::gDot, mag_data_s::h, mag_data_s::hDot, jd_to_jcent(), p_gauss(), RPhiTheta2Cart(), s_c_harm(), and schmidt().

schmidt()

ml_matrix schmidt	(	int	nMax,
		int	mMax
	)

Schmidt normalization.

Schmidt normalization.

Used by MagField.

Parameters

nMax	Maximum n coefficient
mMax	Maximum m coefficient

Returns

the normalization coefficients

Referenced by mag_field().

albedo_flux()

double albedo_flux	(	const ml_matrix &	r,
		const ml_matrix &	rPlanet,
		const ml_matrix &	rSun,
		double	radius,
		double	albedo
	)

Albedo flux.

Parameters

r	Position vector
rPlanet	Location of the planet in the same frame
rSun	Position vector of the sun
radius	Planet radius
albedo	Albedo fraction (0-1)

Returns

Magnitude of the albedo flux (W/m2)

References SOLAR_FLUX.