sc_environs.h File Reference

Environmental functions. More...

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
double	mol_wt_to_R (double mol_wt)
	Compute gas constant R given the molecular weight.
double	atm_dens_exp (double h, int planet=kEarth)
	Atmospheric density using an exponential model.
double	atm_dens_scale (double h)
	Atmospheric density using scale heights.
double	earth_radiation_total (const ml_matrix &pos, const ml_matrix &u_sun)
	Computes the total earth radiation including albedo.
double	earth_radiation (const ml_matrix &pos)
	Computes the earth radiation.
ml_matrix	b_dipole (const ml_matrix &pos, double jd)
	Computes the magnetic field based on a tilted dipole model.
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.
ml_matrix	schmidt (int nMax, int mMax)
	Schmidt normalization.
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.

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Detailed Description

Atmosphere, magnetic field, and radiation models.

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Function Documentation

double mol_wt_to_R

(

double

mol_wt )

Compute gas constant R given the molecular weight.

Parameters:

mol_wt

The molecular weight.

Returns:

Gas constant

References GAS_R.

double atm_dens_exp	(	double	h,
		int	planet
	)

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.

double atm_dens_scale

(

double

h )

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)

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

Computes the total earth radiation including albedo.

Parameters:

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

Returns:

Combined earth and albedo radiation flux

References RADIUS_EARTH.

double earth_radiation

(

const ml_matrix &

pos )

Parameters:

pos	Position vector relative to the Earth (km)

Returns:

Combined earth and albedo radiation flux

References RADIUS_EARTH.

ml_matrix b_dipole	(	const ml_matrix &	pos,
		double	jd
	)

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).

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.

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 mag_data_s::dateOfModel, mag_data_s::g, mag_data_s::gDot, mag_data_s::h, and mag_data_s::hDot.

ml_matrix schmidt	(	int	nMax,
		int	mMax
	)

Schmidt normalization.

Used by MagField.

Parameters:

nMax	Maximum n coefficient
mMax	Maximum m coefficient

Returns:

the normalization coefficients

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

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
Maximum	m coefficient

Returns:

magnitude of the albedo flux