orbital_mechanics_module – fortran-astrodynamics-toolkit

Basic orbital mechanics routines.

Uses

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Used by

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Graph Key

Nodes of different colours represent the following:

Solid arrows point from a submodule to the (sub)module which it is descended from. Dashed arrows point from a module or program unit to modules which it uses.

Functions

public pure function orbit_period(mu, a) result(period)

Compute the two-body orbital period.

Arguments

Type	Intent	Optional	Attributes		Name
real(kind=wp),	intent(in)			::	mu	gravitational parameter [ $km^{3}/s^{2}$ ]
real(kind=wp),	intent(in)			::	a	semimajor axis [km]

Return Value real(kind=wp)

two-body orbital period [s]

public pure function orbit_energy(mu, rv) result(energy)

Compute the two-body orbital energy.

Arguments

Type	Intent	Optional	Attributes		Name
real(kind=wp),	intent(in)			::	mu	gravitational parameter [ $km^{3}/s^{2}$ ]
real(kind=wp),	intent(in),		dimension(6)	::	rv	position and velocity vector [km,km/s]

Return Value real(kind=wp)

two-body orbital energy [ $km^{2}/s^{2}$ ]

public pure function sphere_of_influence(mu_primary, mu_secondary, r_ps) result(r_soi)

Computes the sphere-of-influence radius of the secondary body.

Arguments

Type	Intent		Name
real(kind=wp),	intent(in)	::	mu_primary	primary body gravitational parameter [km^3/s^2]
real(kind=wp),	intent(in)	::	mu_secondary	secondary body gravitational parameter [km^3/s^2]
real(kind=wp),	intent(in)	::	r_ps	distance between the two bodies [km]

Return Value real(kind=wp)

sphere of influence radius [km]

public pure function sphere_of_influence_earth_moon(mu_primary, mu_secondary, r, r_sp) result(r_soi)

Computes the sphere-of-influence radius of the secondary body.

Arguments

Type	Intent	Attributes		Name
real(kind=wp),	intent(in)		::	mu_primary	primary body gravitational parameter [km^3/s^2]
real(kind=wp),	intent(in)		::	mu_secondary	secondary body gravitational parameter [km^3/s^2]
real(kind=wp),	intent(in),	dimension(3)	::	r	vector from the secondary body to the spacecraft [km]
real(kind=wp),	intent(in),	dimension(3)	::	r_sp	vector from the secondary to the primary body [km]

Return Value real(kind=wp)

sphere of influence radius of the secondary body [km]

Subroutines

public pure subroutine rv_to_orbital_elements(mu, r, v, p, ecc, inc, raan, aop, tru)

Convert position and velocity vectors to orbital elements.

Arguments

Type	Intent	Attributes		Name
real(kind=wp),	intent(in)		::	mu	gravitational parameter [ $km^{3}/s^{2}$ ]
real(kind=wp),	intent(in),	dimension(3)	::	r	position vector [km]
real(kind=wp),	intent(in),	dimension(3)	::	v	velocity vector [km/s]
real(kind=wp),	intent(out)		::	p	semiparameter $a(1-e^{2})$ [km]
real(kind=wp),	intent(out)		::	ecc	eccentricity [--]
real(kind=wp),	intent(out)		::	inc	inclination [rad]
real(kind=wp),	intent(out)		::	raan	raan [rad]
real(kind=wp),	intent(out)		::	aop	argument of peripsis [rad]
real(kind=wp),	intent(out)		::	tru	true anomaly [rad]

public pure subroutine orbital_elements_to_rv(mu, p, ecc, inc, raan, aop, tru, r, v)

Convert orbital elements to position and velocity vectors.

Arguments

Type	Intent	Attributes		Name
real(kind=wp),	intent(in)		::	mu	gravitational parameter [ $km^{3}/s^{2}$ ]
real(kind=wp),	intent(in)		::	p	semiparameter $a(1-e^{2})$ [km]
real(kind=wp),	intent(in)		::	ecc	eccentricity [--]
real(kind=wp),	intent(in)		::	inc	inclination [rad]
real(kind=wp),	intent(in)		::	raan	raan [rad]
real(kind=wp),	intent(in)		::	aop	argument of peripsis [rad]
real(kind=wp),	intent(in)		::	tru	true anomaly [rad]
real(kind=wp),	intent(out),	dimension(3)	::	r	position vector [km]
real(kind=wp),	intent(out),	dimension(3)	::	v	velocity vector [km/s]

private pure subroutine orbit_check(ecc, inc, circular, equatorial)

Check the orbit for singularities.

Arguments

Type	Intent		Name
real(kind=wp),	intent(in)	::	ecc	eccentricity
real(kind=wp),	intent(in)	::	inc	inclination [rad]
logical,	intent(out)	::	circular	is the orbit circular?
logical,	intent(out)	::	equatorial	is the orbit equatorial?

public pure subroutine periapsis_apoapsis(mu, a, e, rp, ra, vp, va)

Compute the periapsis and apoapsis position and velocity magnitudes.

Arguments

Type	Intent		Name
real(kind=wp),	intent(in)	::	mu	gravitational parameter [ $km^{3}/s^{2}$ ]
real(kind=wp),	intent(in)	::	a	semimajor axis [km]
real(kind=wp),	intent(in)	::	e	eccentricity [--]
real(kind=wp),	intent(out)	::	rp	periapsis position magnitude [km]
real(kind=wp),	intent(out)	::	ra	apoapsis position magnitude [km]
real(kind=wp),	intent(out)	::	vp	periapsis velocity magnitude [km/s]
real(kind=wp),	intent(out)	::	va	apoapsis velocity magnitude [km/s]

orbital_mechanics_module Module

Contents

Functions

Subroutines

Uses

Used by

Functions

public pure function orbit_period(mu, a) result(period)

Arguments

Return Value real(kind=wp)

public pure function orbit_energy(mu, rv) result(energy)

Arguments

Return Value real(kind=wp)

public pure function sphere_of_influence(mu_primary, mu_secondary, r_ps) result(r_soi)

Arguments

Return Value real(kind=wp)

public pure function sphere_of_influence_earth_moon(mu_primary, mu_secondary, r, r_sp) result(r_soi)

Arguments

Return Value real(kind=wp)

Subroutines

public pure subroutine rv_to_orbital_elements(mu, r, v, p, ecc, inc, raan, aop, tru)

Arguments

public pure subroutine orbital_elements_to_rv(mu, p, ecc, inc, raan, aop, tru, r, v)

Arguments

private pure subroutine orbit_check(ecc, inc, circular, equatorial)

Arguments

public pure subroutine periapsis_apoapsis(mu, a, e, rp, ra, vp, va)

Arguments