def parabolic(cls,
attractor,
p,
inc,
raan,
argp,
nu,
epoch=J2000,
plane=Planes.EARTH_EQUATOR):
"""Return parabolic `Orbit`.
Parameters
----------
attractor : Body
Main attractor.
p : ~astropy.units.Quantity
Semilatus rectum or parameter.
inc : ~astropy.units.Quantity, optional
Inclination.
raan : ~astropy.units.Quantity
Right ascension of the ascending node.
argp : ~astropy.units.Quantity
Argument of the pericenter.
nu : ~astropy.units.Quantity
True anomaly.
epoch: ~astropy.time.Time, optional
Epoch, default to J2000.
plane : ~poliastro.frames.Planes
Fundamental plane of the frame.
"""
ss = classical.ClassicalState(attractor, p, 1.0 * u.one, inc, raan,
argp, nu)
return cls(ss, epoch, plane)
def from_classical(cls, attractor, a, ecc, inc, raan, argp, nu, epoch=J2000):
"""Return `Orbit` from classical orbital elements.
Parameters
----------
attractor : Body
Main attractor.
a : ~astropy.units.Quantity
Semi-major axis.
ecc : ~astropy.units.Quantity
Eccentricity.
inc : ~astropy.units.Quantity
Inclination
raan : ~astropy.units.Quantity
Right ascension of the ascending node.
argp : ~astropy.units.Quantity
Argument of the pericenter.
nu : ~astropy.units.Quantity
True anomaly.
epoch : ~astropy.time.Time, optional
Epoch, default to J2000.
"""
if ecc == 1.0 * u.one:
raise ValueError("For parabolic orbits use Orbit.parabolic instead")
if not 0 * u.deg <= inc <= 180 * u.deg:
raise ValueError("Inclination must be between 0 and 180 degrees")
if ecc > 1 and a > 0:
raise ValueError("Hyperbolic orbits have negative semimajor axis")
ss = classical.ClassicalState(
attractor, a, ecc, inc, raan, argp, nu)
return cls(ss, epoch)
def to_classical(self):
p, ecc, inc, raan, argp, nu = mee2coe(
self.p.to(u.km).value,
self.f.to(u.rad).value,
self.g.to(u.rad).value,
self.h.to(u.rad).value,
self.k.to(u.rad).value,
self.L.to(u.rad).value)
return classical.ClassicalState(self.attractor, p * u.km, ecc * u.one,
inc * u.rad, raan * u.rad,
argp * u.rad, nu * u.rad)
def to_classical(self):
"""Converts to classical orbital elements representation.
"""
(p, ecc, inc, raan, argp, nu) = rv2coe(
self.attractor.k.to(u.km**3 / u.s**2).value,
self.r.to(u.km).value,
self.v.to(u.km / u.s).value)
return classical.ClassicalState(self.attractor, p * u.km, ecc * u.one,
inc * u.rad, raan * u.rad,
argp * u.rad, nu * u.rad)
