def test_compute_missing_body_laplace_radius_raises_error(missing_body):
with pytest.raises(RuntimeError) as excinfo:
laplace_radius(missing_body)
assert (
"To compute the semimajor axis for Moon and Pluto use the JPL ephemeris"
in excinfo.exconly()
)
def change_attractor(self, new_attractor, force=False):
"""Changes orbit attractor.
Only changes from attractor to parent or the other way around are allowed.
Parameters
----------
new_attractor : poliastro.bodies.Body
Desired new attractor.
force : bool
If `True`, changes attractor even if physically has no-sense.
Returns
-------
ss: poliastro.twobody.orbit.Orbit
Orbit with new attractor
"""
if self.attractor == new_attractor:
return self
elif self.attractor == new_attractor.parent: # "Sun -> Earth"
r_soi = laplace_radius(new_attractor)
barycentric_position = get_body_barycentric(new_attractor.name, self.epoch)
# Transforming new_attractor's frame into frame of attractor
new_attractor_r = (
ICRS(barycentric_position)
.transform_to(self.get_frame())
.represent_as(CartesianRepresentation)
.xyz
)
distance = norm(self.r - new_attractor_r)
elif self.attractor.parent == new_attractor: # "Earth -> Sun"
r_soi = laplace_radius(self.attractor)
distance = norm(self.r)
else:
raise ValueError("Cannot change to unrelated attractor")
if distance > r_soi and not force:
raise ValueError(
"Orbit is out of new attractor's SOI. If required, use 'force=True'."
)
elif self.ecc < 1.0 and not force:
raise ValueError("Orbit will never leave the SOI of its current attractor")
else:
warn(
"Leaving the SOI of the current attractor",
PatchedConicsWarning,
stacklevel=2,
)
new_frame = get_frame(new_attractor, self.plane, obstime=self.epoch)
coords = self.get_frame().realize_frame(
self.represent_as(CartesianRepresentation, CartesianDifferential)
)
ss = Orbit.from_coords(new_attractor, coords.transform_to(new_frame))
return ss
def test_laplace_radius(body, expected_r_SOI):
if expected_r_SOI is not None:
expected_r_SOI = expected_r_SOI * u.m
r_SOI = laplace_radius(body)
assert_quantity_allclose(r_SOI, expected_r_SOI, rtol=1e-1)
def test_laplace_radius(body, expected_r_SOI):
if expected_r_SOI is not None:
expected_r_SOI = expected_r_SOI * u.m
r_SOI = laplace_radius(body)
assert_quantity_allclose(r_SOI, expected_r_SOI, rtol=1e-1)
def change_attractor(self, new_attractor):
"""Changes orbit attractor.
Only changes from attractor to parent or the other way around are allowed.
Parameters
----------
new_attractor: poliastro.bodies.Body
Desired new attractor.
Returns
-------
ss: poliastro.twobody.orbit.Orbit
Orbit with new attractor
"""
if self.attractor == new_attractor:
return self
elif self.attractor == new_attractor.parent: # "Sun -> Earth"
r_soi = laplace_radius(new_attractor)
distance = norm(
self.r -
get_body_barycentric(new_attractor.name, self.epoch).xyz)
elif self.attractor.parent == new_attractor: # "Earth -> Sun"
r_soi = laplace_radius(self.attractor)
distance = norm(self.r)
else:
raise ValueError("Cannot change to unrelated attractor")
if distance > r_soi:
raise ValueError("Orbit is out of new attractor's SOI")
elif self.ecc < 1.0:
raise ValueError(
"Orbit will never leave the SOI of its current attractor")
else:
warn("Leaving the SOI of the current attractor",
PatchedConicsWarning)
new_frame = get_frame(new_attractor, self.plane, obstime=self.epoch)
coords = self.frame.realize_frame(
self.represent_as(CartesianRepresentation))
ss = Orbit.from_coords(new_attractor, coords.transform_to(new_frame))
return ss
def _calculate_system_laplace_radii(self):
body_soi = {}
for body in self.body_list:
if body.name == "Sun":
pass
else:
try:
soi_rad = laplace_radius(body)
body_soi[body.name] = soi_rad
except KeyError:
pass
# a = get_mean_elements(body).a <- semimajor axis
# r_SOI = a * (body.k / body.parent.k) ** (2 / 5)
# todo: calculate laplace radius from mass ratio and semimajor axis
# for bodies where get_mean_elements fails
return body_soi
def test_laplace_radius_given_a():
parent = Body(None, 1 * u.km**3 / u.s**2, "Parent")
body = Body(parent, 1 * u.km**3 / u.s**2, "Body")
r_SOI = laplace_radius(body, 1 * u.km)
assert r_SOI == 1 * u.km
def test_laplace_radius(body, expected_r_SOI):
r_SOI = laplace_radius(body)
assert_quantity_allclose(r_SOI, expected_r_SOI, rtol=1e-1)
def test_laplace_radius_given_a():
parent = Body(None, 1 * u.km ** 3 / u.s ** 2, "Parent")
body = Body(parent, 1 * u.km ** 3 / u.s ** 2, "Body")
r_SOI = laplace_radius(body, 1 * u.km)
assert r_SOI == 1 * u.km
