def test_atmospheric_demise_coesa76():
# Test an orbital decay that hits Earth. No analytic solution.
R = Earth.R.to(u.km).value
orbit = Orbit.circular(Earth, 250 * u.km)
t_decay = 7.17 * u.d
# Parameters of a body
C_D = 2.2 # Dimensionless (any value would do)
A_over_m = ((np.pi / 4.0) * (u.m**2) / (100 * u.kg)).to_value(
u.km**2 / u.kg) # km^2/kg
tofs = [365] * u.d
lithobrake_event = LithobrakeEvent(R)
events = [lithobrake_event]
coesa76 = COESA76()
def f(t0, u_, k):
du_kep = func_twobody(t0, u_, k)
# Avoid undershooting H below attractor radius R
H = max(norm(u_[:3]), R)
rho = coesa76.density((H - R) * u.km).to_value(u.kg / u.km**3)
ax, ay, az = atmospheric_drag(
t0,
u_,
k,
C_D=C_D,
A_over_m=A_over_m,
rho=rho,
)
du_ad = np.array([0, 0, 0, ax, ay, az])
return du_kep + du_ad
rr, _ = cowell(
Earth.k,
orbit.r,
orbit.v,
tofs,
events=events,
f=f,
)
assert_quantity_allclose(norm(rr[0].to(u.km).value), R,
atol=1) # Below 1km
assert_quantity_allclose(lithobrake_event.last_t, t_decay, rtol=1e-2)
def test_atmospheric_demise_coesa76():
# Test an orbital decay that hits Earth. No analytic solution.
R = Earth.R.to(u.km).value
orbit = Orbit.circular(Earth, 250 * u.km)
t_decay = 7.17 * u.d
# parameters of a body
C_D = 2.2 # dimentionless (any value would do)
A_over_m = ((np.pi / 4.0) * (u.m**2) / (100 * u.kg)).to_value(
u.km**2 / u.kg) # km^2/kg
tofs = [365] * u.d
lithobrake_event = LithobrakeEvent(R)
events = [lithobrake_event]
coesa76 = COESA76()
def f(t0, u_, k):
du_kep = func_twobody(t0, u_, k)
ax, ay, az = atmospheric_drag_model(t0,
u_,
k,
R=R,
C_D=C_D,
A_over_m=A_over_m,
model=coesa76)
du_ad = np.array([0, 0, 0, ax, ay, az])
return du_kep + du_ad
rr, _ = cowell(
Earth.k,
orbit.r,
orbit.v,
tofs,
events=events,
f=f,
)
assert_quantity_allclose(norm(rr[0].to(u.km).value), R,
atol=1) # below 1km
assert_quantity_allclose(lithobrake_event.last_t, t_decay, rtol=1e-2)
def test_propagate_instance():
tof = 1.0 * u.min
ss0 = Orbit.from_classical(
Earth,
1000 * u.km,
0.75 * u.one,
63.4 * u.deg,
0 * u.deg,
270 * u.deg,
80 * u.deg,
)
C_D = 2.2 * u.one # dimentionless (any value would do)
A = ((np.pi / 4.0) * (u.m**2)).to(u.km**2)
m = 100 * u.kg
spacecraft = Spacecraft(A, C_D, m)
earth_satellite = EarthSatellite(ss0, spacecraft)
orbit_with_j2 = earth_satellite.propagate(tof=tof, gravity=EarthGravity.J2)
orbit_without_perturbation = earth_satellite.propagate(tof)
orbit_with_atmosphere_and_j2 = earth_satellite.propagate(
tof=tof, gravity=EarthGravity.J2, atmosphere=COESA76())
assert isinstance(orbit_with_j2, EarthSatellite)
assert isinstance(orbit_with_atmosphere_and_j2, EarthSatellite)
assert isinstance(orbit_without_perturbation, EarthSatellite)
import pytest
from astropy import units as u
from astropy.tests.helper import assert_quantity_allclose
from poliastro.earth.atmosphere import COESA76
from poliastro.earth.atmosphere.coesa76 import p_coeff, rho_coeff
coesa76 = COESA76()
def test_outside_altitude_range_coesa76():
with pytest.raises(ValueError) as excinfo:
r0 = 6356.766 * u.km
coesa76._check_altitude(1001 * u.km, r0)
assert (
"ValueError: Geometric altitude must be in range [0.0 km, 1000.0 km]"
in excinfo.exconly())
def test_get_index_coesa76():
expected_i = 7
z = 86 * u.km
i = coesa76._get_index(z, coesa76.zb_levels)
assert i == expected_i
def test_coefficients_over_86km():
# Expected pressure coefficients
expected_p = [
9.814674e-11, -1.654439e-07, 1.148115e-04, -0.05431334, -2.011365
]