def test_propagation_mean_motion_parabolic():
# example from Howard Curtis (3rd edition), section 3.5, problem 3.15
p = 2.0 * 6600 * u.km
_a = 0.0 * u.deg
orbit = Orbit.parabolic(Earth, p, _a, _a, _a, _a)
orbit = orbit.propagate(0.8897 / 2.0 * u.h, method=mean_motion)
_, _, _, _, _, nu0 = rv2coe(Earth.k.to(u.km**3 / u.s**2).value,
orbit.r.to(u.km).value,
orbit.v.to(u.km / u.s).value)
assert_quantity_allclose(nu0, np.deg2rad(90.0), rtol=1e-4)
orbit = Orbit.parabolic(Earth, p, _a, _a, _a, _a)
orbit = orbit.propagate(36.0 * u.h, method=mean_motion)
assert_quantity_allclose(norm(orbit.r), 304700.0 * u.km, rtol=1e-4)
def test_propagation_mean_motion_parabolic():
# example from Howard Curtis (3rd edition), section 3.5, problem 3.15
p = 2.0 * 6600 * u.km
_a = 0.0 * u.deg
orbit = Orbit.parabolic(Earth, p, _a, _a, _a, _a)
orbit = orbit.propagate(0.8897 / 2.0 * u.h, method=mean_motion)
_, _, _, _, _, nu0 = rv2coe(Earth.k.to(u.km**3 / u.s**2).value,
orbit.r.to(u.km).value,
orbit.v.to(u.km / u.s).value)
assert_quantity_allclose(nu0, np.deg2rad(90.0), rtol=1e-4)
orbit = Orbit.parabolic(Earth, p, _a, _a, _a, _a)
orbit = orbit.propagate(36.0 * u.h, method=mean_motion)
assert_quantity_allclose(norm(orbit.r.to(u.km).value), 304700.0, rtol=1e-4)
def test_parabolic_has_proper_eccentricity():
attractor = Earth
_d = 1.0 * u.AU # Unused distance
_a = 1.0 * u.deg # Unused angle
expected_ecc = 1.0 * u.one
ss = Orbit.parabolic(attractor, _d, _a, _a, _a, _a)
assert_allclose(ss.ecc, expected_ecc)
def test_parabolic_has_zero_energy():
attractor = Earth
_d = 1.0 * u.AU # Unused distance
_ = 0.5 * u.one # Unused dimensionless value
_a = 1.0 * u.deg # Unused angle
ss = Orbit.parabolic(attractor, _d, _a, _a, _a, _a)
assert_allclose(ss.energy.value, 0.0, atol=1e-16)
def test_parabolic_has_proper_eccentricity():
attractor = Earth
_d = 1.0 * u.AU # Unused distance
_a = 1.0 * u.deg # Unused angle
expected_ecc = 1.0 * u.one
ss = Orbit.parabolic(attractor, _d, _a, _a, _a, _a)
assert_allclose(ss.ecc, expected_ecc)
def test_parabolic_has_zero_energy():
attractor = Earth
_d = 1.0 * u.AU # Unused distance
_ = 0.5 * u.one # Unused dimensionless value
_a = 1.0 * u.deg # Unused angle
ss = Orbit.parabolic(attractor, _d, _a, _a, _a, _a)
assert_almost_equal(ss.energy.value, 0.0)
def test_parabolic_has_proper_eccentricity():
attractor = Earth
_d = 1.0 * u.AU # Unused distance
_ = 0.5 * u.one # Unused dimensionless value
_a = 1.0 * u.deg # Unused angle
expected_ecc = 1.0 * u.one
ss = Orbit.parabolic(attractor, _d, _a, _a, _a, _a)
assert_almost_equal(ss.ecc, expected_ecc)
def test_parabolic_has_proper_eccentricity():
attractor = Earth
_d = 1.0 * u.AU # Unused distance
_ = 0.5 * u.one # Unused dimensionless value
_a = 1.0 * u.deg # Unused angle
expected_ecc = 1.0 * u.one
ss = Orbit.parabolic(attractor, _d, _a, _a, _a, _a)
assert_almost_equal(ss.ecc, expected_ecc)
def test_propagation_parabolic(propagator):
# example from Howard Curtis (3rd edition), section 3.5, problem 3.15
# TODO: add parabolic solver in some parabolic propagators, refer to #417
if propagator in [mikkola, gooding]:
pytest.skip()
p = 2.0 * 6600 * u.km
_a = 0.0 * u.deg
orbit = Orbit.parabolic(Earth, p, _a, _a, _a, _a)
orbit = orbit.propagate(0.8897 / 2.0 * u.h, method=propagator)
_, _, _, _, _, nu0 = rv2coe(
Earth.k.to(u.km ** 3 / u.s ** 2).value,
orbit.r.to(u.km).value,
orbit.v.to(u.km / u.s).value,
)
assert_quantity_allclose(nu0, np.deg2rad(90.0), rtol=1e-4)
orbit = Orbit.parabolic(Earth, p, _a, _a, _a, _a)
orbit = orbit.propagate(36.0 * u.h, method=propagator)
assert_quantity_allclose(norm(orbit.r), 304700.0 * u.km, rtol=1e-4)
def orbit_check(date, v, m, Isp):
# sprawdzenie czy orbita została osiągnieta
date_iso = time.Time(str(date.iso), format='iso', scale='utc')
r_out = Orbit.from_body_ephem(Jupiter,
date_iso) # polozenie Jowisza po asyscie
r_out1, vp_out1 = r_out.rv()
v_exit = v + (vp_out1 /
(24 * 3600) * u.day / u.s) # predkosc satelity po manewrach
epoch_out = date.jyear
ss_out = Orbit.from_vectors(Sun, r_out1, v_exit,
epoch=epoch_out) # wyjsciowe parametry orbity
print('Sprawdzanie osiągnięcia orbity ...')
print()
if ss_out.ecc >= 1: # ekscentrycznosc orbity
print('Predkosc jest okej')
else:
print('Predkosc jest za mała')
print()
print('Dostosuj się do minimalnej orbity wyjściowej ')
# minimalna orbita wyjsciowa paraboliczna:
ss_out_new = Orbit.parabolic(Sun,
ss_out.p,
ss_out.inc,
ss_out.raan,
ss_out.argp,
ss_out.nu,
epoch=epoch_out)
v_out_new = ss_out_new.rv()[1] - v_exit # obliczenia nowej predkosci
dv_out_new = np.linalg.norm(v_out_new) * u.km / u.s
m_p_new = m * (math.exp(dv_out_new / Isp) - 1
) # obliczenia brakujace masy paliwa
# Odpowiedz:
print('Potrzebna delta V: %.3f km/s' % float(dv_out_new / u.km * u.s))
print('Potrzebna dod. masa paliwa: %i kg' % int(m_p_new / u.kg))
def test_parabolic_has_zero_energy():
attractor = Earth
_d = 1.0 * u.AU # Unused distance
_a = 1.0 * u.deg # Unused angle
ss = Orbit.parabolic(attractor, _d, _a, _a, _a, _a)
assert_allclose(ss.energy.value, 0.0, atol=1e-16)
