def test_sso_disposal_numerical(ecc_0, ecc_f):
a_0 = Earth.R.to(u.km).value + 900 # km
f = 2.4e-7 # km / s2, assumed constant
# Retrieve r and v from initial orbit
s0 = Orbit.from_classical(
attractor=Earth,
a=a_0 * u.km,
ecc=ecc_0 * u.one,
inc=0 * u.deg,
raan=0 * u.deg,
argp=0 * u.deg,
nu=0 * u.deg,
)
a_d, _, t_f = change_ecc_quasioptimal(s0, ecc_f, f)
# Propagate orbit
def f_ss0_disposal(t0, u_, k):
du_kep = func_twobody(t0, u_, k)
ax, ay, az = a_d(t0, u_, k)
du_ad = np.array([0, 0, 0, ax, ay, az])
return du_kep + du_ad
sf = s0.propagate(t_f * u.s, method=cowell, f=f_ss0_disposal, rtol=1e-8)
assert_allclose(sf.ecc.value, ecc_f, rtol=1e-4, atol=1e-4)
def test_sso_disposal_time_and_delta_v(ecc_0, ecc_f):
a_0 = Earth.R.to(u.km).value + 900 # km
f = 2.4e-7 # km / s2, assumed constant
expected_t_f = 29.697 # days, reverse-engineered
expected_delta_V = 0.6158 # km / s, lower than actual result
s0 = Orbit.from_classical(Earth, a_0 * u.km, ecc_0 * u.one, 0 * u.deg,
0 * u.deg, 0 * u.deg, 0 * u.deg)
_, delta_V, t_f = change_ecc_quasioptimal(s0, ecc_f, f)
assert_allclose(delta_V, expected_delta_V, rtol=1e-4)
assert_allclose(t_f / 86400, expected_t_f, rtol=1e-4)
def test_sso_disposal_time_and_delta_v(ecc_0, ecc_f):
a_0 = Earth.R.to(u.km).value + 900 # km
f = 2.4e-7 # km / s2, assumed constant
expected_t_f = 29.697 # days, reverse-engineered
expected_delta_V = 0.6158 # km / s, lower than actual result
s0 = Orbit.from_classical(Earth, a_0 * u.km, ecc_0 * u.one,
0 * u.deg, 0 * u.deg, 0 * u.deg, 0 * u.deg)
_, delta_V, t_f = change_ecc_quasioptimal(s0, ecc_f, f)
assert_allclose(delta_V, expected_delta_V, rtol=1e-4)
assert_allclose(t_f / 86400, expected_t_f, rtol=1e-4)
def test_sso_disposal_numerical(ecc_0, ecc_f):
a_0 = Earth.R.to(u.km).value + 900 # km
f = 2.4e-7 # km / s2, assumed constant
# Retrieve r and v from initial orbit
s0 = Orbit.from_classical(Earth, a_0 * u.km, ecc_0 * u.one,
0 * u.deg, 0 * u.deg, 0 * u.deg, 0 * u.deg)
a_d, _, t_f = change_ecc_quasioptimal(s0, ecc_f, f)
# Propagate orbit
sf = s0.propagate(t_f * u.s, method=cowell, ad=a_d, rtol=1e-8)
assert_allclose(sf.ecc.value, ecc_f, rtol=1e-4, atol=1e-4)