class KeplerianPredictorTests(TestCase):
def setUp(self):
# Data from Vallado, example 2.4
# Converted to classical orbital elements
sma = 7200.478692389954
ecc = 0.00810123424807035
inc = 98.59998936154028
raan = 319.7043176816153
argp = 70.87958362589532
ta = 0.004121614893481961
self.epoch = datetime(2000, 1, 1, 12, 0)
self.predictor = KeplerianPredictor(sma, ecc, inc, raan, argp, ta,
self.epoch)
def test_initial_position(self):
expected_position = np.array([1131.340, -2282.343, 6672.423])
expected_velocity = np.array([-5.64305, 4.30333, 2.42879])
position_eci, velocity_eci = self.predictor._propagate_eci(self.epoch)
assert_allclose(position_eci, expected_position, rtol=1e-7)
assert_allclose(velocity_eci, expected_velocity, rtol=1e-6)
def test_propagate_eci(self):
expected_position = np.array([-4219.7527, 4363.0292, -3958.7666])
expected_velocity = np.array([3.689866, -1.916735, -6.112511])
when_utc = self.epoch + timedelta(minutes=40)
position_eci, velocity_eci = self.predictor._propagate_eci(when_utc)
assert_allclose(position_eci, expected_position, rtol=1e-5)
assert_allclose(velocity_eci, expected_velocity, rtol=1e-5)
def test_from_tle_with_no_date_works(self):
# https://github.com/satellogic/orbit-predictor/issues/52
start = dt.datetime(2017, 3, 6, 7, 51)
db = MemoryTLESource()
db.add_tle(self.SATE_ID, self.LINES, start)
KeplerianPredictor.from_tle(self.SATE_ID, db)
def setUp(self):
# Converted to classical orbital elements
sma = 6780
ecc = 0.001
inc = 28.5
raan = 67.0
argp = 355.0
ta = 250.0
self.epoch = datetime(2000, 1, 1, 12, 0)
self.predictor = KeplerianPredictor(sma, ecc, inc, raan, argp, ta, self.epoch)
def setUp(self):
# Data from Vallado, example 2.4
# Converted to classical orbital elements
sma = 7200.478692389954
ecc = 0.00810123424807035
inc = 98.59998936154028
raan = 319.7043176816153
argp = 70.87958362589532
ta = 0.004121614893481961
self.epoch = datetime(2000, 1, 1, 12, 0)
self.predictor = KeplerianPredictor(sma, ecc, inc, raan, argp, ta, self.epoch)
class KeplerianPredictorOneDayTests(TestCase):
def setUp(self):
# Converted to classical orbital elements
sma = 6780
ecc = 0.001
inc = 28.5
raan = 67.0
argp = 355.0
ta = 250.0
self.epoch = dt.datetime(2000, 1, 1, 12, 0)
self.predictor = KeplerianPredictor(sma, ecc, inc, raan, argp, ta,
self.epoch)
def test_initial_position(self):
expected_position = np.array(
[3852.57404763, -4749.1872318, -2933.02952967])
expected_velocity = np.array([5.33068317, 5.28723659, -1.54255441])
position_eci, velocity_eci = self.predictor.propagate_eci(self.epoch)
assert_allclose(position_eci, expected_position, rtol=1e-7)
assert_allclose(velocity_eci, expected_velocity, rtol=1e-6)
def test_propagate_eci(self):
expected_position = np.array(
[-5154.02724044, 3011.19175291, 3214.77198183])
expected_velocity = np.array([-3.67652279, -6.71613987, 0.41267465])
when_utc = self.epoch + dt.timedelta(hours=23.999999999)
position_eci, velocity_eci = self.predictor.propagate_eci(when_utc)
assert_allclose(position_eci, expected_position, rtol=1e-2)
assert_allclose(velocity_eci, expected_velocity, rtol=1e-2)
def test_propagate_one_day(self):
expected_position = np.array(
[-5154.02724044, 3011.19175291, 3214.77198183])
expected_velocity = np.array([-3.67652279, -6.71613987, 0.41267465])
when_utc = self.epoch + dt.timedelta(hours=24)
position_eci, velocity_eci = self.predictor.propagate_eci(when_utc)
assert_allclose(position_eci, expected_position, rtol=1e-2)
assert_allclose(velocity_eci, expected_velocity, rtol=1e-2)
def test_from_tle_returns_same_initial_conditions_on_epoch(self):
start = datetime(2017, 3, 6, 7, 51)
db = MemoryTLESource()
db.add_tle(self.SATE_ID, self.LINES, start)
keplerian_predictor = KeplerianPredictor.from_tle(self.SATE_ID, db, start)
tle_predictor = TLEPredictor(self.SATE_ID, db)
epoch = keplerian_predictor._epoch
pos_keplerian = keplerian_predictor.get_position(epoch)
pos_tle = tle_predictor.get_position(epoch)
assert_allclose(pos_keplerian.position_ecef, pos_tle.position_ecef, rtol=1e-11)
assert_allclose(pos_keplerian.velocity_ecef, pos_tle.velocity_ecef, rtol=1e-13)
def equatorial_orbits(
draw,
sma=floats(R_E_KM, 42000),
ecc=floats(0, 1, exclude_max=True),
argp=floats(0, 360),
ta=floats(0, 360),
epoch=datetimes(),
):
return KeplerianPredictor(
draw(sma),
draw(ecc),
0,
0,
draw(argp),
draw(ta),
draw(epoch),
)
def elliptical_orbit():
return KeplerianPredictor(7000, 0.2, 0, 0, 0, 0,
dt.datetime(2020, 2, 26, 0, 0, 0))