def test_read_write_bsp( plot = False ):
'''
Propagate a 30 degree inclination orbit (20 periods),
write BSP kernel, then read back the BSP kernel, ensuring
that latitudes are within +-30 degrees before and after
writing kernel
'''
spice.furnsh( sd.pck00010 )
sc = SC( {
'coes' : [ 8000.0, 0.01, 30.0, 0, 0, 0 ],
'tspan': '20'
} )
'''
Ensure latitudes are +-30 degrees
'''
sc.calc_latlons()
assert np.all( sc.latlons[ :, 2 ] <= 30.0 )
assert np.all( sc.latlons[ :, 2 ] >= -30.0 )
'''
spice.spkopn will error if a bsp with the requested
filename already exists
'''
filename = 'test_read_write_bsp.bsp'
if os.path.isfile( filename ):
os.remove( filename )
'''
Write bsp with all the default arguments except filename
'''
st.write_bsp( sc.ets, sc.states[ :, :6 ],
{ 'bsp_fn': filename } )
'''
Now read back the bsp and ensure that
latitudes are still within +-30 degrees
'''
spice.furnsh( filename )
states = st.calc_ephemeris( -999, sc.ets, 'IAU_EARTH', 399 )
latlons = nt.cart2lat( states[ :, :3 ] )
assert np.all( latlons[ :, 2 ] <= 30.0 )
assert np.all( latlons[ :, 2 ] >= -30.0 )
os.remove( filename )
states_list.append(states)
ets += spice.str2et('2021-12-26')
pt.plot_orbits(
states_list, {
'labels': ['0', '45', '75', '100'],
'colors': ['crimson', 'lime', 'c', 'm'],
'traj_lws': 2,
'show': True
})
latlons = []
for states in states_list:
latlons.append(
nt.cart2lat(states[:1000, :3], 'J2000', 'IAU_EARTH', ets))
pt.plot_groundtracks(
latlons, {
'labels': ['0', '45', '75', '100'],
'colors': ['crimson', 'lime', 'c', 'm'],
'show': True
})
'''
This part is outside the scope of this lesson, but for those
who are curious this is how to write the trajectory to a
SPICE .bsp kernel to then use in Cosmographia
In general, it is bad practice to have imports in this
part of the code, so don't try this at home!
'''
if False:
# AWP libraries
from Spacecraft import Spacecraft as SC
import numerical_tools as nt
import plotting_tools as pt
import spice_data as sd
from planetary_data import earth
if __name__ == '__main__':
spice.furnsh(sd.pck00010)
ER = earth['radius']
coes0 = [ER + 400, 0.01, 45.0, 0, 0.0, 0] # LEO
coes1 = [42164.0, 0.2, 55.0, 0, -80, 0] # geosync
coes2 = [ER + 890.0, 0.0, 99.0, 0, 0, 0] # sunsync
coes3 = [ER + 500, 0.01, 135.0, 0, 0, 0] # retrograde
latlons = []
sc_config = {'tspan': '3', 'dense_output': True}
for coes in [coes0, coes1, coes2, coes3]:
sc_config['coes'] = coes
sc = SC(sc_config)
ets = arange(sc.ets[0], sc.ets[-1], 15.0)
rs = sc.ode_sol.sol(ets).T[:, :3]
latlons.append(nt.cart2lat(rs, 'J2000', 'IAU_EARTH', ets))
pt.plot_groundtracks(
latlons, {
'labels': ['LEO', 'Geosynchronous', 'Sun Sync', 'Retrograde'],
'show': True
})