def __init__(self, arrival_time):
# Start with earth parking orbit
leo = Orbit.circular(PatchedConic.mu_earth, 6378136.6 + 185000.0)
# Get the state of the moon at arrival so we know how far out
# we need to go and how fast.
x_moon_arrive = spice.spkez(301, arrival_time, 'J2000', 'NONE',
399)[0] * 1000.0
# Produce patched conic
x, pcx = pc.optimize_deltav(np.array(
[49.9 * np.pi / 180.0, leo.v + 3200.0]),
1837400.0,
leo.r,
leo.phi,
norm(x_moon_arrive[0:3]),
norm(x_moon_arrive[3:6]),
conjugate=True)
depart_time = arrival_time - pcx.tof
free_flight_sweep_angle = pcx.nu1 - pcx.nu0
# Get state of moon at departure so we can figure out the
# plane of our trajectory.
x_moon_depart = spice.spkez(301, depart_time, 'J2000', 'NONE',
399)[0] * 1000.0
# Get earth--moon frame at SOI arrival time
rm0 = x_moon_depart[:3]
rm0hat = rm0 / norm(rm0)
rm1 = x_moon_arrive[:3]
rm1hat = rm1 / norm(rm1)
hhat = np.cross(rm0hat, rm1hat)
hhat /= norm(hhat)
T_eci_to_pqw = spice.twovec(rm1hat, 1, hhat, 3)
# Get directions to initial and final vectors
r1hat = T_eci_to_pqw.T.dot(
rotate_z(pcx.gam1).dot(np.array([1.0, 0, 0])))
r0hat = T_eci_to_pqw.T.dot(
rotate_z(pcx.gam1 - free_flight_sweep_angle).dot(
np.array([1.0, 0.0, 0.0])))
v0hat = np.cross(hhat, r0hat)
# post delta-v state:
r0 = r0hat * leo.r
v0 = v0hat * x[1]
# pre delta-v state:
v0m = v0hat * leo.v
# arrival state:
# r1 = r1hat * pcx.arrive.r
# v1 = ?
self.free_flight_sweep_angle = free_flight_sweep_angle
self.depart_time = depart_time
self.arrival_time = arrival_time
self.x_depart_post = np.hstack((r0, v0))
self.x_depart_pre = np.hstack((r0, v0m))
self.x_moon_depart = x_moon_depart
self.x_moon_arrive = x_moon_arrive
self.deltav = v0 - v0m
conjugate=conjugate,
maxiter=alpha_maxiter,
alphatol=alphatol,
plot=plot_alpha,
disp=disp)
print("Warning: exceeded max iterations (gradient phase)")
return x, pcx
if __name__ == '__main__':
D = 384402000.0
V = 2.649e-6 * D
leo = Orbit.circular(PatchedConic.mu_earth,
6378136.6 + 185000.0) # earth parking
XS = []
YS = []
optimize_deltav(np.array([49.9 * np.pi / 180.0, leo.v + 3200.0]),
1837400.0,
leo.r,
leo.phi,
D,
V,
conjugate=True)
YS = np.vstack(YS)
import matplotlib.pyplot as plt
fig = plt.figure()