def flyby_height_objective(periapsis, *params):
aIn, aOut, deltaAngle, body = params
eccIn = 1 - periapsis / aIn
eccOut = 1 - periapsis / aOut
inOrb = Orbit(aIn, eccIn, 0, 0, 0, 0, 0, body)
outOrb = Orbit(aOut, eccOut, 0, 0, 0, 0, 0, body)
deltaIn = inOrb.get_flight_angle_at_soi()
deltaOut = outOrb.get_flight_angle_at_soi()
return abs(deltaAngle - deltaIn - deltaOut)
def get_flyby_orbit(a, ecc, body, inOutDir, nDir, isOut=False):
periapsis = a * (1 - ecc)
tempOrb = Orbit(a, ecc, 0, 0, 0, 0, 0, body)
delta = tempOrb.get_flight_angle_at_soi(isOut)
rpDir = rodrigues_rotate(inOutDir, nDir, delta)
vpDir = cross(nDir, rpDir)
rp = rpDir * periapsis
vp = vpDir * math.sqrt(body.mu * (2 / periapsis - 1 / a))
return Orbit.from_state_vector(rp, vp, 0, body)
