Example - 71 - Uranus Arrival, Approach, Entry State

In this example we illustrate the use of AMAT to compute the state at atmospheric entry for two approach trajectories: one prograde and other retrograde.

import numpy as np
from astropy.time import Time
import matplotlib.pyplot as plt

from AMAT.planet import Planet
from AMAT.arrival import Arrival
from AMAT.approach import Approach
from AMAT.vehicle import Vehicle

arrival = Arrival()
arrival.set_vinf_vec_from_lambert_arc('JUPITER',
                                  'URANUS',
                                  Time("2035-09-04 00:00:00", scale='tdb'),
                                  Time("2039-05-18 00:00:00", scale='tdb'))

# prograde approach
approach1 = Approach("URANUS", v_inf_vec_icrf_kms=arrival.v_inf_vec,
                            rp=(25559+400)*1e3, psi=3*np.pi/2,
                            is_entrySystem=True, h_EI=1000e3)

print("Entry altitude, km: "+ str(approach1.h_EI/1e3))
print("Entry longitude BI, deg: "+ str(round(approach1.longitude_entry_bi*180/np.pi, 2)))
print("Entry latitude BI, deg: "+ str(round(approach1.latitude_entry_bi*180/np.pi, 2)))
print("Atm. relative entry speed, km/s: "+str(round(approach1.v_entry_atm_mag/1e3, 4)))
print("Atm. relative heading angle, deg: "+str(round(approach1.heading_entry_atm*180/np.pi, 4)))
print("Atm. relative EFPA, deg: "+str(round(approach1.gamma_entry_atm*180/np.pi, 4)))

Entry altitude, km: 1000.0
Entry longitude BI, deg: -80.95
Entry latitude BI, deg: 25.22
Atm. relative entry speed, km/s: 27.5946
Atm. relative heading angle, deg: 132.066
Atm. relative EFPA, deg: -11.1875

# retrograde approach
approach1 = Approach("URANUS", v_inf_vec_icrf_kms=arrival.v_inf_vec,
                            rp=(25559+400)*1e3, psi=np.pi/2,
                            is_entrySystem=True, h_EI=1000e3)

print("Entry altitude, km: "+ str(approach1.h_EI/1e3))
print("Entry longitude BI, deg: "+ str(round(approach1.longitude_entry_bi*180/np.pi, 2)))
print("Entry latitude BI, deg: "+ str(round(approach1.latitude_entry_bi*180/np.pi, 2)))
print("Atm. relative entry speed, km/s: "+str(round(approach1.v_entry_atm_mag/1e3, 4)))
print("Atm. relative heading angle, deg: "+str(round(approach1.heading_entry_atm*180/np.pi, 4)))
print("Atm. relative EFPA, deg: "+str(round(approach1.gamma_entry_atm*180/np.pi, 4)))

Entry altitude, km: 1000.0
Entry longitude BI, deg: 50.51
Entry latitude BI, deg: 25.22
Atm. relative entry speed, km/s: 31.0646
Atm. relative heading angle, deg: 41.2577
Atm. relative EFPA, deg: -9.9243