Earth-Moon orbit simulator

earthmoonsim.py

from math import *

#All distance units are in m, velocity in m/s

#Enter initial simulation data here

initial_x = -6.38E6
initial_y = 12E6

initial_vx = 1.1E4  #-6.38E6,12E6,1.1E4,3.5E3
initial_vy = 3.5E3
M = 50 #satellite mass

end_time = 10000 #This is how many seconds you want the simulation to go.

#Data about Earth and the Moon goes here:
Earth = [0.0,0.0]
Moon = [385E6,0]

mE = 6.0E24
mM = 7.0E22

rE = 6.38E6
rM = 1.738E6

G = 6.67E-11

Fburn = 3850       #F = 3850, start 43080, end 43180
startBurn = 43080
endBurn = 43180

#Simulation data goes here
t = 0
delta_t = 1

crashed = False

data = []
data.append([initial_x,initial_y,initial_vx,initial_vy,crashed])
i = 0

def isBurnTime(startBurn,endBurn):
    if(t>=startBurn and t<=endBurn):
        return 1
    else:
        return 0


while (t<end_time and crashed == False):
    
    isBurning = isBurnTime(startBurn,endBurn)

    dE = sqrt((data[i][0] - Earth[0])**2+(data[i][1] - Earth[1])**2)
    dM = sqrt((data[i][0] - Moon[0])**2+(data[i][1] - Moon[1])**2)
    
    Fe = G*M*mE*1./(dE**2)
    Fm = G*M*mM*1./(dM**2)

    speed = sqrt(data[i][2]**2+data[i][3]**2)

    
    accel_x = 1./M*(-1*Fe*(data[i][0]-Earth[0])*1./dE -Fm*(data[i][0]-Moon[0])*1./dM - isBurning*Fburn*data[i][2]*1./speed)
    accel_y = 1./M*(-1*Fe*(data[i][1]-Earth[1])*1./dE -Fm*(data[i][1]-Moon[1])*1./dM - isBurning*Fburn*data[i][3]*1./speed)

    v_x = data[i][2]+accel_x*delta_t
    v_y = data[i][3]+accel_y*delta_t

    x = data[i][0]+ data[i][2]*delta_t+0.5*accel_x*delta_t**2
    y = data[i][1] + data[i][3]*delta_t + 0.5*accel_y*delta_t**2

    if(dE<rE or dM<rM):
        crashed = True
        print "Crash!"
    

    data.append([x,y,v_x,v_y,crashed])
    i = i + 1
    t+=delta_t

print "Completed calculations."

outFile = open('output.txt','w')


time_int = 600
count = 0
for row in data:
    
   count+=1
   if(count>=time_int):
       count = 0
       new_x = row[0]*1./(1.0E6)
       new_y = row[1]*1./(1.0E6)
       output = str(new_x)+','+str(new_y)+'\n'
       outFile.write(output)
 
    
outFile.close()