Ikaris flight

#!/usr/bin/env python3
# -*- coding: utf-8 -*-


dt = 0.01

v0 = 379.9
R_au = 149597871000
G = 6.67408e-11
M_earth = 5.972e24
M_sun = 1.9885e30

x0 = 6371000+10000
xend = R_au-696340000

a_icaris = 10.04

def acc_earth(x):
    return -G*M_earth/x**2


def acc_sun(x):
    return G*M_sun/(R_au-x)**2

def acceleration(x):
    return a_icaris+acc_earth(x)+acc_sun(x)

def leap_frog(x,v,a):
    global dt
    xnew = x+v*dt+0.5*a*dt**2
    anew = acceleration(xnew)
    vnew = v+0.5*(a+anew)*dt
    return xnew, vnew, anew

def fly():
    x = x0
    v = v0
    a = acceleration(x)
    t = 0.0
    frm = 0
    while(x<xend):
        if(frm%6000==0):
            print(x/R_au,v,a)
        x,v,a = leap_frog(x,v,a)
        frm+=1
        t+=dt

    print(x/R_au,v, a)
    print(t/3600)

if __name__ == '__main__':
    fly()