orbit.py

Created by vnap0v

Created on June 21, 2025

1.44 KB

This script simulates the trajectory of orbiting satellites.

It shows one geostationary orbit and one elliptical.

Uses the libraries

kandinsky for output
time to pace the simulation
math for the sqrt() function
ion to be able to stop the simulation by hitting the EXE key

from math import *
import kandinsky
import time
import ion

#constants
G=6.6743015e-11 #m3/(kg.s2)
m_earth=5.97219e24 #kg
h_geostat=35786e3 #m
r_earth=6378e3 #m
v_geostat=3.07e3 #m/s
# parameter
scale=6e5 #size of the image

# acceleration due to gravity
def accel(x,y):
  r=sqrt(x**2+y**2) #distance
  a=-G*m_earth/r**2 #total acceleration
  ax=a*x/r # x and y components
  ay=a*y/r
  return ax,ay

# calculate and draw 1 trajectory
def draw_traject(x,y,vx,vy,T,N,col):
  dt=T/N
  for k in range(N):
    x_scr=int(160.5+x/scale)
    y_scr=int(115.5-y/scale)
    kandinsky.set_pixel(x_scr,y_scr,col)
    ax,ay=accel(x,y)
    vx+=ax*dt; vy+=ay*dt
    x+=vx*dt; y+=vy*dt
    if k%50==0:
      kandinsky.draw_string("x={0:.1f} km y={1:.1f} km  ".format(x/1e3,y/1e3),10,5,"white","black")
      time.sleep(.08)
      if ion.keydown(ion.KEY_EXE):
        return True
  return False

# show 2 trajectories
# parameters
N_points=2000 
T_total=9e4 #s
# loop
stop=False
while not stop:
  kandinsky.fill_rect(0,0,320,230,"black")
  kandinsky.fill_rect(158,113,4,4,"blue")
  kandinsky.draw_string("EXE to stop",10,200,"white","black")
  # trajectory 1
  kandinsky.draw_string("Geostationary orbit",60,25,"green","black")
  stop=draw_traject(r_earth+h_geostat,0,0,v_geostat,T_total,N_points,"green")
  # trajectory 2
  kandinsky.draw_string("Elliptical orbit",120,190,"red","black")
  stop=draw_traject((r_earth+h_geostat)*1.8,0,0,v_geostat*0.3,T_total,N_points,"red")