your code
mothership(500,400);
shuttle(50,450,500);
planet(200,200,"jupiter");
fuel(150,250,650);
asteroid(500,300);
wall(50,300,350,300);
wall(300,50,300,300);
alien(100,100,300,100);
wall(300,300,300,500);
fuel(400,300,750);
wall(300,150,500,150);
fuel(400,100,400);