Back on Earth, the world prepares for a final conflict against the Natal. Rocket Fighter Planes (based on the North American X-15 experimental rocket plane) and Atomic Heat Cannons are built to counter the invasion fleet. Eventually, the Natal saucers and their mothership approach Earth. Squadrons of Scout Ships (converted into Space Fighters) are sent up into space and engage in a massive dogfight with the saucers. The Natal mothership launches Space Torpedoes that hit New York and San Francisco. The mothership descends upon Tokyo and lays the metropolis to waste with its anti-gravity ray. The remaining saucers and mothership advance on the Space Research Center. But the Atomic Heat Cannons finally destroy the mothership and Earth is saved.