- "...and these orbiting units, which have a big punch to them."
- ―David Levinson
The Orbital Defense System was a geostationary ring of weaponized satellites, which were equipped with cannon turrets based on the technology of the City Destroyer cannons, that served as Earth's first line of defense along with the ESD Moon Base.
In July 4, 2016, Earth was again invaded by the aliens. After the ESD Moon Base was destroyed by the alien mothership as it proceeded to enter Earth's atmosphere, U.S. President Elizabeth Lanford gave the orders to activate the Orbital Defense System against the massive vessel; even though the orbital defense cannons would not be enough to seriously damage it. The ESD under General Joshua T. Adams had the cannons to initiate a simultaneous countdown in order to have the ODS firing simultaneously at the mothership to inflict sufficient damage. Unfortunately the mothership fired a barrage of energy beams that annihilated the orbital turrets before they can fire.
The Orbital Defense System form two rings (longitude and latitude) around the Earth. They are controlled remotely from Earth's control centers. Their weapon, just like that of the City Destroyer, is enclosed by some doors. In the attack phase, the doors open and a beam is pointed against the enemy object. It then begins a countdown of ten seconds, in which the cannon charge their energy, before opening fire.