SDS-058 was developed in the 2050's by the U.S. Army, in cooperation with Lawrence Livermore National Laboratory and the United States Space Agency. SDS-058 stood for S'trategic 'Defense System-2058, a simple codename. During the early years of development, many scientists at Lawrence Livermore began to fear that Communist spies would eventually figure out the name of the weapon, and thus began calling it "The Gadget".
The satellite was no ordinary military satellite, of course, as it's purpose was not meant for tracking enemy movements. The SDS-058 was armed with 90 Megaton-tipped missiles, which could be launched from space using a specific code on a transmitter frequency. From there on, the missiles could then propell towards its target and annihilate it all around the globe.
The Gadget, luckily for some cities, was never used in the Great War at all. It was only tested on July 4th, 2066 to demoralize the Chinese in America's Bikini Atoll islands. . After the Great War destroyed most of the operating systems for the Gadget, the satellite remained floating aimlessly in space for almost two hundred years. However in 2299 it was once again re-established and put into use by the Restored U.S. as a deterent rather than a weapon.