The ISS was built over a period of several years in the early 2000s and was used by several countries of the Earth as a base of operations for space exploration. The ISS originally had no weapons, but in 2020 it was fitted with experimental plasma beam projectors which were scavenged from ancient Dalek technology. At that point, the ISS officially became Earth's first (at, at that time, only) orbital defence platform.
Over the next few years the ISS helped to combat several alien invasions, from Slitheen to Reapers, and was left relatively unscathed throughout its operational lifespan. Several smaller stations were added to the orbital defence fleet which was rapidly swelling to have outposts across the entire Earth. Despite several asteroid and solar flare scares, the ISS remained in orbit for over 100 years.
In the year 2105 PLF Earth was once again invaded by Daleks, who swept away most of the orbital defence grid before laying waste to the planet. The ISS had just been fitted with rudimentary shield technology and had its first photon torpedo tube fitted in 2104, making it capable of taking on the Daleks, in theory. The ageing station was successful in destroying several smaller Dalek taskforces, buying time for the majority of the NASA fleet to arrive. However, as the larger cruisers moved in to engage the Daleks, the ISS was obliterated by a blast of a Dalek flagship, with all hands aboard lost.
The ISS, despite originally being built as an observation post, was remembered mostly for its use as a weapon, with many Humans believing it to be Humanity's most successful weapon ever. Despite never actually seeing the rise of the MAC Cannon, the ISS would continue to live on as the inspiration for the Orbital MAC Cannons that would later be adapted to establish the Empire of the Hood, and Humanity's darkest era.