Interplanetary Space Command was an organisation in the 29th century. It operated at least two space station beacons: Nerva Beacon and Ganymede Beacon. Both orbited the planet Jupiter. The ISC's job was to direct space traffic between Earth and Pluto. Their chain of command ended with a higher authority/headquarters known as Earth Centre.
ISC officers had access to bullet-based ballistic sub-machine guns. The exact capabilities of these weapons were unclear, although they were not powerful enough to penetrate Cyberman armour. (TV: Revenge of the Cybermen)
ISC personnel wore brown shirts, trousers, boots, ties and jackets. The ISC insignia was displayed on the right breast. A tab displaying the officer's rank stripes was pinned to the left breast. A commander had three gold stripes on breast tab, one looping gold stripe on the epaulettes and one gold aigulette. One rank had two gold stripes on their breast tab and plain epaulettes. (TV: Revenge of the Cybermen)