Somewhat interested in the RP, but first thing's first:

@Wilson:

Space assets aren't immune to ground-based retaliation. 

With the advent of the spy satellite, anti-satellite weapons were created as a respectable counter to such daunting technology. Space stations, no matter the armor that they sport, aren't going to stand up to the point-blank detonation of a nuclear missile launched from a mass driver, a combustion light-gas gun, an electrothermal chemical gun, or your run-of-the-mill air superiority fighter. Integrating a nuclear-shaped charge into such a missile enables the projectile to not only deliver its payload from a much longer range, but it also does far more damage than a conventional nuclear weapon of similar size could output, as the radiation and heat generated from the explosion is focused in the shape of a cone as opposed to a rapidly-expanding ball. Bomb-pumped lasers are also a viable, cheap and disposal solution to spaceborne assets. 

You can also use standard rocket-assisted 'smart' shells that can correct their own courses. Much cheaper, though perhaps less reliable. Unsure. 

Ground weaponry can also be made larger, more powerful and be better protected than any space station or military-grade spaceship that 2080-era Earth can conceivably come up with due to the very strict weight, internal volume and cost limitations forced upon spacecraft and space stations. Hiding your launch facilities and gun platforms within Mount Everest, for example, affords you nigh-immunity to spacebased weaponry. If a mountain can laugh off a multi-megaton yield nuclear weapon, it's going to laugh off a railgun shot with impunity---especially one fired from space, which is going to be smaller. The threat of bunker-buster munitions grating on your nerves? Dig your bunkers deeper, for you have the mining technology to do it. Reinforced tunnels and hardened bunkers are unbelievably resistant to kinetic-based munitions. 

[url=http://en.wikipedia.org/wiki/Cheyenne_Mountain_nuclear_bunker] 

[url=http://en.wikipedia.org/wiki/Anti-satellite_weapon]

[url=http://en.wikipedia.org/wiki/Davy_Crockett_(nuclear_device)]

[url=http://en.wikipedia.org/wiki/Space_gun]

[url=http://en.wikipedia.org/wiki/Combustion_light_gas_gun]

[url=http://en.wikipedia.org/wiki/Space_gun]

Information on plausible space weaponry:

[url=http://www.projectrho.com/public_html/rocket/spacegunconvent.php]