Although wikipedia isn't tremendously reliable : "In the case of the system mentioned in the 2003 USAF report above, a 6.1 m × 0.3 m tungsten cylinder impactin

Although wikipedia isn't tremendously reliable : "In the case of the system mentioned in the 2003 USAF report above, a 6.1 m × 0.3 m tungsten cylinder impacting at Mach 10 has a kinetic energy equivalent to approximately 11.5 tons of TNT (or 7.2 tons of dynamite). The mass of such a cylinder is itself greater than 9 tons, so it is clear that the practical applications of such a system are limited to those situations where its other characteristics provide a decisive advantage - a conventional bomb/warhead of similar weight to the tungsten rod, delivered by conventional means, provides similar destructive capability and is a far more practical method. Some other sources suggest a speed of 36,000 ft/s (11,000 m/s),[8] which for the aforementioned rod would amount to a kinetic energy equivalent to 120 tons of TNT or 0.12 kt. With 6-8 satellites on a given orbit, a target could be hit within 12–15 minutes from any given time, less than half the time taken by an ICBM and without the warning. Such a system could also be equipped with sensors to detect incoming anti-ballistic missile-type threats and relatively light protective measures to use against them (e.g. Hit-To-Kill Missiles or megawatt-class chemical laser) http://en.wikipedia.org/wiki/Kinetic_bombardment http://en.wikipedia.org/wiki/Kinetic_bombardment It's not the idea to have one single bombardment weapon, but many in an orbit. That's what makes it a quick reaction. A single unit could likely be a testing platform for such a system.