From the tutorial, it appears that a mass driver capable of launching payload to low earth orbit is technically possible. Assuming a launch altitude of 3,000 meters, how much energy per kg needs to be imparted to reach LEO? Has anyone done a cost estimate on constructing a 3 kilometer mass driver to do this? I keep reading that it is expensive, but the current cost of over $20,000 per kg prohibits industrializing space. Amortizing the cost of a mass driver over a million tons may make the cost acceptable.