A quick cost-benefit analysis says this makes sense. But does the technology? Here's the gist, according to Startram (which, incidentally, is co-invented by one of the people who invented the superconducting maglev, Dr. James Powell): start a maglev train in a vacuum sealed tunnel on the ground, accelerate it for five straight minutes to speeds up to 5.6 miles per second, and launch it from the end of said tunnel--which, as it happens, needs to be raised about 12 miles into the sky where the air is thin enough that it won't destroy the spacecraft-train, which is now moving about 20,000 miles per hour.