StarTram: a new approach for low-cost Earth-to-orbit transport

StarTram is a revolutionary concept for low-cost, high volume Earth-to-Orbit transport of passengers and/or cargo. StarTram is an evacuated launch tube that is magnetically levitated above the Earth's surface, up to a maximum altitude of /spl sim/18 km above the local terrain. Although the concept is advanced, it is within the limits of existing technology. The launch tube is levitated by the magnetic repulsive force between a set of superconducting (SC) cables attached to the tube and a set of SC cables on the ground beneath. A total current of 14 mega-amps in the levitated cables and an oppositely directed current of 280 mega-amps in the ground cables, produces a repulsive force of 4 tonnes/m at an altitude of 22 km above sea level (18 km above local ground level). These forces levitate a robust 7 meter diameter launch tube with an adequate margin of safety. The launch tube is stabilized, both vertically and horizontally, against the net upwards magnetic force and wind forces, by an array of high tensile strength (e.g., Kevlar) tethers that are anchored to the ground. Traveling inside the launch tube is a reusable StarTram Space Vehicle (SSV) that is magnetically levitated and accelerated to near orbital velocity in an evacuated tunnel at ground level. The SSV carries a set of lightweight SC magnets that inductively interact with a guideway of simple normal aluminum loops that operate at ambient temperature to stably levitate the moving vehicle. A separate AC current winding in the guideway pushes on the SSV's SC magnets, accelerating it. After the SSV reaches 8 km/sec at the end of its 1280 km long acceleration tunnel, it transitions into the ascending, magnetically levitated 220 km long launch tube, in which it coasts upwards to the launch point at an altitude of /spl sim/22 km The SSV then enters the upper atmosphere at a launch angle of 5 degrees. A subsequent 0.34 km/sec /spl Delta/V burn by a conventional LOX-kerosine rocket engine on the SSV inserts it into orbit. For a high-traffic system, StarTram can deliver payloads into orbit at a projected cost of $30 per kilogram This includes amortization of the launch complex, vehicle, and energy costs.