Can electromagnetic augmentation reduce space launch costs?

A ground-based electromagnetic (EM) acceleration system to provide a launch-to-orbit capability is described. A study was undertaken to determine if such a system could achieve a useful reduction in launch costs compared with current large chemical boosters, while increasing launch safety and reliability. The study evaluated how an EM launch system would augment the chemical boost capability for a two-stage-to-low-Earth-orbit system, with the extreme case being a complete EM launch. Available EM acceleration options include linear motors, magnetic levitation, and railgun technology, but railguns were chosen for this example. The second stage of the system was assumed to be a chemical rocket or a reusable scramjet to carry a reusable orbiter vehicle into low-Earth orbit. EM launch systems of this type will be noticeably different from those for tactical gun applications but will be governed by the same fundamental principals. One major difference is that the EM accelerator track-which could be several km in length-cannot be powered only from the “breech” as in a tactical gun, since electrical resistive losses will be unacceptably large. To overcome this, a distributed feed system of the type demonstrated under our recent Air Force Office of Scientific Research study will be required. This study shows that the capital cost of the pulsed power system for the EM accelerator will dominate the system economics. Present pulsed power approaches will require many launches to offset the capital cost. Novel pulsed power concepts or low-cost manufacturing approaches will need to be developed for such a concept to be economically attractive.