Lightcraft
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A lightcraft is a vehicle currently under development that uses an external source of laser or maser energy to provide power for producing thrust (beam-powered propulsion).
The laser shines on a parabolic reflector on the underside of the vehicle that concentrates the light to produce a region of extremely high temperature. The air in this region is heated and expands violently, producing thrust. In space, a lightcraft would need to provide this gas itself from onboard tanks or from an ablative solid. By leaving the vehicle's power source on the ground and by using ambient atmosphere as reaction mass for much of its ascent, a lightcraft would be capable of delivering a very large percentage of its launch mass to orbit. It could also potentially be very cheap to manufacture. This method is dependent entirely on the laser's power, however, and even the most powerful models currently can only serve for modest test purposes.
Recent tests by Leik Myrabo, with the US Army, have demonstrated the feasibility of using ground-based lasers to propel objects into orbit. The test succeeded in reaching over one hundred feet, which compares to Robert Goddard's first test flight of his rocket design.
