Laser propulsion
Laser propulsion is a form of beam-powered propulsion where the energy source is a remote (usually ground-based) laser system and separate from the reaction mass. This form of propulsion differs from a conventional chemical rocket where both energy and reaction mass come from the solid or liquid propellants carried on board the vehicle.
There are two main approaches: off-board, where the laser source is external to the spacecraft, and onboard, where the laser is part of the spacecraft's propulsion system. Off-board laser propulsion, which includes laser-powered launches and laser light sails, eliminates the need for the spacecraft to carry its own energy source.[1] Onboard laser propulsion involves using lasers in nuclear fusion or ionizing interstellar gas for propulsion.[1]
History[edit]
The basic concepts underlying a photon-propelled "sail" propulsion system were developed by Eugene Sanger and the Hungarian physicist György Marx. Propulsion concepts using laser-energized rockets were developed in the 1970s by Arthur Kantrowitz and Wolfgang Moekel,[2] with a variant using laser ablation pioneered by Leik Myrabo.[3] An exposition of Kantrowitz's laser propulsion ideas was published in 1988.[4]
Laser propulsion systems may transfer momentum to a spacecraft in two different ways. The first way uses photon radiation pressure to drive momentum transfer and is the principle behind solar sails and laser sails. The second method uses the laser to help expel mass from the spacecraft as in a conventional rocket. Thus, the first uses the laser for both energy and reaction mass, while the second uses the laser for energy, but carries reaction mass. Thus, the second is fundamentally limited in final spacecraft velocities by the rocket equation.