Review of direct-drive laser space propulsion concepts

Abstract

Laser impulse space propulsion (LISP) involves the direct drive of objects which are remote from their energy source, via the thrust produced by laser ablation of the object mass. A repetitively-pulsed laser is favored relative to CW operation because high peak-to-average power ratio allows achievement of the necessary conditions for most efficient thrust production at greater range for each mission, with smaller optics—plus avoidance of certain deleterious nonlinear processes in the atmosphere. We discuss nearterm as well as far-future LISP applications ranging from the clearance of near-Earth, manmade space debris [the ORION concept] to lifting a 10-tonne payload into low-Earth orbit (LEO). The ORION concept employs a 30-kW laser system, optical tracker and telescope with adaptive optics to lock on and ignite a plasma jet on the surface of 1–10-cm space debris objects at range up to 1500 km. The ablation jet slows the object sufficiently (≈150 m/s) to produce re-entry and burnup. Direct insertion illustrates the distant future of LISP. A 10-tonne payload is delivered from the launch pad to LEO at a cost of order $100/kg delivered, two orders of magnitude less than current LEO insertion cost. This cost is based on 5 launches per day.