|Schematic view on the launch of a small satellite by a ground based high energy laser.|
The principle of laser propulsion has been demonstrated worldwide in numerous terrestrial experiments. The initial goal of thermal laser propulsion investigations was the development of an alternative propulsion concept for the launch of small satellites (nanosats) from the Earth's surface into low Earth orbit (LEO). However, the pulsed laser output required for this is not available in the short and medium term.
Based on advances in the field of solid state laser technology which permit the development of more powerful, compact pulsed laser sources even for application in space and zero gravity environments, laser propulsion offers new possibilities for the position keeping and attitude control of satellites or satellite constellations in orbit. Beam guidance and control based on active optical systems enable remote laser propulsion applications. Therefore, in a further step, missions with small probes are conceivable, for instance to "take samples" on asteroids or (small) planets and to return on a "tractor beam".
The latest research objective is the development and qualification of highly precise thrusters with thrusts levels in the range of 0.1 µN to 1 mN. Alternative micro propulsion concepts which are necessary for many missions with precise position and orbit control are urgently required. A growing need has not only arisen in the case of geodetic missions to measure the Earth's gravitational field (follow-up missions to CHAMP, GRACE or GOCE) or astronomical missions for X ray astronomy in which the telescopes are made of two satellites with highly precise distance control (up to 50 m), but also for astronomical projects which require greater formations (such as Dar-win).
Laser propulsion is ideally suited to micro propulsion as a result of its high precision and very simple (propellant) infrastructure. Laser induced ablation of metals or composites with pulsed laser sources is a promising technology to provide a new type of thrusters with highly precise thrust control.