The competition really heats up! A research team at the University of California, Santa Barbara (UCSB) has proposed that an array of space-based lasers can be used to accelerate a solar sail to speeds as much as 26% the speed of light, thus making interstellar travel possible.
[The] key breakthrough was the development of modular arrays of synchronized high-power lasers, fed by a common “seed laser.” The modularity removes the need for building powerful lasers as a single device, splitting them instead into manageable parts and powering the seed laser with relatively little energy. Lockheed Martin has recently exploited this advance to manufacture powerful new weapons for the US Army. In March last year, the aerospace and defense giant demonstrated a 30 kW laser weapon (and its devastating effect on a truck). By October, the laser’s power had already doubled to 60 kW and offered the option to reach 120 kW by linking two modules using off-the-shelf components.
The UCSB researchers refer to their own planned arrays as DE-STAR (Directed Energy System for Targeting of Asteroids and ExploRation), with a trailing number to denote their size. A DE-STAR-1 would be a square array 10 meters (33 ft) per side and about as powerful as Lockheed’s latest; at the other end of the spectrum, a DE-STAR-4 would be a 70 GW array covering a massive area of 100 square kilometers (39 square miles).
…Lubin stresses that even a relatively modest orbital array could offer interesting propulsion capabilities to CubeSats and nanosatellites headed beyond Earth orbit, and that useful initial tests would still be conducted on the ground first on one-meter (3-ft) arrays, gradually ramping up toward assembling small arrays in orbit. While even a small laser array could accelerate probes of all sizes, the larger 70-GW system would of course be the most powerful, capable of generating enough thrust to send a CubeSat probe to Mars in eight hours – or a much larger 10,000-kg (22,000-lb) craft to the same destination in a single month, down from a typical six to eight.
Further upgrades would make it possible to send a cubesate and its lightsail to Alpha Centuri in about fifteen years.
The important point here is that it appears that all the technology for building this already exists, or is relatively straightforward to develop.