A new propulsion technique using an amplified laser beam could push a spacecraft to reach Mars in just three days. Philip Lubin, an experimental astrophysicist at the University of California, Santa Barbara, has been awarded a NASA grant to explore whether electromagnetic acceleration could actually be used for long distance space travel. While spacecraft usually launch from earth using thrust created by rocket fuel, Lubin proposes an alternative “photonic propulsion system” where a laser on Earth would fire photons into the sail of a spacecraft, much like the solar-powered LightSail that the Planetary Society has developed.
Instead of using sunlight, the new system, called DE-STAR (Directed Energy System for Targeting of Asteroids and ExploRation), would use laser amplifiers to push the spacecraft along at speeds as fast as 26% the speed of light for a tiny spacecraft, or larger spacecraft at (still impressive) 1-3% the speed of light.
Photonic propulsion is not a new idea, it goes back to the beginnings of thinking about light in both the classical and the quantum mechanical way. There are recent advances which take this from science fiction to science reality. There is no known reason why we cannot do this.
In a paper that outlines a roadmap for DE-STAR, Lubin said that recent advancements in directed energy technology make electromagnetic acceleration a real possibility. He wrote, “Recent advances in photonics now allow for a 2D array of phase locked laser amplifiers fed by a common low power seed laser that have already achieved near 50% wall plug conversion efficiency and have been built into small phased arrays.” If Lubin’s theory is correct, space travel could reach speeds that were previously unimaginable. While the Curiosity rover took 253 days to reach Mars using conventional thrust, a DE-STAR could send a small spacecraft there in less than an hour, or it could travel much farther in the same amount of time.