Riding on a laser beam

Photo: European Southern Observatory
Laser propulsion could let us reach the nearby triple star system Alpha Centauri in just a few decades.

Zac Manchester reports at IEEE Spectrum,

In the 1960s, the physicist and space futurist Robert Forward proposed a radical method of sending a spacecraft to the stars. Roughly speaking, the idea was to attach the spacecraft to a large light sail, and then push it by illuminating the sail with an enormous laser. Forward suggested that a powerful laser could accelerate a spacecraft to a large fraction of the speed of light, allowing it to reach some of our nearest stellar neighbors within a few decades.

Until very recently, this idea remained solidly within the realm of science fiction. But today the outlook is beginning to change. In April, the physicist-turned-internet-billionaire Yuri Milner, together with Stephen Hawking and other notable scientists and engineers, announced that the Breakthrough Foundation would begin funding work on the concept of a laser-propelled starship, with the long-term goal of reaching the closest neighboring star system to our own, Alpha Centauri. Their initiative, dubbed Breakthrough Starshot, is a Silicon Valley take on Forward’s vision that imagines shrinking the spacecraft down to a mass of a few grams. A fleet of such “nanocraft”, each tethered to a light sail a few meters wide, could be economically launched into space and then accelerated toward Alpha Centauri with a terrestrial laser system. Illuminated by tens of gigawatts of laser light, the miniature spacecraft would reach 20 percent of the speed of light in about 4 minutes. After a 20-year cruise, they would zip through the Alpha Centauri system in a few hours and send data and images back to Earth from the brief encounter.

Read more here.