These Tiny Spaceships Will Hunt for Alien Life

A spacecraft the size of a postage stamp may be humanity's best chance of ever finding extraterrestrial intelligence.

Breakthrough Starshot—a $100 million venture headed by Russian billionaire Yuri Milner and supported by physicist Stephen Hawking—is developing light-propelled nanocraft equipped with cameras, photon thrusters, navigation and communication equipment. The plan is to send the nanocrafts towards Alpha Centauri, our closest neighbouring star system, in an attempt to locate habitable planets and hopefully even alien life.

Travelling at 20 percent of the speed of light, the miniature spaceships are expected to take around 20 years to make the 25-trillion mile journey to Alpha Centauri. By way of comparison, the most distant human spacecraft is Voyager 1, which has taken almost 40 years to reach just beyond the edge of the Solar System. It would take another 40,000 years to reach another star.

"For the first time in human history, we can do more than look at the stars, we can reach them," Milner said on Tuesday at the news conference in New York that unveiled the project. "The human story is one of great leaps. 55 years ago today, Yuri Gagarin became the first human in space. Today we are preparing for the next great leap: to the stars."

The key to interstellar space exploration, Milner claims, is light propulsion. It means that spacecraft don't need engines or fuel, instead they "sail" at speeds thousands of times faster than rockets using Earth-based lasers to provide the initial thrust.

Using light as a method of propulsion may sound like science fiction, but the concept is rooted in fundamental scientific principles. The theory of relativity states that mass has no mass, however it does have momentum. When light hits a mirror, it therefore exerts a small amount of pressure. If the mirror is light enough, and the light is powerful enough, it will move.

This solar sail concept was first theorized in 1610 by German astronomer Johannes Kepler, who envisioned "heavenly breezes" that could power ships. More than 400 years later, Cornell University researcher Zac Manchester designed, built, and tested a tiny spacecraft called Sprite. Manchester is now involved with Breakthrough Starshot to help develop the $20 Sprite spaceship into one that can survive interstellar space travel.

"Earth is a wonderful place, but it might not last forever," Hawking said at the event. "Sooner or later we must look to the stars. Breakthrough Starshot is a very exciting first step on that journey.

"The limit that confronts us now is the great void between us and the stars. But now we can transcend it, with light beams, light sails, and the lightest spacecraft ever built. Today we commit to this next great leap into the cosmos, because we are human and our nature is to fly.