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New ‘Starshot’ Mission Aims to Send Tiny Spaceships to the Nearest Star System

Alpha Centauri, here we come.
The Alpha Centauri binary star system, with Proxima Centauri red dwarf circled. Image: Skatebiker

The Latin phrase per aspera ad astra, meaning "through hardships to the stars," has become a beloved catchphrase for the worldwide spaceflight community.

Now, billionaire entrepreneur Yuri Milner and renowned physicist Stephen Hawking have partnered to bring that lofty goal into a genuine reality with Breakthrough Starshot, an ambitious mission to the nearest star system, Alpha Centauri, 4.37 light years away.


"55 years ago today, Yuri Gagarin became the first human in space," said Milner, who is named after Gagarin and was born the same year as his historic flight, in a statement. "Today, we are preparing for the next great leap—to the stars."

Milner and Hawking announced an overview of the Breakthrough Starshot plan in a livestreamed press conference on Tuesday, at One World Observatory in New York City. To bridge the enormous distance between our Solar System and Alpha Centauri, the pair proposed revving thousands of tiny postage-stamp-sized "nanocrafts" to relativistic speeds reaching 20 percent the speed of light.

Here's how that would theoretically go down: A mothership carrying the nanocraft fleet would be launched into a high altitude orbit around Earth. Each individual unit would consist of a small "StarChip," equipped with cameras, sensors, and communications equipment, along with an ultrathin "lightsail" measuring about ten feet in length. Together, these components would weigh only a few grams.

Animation of Breakthrough Starshot concept. Video: Breakthrough/YouTube

Once deployed into a high elevation orbit, the chips would unfurl their sails and catch a wave of lasers shot at them from a powerful kilometer-scale phased array located on Earth. According to Breakthrough Starshot's new homepage, this burst of photonic propulsion could "accelerate individual nanocrafts to the target speed within minutes."

The kinks in this futuristic concept will take a lot of time and money to work out, and the team leads estimate it may cost as much as $10 billion to bring the project to fruition, of which Milner has already invested $100 million.

But if this kind of technological platform were to be feasible, it would allow human-made probes to visit another star system within a generation—a truly mind-boggling feat. Alpha Centauri is a tantalizing target destination not only due to its proximity, but because it consists of at least two—and possibly three—orbitally entangled stars, and may also host planets.

Along with Milner and Hawking, Facebook founder Mark Zuckerberg will be on the board of the new mission, and the science arm will be led by Pete Worden, former director of NASA's Ames Research Center.

"Once we launch these things and deliver close-up images of a planet around another star, that begins to define humanity as a whole and humanity's future," Worden told Scientific American. "This is something that, if it works, changes how we think about ourselves as a species and as a planet."