Breakthrough Starshot started with a bang

If not for an unexpected interplanetary visitor three years ago, last month’s announcement of the interstellar mission Breakthrough Starshot almost certainly wouldn’t have happened.

On 14 February 2013, the University of California, Santa Barbara, put out a press release about physicist Philip Lubin, who was exploring the possibility of building an array of lasers capable of vaporizing incoming meteors. The timing seemed right because the 45 m asteroid 2012 DA14 was predicted to safely buzz past Earth the next day.

Unfortunately for Lubin, no journalists were interested—that is, until a far more memorable space rock exploded in the atmosphere just south of Chelyabinsk, Russia.

The Chelyabinsk meteorite, which struck 16 hours before the DA14 flyby, transformed Lubin’s work from an unpublicized pet project to a focused effort in the spotlight. Suddenly he was inundated with press requests and invited to speak at conferences. About a year ago NASA gave Lubin a $100 000 grant to pursue another application of his “directed energy” technology: propelling spacecraft to relativistic speeds.

The course of Lubin’s career took another unexpected turn last October when he ran into Pete Worden, formerly director of NASA’s Ames Research Center in California, at the 100 Year Starship symposium . A few weeks later, Worden said he wanted to share Lubin’s ideas with some friends.

Those friends, it turned out, included Yuri Milner.

In January Lubin met the Russian entrepreneur and got drilled with questions. Having considered options like antimatter and nuclear fusion, Milner was skeptical but hopeful that Lubin had hit on a viable method of propulsion. Milner wasn’t interested in an R&D program; he wanted to experience an interstellar mission during his lifetime. He said that Lubin’s plan to put the laser array in space wasn’t practical politically or economically, so Lubin went to work crunching the numbers on what it would take to build it on the ground.

In the following weeks, Milner asked outside scientists for their opinions, while Lubin shared technical details and cost analyses in frequent teleconferences. Milner did his due diligence, but he was far more decisive than any funding agency. In late March, 10 weeks after their first meeting, Milner told Lubin he was putting $100 million into the effort. “I still cannot believe it,” Lubin says.

And so it came to be that on 12 April, the 55th anniversary of Yuri Gagarin’s historic spaceflight , Lubin joined Milner, Worden, Stephen Hawking, and others to announce a plan to propel miniature spacecraft to Alpha Centauri.

Nobody, including Lubin and Milner, thinks the project will be easy. As physicist Howard Milchberg wrote on 26 April for Physics Today Online, the laser array will have to be perfectly calibrated so that a million separate beams combine in phase to act as one. The laser output will have to be adjusted to compensate for turbulence in the atmosphere, some of it induced by heating from the beams themselves.

In a response posted today, Lubin acknowledges those challenges. He says he’s particularly concerned about merging the beams in phase. (He’s less worried about atmospheric turbulence because the array could always be built in space—though he seems to discount how much the rest of the world might resist construction of a giant space laser.) Still, he finds reason to be optimistic, particularly when it comes to optical technology and cost.

I encourage you to read both pieces to get details, not vague statements, about the challenges and potential of the project. Those articles focus on the laser technology; check out coverage by Popular Science and others to learn about additional questions facing the bold mission.