The Breakthrough Starshot is an effort backed by US$100 million from Russian investor Yuri Milner to vastly accelerate research and development of an interstellar space probe.

Leaders of the mission plan to start funding technology-development projects within months, with the aim of launching a fleet of tiny, laser-propelled probes in the next 20 years. The effort would ultimately cost about $10 billion, leaders hope, and take another 20 years to reach Alpha Centauri.

The first truly challenging step in any mission such as Breakthrough Starshot is to accelerate the spacecraft to interstellar velocities.