Some of the world’s top scientists are looking to reach for our nearest stars

Reported by David Crookes

© Tobias Roetsch

If you gaze into the night sky from Earth’s Southern Hemisphere, you should be able to catch sight of our nearest stellar neighbour, Alpha Centauri. It appears to the naked eye as a single, brightly glowing celestial object and has long been a source of fascination for astronomers.

Alpha Centauri was discovered to be a binary star system in 1689, made up of Alpha Centauri A and Alpha Centauri B, and in 1915 a fainter star called Proxima Centauri was observed relatively close by. However, there has been some doubt cast over more recent theories about the star system. In October 2012 a team of European observers claimed to have evidence of an exoplanet orbiting Alpha Centauri B, and yet, almost exactly three years later, the theory was dismissed by a group of astronomers at Oxford University. Other theories relating to exoplanets within the star system are similarly up in the air.

The key issue with Alpha Centauri is that it is 4.37 light years away, and while Proxima Centauri is closer, it is still distant by a just-as-daunting 4.24 light years. Travelling to the star system would entail a journey of some 40 trillion kilometres (25 trillion miles), and with current spacecraft speeds, like NASA’s Parker Solar Probe, you’d have to be travelling for more than 6,300 years to reach it. It’s no surprise so few have seriously considered launching a craft that would, quite literally, reach for the stars. Yet that is just what a group of some of the world’s most respected scientists and engineers are now hoping to do in their bid to vault into the interstellar age. Advances in technology, combined with the financial backing of Russian entrepreneur and physicist Yuri Milner, are set to place what was felt to be the impossible very much on the table of possibility. “The problem is, space travel as we know it is slow,” says Milner. “If Voyager had left our planet when humans first left Africa, travelling at 18 kilometres (11 miles) per second, it would be arriving at Alpha Centauri just about now. How do we go faster and how do we go further? How do we make this next leap?”

In 2015 Milner and Stephen Hawking created the privately funded company, Breakthrough Initiatives. Almost immediately it launched a program called Breakthrough Listen, which heralded a cash-rich search for alien life beyond the Solar System. Now, with Facebook founder Mark Zuckerberg also on board, it has unveiled a new project: Breakthrough Starshot. Its aim is to develop a craft and propellant system capable of reaching Alpha Centauri just 20 years after launch.

The central idea of Starshot is to send a fleet of tiny probes called nanocrafts deep into the more remote regions of space. It would involve shooting a powerful laser beam to propel them to one-fifth of the speed of light. When they reach their destination the probes will be able to take photographs of the celestial bodies they encounter and gather other scientific data before sending the information back down to Earth. The research and engineering program would enable many of today’s scientists to search for extraterrestrial life, seek exoplanets and maybe even discover an Earth-like body in a habitable zone. It would also prove useful in quickly exploring planets and other bodies far closer to home. The potential is huge.