Anybody who longs to see an alien world up close got an exciting gift last year. In August, researchers reported the discovery of a potentially habitable, Earth-sized planet orbiting the Sun’s closest stellar neighbour — Proxima Centauri, a mere 1.3 parsecs, or 4.22 light years, away.
It’s a tempting — some might say irresistible — destination. Sending a spacecraft to the planet, dubbed Proxima b, would give humans their first view of a world outside the Solar System. “Clearly it would be a huge step forward for humanity if we could reach out to the nearest star system,” says Bruce Betts, director of science and technology for the Planetary Society in Pasadena, California. The data beamed back could reveal whether the alien world offers the right conditions for life — and maybe even whether anything inhabits it.
The idea of reaching Proxima b is not just science fiction. In fact, a few months before the discovery of the exoplanet, a group of business leaders and scientists took the first steps towards visiting the Alpha Centauri star system, thought to be home to Proxima. They announced Breakthrough Starshot, an effort backed by US$100 million from Russian investor Yuri Milner to vastly accelerate research and development of a space probe that could make the trip. When Proxima b was found (Nature 536, 437–440; 2016), the project gained an even more tantalizing target. et al.