
At the space shuttle’s orbital speed of roughly 28,000 kilometres per hour, the journey to Alpha Centauri would take about 165,000 years. Breakthrough Starshot proposes sending a gram-scale chip attached to a metre-wide sail—accelerated by Earth-based lasers—to make the same journey in just over 20 years.
The 165,000-year shuttle comparison is sound arithmetic rather than a mission profile, while Starshot’s 20-year result depends on a gram-scale flyby probe, a metre-scale sail and an unbuilt Earth-based laser array.














