The Planetary Society's LightSail 2 spacecraft successfully launched into orbit this month aboard a Falcon Heavy rocket. It is a beautiful, elegant concept: using a massive, ultra-thin Mylar sail to harness the subtle momentum of photons emitted by the Sun for propulsion.



No fuel, no heavy engines—just sailing on beams of light. Carl Sagan championed this idea decades ago, and to see a crowdfunded spacecraft successfully testing the technology in Earth orbit is a brilliant tribute to his vision. It could completely revolutionise how we send small probes across the solar system.