World's smallest spacecraft sends back first signal to Earth
The world's smallest spacecraft ever launched, designed by Stephen Hawking-backed 'Breakthrough Starshot', has sent back first signals from its orbit 640 km away. The chip measures 3.5cmx3.5cm and weighs 4 grams. The program, with Mark Zuckerberg and billionaire Yuri Milner on its board, aims to propel tiny probes at 60,000 km/sec using lasers to the nearest star system Alpha Centauri.