Using a few mirrors, solar panels and a microwave transmitter, Fan Guanheng and his team can send power over 100 metres (330 feet) through the air. But they are dreaming much bigger – 36,000km (23,460 miles) bigger. The team at Xidian University in Xian, capital of northwest China’s Shaanxi province, are testing hardware that could one day be used to generate power in space and send it back to Earth.