The US Navy is developing a pilotless solar-powered plane that can fly for 90 days at a time to help keep a watchful eye on naval ships below or act as a communications relay platform. The plane, dubbed'Skydweller' and developed by Skydweller Aero, builds on the manned Solar Impulse 2 aircraft that flew around the world in 2015 and 2016, but had to stop every five days. The upgraded version will eliminate the cockpit, allowing space for hardware that allows for autonomous abilities. Skydweller Aero CEO Robert Miller told New Scientist: 'When we remove the cockpit, we are enabling true persistence and providing the opportunity to install up to about 400 kilograms of payload capacity.' The pilotless craft will feature 236-foot long wings that are blanked in solar cells, but its makers may add hydrogen fuel cells for an additional boost.

Ordnance survey has unveiled a solar-powered drone that is capable of flying for 90 days at a time without needing to come back to Earth and will be used to provide higher quality images of Earth. It will circle at approximately 67,000 ft (20,400m) above the ground and snap images to sell to organisations and businesses. First tests of the Astigan unmanned aerial vehicle are scheduled to take place before the end of 2019. Ordnance Survey is the majority stakeholder in Astigan, a firm based in Bridgwater, Somerset. The company works in the same factory that was once home to Facebook's Aquila internet drone project.