A British solar plane recently broke the longest unmanned flight record. The Zephyr is a lightweight solar-powered plane built by British defense and security tech company QinetiQ. The unmanned aircraft stayed in flight continuously for 54 hours. The Zephyr has solar panels on its wings to power it by day. Sunlight also recharges the lithium sulphur batteries that keep it aloft throughout the night.
NASA Helios has hopes that the vehicles could one day be used as a replacement for satellites or as unmanned drones to explore other planets such as Mars. Helios, the successor of Pathfinder, set an altitude record in 2001 for a non-rocket-powered winged aircraft when it climbed to 96,863 feet (29.5km). But in 2003 the vehicle broke up during a flight from the US Navy's Pacific Missile Range Facility.