Each plane has a 3m wingspan and weighs 13.1 kg. During normal operations the craft will measure temperature, humidity and pressure over the ocean. At a cost of just $25000 each, the planes could dramatically cut the costs of gathering such information.

Meanwhile, during a test flight in Hawaii, NASA's Pathfinder-Plus - a remote controlled propeller driven plane - reached a record altitude of more than 23km (80000 ft). Unlike Aerosonde, Pathfinder-Plus is solar powered, giving it the potential to stay aloft for several months at a time. The craft is a prototype for a larger plane called Centurion which has a wing span of 62m and intended to fly at an altitude of 30.5 km. Scientists on the project believe this will allow similar aircraft to act as stratospheric satellites at a fraction of the cost of space-based observation platforms.