From CNET News:
The race to develop an unmanned aircraft that can stay aloft for five years at a stretch has entered its second phase, where the prize is a $155 million DARPA contract to build a small-scale demonstrator model.
The project, called Vulture II, will pit three defense contractor teams--Aurora Flight Sciences, Boeing, and Lockheed Martin--against one another and the clock for the right to build a small-scale, working version of a high-altitude, electric-propelled UAV capable of remaining aloft and on station for three months.
My Comment: I guess the goal is to have UAVs capable of flying for days while conducting surveillance and observation operations ... a prospect that appears to be closer than what many have thought possible.