Aerial drone designers have been pushing hard to get devices that can stay airborne for days. After all, what's the point of having an observer that routinely lets its guard down? Lockheed Martin must have this question forever etched in its collective mind, as it just completed tests of a modified Stalker drone that was continually charged by laser power beamed from a ground-based source. The LaserMotive-built test was admittedly conducted in a wind tunnel, not a wind-swept battlefield, but it kept the drone aloft for more than 48 hours and was so efficient that it might even have gone indefinitely, if it weren't for staff intentionally bringing the trial to a halt. The true test is coming next, when Lockheed Martin and LaserMotive fly the drone on laser power outdoors. Should the Stalker sail the friendly skies for long enough, it could help usher in an era of UAVs that can spot intruders at all hours -- a little too close to the aircraft's name for comfort, perhaps, but potentially vital for Special Operations troops that might not have to put themselves in danger. You can check the underpinnings of both the laser power system and the Stalker in videos after the break.