http://spectrum.ieee.org/automaton/...-the-friendliest-kind-of-indoor-flying-robots Wasting no energy at all to stay aloft, these new lighter than air drones developed at Georgia Tech seem perfectly suited to noiselessly following people around, even if they are not exactly what you would term inconspicuous, or immune to the fate of runaway kites due to the deleterious navigational challenges of high winds if deployed outdoors. Or, if you are going for a quick getaway from small arms fire or terrorist activity, perhaps it could autonomously hide and later deploy a homing beacon and retractable sail when sufficient winds to carry it away became available, or have the ability to deflate the balloon and deploy it as a parchute once it is secured a safe distance from hostile territory. This is a nice bit of technology, and I can see that it has many intriguing possibilities. Before reading this article, I had no idea that quadcopter battery life necessary to remain aloft was so short, measured in minutes, not hours, but it makes perfect sense.