>but that the whole concept of "stealth" aircraft may be limited in the future thanks to ever increasing computation power and clever usage of existing radio wa

>but that the whole concept of "stealth" aircraft may be limited in the future thanks to ever increasing computation power and clever usage of existing radio waves (making effective, passive, "radar" that cannot be easily overcome) This. One solution is to simply deploy a considerable number of ground and orbital (or even use blimps/balloons like some companies want to do for wireless internet, or for quicker deployment during a developing incident a fleet of autonomous drones) IR sensors and simply follow the exhaust, with low enough latency and a little predictive maths you could probably know where an aircraft is, and will be, for the next several seconds at any given second with an almost perfect degree of accuracy unless the aircraft is actively conducting evasive maneuvers. Tie that together with traditional radar, x-ray, terrestrial radio broadcasts, etc and you can make a system that would be hard to evade detection from. The larger an area you are attempting to detect aircraft in, the harder it would be, but you could protect specific facilities by deploying much smaller grids over likely approach paths with say ground based IR sensors to detect exhaust trails of anything on approach and then in a much tighter area close to the strategic target. You could also probably deploy atmospheric microphones in blimps/balloons that report their location with GPS and use some sound detection algorithm to detect aircraft moving away from them and use a network of such microphones to dial in an approximate location, heading and speed. Not unlike commercial gunshot/shooter detection systems that already exist.