>Can satellites provide active radar tracking Physically, yes. There are plenty of radar satellites. Power is a problem. AWACS radars draw dozens of kilowatts

>Can satellites provide active radar tracking Physically, yes. There are plenty of radar satellites. Power is a problem. AWACS radars draw dozens of kilowatts. You very much want lots of power in military radar, since you're often illuminating something that can be engineered to have a small RCS or is actively spoofing the return signal. This forces you to have big solar panels, big radiator panels for electronics waste heat, big batteries so you can actually run the radar in the 50% of the orbit when you're in Earthshade, big antenna for high gain, big fuel tanks because you have so much atmospheric drag that you're reboosting all the time. An AWACS satellite would be bus-sized, if not bigger. This hypothetical AWACS satellite would also have the problem that it would have a perfectly predictable orbital track, so you could target it with a very high gain antenna for jamming. And, of course, antisatellite missiles exist, and AWACS birds would badly tempt future adversaries to make yet more orbital debris. Some of these problems could be mitigated with a larger constellation, which you would want anyway so you can run lower altitudes and (as you note) better coverage. Unfortunately, running a Starlink-style megaconstellation with hardware purchased from military aerospace contractors would cost hundreds of trillions of dollars. Several NRO birds are known to use synthetic aperture radar, (LACROSSE/ONYX) but almost certainly not for detecting aircraft in flight. Others are for detecting radiated signals. (NOSS) For civilian (-ish) attempts to launch surveillance megaconstellations, see PlanetScope: https://www.planet.com/products/planet-imagery/ https://www.planet.com/products/planet-imagery/