BTW, even modern humanity knows how to hide IR signatures of small objects (yes, Stealth fighters use slit nozzle, mix hot engine gases with cold air, and super

BTW, even modern humanity knows how to hide IR signatures of small objects (yes, Stealth fighters use slit nozzle, mix hot engine gases with cold air, and supersonic without afterburner, to hide IR). And I hear once, about laser cooling technology, so it is possible, to emit IR exhaust in directions, where no observer.