I get what you're saying here, but actually though, IR and EM are simply bandwidths of the same EM Spectrum. IR is just high frequency EM. There is no difference between them other than the frequency of the emission. You can have all the electronics you want, and light a camp fire. Both have EM emissions. the camp fire has a lot more IR than radio frequency, the electronics will have both. Heat is the result of absorbing EM emissions. (or any form of energy).
yeah I get it, in modern aircraft they have heat seeking missiles, and radar guided missiles. In a thick atmosphere, IR causes more heat than EM, but in space that is not so - so a radar guided missile, could home in on your electronic signature, or your IR signature. No difference to it, because there's no air.
[Edit] If you're familiar with heat seeking missiles, they have what looks like a camera lens on the front that detects IR frequencies. Now look at a radar detector from a radar guided missile. It's made of a metallic composite. yep. but look at it's shape. It's the same shape a lens, isn't it? That's because at high frequencies, glass is transparent to EM. At low frequencies, metals are.
