(photo by expertinfantry)
Have you ever been so hungry that you can smell food even when you’re a room away?
Your nose picks up on the passive signal that is the heavenly scent your favourite lasagna is wafting from the kitchen, and you promptly get off your lazy bum to go chase after it. Even when you don’t see the physical food just yet, but you can pinpoint where it is just by following the trace.
That’s technically how seeker missiles work.
These missiles consist of a seeker head mounted at the tip of the missile, you can compare it to the ‘Nose’ in our previous analogy. The seeker head is technically a suite of extremely sensitive and expensive sensors that pick up on infrared light.
The missile in itself cannot really ‘See’ its target – it can’t differentiate between a hot air balloon and an F-35, it just sees the track that the target it has locked on makes.
For example, this is how a jet fighter would look like from an IR-homing missile’s point of view:
While we see the jet in its full glory, the missile just sees the gas shooting out o the aircraft’s aft. The brightest thing in a missile’s field of view would be the engines, since it is the hottest part of the jet, and where the most IR signature would be emitted. So missiles, using their tiny minds, just follow this light like moths to light bulbs, zombies to brains, and you to lasagna. Up until it either hit the target, ran out of fuel, or lost sight of the target.
IR-tracking is the most popular type of guidance to be equipped on a missile, most commonly anti-air, or air-to-air missiles. Since aircraft are very maneuverable, having the edge of smart guidance will certainly benefit your military campaign.
But that doesn’t mean it’s not used for ground purposes. Anti-tank missiles such as the Javelin:
…use an IR head to guide the missile to its desired target.
Naturally, that weakness can be exploited. Since IR-seeking missiles follow the brightest IR traces and in the same light band as the target that it was locked on to, you can easily make counter-measures in the forms of flares.
(photo by SurfaceWarriors)
It’s like suddenly finding that the smell of lasagna is permeating from several places at once around your house. You would be instantly confused.
Applicable also to missiles. Flares when popped by jet fighters will blind and confuse the seeker head in the missile since it sees engines’ exhausts everywhere and don’t know which one to actually follow. It’ll pick one closest to its impression of the jet engine that it has been following.
But since jet fighters usually pop dozens at once, the probability of hitting once flares are popped for a single missile is dozens to one.
– Matthew Lee