How do homing missiles always stay on target?

Modern missiles can be guided to a target, often by their own systems. The most common kind of homing technology detects and locks on to infrared (IR) radiation, such as the heat from a jet exhaust. Modern systems detect two wavelengths: 3-5 micrometres and 8-13 micrometres. The second wavelength isn’t absorbed by the atmosphere, so it’s much easier to track. This also makes flares – the intense infrared countermeasures that are ejected by a target in order to lure the missile off course – less effective. Missiles are essentially rockets fitted with an explosive warhead and an infrared detection sensor connected to a flight computer. These sensors are often made of mercury cadmium telluride to pick up the specific infrared wavelengths emitted by the enemy target.

However, sometimes missiles need to be fed targeting information constantly from their launcher, while the on-board fl ight control system steers the weapon. Indeed, on some occasions this means the target will be ‘painted’ with a laser; that energy signature will then guide the missile. Others still make use of mounted cameras which let an operator direct the missile post-launch and guarantee it’s not duped by countermeasures.