ICBMs are the country's most important weapons with a real strategic deterrent effect, with a long range and great power, but why do all countries in the world today use inertial guidance instead of GPS satellite positioning guidance?
First of all, what is an ICBM?In fact, it is the abbreviation of intercontinental ballistic missile. As the name suggests, only long-range ballistic missiles that can hit another continent from one continent can be called intercontinental missiles, and usually ballistic missiles with a range of more than 8,000 kilometers can be considered intercontinental missiles. At military parades, ICBMs are often the last to appear, and there is no dispute that they are the real finale heavyweights.
Ballistic missiles capable of reaching a range of 8,000 kilometers are definitely not something that ordinary countries can have, so at present, only a handful of major countries in the world possess them.
ICBMs are an important component of strategic nuclear forces and are mainly used to attack important military, political and economic targets on enemy territory. ICBMs have a larger range, faster speed, and of course more powerful than intermediate-range ballistic missiles and shorter-range ballistic missiles.
ICBMs are generally nuclear warheads, and most of them use multiple warheads, such as the "Minuteman 3" (MK-12A) ICBM of the United States, which carries 3 of 33 each50,000 tons of nuclear warheads. Russia's SS-19 "Satan" intercontinental missiles are even more powerful, carrying 10 nuclear warheads with a yield of 1.5 million tons each. Therefore, there is no doubt that intercontinental missiles are the most strategic deterrent nuclear weapons and the cornerstone of real security.
Figure 2: SS-19 Satan ICBM.
It stands to reason that this kind of high-precision ** will definitely use the latest high-end technology. But why is it that all ICBMs in the world use relatively backward inertial guidance in the way of guidance, instead of the more advanced GPS satellite positioning guidance?
The missile guidance system is the missile's guidance and control system, which is a system that measures and calculates the missile's relative position to the target or space reference line, and controls the missile's flight to the target with a predetermined guidance law. Its function is to measure and calculate the difference between the actual flight path and the theoretical flight path of the missile, form a guidance command, and after amplification and conversion, the servo mechanism adjusts the engine thrust direction or rudder deflection angle of the missile, and controls the flight path of the missile, so as to hit or get as close to the target as possible with the allowable error.
Missile guidance systems can be roughly divided into four categories: autonomous guidance systems, homing guidance systems, remote control guidance systems, and composite guidance systems. ICBMs generally use composite guidance, that is, a combination of multiple guidance methods, but in the composite guidance of ICBMs, inertial guidance is basically the most important guidance method.
The missile guidance system is the guidance and control system of the missile.
Inertial guidance is a technology that uses the principle of inertia to control and guide a missile to fly towards a target. The principle of inertial guidance is to use the inertial measurement device to measure the motion parameters of the missile, form a guidance command, and guide the missile to the target area by controlling the direction, magnitude and action time of the engine thrust.
In the 60s of the last century, intercontinental missiles mainly used mechanical inertial guidance, and by controlling the shutdown time of the missile engine within one millionth of a second, the accuracy of the missile entering the preset trajectory reached the decimeter level. In this way, the accuracy of an ICBM with a range of 10,000 km can reach less than 5 km.
After entering the 80s, laser fiber gyroscopes with higher accuracy appeared, coupled with computers with faster calculation speed to control, which could theoretically make the hitting accuracy of ICBMs with a range of 10,000 kilometers reach within 100 meters.
At present, the accuracy of GPS satellite positioning guidance is higher, and the hit accuracy of missiles using satellite positioning guidance can reach less than 1 meter, but why don't intercontinental missiles use satellite positioning guidance with much higher accuracy than inertial guidance?
Figure 4: PS satellite positioning guidance, while highly accurate, is susceptible to interference.
There are two main reasons, the first is that ICBMs do not need such high accuracy, inertial guidance can achieve a hit error of 100 meters to 150 meters from the target, it seems that the error is not small, but don't forget that ICBMs are not bullets, they use nuclear warheads, and they are nuclear warheads with a yield of hundreds of thousands of tons or even millions of tons. In the face of millions of tons of nuclear **, there is no difference, and within a range of 5 kilometers from the center of the nuclear warhead, the same will be completely destroyed!
The second reason, which is also the most critical, is that although inertial guidance is not as accurate as satellite positioning, inertial guidance works in an autonomous way and does not need to have any contact with the outside world during the entire working period, so it has strong anti-interference and good concealment.
When the satellite positioning guidance is working, it needs to contact the satellite to continuously determine the target position and correct its own flight trajectory, so it is easy to be interfered with, and the trajectory of the missile's flight will also be exposed, which is obviously far more important than the accuracy of the hit for the intercontinental missile.
Therefore, the primary consideration of ICBMs is reliability, and it is absolutely reliable, and in this regard, inertial guidance has an incomparable advantage over satellite positioning guidance. It is precisely on the basis of this consideration that the guidance of ICBMs must be based on inertial guidance, and no matter how accurate the other guidance means are, they can only be used as auxiliary means at most.