By Krishna Santos
Could a North Korea Nuclear missile hit the US? Who supplied missile components and warhead designs to N.Korea?
HS-14 Missile readied for launch on TEL
(Transporter Erector Launcher)
Testing a long range missile (ICBM) is different from targeting it to exact location. Long range missiles need fine, very fine trajectory corrections. A slight deviation in angle or trajectory would cause hundreds of kilometers of error, the missile fired may fall on some nation or into the ocean. The missile guidance system or sometimes referred to as Missile guidance set (MG set) as shown below is responsible for directing a missile during flight and does fine trajectory corrections.
Missile guidance (MG set)
Missile Guidance Set
Missile Guidance is the most complicated technology in the development of a fully functional Inter-continental ballistic missile (ICBM). Till now only U.S. and Russia are considered as masters in long range Missile guidance (seeker) technology. Most countries buy missile seekers from the U.S. or Russia. China, India, and France have the technology but they aren’t that advanced and sophisticated compared to the U.S. or Russia.
Guidance & Navigation
Guidance is like a driver for the missile, the way we drive a car, the same way the guidance drives and steers the missile.
The way we instruct our driver where to go, the same way navigation tells the guidance where to go and release or drop the warhead having two stage Thermo Nuclear bomb.
Missile steering is done by moving the engine nozzles, or if the missile has fins/flaps, they are moved to change or adjust missile flight path. So guidance takes the help of hydraulic Actuators which mechanically move the Engine Nozzle or fins/flaps to change missile course.
Space rocket engines and long range missile engines are both the same. The only difference is after leaving the earth’s atmosphere, rocket engines release a satellite which circles the earth, where as long range missiles (ICBMs) travel a long distance in space and re-enter back to earth on an enemy’s mainland.
For example, an Iranian or Israeli Space Rocket capable of orbiting a satellite can also be used to develop long range missiles. But there are three technological challenges where many nations failed to develop a fully functional Inter continental ballistic missile (ICBM), those challenges include:
1) Warhead Miniaturization — Just having a nuclear bomb isn’t sufficient. The most common method of delivering a nuclear bomb is via aircraft. But that is a big sized bomb which is to be reduced in size so that it can be mounted on a missile.
On March 09, 2016 Kim Jong-Un said North Korean scientists have developed nuclear warheads small enough to fit on ballistic missiles.
Miniaturized Nuclear Warhead
2) Re-entry Test: As mentioned above, the warhead after traveling a long distance in space re-enters earth back on the enemy’s mainland. It travels more than 20 minutes in space where there is almost no friction and drag. But once the warhead re-enters the earth, the atmospheric drag starts to slow down the warhead and due to friction, the fast moving warhead is heated to very high temperatures. The warheads start glowing upon atmospheric entry which happens to be at 100Km from the ground. Temperatures generated during warhead re-entry may exceed 15,000 degrees Fahrenheit.
Re-entry vehicle or warhead
The technology to protect a warhead from high temperature and vibration at the time of atmospheric re-entry is essential for an intercontinental ballistic missile to become operational, but it is difficult to attain. If warheads fail to withstand temperature and re-entry pressure it will burn up like a Meteor.
According to analysts on May 14, 2017, a North Korean missile successfully re-entered the Earth’s atmosphere, a significant breakthrough for Pyongyang’s missile program.
3) Missile Guidance — long range Missile Guidance technology is the most complicated part in the development of an ICBM. The MG set is an inertial guidance system which directs the flight of the missile.
How North Korea got the technology?
North Korea and China both aren’t members of MTCR (Missile Technology Control Regime). For non-members, MTCR restricts the transfer of sophisticated technologies used for missiles of ranges above 300km. MTCR actually stops the spread of missile technology.
But the missile technology control regime has not prevented North Korea from making important, some of which are indigenous advances in missile research and development.
Sensitive software and other items specifically banned for export to North Korea under U.N. Security Council sanctions were sold by the Chinese. Some sources claim the warhead technology that Pakistan obtained from China was transferred to North Korea or China directly supplied warhead designs to North Korea.
Also, Iran acquired ballistic missile technology from China other than North Korea and Pakistan. Because of US technology sanctions, China announced in November 2000, that it would stop exporting ballistic missile technology. Four years later, China applied for MTCR membership but has been denied entry because of suspicion that some companies in the country are secretly supplying technology to North Korea.
Nuclear bomb technology
The father of Pakistan atomic bomb Abdul Khadeer Khan admitted that he sold nuclear weapons secrets to Iran, North Korea, and Libya. He provided the secrets to Muslim countries Iran and Libya so they could become nuclear powers and strengthen the Islamic world. The successive governments had failed to control the activities of Mr. Khan. American intelligence operatives tracked Abdul Qadeer Khan’s nuclear network. The ship carrying centrifuge parts loaded in large cargo containers was tracked by U.S. spy satellites from Malaysia to Dubai. The ship was seized when it headed to Suez canal which led to the crackdown on the whole nuclear trading network.
Long range missile guidance: Inertial navigation systems (INS)
Normally long range missiles have Inertial guidance with GPS backup. Inertial guidance is most favored for the initial guidance and re-entry vehicles of strategic missiles because it doesn’t depend on any external signal and cannot be jammed. No external signal means there is no ground radio signal or ground based radar to guide the missile. Ground based signals could be easily jammed. But inertial guidance has everything inside the missile, so it doesn’t depend on any external signal (after initialization) to guide the missile to its target.
I said “after initialization” because the inertially guided missile gets its initial position (launch coordinates) and initial missile orientation information by a human operator or by a GPS receiver. But once in flight, it thereafter computes its own updated position and velocity by integrating information received from the sensors like accelerometers, gyroscope and other motion sensors aboard missile.
The basic components of an inertial guidance system are rotation sensors like gyroscopes, Motion sensors like accelerometers, and a computer.
Inertial Navigation in an ICBM keeps track of its position by accurately measuring acceleration (by accelerometers) and rotation or angular velocity (by gyroscopes).
Inertial platform with mechanical gyroscopes and accelerometers
By measuring all the accelerations and rotations and integrating them into speed and direction, the position of an ICBM is tracked. In doing this, the INS has to correct for the rotation of the earth and the related Coriolis force.
We know a basic formula Distance traveled by an ICBM = ICBM speed x travel time.
Speed input we are getting from accelerometers and when multiplied by travel time gives you the present distance traveled by an ICBM.
Advanced Ring laser gyroscope.
North Korea doesn’t have an advanced ring laser gyroscope (RLG) or fiber optic gyroscopes. The advantage of using an RLG is that there are no moving parts compared to the conventional spinning gyroscope and hence highly accurate. But the technology could find its way into North Korea’s ballistic missiles. Minute errors in the measuring capabilities of the accelerometers or in the balance of the gyroscopes can introduce large errors in position. That’s why I said earlier the missile fired from North Korea may fall on some nation or fall in the ocean.
Since the new missile position is calculated from the previously calculated position and the measured acceleration and angular velocity, these errors accumulate roughly proportionally to the time since the initial position was input. Therefore, the position must be periodically corrected by input from some other type of navigation system.
This is why we need GPS in addition to Inertial navigation systems. Also, in the event of war, GPS is shut off or limited to hinder opponents attack. Only a few nations have their own navigation systems USA– Global Positioning System(GPS), Russia–Globalnaya Navigazionnaya Sputnikovaya Sistema(GLONASS), European Union–Galileo satellite navigation system, China– Beidou Navigation satellite system, IRNSS–Indian Regional Navigation satellite systems.
GPS allows accurate targeting of various military weapons including ICBMs, Cruise missiles, GPS guided bombs etc.
About Krishna Santos KK
Krishna is a B.Tech graduate in Electrical Engineering and PGDC in Thermal power (operation and maintenance) under Ministry of power.
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