A missile is a weapon that is self-propelled or directed by remote control, carrying conventional or nuclear warhead. There are many types of missile from mere tactical to advanced guided kinds. This time, we’re going to highlight a type of missile which is known for its’ ability to aim for faraway targets, and by faraway I mean targets located in different continents from its’ launch site. This type of missile is called — you saw it coming — Intercontinental Ballistic Missile, also known as ICBM. This type of missile can travel at least 5,500 kilometers and some designs can go a lot farther. I’m not going to get into the process of creating one since I’m absolutely not capable of doing so. Instead, I’m going to explain how this weapon of mass destruction works and some basic principles being used in designing it.
We’re going to start from the goal — to destroy a non-moving target at specific location on the globe. It means that the missile must hit the predetermined target with high precision. The missile must hit the target from the air since a missile is a flying object. But it should be from above the target, not parallel, let alone from below the target, and the target should be non-moving (except it can be guaranteed that a moving target occupies the specific space at the right time). Why? Because a ballistic object is an object that moves using only the help of gravity. In this case, a ballistic weapon is a weapon which uses gravity to accomplish its’ goal, which is to hit the target. Gravity pulls the weapon to the ground, this means that gravity gives the weapon a tendency to move downward. But the missile was launched prior the the dropping phase which means it already had a “forward” motion (the word forward here refers to the direction where the nose is pointing at). From basic physics, it is easy to conclude that the trajectory of the falling phase is going to be somewhat parabolic.
The falling phase begins usually when an ICBM is at its’ highest altitude — means when it’s farthest from the surface of the earth, where air is thin. As the missile falls, the air around it is getting thicker, thus resulting in higher air resistance. This is the reason the trajectory is going to be somewhat parabolic, not perfectly parabolic. If you have deduced it already, in order to get to a targeted altitude — a checkpoint, in a sense — the missile must penetrate from the ground — the launch point — up to the thin aired level, which means the missile experienced two phases penetrating against spaces with high air resistance, the falling phase and the former climbing phase. An object facing such amount of air resistance can only travel parallel to the earth’s surface so much before it loses its’ forward speed. So how does ICBMs work their way through to hit faraway targets — intercontinental —as the name suggests?
An ICBM must be launched with very high energy (resulting in huge initial velocity) and propel its’ way up and front. This means, an ICBM needs fuel to travel, just like your everyday civilian aircraft. The difference is, the fuel being used must be highly efficient and also contain much more energy to propel the missile, resulting in the use of rocket fuel — a huge amount of it. But we also know that the heavier an object is, the harder it is to maintain its’ altitude — and much fuel is heavy as hell. For this reason, an ICBM is usually designed to have multiple stages — parts, so to speak. All stages are carried when the missile is initially launched. When it gets to a specific checkpoint in the airspace, the system disposes the fuel tank which have become empty due to all the contained fuel have already been used. As the number of stages of the missiles body decrease, the total mass of the whole body decreases — thus resulting in lighter missile body. But a change in a body’s mass affects the body’s motion, resulting in the need of scheduled stabilizer and control system. Lighter missile also means less tendency of the missile to rip through air resistance and less ability to maintain its momentum. Nonetheless, below is the depiction of an ICBM’s mission:
Of course, there are several problems in the development of an ideal ICBM. The previous paragraph already mentioned about the change of the missile’s mass during its’ flight. This characteristic demands engineers to create multiple mathematical models of the missiles for each stage respectively — with minimum error of course. For example, a 1 degree error in an ICBM’s flight trajectory in the air will accumulate to error in distance up to hundreds of kilometers on the surface of the earth. Another challenge is to decrease the heat produced in the launching phase. The launch of an ICBM requires huge amount of energy, thus resulting in a spark in local temperature on the earth’s surface — its’ launch site to be precise. Since the goal of this missile — or any weapon — is to destroy target, it is the best for an ICBM to remain undetected until the damage has been done. It is a huge disadvantage if an enemy’s satellite somehow managed to detect that brief temperature rise during the launching process since the enemy would most likely execute a defense plan soon to anticipate the incoming ICBM. This would result in the waste of a missile — we’re talking millions of dollars here. The most advanced challenge, I assume, lies in the destructive power of the warhead itself. A warhead is a section containing the deadly compound (explosives, radioactive compounds, etc.), usually attached in a missile’s head section — thus the name “warhead”. An ICBM’s warhead section must be strong enough it doesn’t explode in mid air but also weak enough so that when it hits the ground, the structure explodes and the content execute the job as desired. As for the content of the warhead (assuming radioactive chemicals), it must remain stable and non-reactive during the missile’s flight — thus not damaging the container’s structure, and become highly reactive when the container explodes after hitting the ground. Lighter content is always desired since such configuration could result in lighter missile which can uses less energy in the launching and flight process, or pretty much a missile with relatively unchanged initial mass but the decrease in the warhead’s mass might be substituted with more fuel, thus resulting in possibly farther travel distance. There’s no need to get deeper into the mathematics, physics and chemicals behind ICBMs since they’re going to hurt our brains — yes, mine also.
So why did I write about ICBMs in the first place? It is always a pleasure for me to revisit technological advancement every once in a while. As an aerospace engineer, aerospace technologies deserves a reserved spotlight from my point of view. That added with my interest in defense (and/or offense) technology and war-related stuff, well, here it is. In my opinion, regardless the number of available resources, it is important for our nation to begin studies and researches regarding ICBMs or advanced military technologies in general. Although the world is currently not engaged in a war situation — well, most of it, at least — sudden and unpredictable changes might happen in global political and economics, and since whatever the change is unpredictable, I can’t spit out possible upcoming events (which the worst might be something we’ll name World War III). So I think it is best to improve our defense system to anticipate the worst while also keep hoping for the best and working our asses off in order to get closer to that “best” result.
But, as you might know me, I’m using the term defense loosely here. Because as Sun Tzu said in his book The Art of War ( if not mistaken him for someone else):
“Sometimes, the best defense strategy is to attack first.”
