The rocket science behind missiles: Newton's laws, neural networks and algos

Indian Express

27-05-2025

On a summer day in 1944, residents of London heard a strange buzzing sound overhead—like an outboard motor in the sky — followed by silence. Seconds later, a blast ripped through a block of houses. The age of the modern missile had begun.
That sound came from the V-1 flying bomb, a German cruise missile. It wasn't very accurate and could be shot down, but it marked a turning point: the use of guided, long-range, autonomous weapons. Since then, missile technology has grown from noisy buzz bombs to nearly undetectable hypersonic gliders that can maneuver at several times the speed of sound. But behind the scenes, it's all about physics — a complex dance of speed, trajectory, control, and prediction.
From ballistics to brains
The earliest missiles were just arrows and spears—unguided projectiles. In fact, the word 'missile' comes from the Latin missilis, meaning 'that which may be thrown.' The science behind them is ballistics: the study of how objects move through the air under the influence of gravity and drag.
Ballistic missiles still exist today, but modern ones are far from simple. A ballistic missile is one that is powered during only the early phase of its flight. After that, it coasts along a parabolic path—just like a rock thrown into the air, only faster and farther.
A typical intercontinental ballistic missile (ICBM) reaches altitudes of over 1,000 km and speeds of Mach 20 (20 times the speed of sound). Once launched, they are almost impossible to intercept. But pure ballistic paths are predictable — and that's both their strength and their vulnerability. So modern missiles add another ingredient: guidance.
Guided missiles and the problem of precision
To hit a moving target — a plane, a tank, even a ship — you can't just aim and hope. You need to adjust in real time. That's what guided missiles do. They carry sensors (like radar, infrared, or GPS) and control systems (gyroscopes, fins, internal thrusters) that steer them mid-flight.
The problem is harder than it looks. Consider this: you're trying to hit a plane flying at 900 km/h from 40 km away. By the time your missile reaches it, the plane will have moved. So you don't aim at where the target is — you aim at where it will be. This involves solving what's called a 'pursuit curve', a classic problem in mathematics where the pursuer constantly adjusts its path toward the moving target.
In the early days, this was done using analog computers. One famous story involves British engineer Barnes Wallis using bicycle chains and gears to model bombing trajectories. Today's missiles use high-speed processors and AI-based prediction, but the challenge remains the same: predicting future motion in a world full of uncertainty.
A brief look at rocket science
Every missile is, at heart, a rocket. Rocket propulsion follows Newton's Third Law: for every action, there is an equal and opposite reaction. Burn fuel and expel gas out the back, and the missile is pushed forward. The real challenge isn't just going fast — it's controlling flight at those speeds.
When the Mach number crosses 1, the air surrounding the rocket undergoes a process called shocking, resulting in intense friction and heat. Missiles need special heat shields and materials that won't melt at thousands of degrees Celsius. Their electronics must survive g-forces that would crush a human.
Modern missiles push into the realm of the hypersonic — speeds above Mach 5. These include hypersonic glide vehicles, which detach from rockets and surf the upper atmosphere while maneuvering unpredictably. Unlike traditional ballistic missiles, their path is hard to model, making them extremely difficult to intercept.
Both China and the U.S. have invested heavily in these next-generation systems. India's DRDO is also testing hypersonic platforms. These weapons don't just travel fast — they're smart, maneuverable, and virtually impossible to defend against with today's technology.
What makes hypersonic missiles especially disruptive is not just their speed, but the shrinking response time they impose. A traditional ICBM may give its target 30–40 minutes to react; a hypersonic missile could cut that to under 10. That changes the calculus of deterrence and defense. Even tracking these weapons is a challenge: at such speeds, air friction generates plasma that can block radar signals. As a result, militaries worldwide are racing not only to build hypersonic weapons, but also to develop new space-based sensors and directed-energy countermeasures to stop them.
Pigeons and missiles
In World War II, American psychologist B.F. Skinner proposed a bizarre idea: use pigeons to guide missiles. He trained the birds to peck at an image of a target projected on a screen inside the missile's nose cone. Their pecking movements would steer the missile toward its goal.
Though never deployed, Project Pigeon (and its later version, Project Orcon, for 'organic control') showed the creative lengths to which scientists would go in the early days of missile guidance. Today's systems rely on microprocessors, not pigeons—but the principles remain the same: sense, compute, correct.
The science of predicting impact
At its core, missile science is about solving a fundamental problem: how do you strike something that's far away, possibly moving, and maybe trying to avoid you? The answer lies in physics, engineering, and increasingly, artificial intelligence.
That challenge grows more complex as defenses improve. Missiles must now anticipate evasive maneuvers, adjust mid-course using real-time data, and sift through decoys or electronic jamming. A modern air-to-air missile might make hundreds of tiny course corrections per second, all while enduring intense heat, G-forces, and signal noise. The missile, in effect, becomes a high-speed problem-solver — guided not just by brute force, but by algorithms and sensors that mimic decision-making under pressure.
It's a blend of old and new — Newton's laws and neural networks, calculus and code. And while the technologies have evolved dramatically, the underlying science has stayed remarkably consistent. Even the most advanced missiles still obey the same principles as a stone flung from a slingshot. The only difference is that today, the stone flies at Mach 10, thinks for itself, and rarely misses.