Difference Between Rocket and Missile

Rocket vs Missile
 

When discussing about rockets the impression is that they are high tech and complicated machinery used in defence and space exploration. Even these are often related to almost fantastical feats in human history; rockets have both simple and ancient origins.

Today they are used in many forms to obtain range, high velocities, and accelerations. Missiles can be considered as a defence application of the rocket technology.

Rocket

In general, a vehicle powered by a rocket engine is called a rocket. A rocket engine is a type of engine that uses stored propellant or other means to create a high velocity gas jet. It may carry the oxidizer or use the oxygen in the atmosphere. The vehicle can be a spacecraft, a satellite, or even a car. Rockets operate on Newton`s third law.

Modern rockets were developed in the late 19th century and early 20th century. Even though the Chinese are credited with the invention of the rocket, the form used in modern rockets was not developed until much later.

The very early rockets were bamboos with gunpowder stored inside. These were used for amusement as well as weapons. It is known that these rockets were fired towards the Mongol invaders from the great wall. In modern terminology, these were solid propelled rockets, where the propellant was gunpowder.

Russian scientist Tsiokolvsky and American scientist Robert H. Goddard made significant contributions in advancing the rocket design from solid propellants to liquid fuels. In WWII, the rocket was used as a weapon in the latter phases of the war. The Germans fired solid propelled V2 rockets towards London. Even though these did not carry a large warhead to create extensive damage, the novelty of the weapon had a significant psychological impact. After the war, both the advantage and the threat of nuclear bombs used as the warhead in these rockets lead to accelerated developments in rocket science.

Two classes of rockets are majorly used at present; those are chemically powered rockets and electrically powered rockets. Of the two classes, chemically powered is the older and more predominant form and is used in both atmospheric and space missions. Electric powered rockets are used only in space missions.

Chemically powered rockets use solid fuel or liquid fuel. Solid propellants include three key components; fuel, oxidizer, and a binding agent. Fuel is usually a nitrogen based compound, aluminium or magnesium powder, or any other substitute that burns quickly to release a lot of energy. The oxidizer supplies the oxygen required for combustion and provides even and fast burning. Within atmosphere, the atmospheric oxygen is also used. The binding agent holds the fuel and the oxidizer together. Ballistite and cordite are two solid propellant types used.

Liquid fuel can be a fuel such as kerosene (or another similar hydrocarbon) or hydrogen and the oxidizer is liquid oxygen (LOX). Above mentioned fuels are in a gaseous state at the room temperature; therefore, has to be kept at low temperatures to sustain them in the liquid state. These fuels are known as cryogenic fuels. The main rocket engines of space shuttles operated using cryogenic fuel. Hypergolic fuels such as Nitrogen tetroxide (N2O4) and hydrazine (N2H4), Mono Methyl Hydrazine (MMH), or Unsymmetrical dimethylhydrazine (UDMH) are also used. These fuels have a relatively higher melting point and, therefore, can be kept at liquid state with less effort for a long time. Monopropellants such as hydrogen peroxide, hydrazine, and nitrous oxide are also used.

Each propellant has its own characteristics; therefore, has self-evident advantages and disadvantages. When designing vehicles these factors are taken into consideration, and each stage is designed accordingly. For example, kerosene was used in the first stage of the Apollo Saturn V rockets, and liquid hydrogen and liquid oxygen were used for the space shuttle.

Missile

Missiles are vehicles powered by rockets, to carry warheads. The first modern missiles were the V2 rockets developed by the Germans.

Missiles are categorized by the launch platform, intended target, and the navigation and guidance. The categories are Surface-to-Surface, Air-to-Surface, Surface-to-Air, and anti-satellite missiles. Depending on the guidance system, missiles are categorized into ballistic, cruise, and other types. They also can be classified using the intended target. Anti-ship, anti-tank, and anti-aircraft are examples for those categories.

Individually, these categories may contain numerous missiles with hybrid capabilities; therefore, an explicit classification cannot be provided.

Any missile consists of four fundamental subsystems; Guidance/Navigation/Targeting Systems, Flight systems, Rocket engine, and the Warhead.

Rocket vs Missile

• A rocket is a type of engine designed to deliver thrust by high velocity exhaust through a nozzle.

• The rocket can be mechanically, chemically, or electrically propelled. Even thermonuclear propulsion is proposed but not implemented. At present chemical propellants are the most predominant forms.

• A vehicle powered by rockets (self-propelled) to carry a warhead is known as a missile.

• A rocket is only a single component of the missile.