Introduction
PhD Research Analysis: Rocket and Missiles, A rocket is a non-air breathing propulsive vehicle. Which contains its own oxidation system. A cylindrical projectile that can be propelled to a greater height or distance by the combustion of its contents, used typically as a firework or signal. Rocket exhaust is formed entirely from propellant carried within the rocket. Rocket engines work by action and reaction and push rockets forward. According to newton’s third law of motion. Simply by expelling their exhaust in the opposite direction at high speed, and therefore can work in the vacuum of space. Rockets works more efficiently in space than in atmosphere. Missile, a rocket-propelled weapon designed to deliver an explosive warhead with great accuracy at high speed. Missiles vary from small tactical weapons that are effective out to only a few hundred feet to much larger strategic weapons that have ranges of several thousand miles. In military language, a missile, also known as a guided missile, is a guided self-propelled flying weapon usually propelled by a jet engine or rocket motor using many research topics in aerodynamic principles.

Parts of Rocket
•     Propellant (such as propellant tank)
•    Nozzle
•    Rockets engines
•    Directional stabilization device
•    Monocoque (typically structure)
•    Nose cone (usually holds the payload)
•    Re-entry vehicle

Rocket Engine
A rocket engine uses stored rocket propellants as reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust in accordance with Newton's third law. Most rocket engines use the combustion of reactive chemicals to supply the necessary energy, but non-combusting forms such as cold gas thrusters and nuclear thermal rockets also exist. In Thesis Writing Services, vehicles propelled by rocket engines are commonly called rockets. Rocket vehicles carry their own oxidizer, unlike most combustion engines, so rocket engines can be used in a vacuum to propel spacecraft and ballistic missiles.

Types of Rocket Engines
•    Physically powered
•    Chemically powered
•    Electrically powered
•    Thermally powered
•    Nuclear powered
•    Cryogenic propellant
•    Galled propellant (jelled type)

Missile
In military language, a missile, also known as a guided missile, is a guided self-propelled flying weapon usually propelled by a jet engine or rocket motor. This is in contrast to an unguided self-propelled flying munition, referred to as a rocket (although these too can also be guided). Missiles have four system components: targeting or missile guidance, flight system, engine, and warhead. Missiles come in types adapted for different purposes: surface-to-surface and air-to-surface missiles (ballistic, cruise, anti-ship, anti-tank, etc.), surface-to-air missiles (and anti-ballistic), air-to-air missiles, and anti-satellite weapons. Non-self-propelled airborne explosive devices are generally referred to as shells and usually have a shorter range than missiles. In ordinary language the word means an object which can be thrown, shot, or propelled toward a target.

Basic Roles of Missiles
•    Ballistic
•    Surface to air and subsurface to air
•    Air to air
•    Anti-satellite
•    Ground to ground
 
Conclusion
In this PhD research analysis the major principles and the types of rockets and missiles. And their roles are described besides the detailed definition of rockets and missiles are mentioned. The developments of technology by source of NASA, ISRO. The technologies is developing rapidly for future advantages and research. Some types of rockets are MX-774 (1946), Minotaur-C/Taurus (1994–present), Falcon Heavy (2018–present). Indian rockets Aryabhatta (19th April 1975), IRNSS-1E (Indian Regional Navigation Satellite System) (20th January 2016), Chandrayaan-2 (22nd July 2019). Many PhD research is going on till now in aerospace industries. Therefore it is just an introduction, definition, roles, and parts are given hence there is many detailed study about rocket and missiles.