rockets

Rockets are vehicles or devices that obtain thrust by expelling reaction mass at high speed, enabling propulsion in space and in the atmosphere. The principle relies on Newton's third law: for every action there is an equal and opposite reaction. Rockets do not require atmospheric oxygen and can operate in vacuum.

The concept dates back to Chinese fire arrows and later developed for military rocket artillery. In 1926, Robert Goddard demonstrated the first practical liquid-fueled rocket, a milestone for modern rocketry. In the 1930s and 1940s, Germany developed the V-2 long-range missile. After World War II, rocket technology expanded into space exploration, with engineers such as Wernher von Braun contributing to orbital launch vehicles.

Propulsion relies on chemical reactions. Solid rockets burn a fixed propellant in a casing, while liquid rockets use separate fuels and oxidizers in a combustion chamber, often with turbopumps. Hybrid rockets blend solid and liquid elements. Modern launchers typically use multiple stages, each with its own engine and propellant. A rocket includes a nozzle, and guidance and control systems such as inertial navigation, timing, and thrust vectoring to steer the vehicle.

Rockets are used to place payloads into space, deploy satellites, and conduct suborbital or orbital scientific missions. Ballistic missiles rely on rocket propulsion to reach targets, while space launch vehicles deliver satellites and crewed missions. Suborbital trajectories provide brief flights for experiments, training, or testing.

Current trends include reusability, with first stages recovered and reused to lower costs. Advances in engine design, propulsion efficiency, guidance, and materials have improved reliability and safety. Research continues into electric and hybrid propulsion for specific missions and into minimizing environmental impact.