Launch vehicle

A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage rocket, but the term is more general and also encompasses vehicles like the Space Shuttle. Most launch vehicles operate from a launch pad, supported by a launch control center and systems such as vehicle assembly and fueling. Launch vehicles are engineered with advanced aerodynamics and technologies, which contribute to high operating costs. An orbital launch vehicle must lift its payload at least to the boundary of space, approximately and accelerate it to a horizontal velocity of at least . Suborbital vehicles launch their payloads to lower velocity or are launched at elevation angles greater than horizontal. Practical orbital launch vehicles use chemical propellants such as solid fuel, liquid hydrogen, kerosene, liquid oxygen, or hypergolic propellants. Launch vehicles are classified by their orbital payload capacity, ranging from small-, medium-, heavy- to super-heavy lift. Launch vehicles are classed by NASA according to low Earth orbit payload capability: Small-lift launch vehicle: < - e.g. Vega Medium-lift launch vehicle: - e.g. Soyuz ST Heavy-lift launch vehicle: > - e.g. Ariane 5 Super-heavy lift vehicle: > - e.g. Saturn V Sounding rockets are similar to small-lift launch vehicles, however they are usually even smaller and do not place payloads into orbit. A modified SS-520 sounding rocket was used to place a 4-kilogram payload (TRICOM-1R) into orbit in 2018. Orbital spaceflight requires a satellite or spacecraft payload to be accelerated to very high velocity. In the vacuum of space, reaction forces must be provided by the ejection of mass, resulting in the rocket equation. The physics of spaceflight are such that rocket stages are typically required to achieve the desired orbit.