Launch vehicle

In spaceflight, a launch vehicle or carrier rocket is a rocket used to carry a payload from Earth's surface into outer space. A launch system includes the launch vehicle, the launch pad, and other infrastructure. Although a carrier rocket's payload is often an artificial satellite placed into orbit, some spaceflights, such as sounding rockets, are sub-orbital, while others enable spacecraft to escape Earth orbit entirely.

Earth orbital launch vehicles typically have at least two stages, and sometimes as many as four or more.

Types


Expendable launch vehicles are designed for one-time use. They usually separate from their payload and disintegrate during atmospheric reentry. In contrast, reusable launch vehicles are designed to be recovered intact and launched again. The Space Shuttle was a launch vehicle with components used for multiple orbital spaceflights. SpaceX is developing a reusable rocket launching system for their Falcon 9 and Falcon Heavy launch vehicles. A second-generation VTVL design was announced in 2011. The low-altitude flight test program of an experimental technology-demonstrator launch vehicle began in 2012, with more extensive high-altitude over-water flight testing planned to begin in mid-2013, and continue on each subsequent Falcon 9 flight. Non-rocket spacelaunch alternatives are at the planning stage, although it is known that some companies are developing actual launch platforms, such as the Spanish zero2infinity with their rockoon-based launcher "bloostar".

Launch vehicles are often classified by the amount of mass they can carry into orbit. For example, a Proton rocket can lift 22000 kg into low Earth orbit (LEO). Launch vehicles are also characterized by their number of stages. Rockets with as many as five stages have been successfully launched, and there have been designs for several single-stage-to-orbit vehicles. Additionally, launch vehicles are very often supplied with boosters supplying high early thrust, normally burning with other engines. Boosters allow the remaining engines to be smaller, reducing the burnout mass of later stages to allow larger payloads.

Other frequently-reported characteristics of launch vehicles are the launching nation or space agency and the company or consortium manufacturing and launching the vehicle. For example, the European Space Agency is responsible for the Ariane V, and the United Launch Alliance manufactures and launches the Delta IV and Atlas V rockets. Many launch vehicles are considered part of a historical line of vehicles of same or similar name; e.g., the Atlas V is the latest Atlas rocket.

By launch platform

 * Land: spaceport and fixed missile silo (Strela) for converted ICBMs
 * Sea: fixed platform (San Marco), mobile platform (Sea Launch), submarine (Shtil', Volna) for converted SLBMs
 * Air: aircraft (Pegasus, Virgin Galactic LauncherOne, Stratolaunch Systems), balloon (zero2infinity's bloostar, ARCASPACE), JP Aerospace Orbital Ascender, proposal for permanent Buoyant space port

By size
There are many ways to classify the sizes of launch vehicles. The US civilian space agency, NASA, uses a classification scheme that was articulated by the Augustine Commission created to review plans for replacing the Space Shuttle:


 * A sounding rocket, used to study the atmosphere or perform brief experiments, is only capable of sub-orbital spaceflight and cannot reach orbit.
 * A small-lift launch vehicle is capable of lifting up to 2000 kg of payload into low Earth orbit (LEO).
 * A medium-lift launch vehicle is capable of lifting between 2000 to 20000 kg of payload into LEO.
 * A heavy-lift launch vehicle is capable of lifting between 20000 to 50000 kg of payload into LEO.
 * A super-heavy lift vehicle is capable of lifting more than 50000 kg of payload into LEO.

The leading European launch service provider, Arianespace, also uses the "heavy-lift" designation for its >20000 kg-to-LEO Ariane 5 launch vehicle and "medium-lift" for its array of launch vehicles that lift 2000 - 20000 kg to LEO, including the Starsem/Arianespace Soyuz ST and pre-1999 versions of the Ariane 5. It refers to its 1500 kg to LEO Vega launch vehicle as "light lift".

Suborbital
Suborbital launch vehicles are not capable of taking their payloads to the minimum horizontal speed necessary to achieve low Earth orbit with a perigee less than the Earth's mean radius, which speed is about 7800 m/s. Sounding rockets have long been used for brief, inexpensive unmanned space and microgravity experiments. The first US human spaceflight program, Project Mercury, used a single-stage derivative of the Redstone rocket family to launch its first two astronauts, Alan Shephard and Gus Grissom on suborbital flights, before sending astronauts into orbit on later flights. Current human-rated suborbital launch vehicles include SpaceShipOne and the upcoming SpaceShipTwo, among others (see space tourism).

Orbital


The delta-v needed for orbital launch from the Earth's surface is greater than the minimum orbital speed; at least 9300 m/s, because of aerodynamic drag, (determined by ballistic coefficient), as well as gravity losses, and potential energy required if higher altitude is desired.

Minimizing air drag requires a reasonably high ballistic coefficient, a ratio of length to diameter greater than ten. This generally results in a launch vehicle that is at least 20 m long. Leaving the atmosphere as early on in the flight as possible provides a velocity loss due to air drag of around 300 m/s.

The calculation of the total delta-v for launch is complicated, and in nearly all cases numerical integration is used; adding multiple delta-v values provides a pessimistic result, since the rocket can thrust while at an angle in order to reach orbit, thereby saving fuel as it can gain altitude and horizontal speed simultaneously.

Translunar and interplanetary
For a spacecraft to reach the Moon, Earth escape velocity of 11200 m/s is not required, but a velocity close to this places the craft into an Earth orbit with a very high apogee which, if launched at the correct time, takes it to a point where the Moon's gravity will capture it.

Interplanetary flight requires exceeding escape velocity; the excess velocity either adds to the Earth's orbital velocity around the Sun to reach the outer planets or asteroids, or subtracts from it to reach Venus or Mercury, depending on the direction in which the terminal velocity is achieved.

Launch vehicles of sufficient size are capable of launching payloads smaller than their orbital capability, to the Moon or beyond. Translunar and interplanetary flights are commonly launched with the vehicle's final stage into a temporary parking orbit, to allow spacecraft checkout, and more precise control of the final injection maneuver, rather than being launched directly to terminal velocity.

Assembly
Each individual stage of a rocket is generally assembled at its manufacturing site and shipped to the launch site; the term vehicle assembly refers to the mating of rocket stage(s) with the spacecraft payload into a single assembly known as a space vehicle. Single-stage vehicles (such as sounding rockets), and multistage vehicles on the smaller end of the size range, can usually be assembled vertically, directly on the launch pad by lifting each stage and the spacecraft sequentially in place by means of a crane.

This is generally not practical for larger space vehicles, which are assembled off the pad and moved into place on the launch site by various methods. NASA's Apollo/Saturn V manned Moon landing vehicle, and Space Shuttle, were assembled vertically onto mobile launcher platforms with attached launch umbillical towers, in the Vehicle Assembly Building, and then a special crawler-transporter moved the entire vehicle stack to the launch pad in an upright position. In contrast, vehicles such as the Russian Soyuz rocket and the SpaceX Falcon 9 are assembled horizontally in a processing hangar, transported horizontally, and then brought upright at the pad.

Related term
In the English language, the phrase carrier rocket was used earlier, and still is occasionally, in Britain.

Regulation
Under international law, the nationality of the owner of a launch vehicle determines which country is responsible for any damages resulting from that vehicle. Due to this, some countries require that rocket manufacturers and launchers adhere to specific regulations in order to indemnify and protect the safety of people and property that may be affected by a flight.

In the US, any rocket launch that is not classified as amateur, and also is not "for and by the government," must be approved by the Federal Aviation Administration's Office of Commercial Space Transportation (FAA/AST), located in Washington, DC.