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In spaceflight, a launch vehicle or carrier rocket is a rocket used to carry a payload from the Earth's surface into outer space. A launch system includes the launch vehicle, the launch pad and other infrastructure. Usually the payload is an artificial satellite placed into orbit, but some spaceflights are sub-orbital while others enable spacecraft to escape Earth orbit entirely. A launch vehicle which carries its payload on a suborbital trajectory is often called a sounding rocket.
Launch vehicles, particularly orbital launch vehicles, have at least two stages, but sometimes up to 4 are employed.
Types of launch vehicles
Expendable launch vehicles are designed for one-time use. They usually separate from their payload, and may break up during atmospheric reentry. Reusable launch vehicles, on the other hand, are designed to be recovered intact and used again for subsequent launches. For orbital spaceflights, the Space Shuttle has been the only launch vehicle with components which have been used for multiple flights. SpaceX is currently developing a reusable rocket launching system slated for use on both the 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.
Launch vehicles are often characterized by the amount of mass they can lift into orbit. For example, a Proton rocket has a launch capacity of 22,000 kilograms (49,000 lb) into low Earth orbit (LEO). Launch vehicles are also characterized by the number of stages they employ. 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, which supply high thrust early on in the flight, and normally in parallel with other engines on the vehicle. Boosters allow the remaining engines to be smaller, which reduces the burnout mass of later stages, and thus allows for larger payloads.
Other frequently-reported characteristics of launch vehicles are the nation or space agency responsible for the launch, and the company or consortium that manufactures and launches 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 an historical line of vehicles which share the same or similar names such as the Atlas V being the latest member of the Atlas rocket family.
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 (ARCASPACE), JP Aerospace Orbital Ascender, proposal for permanent Buoyant space port
|This section relies largely or entirely upon a single source. (May 2013)|
||The examples and perspective in this section deal primarily with the United States and do not represent a worldwide view of the subject. (May 2013)|
- A sounding rocket cannot reach orbit and is only capable of sub-orbital spaceflight
- A small lift launch vehicle is capable of lofting up to 2,000 kg (4,400 lb) of payload into low earth orbit (LEO)
- A medium lift launch vehicle is capable of lofting between 2,000 to 20,000 kg (4,400 to 44,000 lb) of payload into LEO
- A heavy lift launch vehicle is capable of lofting between 20,000 to 50,000 kg (44,000 to 110,000 lb) of payload into LEO
- A super-heavy lift vehicle is capable of lofting more than 50,000 kg of payload into LEO
Various methods are used to move an assembled launch vehicle onto its launch pad, each method with its own specialized equipment. These assembly activities take place as part of the overall launch campaign for the vehicle. In some launch systems, like the Delta II, the vehicle is assembled vertically on the pad, using a crane to hoist each stage into place. The Space Shuttle orbiter, including its external tank, and solid rocket boosters, was assembled vertically in NASA's Vehicle Assembly Building, and then a special crawler-transporter moved the entire stack to the launch pad while it was in an upright position. In contrast, the launch vehicles such as the Soyuz rocket and the Falcon 9 are assembled horizontally in a processing hangar, transported horizontally, and then brought upright once at the pad.
As an alternative, Project Vanguard provided a contraction of the phrase "Satellite Launching Vehicle" abbreviated to "SLV". This provided a term in the list of what the rockets were allocated for: flight test, or actually launching a satellite. The contraction would also apply to rockets which send probes to other worlds or the interplanetary medium.
Orbital launch vehicles
Sounding rockets are normally used for brief, inexpensive space and microgravity experiments. Current human-rated suborbital launch vehicles include SpaceShipOne and the upcoming SpaceShipTwo, among others (see space tourism). The delta-v needed for orbital launch using a rocket vehicle launching from the Earth's surface is at least 9,300 m/s (31,000 ft/s). This delta-v is determined by a combination of air-drag, which is determined by ballistic coefficient as well as gravity losses, altitude gain and the horizontal speed necessary to give a suitable perigee. The delta-v required for altitude gain varies, but is around 2 km/s (1.2 mi/s) for 200 km (120 mi) altitude.
Minimising air-drag entails having a reasonably high ballistic coefficient, which generally means having a launch vehicle that is at least 20 m (66 ft) long, or a ratio of length to diameter greater than ten. Leaving the atmosphere as early on in the flight as possible provides an air drag of around 300 m/s (980 ft/s). The horizontal speed necessary to achieve low earth orbit is around 7,800 m/s (26,000 ft/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.
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[who?] 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.
Specific to launch vehicles
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- See for example: "NASA Kills 'Wounded' Launch System Upgrade at KSC". Florida Today.
- "SpaceX says 'reusable rocket' could help colonize Mars". Agence France-Presse. Retrieved 4 October 2011.
- "Elon Musk says SpaceX will attempt to develop fully reusable space launch vehicle". Washington Post. 2011-09-29. Retrieved 2011-10-11. "Both of the rocket’s stages would return to the launch site and touch down vertically, under rocket power, on landing gear after delivering a spacecraft to orbit."
- Lindsey, Clark (2013-03-28). "SpaceX moving quickly towards fly-back first stage". NewSpace Watch. Retrieved 2013-03-29. (subscription required (. ))
- there are no Russian roadless terrain or railway car based mobile launchers converted for spacecraft launches.
- NASA Space Technology Roadmaps - Launch Propulsion Systems, p.11: "Small: 0-2t payloads, Medium: 2-20t payloads, Heavy: 20-50t payloads, Super Heavy: >50t payloads"
- HSF Final Report: Seeking a Human Spaceflight Program Worthy of a Great Nation, October 2009, Review of U.S. Human Spaceflight Plans Committee, p. 64-66: "5.2.1 The Need for Heavy Lift ... require a “super heavy-lift” launch vehicle ... range of 25 to 40 mt, setting a notional lower limit on the size of the super heavy-lift launch vehicle if refueling is available ... this strongly favors a minimum heavy-lift capacity of roughly 50 mt ..."
- S. A. Kamal, A. Mirza: The Multi-Stage-Q System and the Inverse-Q System for Possible application in SLV, Proc. IBCAST 2005, Volume 3, Control and Simulation, Edited by Hussain SI, Munir A, Kiyani J, Samar R, Khan MA, National Center for Physics, Bhurban, KP, Pakistan, 2006, pp 27–33 Free Full Text
- S. A. Kamal: Incorporating Cross-Range Error in the Lambert Scheme, Proc. 10th National Aeronautical Conf., Edited by Sheikh SR, Khan AM, Pakistan Air Force Academy, Risalpur, KP, Pakistan, 2006, pp 255–263 Free Full Text
- S. A. Kamal: The Multi-Stage-Lambert Scheme for Steering a Satellite-Launch Vehicle, Proc. 12th IEEE INMIC, Edited by Anis MK, Khan MK, Zaidi SJH, Bahria Univ., Karachi, Pakistan, 2008, pp 294–300 (invited paper) Free Full Text
- S. A. Kamal: Incompleteness of Cross-Product Steering and a Mathematical Formulation of Extended-Cross-Product Steering, Proc. IBCAST 2002, Volume 1, Advanced Materials, Computational Fluid Dynamics and Control Engineering, Edited by Hoorani HR, Munir A, Samar R, Zahir S, National Center for Physics, Bhurban, KP, Pakistan, 2003, pp 167–177 Free Full Text
- S. A. Kamal: Dot-Product Steering: A New Control Law for Satellites and Spacecrafts, Proc. IBCAST 2002, Volume 1, Advanced Materials, Computational Fluid Dynamics and Control Engineering, Edited by Hoorani HR, Munir A, Samar R, Zahir S, National Center for Physics, Bhurban, KP, Pakistan, 2003, pp 178–184 Free Full Text
- S. A. Kamal: Ellipse-Orientation Steering: A Control Law for Spacecrafts and Satellite-Launch Vehicles, Space Science and the Challenges of the twenty-First Century, ISPA-SUPARCO Collaborative Seminar, Univ. of Karachi, 2005 (invited paper)