Launch pad

Last updated
Launch pad at Kennedy Space Center Launch Complex 39B on Merritt Island, Florida Stspad39baerial.jpg
Launch pad at Kennedy Space Center Launch Complex 39B on Merritt Island, Florida
V2 rocket on launch pad, 1942 Bundesarchiv RH8II Bild-B2054-44, Peenemunde, Raketenrampe mit V2.jpg
V2 rocket on launch pad, 1942

A launch pad is an above-ground facility from which a rocket-powered missile or space vehicle is vertically launched. A spaceport (or sometimes launch complex) is a facility which includes, and provides required support for, one or more launch pads; the term launch pad may sometimes be used to describe just the central launch platform. A launch pad typically includes a launch mount or launch platform—to support the vehicle and its service structure with umbilicals to provide propellants, cryogenic fluids, electrical power, communications and telemetry prior to launch—plus storage facilities for propellants and gases, equipment, access roads, drainage and all the requisite infrastructure to support rocket vehicle launches.

Rocket missile, spacecraft, aircraft or other vehicle that obtains thrust from a rocket engine

A rocket is a missile, spacecraft, aircraft or other vehicle that obtains thrust from a rocket engine. Rocket engine exhaust is formed entirely from propellant carried within the rocket before use. Rocket engines work by action and reaction and push rockets forward simply by expelling their exhaust in the opposite direction at high speed, and can therefore work in the vacuum of space.

Missile self-propelled guided weapon system

In modern language, a missile, also known as a guided missile, is a guided self-propelled system, as opposed to an unguided self-propelled munition, referred to as a rocket. 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, surface-to-air missiles, air-to-air missiles, and anti-satellite weapons. All known existing missiles are designed to be propelled during powered flight by chemical reactions inside a rocket engine, jet engine, or other type of engine. Non-self-propelled airborne explosive devices are generally referred to as shells and usually have a shorter range than missiles.

A space vehicle or spaceship is a rocket-powered vehicle used to transport unmanned satellites or humans between the Earth's surface and outer space. The earliest space vehicles were expendable launch systems, consisting of rocket launch vehicles carrying spacecraft payloads which were relatively small portions of the total vehicle size and mass. The single or multistage rocket without the payload is referred to as a launch vehicle. Most space vehicles in production use are expendable systems, although reusable launch systems have been envisioned since the late 1960s.


Some launch pads include service structures to provide one or more access platforms to inspect and maintain the vehicle and to allow access to the crew cabin for vehicles carrying humans. The pad may contain a flame deflection structure to prevent the intense heat of the rocket exhaust from damaging the vehicle or pad structures, and a sound suppression system spraying large quantities of water may be employed. The pad may also be protected by lightning arresters. A launch pad is distinct from a missile launch facility (or missile silo or missile complex), which also launches a missile vertically but is located underground in order to help harden it against enemy attack, or conceal it from surveillance.

Lightning arrester Device used to switch a lightning strike

A lightning arrester is a device used on electric power systems and telecommunication systems to protect the insulation and conductors of the system from the damaging effects of lightning. The typical lightning arrester has a high-voltage terminal and a ground terminal. When a lightning surge travels along the power line to the arrester, the current from the surge is diverted through the arrester, in most cases to earth.

Missile launch facility

A missile launch facility, also known as an underground missile silo, launch facility (LF), or nuclear silo, is a vertical cylindrical structure constructed underground, for the storage and launching of intercontinental ballistic missiles (ICBMs).

Cryogenic propellants (liquid oxygen oxidizer, and liquid hydrogen or liquid methane fuel) need to be continuously topped off (i.e., boil-off replaced) during the launch sequence (countdown), as the vehicle awaits liftoff. This becomes particularly important as complex sequences may be interrupted by planned or unplanned holds to fix problems.

Liquid oxygen one of the physical forms of elemental oxygen

Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of elemental oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard. It was later mostly supplanted by gaseous oxidizers such as nitrogen tetroxide because of easier storage, as is the case with the American Titan II missile from the Cold War.

Liquid hydrogen liquid state of the element hydrogen

Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.

Countdown sequence of backward counting to indicate the time remaining before an event is scheduled to occur

A countdown is a sequence of backward counting to indicate the time remaining before an event is scheduled to occur. NASA commonly employs the terms "L-minus" and "T-minus" during the preparation for and anticipation of a rocket launch, and even "E-minus" for events that involve spacecraft that are already in space, where the "T" could stand for "Test" or "Time", and the "E" stands for "Encounter", as with a comet or some other space object. Other events for which countdowns are commonly used include the detonation of an explosive, the start of a race, the start of the New Year, or any anxiously anticipated event. An early use of a countdown once signaled the start of a Cambridge University rowing race. One of the first known associations with rockets was in the 1929 German science fiction movie Frau im Mond written by Thea von Harbou and directed by Fritz Lang in an attempt to increase the drama of the launch sequence of the story's lunar-bound rocket.

Most rockets need stable support for a few seconds after ignition while the engines build up to stable, full thrust. Therefore, the vehicle is commonly held on the pad by hold-down arms or explosive bolts, which are triggered when the vehicle is stable and ready to fly, at which point all umbilical connections with the pad are released.

Thrust reaction force which expels or accelerates mass in one direction

Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction on that system. The force applied on a surface in a direction perpendicular or normal to the surface is also called thrust. Force, and thus thrust, is measured using the International System of Units (SI) in newtons, and represents the amount needed to accelerate 1 kilogram of mass at the rate of 1 meter per second per second. In mechanical engineering, force orthogonal to the main load is referred to as thrust.

Transport of rockets to the pad

Transport of Soyuz rocket to pad by train Soyuz Rolls Out.jpg
Transport of Soyuz rocket to pad by train
Transport of Space Shuttle to pad on Crawler-transporter STS-114 rollout.jpg
Transport of Space Shuttle to pad on Crawler-transporter
SLC 40 with SpaceX Falcon 9 launch infrastructure. The four towers surrounding the rocket are lightning arresters. Falcon 9 preparing to launch DSCOVR (16673054016).jpg
SLC 40 with SpaceX Falcon 9 launch infrastructure. The four towers surrounding the rocket are lightning arresters.

There are several different types of launch site, determined[ according to whom? ] by the means by which the space vehicle gets to the pad.[ citation needed ]

V-2 rocket worlds first long-range guided ballistic missile

The V-2, technical name Aggregat 4 (A4), was the world's first long-range guided ballistic missile. The missile, powered by a liquid-propellant rocket engine, was developed during the Second World War in Germany as a "vengeance weapon", assigned to attack Allied cities as retaliation for the Allied bombings against German cities. The V-2 rocket also became the first man-made object to travel into space by crossing the Kármán line with the vertical launch of MW 18014 on 20 June 1944.

Transporter erector launcher

A transporter erector launcher (TEL) is a missile vehicle with an integrated prime mover that can carry, elevate to firing position and launch one or more missiles. Such vehicles exist for both surface-to-air missiles and surface-to-surface missiles. Early on, such missiles were launched from fixed sites and had to be loaded onto trucks for transport, making them more vulnerable to attack since once they were spotted by the enemy they could not easily be relocated, and if they were it often took hours or even days to prepare them for launch once they reached their new site.

Soyuz (rocket family) Russian and Soviet rocket family

Soyuz is a family of expendable launch systems developed by OKB-1 and manufactured by Progress Rocket Space Centre in Samara, Russia. With over 1700 flights since its debut in 1966, the Soyuz is the most frequently used launch vehicle in the world.

See also

Related Research Articles

Titan (rocket family) rocket family

Titan is a family of United States expendable rockets used between 1959 and 2005. A total of 368 rockets of this family were launched, including all the Project Gemini manned flights of the mid-1960s. Titans were part of the US Air Force's intercontinental ballistic missile fleet until 1987, and lifted other American military payloads as well as civilian agency intelligence-gathering satellites. Titans also were used to send highly successful interplanetary scientific probes throughout the Solar System.

Hypergolic propellant

A hypergolic propellant combination used in a rocket engine is one whose components spontaneously ignite when they come into contact with each other.

Vandenberg Air Force Base census-designated place in California, United States

Vandenberg Air Force Base is a United States Air Force Base 9.2 miles (14.8 km) northwest of Lompoc, California. It is under the jurisdiction of the 30th Space Wing, Air Force Space Command (AFSPC).

Spaceport facility for launching (or receiving) spacecraft

A spaceport or cosmodrome is a site for launching spacecraft, by analogy to seaport for ships or airport for aircraft. The word spaceport, and even more so cosmodrome, has traditionally been used for sites capable of launching spacecraft into orbit around Earth or on interplanetary trajectories. However, rocket launch sites for purely sub-orbital flights are sometimes called spaceports, as in recent years new and proposed sites for suborbital human flights have been frequently referred to or named 'spaceports'. Space stations and proposed future bases on the moon are sometimes called spaceports, in particular if intended as a base for further journeys.

HGM-25A Titan I United States first multistage rocket Intercontinental ballistic missile

The Martin Marietta SM-68A/HGM-25A Titan I was the United States' first multistage intercontinental ballistic missile (ICBM), in use from 1959 until 1965. Though the SM-68A was operational for only three years, it spawned numerous follow-on models that were a part of the US arsenal and later, an important part of the US space launch capability. The SM-68 was unique among the Titan models in that it used liquid oxygen and RP-1 as propellants, while the later Titan ICBM versions all used storable propellants instead.

Vehicle Assembly Building Spacecraft assembly building operated by NASA at the Kennedy Space Center

The VehicleAssembly Building, or VAB, is the large building at NASA's Kennedy Space Center (KSC), designed to assemble the large pre-manufactured space vehicle components, such as the massive Saturn V and the Space Shuttle; and stack them vertically onto the Mobile Launch Platform and crawler transporter. The future Space Launch System (SLS) will also be assembled there.

Cape Canaveral Air Force Station spaceport on Cape Canaveral, USA

Cape Canaveral Air Force Station (CCAFS) is an installation of the United States Air Force Space Command's 45th Space Wing.

Delta IV active expendable launch system in the Delta rocket family

Delta IV is an expendable launch system in the Delta rocket family. The rocket's main components are designed by Boeing's Defense, Space & Security division and built in the United Launch Alliance (ULA) facility in Decatur, Alabama. Final assembly is completed at the launch site by ULA. The rocket was designed to launch payloads into orbit for the United States Air Force Evolved Expendable Launch Vehicle (EELV) program and for the commercial satellite business. The Delta IV is available in five versions: Medium, Medium+ (4,2), Medium+ (5,2), Medium+ (5,4), and Heavy, to cover a range of payload size and weight. The Delta IV was primarily designed to satisfy the needs of the U.S. military.

LGM-25C Titan II intercontinental ballistic missile and space launcher

The Titan II was an intercontinental ballistic missile (ICBM) and space launcher developed by the Glenn L. Martin Company from the earlier Titan I missile. Titan II was originally designed and used as an ICBM, but was later used as a medium-lift space launch vehicle to carry payloads for the United States Air Force (USAF), National Aeronautics and Space Administration (NASA) and National Oceanic and Atmospheric Administration (NOAA). Those payloads included the USAF Defense Meteorological Satellite Program (DMSP), the NOAA weather satellites, and NASA's Gemini manned space capsules. The modified Titan II SLVs were launched from Vandenberg Air Force Base, California up until 2003.

Crawler-transporter NASA rocket transport vehicle

The crawler-transporters, formally known as the Missile Crawler Transporter Facilities, are a pair of tracked vehicles used to transport spacecraft from NASA's Vehicle Assembly Building (VAB) along the Crawlerway to Launch Complex 39. They were originally used to transport the Saturn IB and Saturn V rockets during the Apollo, Skylab and Apollo–Soyuz programs. They were then used to transport Space Shuttles from 1981 to 2011. The crawler-transporters carry vehicles on the Mobile Launcher Platform, and after each launch return to the pad to take the platform back to the VAB.

Service structure structure built on a rocket launch pad to facilitate fueling and loading of cargo and crew into a spacecraft

A service structure is a structure built on a rocket launch pad to facilitate assembly and servicing.

Kennedy Space Center Launch Complex 39 rocket launch site at the John F. Kennedy Space Center, Florida, USA

Launch Complex 39 (LC-39) is a rocket launch site at the John F. Kennedy Space Center on Merritt Island in Florida, United States. The site and its collection of facilities were originally built for the Apollo program, and later modified for the Space Shuttle program.

Mobile Launcher Platform

The Mobile Launcher Platform (MLP) is one of three two-story steel structures used by NASA at the Kennedy Space Center to support the Space Shuttle stack throughout the build-up and launch process: during assembly at the Vehicle Assembly Building (VAB), while being transported to Launch Pads 39A and B, and as the vehicle's launch platform. NASA's three MLPs were originally constructed for the Apollo program to launch the Saturn V rockets in the 1960s and 1970s, and remained in service through the end of the Shuttle program in 2011 with alterations. The Space Launch System rocket will be mounted atop a renovated platform.

Satish Dhawan Space Centre spaceport in Andhra Pradesh, India

Satish Dhawan Space Centre (SDSC) or Sriharikota Range (SHAR) is a rocket launch centre operated by Indian Space Research Organisation (ISRO). It is located in Sriharikota in Andhra Pradesh. Sriharikota Range was renamed in 2002 after ISRO's former chairman Satish Dhawan.

Cape Canaveral Air Force Station Launch Complex 34

Cape CanaveralAir Force Station Launch Complex 34 (LC-34) is a launch site on Cape Canaveral, Florida. LC-34 and its companion LC-37 to the north were used by NASA from 1961 through 1968 to launch Saturn I and IB rockets as part of the Apollo program. It was the site of the Apollo 1 fire, which claimed the lives of astronauts Gus Grissom, Ed White, and Roger Chaffee on January 27, 1967.

Mobile Launcher Platform 3

Mobile Launcher Platform 3 or MLP-3, formerly Mobile Launcher 1 or ML-1 is one of three Mobile Launcher Platforms used at Kennedy Space Center Launch Complex 39. During the late 1960s and early 1970s, it was used for Saturn V and Saturn IB launches, and later for the Space Shuttle. It will be used to launch Northrop Grumman Innovation System's Omega rocket from LC-39B starting in 2021.

SA-500F test model of the Saturn V rocket

SA-500F was a dummy Saturn V used by NASA to test facilities at Launch Complex 39 at the Kennedy Space Center on Merritt Island, Florida throughout 1966. Tests included the mating of the Saturn's stages in the Vehicle Assembly Building (VAB), the fit of the service platforms, the launcher-transporter operation, the propellant loading system, and the test connections to the mobile launcher and support equipment.

SpaceX launch facilities

As of December 2017, SpaceX uses three leased orbital launch sites: Launch Complex 39A of the Kennedy Space Center, Space Launch Complex 40 at Cape Canaveral Air Force Station, both in Florida, and Space Launch Complex 4E of the Vandenberg Air Force Base in California. Space Launch Complex 40 was damaged in the Amos-6 accident on September 2016 and repair work was completed by December 2017. SpaceX is also building a commercial-only launch facility at the Boca Chica site near Brownsville, Texas and is expected to be operational no earlier than 2019.


  1. "LAUNCH COMPLEX 39, PADS A AND B". NASA KSC. 1992. Archived from the original on 2008-09-21.