Atlas (rocket family)

Launch of an Atlas V rocket in 2005

Atlas is a family of U.S. space launch vehicles. The original Atlas missile was designed in the late 1950s and produced by the Convair Division of General Dynamics, to be used as an intercontinental ballistic missile (ICBM). It was a liquid-fuel rocket burning liquid oxygen and RP-1 in three engines configured in an unusual "stage-and-a-half" or "Parallel Staging" design: its two outboard booster engines were jettisoned during ascent, while its center sustainer engine, fuel tanks and other structural elements were retained into orbit.

The missiles saw only brief ICBM service, and the last squadron was taken off operational alert in 1965. From 1962 to 1963, Atlas boosters launched the first four American astronauts to orbit the Earth. Various Atlas II models were launched 63 times between 1991 and 2004. There were only six launches of the Atlas III, all between 2000 and 2005. The Atlas V is still in service, with launches planned until 2020.

More than 300 Atlas launches have been conducted from Cape Canaveral Air Force Station in Florida and 285 from Vandenberg Air Force Base in California.

Atlas family evolution

Intercontinental ballistic missile

Launch of an Atlas B intercontinental ballistic missile		Launch of the first American manned orbital space flight

See also: SM-65 Atlas

The first successful test launch of an SM-65 Atlas missile was on December 17, 1957. Approximately 350 Atlas missiles were built. Many were eventually converted to orbital launch vehicles after they were removed from service as missiles. Missiles converted into Atlas E/F "space boosters" were used to launch the early "Block I" GPS satellites.

Early Atlas rockets were also built specifically for non-military uses. On December 18, 1958, an Atlas was used to launch the Signal Communication by Orbiting Relay Equipment (SCORE) satellite, which was, "The first prototype of a communications satellite, and the first test of any satellite for direct practical applications." The satellite broadcast President Eisenhower’s pre-recorded Christmas message around the world.

The Atlas boosters would collapse under their own weight if not kept pressurized with nitrogen gas in the tank, even when not fueled. The Atlas booster was unusual in its use of balloon tanks for holding its fuel. The tanks were made from very thin stainless steel that offered minimal or no rigid support. It was pressure in the tanks that gave the rigidity required for space flight.

Atlas boosters were also used for the last four manned Project Mercury missions, the first United States manned space program. On February 20, 1962 it launched Friendship 7, which made three earth orbits carrying John Glenn, the first United States astronaut to orbit the Earth. Identical Atlas boosters successfully launched three more manned Mercury orbital missions from 1962 to 1963.

Beginning in 1960, the Agena upper-stage, powered by hypergolic propellant, was used extensively on Atlas launch vehicles. The United States Air Force, NRO and CIA used them to launch SIGINT satellites. NASA used them in the Ranger program to obtain the first close-up images of the surface of the Moon and for Mariner 2, the first spacecraft to fly by another planet. Each of the Agena target vehicles used for the later space rendezvous practice missions of Gemini was launched on an Atlas rocket.

Beginning in 1963, the liquid hydrogen-fueled Centaur upper stage was also used on dozens of Atlas launches. NASA launched the Surveyor program lunar lander spacecraft and most of the Mars-bound Mariner program spacecraft with Atlas-Centaur launch vehicles.

Launch vehicles

An Atlas-Agena launches an Agena Target vehicle for the rendezvous missions of Project Gemini.

Atlas-Vega

Atlas-Vega consisted of an Atlas booster with a storable propellant upper stage. It was planned by NASA at its inception for deep space and planetary missions before the Atlas Centaur was available. Work had already begun when NASA discovered the CIA and the United States Air Force had an essentially identical launch vehicle (Atlas-Hustler, later called Atlas-Agena) in development for the highly-classified Corona reconnaissance satellite program. Atlas-Vega was accordingly canceled. Launch Vehicle: Atlas E. Initial fully operational version of Atlas ICBM. Differed in guidance system from Atlas F. Deployed as missiles from 1960 to 1966. After retirement, the ICBMs were refurbished and used for over 20 years as space launch vehicles.

Atlas-Able

Main article: Atlas-Able

SLV-3 Atlas

The Atlas LV-3B, Atlas D Mercury Launch Vehicle, or Mercury-Atlas Launch Vehicle, was a man-rated version of the Atlas used to launch the four manned orbital flights of Project Mercury. It first flew on July 29, 1960, launching the suborbital Mercury-Atlas 1 test flight. Nine LV-3Bs were launched, two on unmanned suborbital test flights, three on unmanned orbital test flights, and four with manned Mercury spacecraft.

Atlas-Agena

Main article: Atlas-Agena

The Atlas-Agena design was used for 119 orbital launches between 1960 and 1978. Atlas-Agena vehicles were used to launch a number of Missile Defense Alarm System satellites from 1961 to 1963, seven Canyon satellites between 1968 and 1977 and a number of KH-7 Gambit spy satellites from 1963 to 1967, as well as a number of Missile Defense Alarm System satellites.

Atlas-Agenas were also used to launch Agena target vehicles for several Gemini missions.

Atlas-Centaur

Atlas IIB/Centaur launch, circa 1965.

Main article: Atlas-Centaur

The Atlas-Centaur was an American expendable launch system designed and built by the General Dynamics Convair Division. It was derived from the SM-65 Atlas missile. It was used for 61 orbital launches between 1962 and 1983.

Atlas Centaur/LV-3C

Main article: Centaur (rocket stage)

Atlas G

Main article: Atlas G

Atlas H

Main article: Atlas H

Current Atlas family

Atlas Evolved Expendable Launch Vehicle (EELV) family of launch vehicles (U.S. Govt.)

Atlas launch vehicle evolution. (USAF)

• Atlas I
• Atlas II
• Atlas III
• Atlas V

The first flight of an Atlas I launched the CRRES satellite on July 25, 1990.

The Atlas II series had 63 successful flights with the last launched August 31, 2004, it is considered one of the most reliable launchers in the world.

The Atlas III was a major revised version from Atlas II, which both dropped balloon tank design, together with the 1.5 stage in previous Altas family. It is the first Atlas rocket that adopted Russian-designed RD-180 engine at the first stage.

The newest version of Atlas, the Atlas V, is an Atlas in name alone, as it contains little Atlas technology. It no longer uses balloon tanks nor 1.5 staging, but incorporates a rigid framework for its first stage booster, much like the Titan family of vehicles. The rigid fuselage is heavier, but easier to handle and transport, eliminating the need for constant internal pressure.

Ironically, given Atlas' origin as a military ICBM weapon against the Soviet Union/Russia, the Atlas III and Atlas V use Russian-designed/built NPO Energomash RD-180 engines. These engines are now prepared for production under license by Pratt & Whitney in the United States.

Atlas I

Main article: Atlas I

The first stage of the Atlas I is an Atlas H, and the second stage is a Centaur.

Atlas II

Main article: Atlas II

In May 1988, the United States Air Force chose General Dynamics (now Lockheed Martin) to develop the Atlas II. The first Atlas II launch placed a Eutelsat satellite into geostationary orbit on December 7, 1991.

Atlas III

Atlas IIIA

Main article: Atlas III

The Atlas III was used between 2000 and 2005. Atlas III was the first member of the Atlas family to use "normal" staging. Its first stage used a single RD-180 engine.

Atlas V

Main articles: Atlas V and List of Atlas V launches

The Atlas V is built in Denver, Colorado by United Launch Alliance, a joint venture of Lockheed Martin and Boeing. Future production will be shifted to Decatur, Alabama. The first Atlas V launch was on August 21, 2002.

Atlas V Heavy

SM-65A Atlas missile, 1958

Mercury-Atlas 9 at Launch Complex 14

Atlas-Agena

Atlas-Centaur

External links

• Atlas at Encyclopedia Astronautica