Atlas is a family of US missiles and space

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 ...

s that originated with the SM-65 Atlas. The Atlas

intercontinental ballistic missile An intercontinental ballistic missile (ICBM) is a ballistic missile with a range (aeronautics), range greater than , primarily designed for nuclear weapons delivery (delivering one or more Thermonuclear weapon, thermonuclear warheads). Conven ...

(ICBM) program was initiated in the late 1950s under the Convair Division of

General Dynamics General Dynamics Corporation (GD) is an American publicly traded aerospace and defense corporation headquartered in Reston, Virginia. As of 2020, it was the fifth largest defense contractor in the world by arms sales and fifth largest in the Unit ...

. Atlas was a liquid propellant rocket burning

RP-1 RP-1 (Rocket Propellant-1 or Refined Petroleum-1) and similar fuels like RG-1 and T-1 are highly refined kerosene formulations used as rocket fuel. Liquid-fueled rockets that use RP-1 as fuel are known as kerolox rockets. In their engines, RP- ...

kerosene fuel with

liquid oxygen Liquid oxygen, sometimes abbreviated as LOX or LOXygen, is a clear cyan liquid form of dioxygen . It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an application which is ongoing. Physical ...

in three engines configured in an unusual "stage-and-a-half" or "parallel staging" design: two outboard booster engines were jettisoned along with supporting structures during ascent, while the center sustainer engine, propellant tanks and other structural elements remained connected through propellant depletion and engine shutdown. The Atlas name was originally proposed by Karel Bossart and his design team working at Convair on project MX-1593. Using the name of a mighty Titan from Greek mythology reflected the missile's place as the biggest and most powerful at the time. It also reflected the parent company of Convair, the

Atlas Corporation The Atlas Corporation is an American investment firm that was formed in 1928. History Atlas corporation was formed in 1928, in a merger of the United Corporation, an investment firm started in 1923 with $40,000, with Atlas Utilities and Investo ...

. The missiles saw only brief ICBM service, and the last squadron was taken off operational alert in 1965. However, from 1962 to 1963 Atlas boosters launched the first four US

astronaut An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a List of human spaceflight programs, human spaceflight program to serve as a commander or crew member of a spa ...

s to

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

the Earth (in contrast to the preceding two Redstone suborbital launches). The

Atlas-Agena The Atlas-Agena was an American expendable launch system derived from the SM-65 Atlas missile. It was a member of the Atlas (rocket family), Atlas family of rockets, and was launched 109 times between 1960 and 1978. It was used to launch the first ...

and

Atlas-Centaur The Atlas-Centaur was a United States expendable launch vehicle derived from the SM-65 Atlas D missile. The vehicle featured a Centaur (rocket stage), Centaur upper stage, the first such stage to use high-performance liquid hydrogen as fuel. La ...

satellite launch vehicles were also derived directly from the original Atlas. The Atlas-Centaur was evolved into the Atlas II, various models of which were launched 63 times between 1991 and 2004. There were only six launches of the succeeding Atlas III, all between 2000 and 2005. The

Atlas V Atlas V is an expendable launch system and the fifth major version in the Atlas (rocket family), Atlas launch vehicle family. It was developed by Lockheed Martin and has been operated by United Launch Alliance (ULA) since 2006. Primarily used to ...

is still in service, with launches planned into the mid 2020s. More than 300 Atlas launches have been conducted from

Cape Canaveral Space Force Station Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida. Headquartered at the nearby Patrick Space Force Base, the sta ...

in Florida and 285 from

Vandenberg Space Force Base Vandenberg Space Force Base , previously Vandenberg Air Force Base, is a United States Space Force Base in Santa Barbara County, California. Established in 1941, Vandenberg Space Force Base is a space launch base, launching spacecraft from the ...

in California.

Launch vehicles based on original Atlas ICBM

The Atlas was used as an

expendable launch system An expendable launch system (or expendable launch vehicle/ELV) is a launch vehicle that can be launched only once, after which its components are destroyed during reentry or impact with Earth, or discarded in space. ELVs typically consist of s ...

, with both the Agena and Centaur upper stages, for the

Mariner A sailor, seaman, mariner, or seafarer is a person who works aboard a watercraft as part of its crew, and may work in any one of a number of different fields that are related to the operation and maintenance of a ship. While the term ''sailor' ...

space probes used to explore Mercury,

Venus Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...

, and

Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...

(1962–1973); and to launch ten of the

Mercury program Project Mercury was the first human spaceflight program of the United States, running from 1958 through 1963. An early highlight of the Space Race, its goal was to put a man into Earth orbit and return him safely, ideally before the Soviet Un ...

missions (1962–1963).

SM-65 Atlas missile

The first successful test launch of an SM-65 Atlas missile was on 17 December 1957. Approximately 350 Atlas missiles were built. The Atlas boosters would collapse under their own weight if not kept pressurized with nitrogen gas in the tanks when devoid of propellants. The Atlas booster was unusual in its use of "balloon" tanks. The rockets 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. In order to save weight they were not painted and needed a specially designed oil to prevent rust. This was the original use of

WD-40 WD-40 (Water Displacement, 40th formula) is an American manufacturer and the trademark of a penetrating oil manufactured by the WD-40 Company based in San Diego, California. Its formula was invented for the Rocket Chemical Company in 1953, ...

water displacement oil. The SM-65 Atlas was used as a first stage for satellite launch vehicles for half a century. 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.

SM-65B Atlas SCORE launch

Early Atlas rockets were also built specifically for non-military uses. On 18 December 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 A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a Transponder (satellite communications), transponder; it creates a communication channel between a source transmitter and a Rad ...

, and the first test of any satellite for direct practical applications." The communications payload was placed into

low Earth orbit A low Earth orbit (LEO) is an geocentric orbit, orbit around Earth with a orbital period, period of 128 minutes or less (making at least 11.25 orbits per day) and an orbital eccentricity, eccentricity less than 0.25. Most of the artificial object ...

on Atlas serial number 10B without an upper stage. Atlas 10B/SCORE, at was the heaviest artificial object then in orbit, the first voice relay satellite, and the first human-made object in space easily visible to the naked eye due to the large, mirror-polished stainless steel tank. This was the first flight in what would be a long career for the Atlas as a satellite launcher.

Atlas-D based launchers

Atlas D missile-derived SLV-3s were used for

al launches with the RM-81 Agena and

Centaur A centaur ( ; ; ), occasionally hippocentaur, also called Ixionidae (), is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse that was said to live in the mountains of Thessaly. In one version o ...

upper stages. The modified Atlas LV-3B was used for the orbital element of

Project Mercury Project Mercury was the first human spaceflight program of the United States, running from 1958 through 1963. An early highlight of the Space Race, its goal was to put a man into Earth orbit and return him safely, ideally before the Soviet Un ...

, launching four crewed

Mercury spacecraft Project Mercury was the first human spaceflight program of the United States, running from 1958 through 1963. An early highlight of the Space Race, its goal was to put a man into Earth orbital spaceflight, orbit and return him safely, ideally ...

into

. Atlas D launches were conducted from Cape Canaveral Air Force Station, at Launch Complexes 11, 12, 13 and 14, and Vandenberg AFB Launch Complex 576. Two suborbital stage and a half vehicles were used during Project FIRE as

sounding rocket A sounding rocket or rocketsonde, sometimes called a research rocket or a suborbital rocket, is an instrument-carrying rocket designed to take measurements and perform scientific experiments during its sub-orbital flight. The rockets are often ...

s. By 1979, Atlas space launcher variants had been whittled down to just the Atlas-Centaur and some refurbished ICBMs. The launch rate of Atlases decreased in the 1980s due to the advent of the

Space Shuttle The Space Shuttle is a retired, partially reusable launch system, reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. ...

, but Atlas launches continued until 2004, when the last "classic" Atlas with balloon tanks and the jettisonable booster section launched a comsat for the Air Force.

Mercury program

Mercury-Atlas 9 at Cape Canaveral Air Force Station Launch Complex 14, Launch Complex 14 Atlas boosters were also used for the last four crewed

missions, the first United States crewed space program. On February 20, 1962, it launched Mercury-Atlas 6, ''Friendship 7'', which made three Earth orbits carrying

John Glenn John Herschel Glenn Jr. (July 18, 1921 – December 8, 2016) was an American Marine Corps aviator, astronaut, businessman, and politician. He was the third American in space and the first to orbit the Earth, circling it three times in 1 ...

, the first United States

to orbit the Earth. Identical Atlas boosters successfully launched three more crewed Mercury orbital missions from 1962 to 1963. Atlas saw the beginnings of its "workhorse" status during the Mercury-Atlas missions, which resulted in Lt. Col. John H. Glenn Jr. becoming the first American to orbit the Earth in 1962. Atlas was also used throughout the mid-1960s to launch the

Agena Target Vehicle The Agena Target Vehicle (; ATV), also known as Gemini-Agena Target Vehicle (GATV), was an uncrewed spacecraft used by NASA during its Gemini program to develop and practice orbital space rendezvous and docking techniques, and to perform large ...

s used during the Gemini program.

Atlas-Agena

Beginning in 1960, the Agena

upper stage A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''stages'', each of which contains its own Rocket engine, engines and Rocket propellant, propellant. A ''tandem'' or ''serial'' stage is mounted on top of anoth ...

, powered by hypergolic propellant, was used extensively on Atlas launch vehicles. The

United States Air Force The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...

, NRO and CIA used them to launch SIGINT satellites. NASA used them in the

Ranger program The Ranger program was a series of uncrewed space missions by the United States in the 1960s whose objective was to obtain the first close-up images of the surface of the Moon. The Ranger spacecraft were designed to take images of the lunar su ...

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 vehicle The Agena Target Vehicle (; ATV), also known as Gemini-Agena Target Vehicle (GATV), was an uncrewed spacecraft used by NASA during its Gemini program to develop and practice orbital space rendezvous and docking techniques, and to perform large ...

s used for the later

space rendezvous Space is a three-dimensional continuum containing positions and directions. In classical physics, physical space is often conceived in three linear dimensions. Modern physicists usually consider it, with time, to be part of a boundless ...

practice missions of Gemini was launched on an Atlas rocket.

Atlas-Centaur

The Atlas-Centaur was an

derived from the SM-65D Atlas missile. Launches were conducted from two pads of the Launch Complex 36 at

Cape Canaveral Air Force Station Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida. Headquartered at the nearby Patrick Space Force Base, the sta ...

, Florida. The Atlas' engines were upgraded and the structure reinforced for the large upper stage, along with elongated propellant tanks. The first launch attempt of an Atlas-Centaur in May 1962 failed, the rocket exploding after take-off. Footage of this was shown in the penultimate shot of the 1982 art film '' Koyaanisqatsi'', directed by

Godfrey Reggio Godfrey Reggio (born 1940) is an American director of experimental documentary films. Life Reggio was born in New Orleans in 1940 to a Catholic family. He left home at age 14 to join the Catholic Christian Brotherhood. He became a monk, and spe ...

. Beginning in 1963, the

liquid hydrogen Liquid hydrogen () is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecule, molecular H2 form. To exist as a liquid, H2 must be cooled below its critical point (thermodynamics), critical point of 33 Kelvins, ...

-fueled

upper stage was also used on dozens of Atlas launches.

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

launched the Surveyor program lunar lander spacecraft and most of the Mars-bound

Mariner program The Mariner program was conducted by the American space agency NASA to explore other planets. Between 1962 and late 1973, NASA's Jet Propulsion Laboratory (JPL) designed and built 10 robotic interplanetary probes named Mariner to explore the in ...

spacecraft with Atlas-Centaur launch vehicles.

Atlas E/F

Following retirement as an ICBM, the Atlas-E, along with the Atlas-F, were refurbished for

al launches. The last Atlas E/F spacecraft launch was conducted on 24 March 1995, using a rocket which had originally been built as an Atlas-E. The last Atlas E/F launch to use a rocket which had originally been built as an Atlas-F was conducted on 23 June 1981. Atlas E/F was used to launch the Block I series of GPS satellites from 1978 to 1985. The last refurbished Atlas-F vehicle was launched from Vandenberg AFB in 1995 carrying a satellite for the Defense Meteorological Satellite Program.

Tabulated

RD-180 era

Atlas III

The first stage of the Atlas III discontinued the use of three engines and 1.5 staging in favor of a single Russian-built Energomash RD-180 engine, while retaining the stage's balloon tank construction. The Atlas III continued to use the Centaur upper stage, available with single or dual RL10 engines.

Atlas V

The Atlas V, currently in service, was developed by

Lockheed Martin The Lockheed Martin Corporation is an American Arms industry, defense and aerospace manufacturer with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta on March 15, 1995. It is headquartered in North ...

as part of the US Air Force Evolved Expendable Launch Vehicle (EELV) program. The first was launched on August 21, 2002. In 2006, operation was transferred to United Launch Alliance (ULA), a joint venture between Lockheed Martin and

Boeing The Boeing Company, or simply Boeing (), is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, and missiles worldwide. The company also provides leasing and product support s ...

. Lockheed Martin continued to market the Atlas V to commercial customers until September 2021, when it announced that the rocket will be retired after fulfilling the remaining 29 launch contracts. Atlas V is built in

Decatur, Alabama Decatur () is the largest city and county seat of Morgan County, Alabama, Morgan County (with a portion also in Limestone County, Alabama, Limestone County) in the U.S. state of Alabama. Nicknamed "The River City," it is located in North Alabam ...

, and maintains two launch sites: Space Launch Complex 41 at

and Space Launch Complex 3-E at

. The Atlas V's first stage is called the Common Core Booster (CCB), which continues to use the Energomash RD-180 introduced in the Atlas III, but employs a rigid framework instead of balloon tanks. The rigid fuselage is heavier, but easier to handle and transport, eliminating the need for constant internal pressure. Up to five

Aerojet Rocketdyne Aerojet Rocketdyne is a subsidiary of American Arms industry, defense company L3Harris that manufactures rocket, Hypersonic flight, hypersonic, and electric propulsive systems for space, defense, civil and commercial applications. Aerojet traces ...

strap-on solid rocket boosters can be used to augment first stage thrust. The upper stage remains the

, powered by a single or dual Aerojet Rocketdyne RL10 engines.

RD-180 phaseout

In 2014,

US Congress The United States Congress is the legislature, legislative branch of the federal government of the United States. It is a Bicameralism, bicameral legislature, including a Lower house, lower body, the United States House of Representatives, ...

passed legislation restricting the purchase and use of the Russian-supplied RD-180 engine used on the first stage booster of the Atlas V. Formal study contracts were issued in June 2014 to a number of US rocket engine suppliers. In September 2014, ULA announced that it had entered into a partnership with

Blue Origin Blue Origin Enterprises, L.P. is an American space technology company headquartered in Kent, Washington. The company operates the suborbital New Shepard rocket and the heavy-lift New Glenn rocket. In addition to producing engines for its own ...

to develop the

BE-4 The BE-4 (Blue Engine 4) is a liquid rocket engine developed by Blue Origin. It uses an oxygen-rich, liquefied natural gas, liquefied methane fuel and operates on a staged combustion cycle. The BE-4 produces of thrust at sea level. Developmen ...

LOX/

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...

engine to replace the RD-180 on the new Vulcan rocket. The new stage and engine first flew in 2024. In December 2014, legislation to prevent the award of further military launch contracts to vehicles that use Russian-made engines was approved by the

. The bill allows ULA to continue to use the 29 RD-180 engines already on order at the time. In September 2021, ULA announced that Atlas V will be retired after they fulfill their remaining launch contracts, and that all remaining RD-180s for the remaining rockets have been delivered.

Formerly proposed launch vehicles

Prior to the April 2015 announcement of the Vulcan launch vehicle, during the first decade since ULA was formed from Lockheed Martin and Boeing, there were a number of proposals and concept studies of future launch vehicles. None were subsequently funded for full-up development. Two of those concepts were the ''Atlas V Heavy'' and the ''Atlas Phase 2''.

Atlas V Heavy

The ''Atlas V Heavy'' was a ULA concept proposal that would have used three Common Core Booster (CCB) stages strapped together to provide the capability necessary to lift a payload to

. ULA stated that approximately 95% of the hardware required for the Atlas HLV had already been flown on the Atlas V single-core vehicles. A 2006 report, prepared by RAND Corporation for the

Office of the Secretary of Defense The Office of the Secretary of Defense (OSD) is a headquarters-level staff of the United States Department of Defense. It is the principal civilian staff element of the U.S. Secretary of Defense, and it assists the Secretary in carrying out au ...

, stated that Lockheed Martin had decided not to develop an Atlas V heavy-lift vehicle (HLV). The report recommended for the Air Force and the National Reconnaissance Office to "determine the necessity of an EELV heavy-lift variant, including development of an Atlas V Heavy", and to "resolve the RD-180 issue, including coproduction, stockpile, or U.S. development of an RD-180 replacement." The lifting capability of the Atlas V HLV was to be roughly equivalent to the Delta IV Heavy. The latter utilizes RS-68 engines developed and produced domestically by Pratt & Whitney

Rocketdyne Rocketdyne is an American rocket engine design and production company headquartered in Canoga Park, California, Canoga Park, in the western San Fernando Valley of suburban Los Angeles, California, Los Angeles, in southern California. Rocketdyne ...

.Atlas V EELV – Lockheed-Martin Retrieved on 2008-02-08
Globalsecurity.org. Retrieved on 2011-11-19.

Atlas V Phase 2

After December 2006, with the merger of Boeing and Lockheed-Martin space operations into United Launch Alliance, the Atlas V program gained access to the tooling and processes for diameter stages used on Delta IV. An 18 ft diameter stage could have conceivably accepted dual RD-180 engines. The resulting conceptual heavy-lift vehicle was called ''"Atlas Phase 2"'' or "PH2" in the 2009 Augustine Report. An Atlas V PH2-Heavy (three 5 m stages in parallel; six RD-180s) along with Shuttle-derived, Ares V and Ares V Lite, were considered as a possible heavy lifter concept for use in future space missions in the Augustine Report. The Atlas PH2 HLV concept vehicle would have notionally been able to launch a payload mass of approximately into an orbit of 28.5 degree

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

. The concept did not proceed onto full development, and was never built.

References

External links

Atlas at Encyclopedia Astronautica
{{DEFAULTSORT:Atlas (Rocket Family) 1957 in spaceflight 1961 in spaceflight 1962 in spaceflight United Launch Alliance space launch vehicles NASA space launch vehicles Rocket families Convair General Dynamics United Launch Alliance Lockheed Martin