Atlas
Atlas I
Atlas II
Atlas III
Atlas IV
Atlas EELV
Atlas V

Atlas

Atlas began as the first US intercontinental ballistic missile. At the same time Atlas was being developed as an ICBM, the Air Force began supplying the vehicles to the National Aeronautics and Space Administration for space applications. In 1958 the first communication from space was broadcast from an orbiting Atlas with a recorded Christmas message from then President Eisenhower. Atlas went on to become a workhorse in the US space program, launching numerous government, military and civilian payloads.

Atlas was originally developed as a US Air Force weapon system. Early in its development period, Atlas made the transition to become a space booster. It has since undergone a series of improvements, including tank lengthening, engine performance increases, and system updating. The Atlas/Centaur launch vehicle, originally developed by General Dynamics for NASA, has launched a wide variety of spacecraft over two decades of reliable operations. The vehicle has been continuously upgraded to launch progressively larger and heavier spacecraft. Vehicle characteristics include: efficient pressure-stabilized stainless steel structure for high stage mass fraction; advanced inertial guidance and control hardware and software for pinpoint accuracy and flexibility; high-energy liquid hydrogen and oxygen propellant upper stage.(1)

History(2)

The history of the Atlas ballistic missile field goes back to an Air Force request for a proposal just after World War II. In October 1945, the Air Force invited industry to submit proposals for research and development of four types of missiles, the largest of which was to be a weapon with a 5,000-mile range.

By early January 1946, the Downey engineers had roughed out their ideas on two types of 5,000-mile missiles: one subsonic, winged, and jet powered; the other supersonic, ballistic, and rocket powered. A study program was proposed to the Air Force to determine which type would best serve the ultimate purpose.

In April, Convair received a contract for $1,400,000 for a year's study of under Project MX-774. Captive testing of the MX-774 research rockets began in San Diego in 1947. A year later, three MX-774's were test-launched at White Sands Proving Ground, New Mexico. The flights proved the value of three important innovations: gimbaled engines for directional control, lightweight, pressurized airframe structure, and separable nose cones. But defense cutbacks in 1947 forced the Air Force to shelve the ballistic missile in favor of other weapon programs.

The outbreak of the Korean war resulted in increased defense appropriations. The Air Force awarded Convair a new contract to study the respective merits of ballistic and glide rockets (Project MX-1593). In September 1951, Convair proposed a ballistic-type missile to incorporate design features validated by the MX-774. In 1953 (the year Convair merged with and became a division of General Dynamics), Convair division presented a plan to the Air Force for an accelerated program.

The largest propulsion problem in the early 1950's was that of ignition reliability which was, at that time, less than 50 percent. It was this factor that led to the stage-and-a-half concept, wherein all engines are ignited prior to liftoff and the two booster engines are jettisoned during flight. This characteristic, employed for missile reliability, was retained in the Atlas space launch vehicles and permits an assessment of propulsion system operation prior to commitment to actual flight.

A full go-ahead for the Atlas design was ordered in January 1955. The code name established for the Atlas weapon system was WS107A-l; the project was known at Convair division as the Model 7. In September 1955, the highest national research and development priority was assigned to the Atlas project, starting one of the largest and most complex production, testing, and construction programs ever undertaken. The first propulsion system and component tests were conducted in June 1956; the first captive and flight-test missiles were completed later the same year.

1957 witnessed the first Atlas flight test, in near operational configuration (minus sustainer engine), with a dummy nose cone. Following a successful launch, a propulsion system valve malfunction caused by excessive heating resulted in failure of one of the booster engines and the missile was destroyed by the range safety officer. Before the Atlas was destroyed, however, it experienced several seconds of violent maneuvering and tumbling, subjecting the airframe to structural loads much higher than design loads. The airframe remained intact, thus demonstrating the structural integrity of the Atlas. The second flight test missile, launched the same year, was partially successful. Then on 17 December 1957, missile 12-A, the third Atlas flight missile, made the first totally successful flight from Cape Kennedy (then Cape Canaveral). More flights followed, and in November 1958 the first full-range Atlas flight occurred, over a distance of 5, 512 nautical miles. Thus, all major design concepts were demonstrated, and development milestones passed generally ahead of or close to the original schedule.

The Atlas B had 10 successful tests between 1958 and 1959. The Atlas C used an improved guidance system and carried an operational reentry vehicle in tests conducted during 1958 and 1959. Atlas became fully operational as a weapon system in January 1959, when the Air Force declared Vandenberg Air Force Base operational. The Atlas D, the prototype for the operational system used a ground-based guidance system but carried the all-inertial guidance system that the Atlas E would use. The missile satisfied all research and development goals and became operational by August 1959. In September 1959, a crew from the Strategic Air Command marked the initial operational capability by launching an Atlas D from the Pacific Missile Range. The military deployed operationally Atlas D, E, and F as intercontinental ballistic missiles between 1960 and 1966. They phased out the Atlas D in 1964. Shortly thereafter, the Minuteman missile replaced the E and F models.

In December 1958, an entire Atlas B launched itself into an earth-orbit, carrying an Army Signal Corps instrumentation package which broadcast from outer space President Eisenhower's Christmas message to the world. This launch, Project Score, began the new launch vehicle era for the Atlas as well as providing one of the first propaganda "wins" for the United States. A series of scientific space probes and Air Force space project launches followed.

The design of the basic Atlas has changed very little over the years. The Atlas is a liquid-propellant vehicle that includes a booster section and a sustainer section. The booster section consists of two high-thrust engines which ignite at lift-off. The craft jettisons them approximately two minutes into the flight. The sustainer section has a single engine that ignites at lift-off and operates throughout the flight.

The unique 1 1/2-stage design concept of the Atlas space launch vehicle allows it to be used without an upper stage for missions requiring relatively low orbital altitudes. Any type of mission may be performed by adding available upper stages to the Atlas, such as the Agena and Centaur, the most commonly used Atlas upper stages. An additional upper stage, Burner II, permits even greater mission flexibility in the Atlas family of space launch vehicles. Burner II is a small, solid propellant upper stage containing its own guidance and control system and hot- and cold-gas reaction control engines. Hydrogen peroxide engines provide thrust for separation from the lower stage, reaction control thrust during engine firing, and velocity vernier thrust after main engine firing. Gaseous nitrogen thrusters are used for attitude control during coast, spacecraft spinup, and retrothrust at spacecraft separation.(3)

The first Centaur contract was awarded to General Dynamics by the Advanced Research Project Agency in 1958. As the first space vehicle to use liquid hydrogen fuel, Centaur necessitated development of a whole new technology. The problem of materials, handling behavior, fabrication, and testing for liquid hydrogen in a space application had to be solved not only to make Centaur a success, but also because this was the fuel planned for many elements of the Apollo program. Also in 1958, Pratt & Whitney Aircraft was awarded a contract to develop Centaur's RL-10 engines. At the same time, the US Air Force built the first large-quantity liquid hydrogen production facility. NASA's Lewis Research Center (LeRC) did much pioneering work in developing liquid hydrogen technology. LeRC first fired an experimental LO2/LH2 engine of 5,000 pounds thrust in 1953.

In 1962, LeRC was assigned technical management of Centaur. At the same time, the Centaur project was given a DX priority, the nation's most urgent aerospace priority. This reflected its importance to the Surveyor lunar exploration program and to the development of liquid hydrogen technology.

The first successful flight of Centaur atop Atlas occurred in November 1963. This was the world's first inflight ignition of a hydrogen powered vehicle. Centaur's first mission was to inject Surveyor moon landers into trans-lunar orbit. The first operational Centaur mission, in May 1966, was an outstanding achievement. Surveyor l landed within eight miles of its lunar target. Centaur performed the first successful space restart of liquid hydrogen engines in October 1966. With this flight, the Centaur R&D phase was completed.

General Dynamics was given go-ahead on the contract for the D-l Improved Centaur program in April 1969. Objectives of the D- I were to achieve increased reliability and lower recurring, mission-peculiar, and boost vehicle integration costs. The Atlas/Centaur D-IA launch vehicle was used for a variety of planetary, commercial, military, and scientific space missions. Major improvements over its predecessor, Centaur D, were incorporated into Centaur D-l. Primary changes were in avionics and payload area structures. Many former hardware functions were performed by the flight software, including a software digital autopilot. Lower cost and greater mission flexibility were achieved by this approach.(4)

Previous Evolution(5)

Atlas E(6) - The test firing of the Atlas E ICBM took place in October 1960. It met all test objectives by May 1961. The Atlas E used MA-3 engines on the booster and the sustainer. The original Atlas E vehicles, which stood deployed on alert in the 1960s, were completely overhauled for use as space launch vehicles. Known as the "Wheat Field" Atlas, refurbished Atlas E vehicles were launched from Vandenberg for NASA and USAF missions.

Atlas F - Testing of the Atlas F ICBM began in August 1961 with completion coming by the end of 1962. This marked the end of the five-year missile test program. As with the Atlas E, many were subsequently used for space launch operations. The Atlas F used MA-5 engines on the booster and the sustainer.

Atlas/Agena was a multipurpose two-stage liquid propellant rocket. It was used to place unmanned spacecraft in Earth orbit, or inject them into the proper trajectories for planetary or deep space probes. The programs in which the versatile Atlas/Agena was used included early Mariner probes to Mars and Venus, Ranger photographic missions to the Moon, the Orbiting Astronomical Observatory (OAO), and early Applications Technology Satellites (ATS). The Agena upper stage also was used as the rendezvous target vehicle for the Gemini spacecraft during this series of two-man missions in 1965-1966. In preparation for the manned lunar landings, Atlas/Agena launched lunar orbiter spacecraft which went into orbit around the Moon and took photographs of possible landing sites. The Atlas/Agena stood 36.6 meters (120 feet) high, and developed a total thrust at liftoff of approximately 1,725,824 newtons (288,000 pounds). It was last used in 1968 to launch an Orbiting Geophysical Observatory (OGO).

Atlas G(7) - Atlas G/Centaur D-IA was an improved version of the Atlas SLV-3D/Centaur D-IA configuration. Atlas G was 81 inches longer than its predecessor It also incorporated a booster thrust increase of 7,500 pounds leading to a vehicle liftoff thrust of 438,000 pounds. The vehicle became operational on the AC-62 INTELSAT V flight in June 1984. Atlas G has a constant ten-foot diameter tank up to the attach point of the interstage adapter. Total length from forward bulkhead tangency point rearward is 72.7 feet. Equipment is mounted within a pod on the side. A helium pressure system maintains structural integrity and turbopump pressure head during flight.

All Atlas engines of the Rocketdyne MA-5 propulsion system are ignited before liftoff. The two booster engines and the single sustainer engine share the same propellant tanks. The booster engines are jettisoned about two and half minutes into flight after 5.3g acceleration is attained. The sustainer burns until propellant depletion. Two small vernier rockets assist in the early roll maneuver to the desired azimuth and provide roll control during the sustainer phase. Propellants for all engines are LO2 and RP-l.

The Centaur D-lA, used in conjunction with Atlas G, incorporates the following improvements: elimination of hydrogen peroxide boost pumps in the propellant supply system; replacement of hydrogen peroxide reaction control system with an equivalent hydrazine system; incorporation of a silver throat cast insert in the Pratt & Whitney engines (new designation: RL 10A-3-3A).

The Atlas G/Centaur had the capability of launching spacecraft weighing 2,360 kg to geosynchronous altitude from the Eastern Test Range (ETR) at Cape Canaveral, Florida. As of late 1986, General Dynamics was under contract to deliver Atlas/Centaur vehicles through AC-68, which extended production into 1987. Firm launches were scheduled into 1987, with new launch dates available in 1989.

Atlas H(8) - The Atlas H booster, a radio-guided version of the Atlas that boosts Centaur, was used to launch US government missions from the Western Test Range (WTR) at Vandenberg AFB. California. The Atlas H weighed 132,723 kilograms at lift-off and generated 1,948 kilonewtons of thrust.

Atlas LV-3A(9) - Early space launch the LV-3A series were direct derivatives of the radio-inertial guided Series D Atlas ICBM. Each LV-3A vehicle was tailored to meet specific mission requirements. The life cycle of the LV-3A series spanned a period of approximately six years, ending in 1964.

LV-3A vehicles were superseded by the standardized SLV-3. Most of these early space boosters (the LV-3 series) were modified versions of Series D weapon system vehicles, each adapted to its mission requirements. To satisfy each separate mission requirement, these space launch vehicles required individual tailoring of the vehicle structure and subsystems. Some required only minor changes-some required significant modifications. Lead times were necessarily long due to this program tailoring. Program realignments and cancellations caused extensive launch - vehicle storage or re-allocation which, in turn, resulted in launch-vehicle modification due to updating and/or mission-peculiar requirements. This detracted from the inherent flexibility, reliability, and low cost of the Atlas.

On 20 February 1962, the free world's first earth-orbiting Astronaut, Colonel John Glenn, was placed in orbit by an Atlas LV-3B, the first of four such manned flights. Mercury program launch vehicles, designated the LV-3B series, were man-rated derivations of the Atlas D used for the first American manned orbital missions. The Mercury program hardware -- both launch vehicle and spacecraft -- performed so successfully that two LV-3B vehicles remained in the inventory after all Mercury program objectives were achieved. The success of the much-heralded Mercury Program was typical of the reliability achievements of the space programs in which the Atlas was a participant.

LV-3C vehicles launched Centaur vehicles, including the Surveyor I lunar soft-landing mission. These vehicles were constant 10-foot-diameter tank derivatives of the Atlas D, with the guidance system removed and the guidance pod shortened. Atlas vehicles with a Centaur second stage use the all-inertial guidance system on-board the Centaur.

Atlas SLV-3(10) - The increasing demand for space launch vehicles for a broad variety of US Air Force and NASA programs, coupled with the very high reliability which these programs demand, led to the decision to develop a standard space launch vehicle with improved countdown and flight reliability, increased flexibility for mission assignments, shorter launch-site turnaround time, and lower cost. This decision resulted in a contract awarded in 1962 for the design and production of the Alias SLV-3.

Atlas has a tapered forward tank section for use with small-diameter second stages, or a cylindrical forward section (10-foot diameter mating ring) for use with the 10-foot diameter Centaur upper stage. SLV-3 and SLV-3A are of the tapered-tank configuration. SLV-3C had the cylindrical forward tank, as did the LV-3C and SLV-3(0AO) which are no longer in production. An Agena second stage can be used for large-diameter payloads by utilizing the SLV-3B (systems from SLV-3A; tank from SLV-3C) and the OAO fairing system.

Atlas SLV-3A(11) - By early 1965, growing payload requirements dictated the development of space boosters with increased performance characteristics. Convair division submitted proposals to the Air Force for a number of uprated Atlas configurations. Each of these proposed configurations was based on extending the length (and therefore propellant capacity) of the Atlas monocoque tanks, increasing the engine thrust, and reducing overall vehicle weight. As the result of these proposals, contractual authorization was received for design, development, and fabrication of two uprated Atlas space launch vehicle configurations - the SLV-3A and the SLV-3C - to provide increased performance capability for Atlas/Agena and Atlas/Centaur missions, respectively. The first SLV-3A and SLV-3C were delivered to the Air Force in 1967.

SLV-3A vehicles were improved-performance versions of SLV-3, featuring an elongated tank (117-inch extension) and an uprated propulsion system.

The airframe is composed of two major sections: the sustainer or tank section and the booster section. The sustainer section consists of the fuel tank, liquid oxygen tank, and the pods. The sustainer and vernier engines are mounted on this structure. The booster section is composed of the thrust cylinder, engine nacelles, heat shield, and fairings. The booster engines are mounted in this section. The propellant tank is the primary structure of the sustainer section. It is a thin-wall, fully monocoque-structure pressure vessel, deriving its rigidity from internal pressurization. The tank body of the SLV-3 is a resistance-welded structure of corrosion-resistant stainless steel sheets (skins) which vary in thickness from 0.048 to 0.015 in.

SLV-3A maintained the same tank shape as the SLV-3 at its forward and aft ends. However, additional skin sections are welded into the cylindrical section of the tank to make the total tank length 117 inches longer than the SLV-3. The intermediate bulkhead was positioned such that the fuel/oxidizer ratio remained the same for both vehicles. Propellant capacity of SLV-3A was increased approximately 48,000 pounds over the SLV-3 by the increased oxidizer and fuel tank volumes.

The LV-3C was superseded by the uprated and standardized SLV-3C, which had a 51-inch longer propellant tank than LV-3C and the same uprated propulsion system as the SLV-3A. SLV-3C had a different forward-tank shape than the standard SLV-3. Like the LV-3C, the SLV-3C had a constant 10-foot-diameter tank to the forward mating ring, and an ellipsoidal forward bulkhead. The cylindrical tank section of SLV-3C was 51 inches longer than LV-3C. The intermediate bulkhead was relocated (forward) to retain the propellant ratio. Approximately 21,000 pounds more propellants were accommodated by the SLV-3C than the LV-3C.

Atlas SLV-3D

Current Capabilities

Recognizing the trend toward larger and heavier spacecraft designs, General Dynamics in 1986 began evaluating an Atlas K/Centaur with increased performance and a 4.0 meter diameter fairing.(12)

The Atlas-Centaur presently has a lift capacity to LEO of about 13,300 pounds or about 5,100 pounds to geosynchronous transfer orbit. The Atlas-Centaur II is to have an ability to launch 16,150 pounds to LEO, or about 6,100 pounds to geosynchronous transfer orbit. This performance enhancement of almost 3,000 pounds to LEO is to be achieved by increasing the thrust of the booster engines 10 percent, stretching the Atlas propellant tanks 9 feet, and stretching the Centaur tanks 3 feet.(13)

Atlas E

Atlas space boosters launched by the Air Force at Vandenberg AFB are modified ICBMs that were removed from operational use in 1965 and stored at Norton AFB, CA. The boosters are shipped to Vandenberg AFB, CA, for modification and launch by General Dynamics Space Systems Division as needed. Atlas E is capable of boosting a 4,000-pound payload to a 450-nmi orbit. Atlas E is 67 feet long, and 92 feet long with a payload shroud. The Atlas is 10 feet in diameter, with a payload fairing diameter of 7 feet. Weight at liftoff is 278,000 pounds.

Atlas E is a stage-and-a-half, liquid-fueled rocket consisting of a cluster of three Rocketdyne MA-3 engines (two boosters and one sustainer) and two small vernier engines. The propellant is a combination of liquid oxygen and RP-1, a highly refined kerosene. All engines are ignited on the ground and brought up to approximately full thrust before vehicle launch. The Atlas E provides a total thrust of from 388,000 to 392,000 pounds.

All Atlas engines are ignited prior to liftoff. At approximately 2 minutes into the flight the two booster engines are jettisoned and the sustainer engine continues to burn until cutoff at approximately 5 minutes 21 seconds into flight, followed by payload separation at 5 minutes 46 seconds. An airborne autopilot programmer in the launch vehicle flight control system provides preprogrammed steering and backup discrete commands. The General Electric Radio Tracking System (GERTS) ground system acquires the vehicle at approximately liftoff + 85 seconds and performs the guidance function by means of the launch vehicle's pulse beacon decoder.

References

1. General Dynamics Space Systems Division, Atlas Centaur Mission Planners Guide, (April 1983, Revised November 1986), Arlington, Virginia and San Diego, California.

2. Adapted from: General Dynamics Convair Division, Atlas Space Launch Vehicle Systems Summary, GDC-BGJ67-001, February 1967;

Air Command and Staff College (Lt Col Curtis D. Cochran, Lt Col Dennis M. Gorman, Maj Joseph D. Dumoulin {editors}), Space Handbook - AU-18, (Air University Press, Maxwell Air Force Base, Alabama, January 1985); and