Misplaced Pages

#873126

57-563: Atlas II was a member of the Atlas family of launch vehicles , which evolved from the successful Atlas missile program of the 1950s. The Atlas II was a direct evolution of the Atlas ;I , featuring longer first-stage tanks, higher-performing engines, and the option for strap-on solid rocket boosters. It was designed to launch payloads into low Earth orbit , geosynchronous transfer orbit or geosynchronous orbit. Sixty-three launches of

114-465: A Medium fairing could move the most payload to orbit, as that fairing was the lightest. Similarly, rockets with Large or Extended fairings suffered slight hits to their payload capacity. Atlas II was developed into three versions. The original Atlas II was based on the Atlas I and its predecessors . Its lengthened propellant tanks and improved electronics over the Atlas I offered better performance. It

171-550: A common bulkhead, which helped keep mass down. Centaur II was 10.1 m (33 ft) long, carrying almost 17 t (37,000 lb) of fuel. The stage also featured 12 27 N (6.1 lbf) hydrazine thrusters to orient the stage and settle the propellants prior to engine ignition. For the IIA and IIAS versions, Atlas used the Centaur IIA variant which featured 2 RL-10A -4 engines, providing higher thrust and efficiency over

228-551: A comsat for the Air Force. Atlas boosters were also used for the last four crewed Project Mercury missions, the first United States crewed 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 crewed Mercury orbital missions from 1962 to 1963. Atlas saw

285-543: A half vehicles were used during Project FIRE as sounding rockets . 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 , but Atlas launches continued until 2004, when the last "classic" Atlas with balloon tanks and the jettisonable booster section launched

342-531: A long-duration, low-boiloff extension of existing ULA Centaur and Delta Cryogenic Second Stage (DCSS) technology for the Vulcan launch vehicle. Long-duration ACES technology is intended to support geosynchronous , cislunar , and interplanetary missions. Another possible application is as in-space propellant depots in LEO or at L 2 that could be used as way-stations for other rockets to stop and refuel on

399-484: 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 70 metric tons into an orbit of 28.5 degree- inclination . The concept did not proceed onto full development, and was never built. RL-10A The RL10 is a liquid-fuel cryogenic rocket engine built in

456-473: A record for an expander cycle engine of this type. Chugging was eliminated by injector and propellant feed system modifications that control the pressure, temperature and flow of propellants. In 2010, the throttling range was expanded further to a 17.6:1 ratio, throttling from 104% to 5.9% power. In 2012 NASA joined with the US Air Force (USAF) to study next-generation upper stage propulsion, formalizing

513-665: Is built in Decatur, Alabama , and maintains two launch sites: Space Launch Complex 41 at Cape Canaveral Space Force Station and Space Launch Complex 3-E at Vandenberg Space Force Base . 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

570-567: Is heavier, but easier to handle and transport, eliminating the need for constant internal pressure. Up to five Aerojet Rocketdyne strap-on solid rocket boosters can be used to augment first stage thrust. The upper stage remains the Centaur , powered by a single or dual Aerojet Rocketdyne RL10 engines. In 2014, US Congress passed legislation restricting the purchase and use of the Russian-supplied RD-180 engine used on

627-780: Is it worthwhile to build an RL10 replacement?" From the study, NASA hoped to find a less expensive RL10-class engine for the upper stage of the Space Launch System (SLS). USAF hoped to replace the Rocketdyne RL10 engines used on the upper stages of the Lockheed Martin Atlas V and the Boeing Delta IV Evolved Expendable Launch Vehicles (EELV) that were the primary methods of putting US government satellites into space. A related requirements study

SECTION 10

#1732773270874

684-657: 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 in Florida and 285 from Vandenberg Space Force Base in California. The Atlas was used as an expendable launch system , with both the Agena and Centaur upper stages, for the Mariner space probes used to explore Mercury , Venus , and Mars (1962–1973); and to launch ten of

741-640: The Centaur upper stage of an Atlas launch vehicle. The launch was used to conduct a heavily instrumented performance and structural integrity test of the vehicle. Multiple versions of this engine have been flown. The S-IV of the Saturn I used a cluster of six RL10A-3S, a version which was modified for installation on the Saturn and the Titan program included Centaur D-1T upper stages powered by two RL10A-3-3 Engines. Four modified RL10A-5 engines were used in

798-556: The Launch Complex 36 at Cape Canaveral Air Force Station , 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 . Beginning in 1963,

855-588: The MA-5A and shared a common gas generator . They burned for approximately 164 seconds before being jettisoned, when acceleration reached approximately 5.0–5.5  g . The central sustainer engine on the first stage, an RS-56-OSA, would burn for an additional 125 seconds after their jettison. It featured better efficiency at high altitudes than the RS-56-OBAs. The first stage also had the option to be fitted with 4 Castor 4A solid rocket boosters as part of

912-703: The McDonnell Douglas DC-X . A flaw in the brazing of an RL10B-2 combustion chamber was identified as the cause of failure for the 4 May 1999 Delta III launch carrying the Orion-3 communications satellite . The DIRECT version 3.0 proposal to replace Ares I and Ares V with a family of rockets sharing a common core stage recommended the RL10 for the second stage of the J-246 and J-247 launch vehicles. Up to seven RL10 engines would have been used in

969-532: The Mercury program missions (1962–1963). 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

1026-639: 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. The Atlas-Centaur was an expendable launch system derived from the SM-65D Atlas missile. Launches were conducted from two pads of

1083-505: The Space Launch System and the Centaur V of the Vulcan rocket. The expander cycle that the engine uses drives the turbopump with waste heat absorbed by the engine combustion chamber, throat, and nozzle. This, combined with the hydrogen fuel, leads to very high specific impulses ( I sp ) in the range of 373 to 470 s (3.66–4.61 km/s) in a vacuum. Mass ranges from 131 to 317 kg (289–699 lb) depending on

1140-654: The United States by Aerojet Rocketdyne that burns cryogenic liquid hydrogen and liquid oxygen propellants. Modern versions produce up to 110 kN (24,729 lb f ) of thrust per engine in vacuum. Three RL10 versions are in production for the Centaur upper stage of the Atlas V and the DCSS of the Delta IV . Three more versions are in development for the Exploration Upper Stage of

1197-635: 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. Following retirement as an ICBM, the Atlas-E, along with the Atlas-F , was refurbished for orbital launches. The last Atlas E/F spacecraft launch

SECTION 20

#1732773270874

1254-712: 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 . After December 2006, with

1311-597: 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 . The Atlas V Heavy was a ULA concept proposal that would have used three Common Core Booster (CCB) stages strapped together to provide

1368-777: The Atlas II vehicle, primarily to launch Defense Satellite Communications System payloads under the Medium Launch Vehicle II (MLV-II) program. Additional commercial and U.S. Government sales resulted in production increases leading to greater than 60 vehicles being produced and launched. Atlas II was developed from the Atlas I and featured numerous upgrades over that vehicle. Atlas II was launched from Launch Complex 36 at Cape Canaveral Space Force Station in Florida as well as Space Launch Complex 3E at Vandenberg Space Force Base in California. All launches were successful. Atlas II provided higher performance than

1425-500: The Atlas II: The Medium variant was not commonly used for Atlas II but was often used in earlier Atlas rockets. The Large and Extended fairing options were also later used on the Atlas III and Atlas V rockets. For the Atlas V, these fairings were part of the 400-series of that rocket, and a further extended option ("Extra Extended") was available. The 4-meter Atlas fairing last flew in 2022. Atlas II rockets flying with

1482-546: The Atlas as a satellite launcher. Atlas D missile-derived SLV-3s were used for orbital launches with the RM-81 Agena and Centaur upper stages. The modified Atlas LV-3B was used for the orbital element of Project Mercury , launching four crewed Mercury spacecraft into low Earth orbit . 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

1539-474: The Atlas ;II, IIA and IIAS models were carried out between 1991 and 2004; all sixty-three launches were successes, making the Atlas II a highly reliable space launch system. The Atlas line was continued by the Atlas III , used between 2000 and 2005, and the Atlas V , which is still in use as of 2024. In May 1988, the US Air Force chose General Dynamics (now Lockheed Martin ) to develop

1596-498: The Centaur V flying on the Vulcan rocket will only utilize two RL-10 engines. The Integrated Apogee Boost Stage was an optional upper stage, used only as an apogee kick stage when launching Defense Satellite Communications System III satellites (which were designed to be delivered directly to geostationary orbit using the Transtage or Inertial Upper Stage , and so were not capable of performing their own circularization burn at

1653-422: The Centaur upper stage. Centaur II featured 2 RL-10A -3-3A engines, burning liquid hydrogen and liquid oxygen. It featured propellant tanks 0.9 meters longer than its predecessor, Centaur I, giving the stage more propellant and therefore higher performance. Due to the super cold propellants inside Centaur, foam insulation was installed onto the outer metal skin on the stage to help mitigate propellant boiloff inside

1710-598: The Defense Meteorological Satellite Program. 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. The Atlas V, currently in service, was developed by Lockheed Martin as part of

1767-518: The IIAS version, each providing an additional 478.3 kN (107,500 lb f ) of thrust for 56 seconds. The first two boosters were ignited at liftoff, and the other two were ignited after the first two burnt out. Both pairs of boosters were jettisoned shortly after their respective burns. The second stage of Atlas II, the Centaur II, was the result of over 3 decades of flights and enhancements of

Atlas II - Misplaced Pages Continue

1824-565: The RL-10A-3-3A. The two engines could be fitted with extendable nozzles, which would provide an increase in efficiency and therefore performance. Centaur II was further refined to create the Centaur III, which flew on the Atlas III and continues to fly today on the Atlas V . Atlas II was the final Atlas rocket that only had a dual-engine Centaur available, future rockets had the option for one or two RL-10 engines on Centaur. However,

1881-548: 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 . 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

1938-532: The agencies' joint interests in a new upper stage engine to replace the Aerojet Rocketdyne RL10. "We know the list price on an RL10. If you look at cost over time, a very large portion of the unit cost of the EELVs is attributable to the propulsion systems, and the RL10 is a very old engine, and there's a lot of craftwork associated with its manufacture. ... That's what this study will figure out,

1995-439: The apogee of their geostationary transfer orbit ) on board the Atlas II and, later, the Delta IV . It was powered by two R-4D engines and could operate on-orbit for up to twelve days before deploying its payload, allowing additional flexibility in mission planning. The IABS measured 2.9 m in diameter, and 0.68 m in length, carrying 1303 kg of propellant with a dry mass of 275 kg. Three fairing models were available for

2052-479: The award of further military launch contracts to vehicles that use Russian-made engines was approved by the US Congress . 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. Prior to

2109-769: 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 Vehicles used during the Gemini program . 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

2166-589: The capability necessary to lift 25 tonne payload to low Earth orbit . 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 , stated that Lockheed Martin had decided not to develop an Atlas V heavy-lift vehicle (HLV). The report recommended for

2223-480: The earlier Atlas I by using engines with greater thrust and longer propellant tanks for both stages. The increased thrust, engine efficiency, and propellant capacity enabled the vehicle to lift payloads of 6,100 pounds (2,767 kg) into geostationary transfer orbit (GTO), or more on later Atlas II variants. Atlas II also featured lower-cost electronics, an improved flight computer, and longer propellant tanks than its predecessor, Atlas I . The Atlas II first stage

2280-473: The early "Block I" GPS satellites . 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 , and the first test of any satellite for direct practical applications." The communications payload

2337-512: The first four US astronauts to orbit the Earth (in contrast to the preceding two Redstone suborbital launches). The Atlas-Agena and Atlas-Centaur 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 II - Misplaced Pages Continue

2394-514: 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 to develop the BE-4 LOX / methane 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

2451-529: 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 5.4 m diameter stages used on Delta IV . A 5.4 m 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

2508-714: The proposed Jupiter Upper Stage, serving an equivalent role to the Space Launch System Exploration Upper Stage . In the early 2000s, NASA contracted with Pratt & Whitney Rocketdyne to develop the Common Extensible Cryogenic Engine (CECE) demonstrator. CECE was intended to lead to RL10 engines capable of deep throttling. In 2007, its operability (with some "chugging") was demonstrated at 11:1 throttle ratios. In 2009, NASA reported successfully throttling from 104 percent thrust to eight percent thrust,

2565-407: The tank. Centaur II's foam insulation was permanently attached to the side of the stage, whereas previous versions of the stage (including Centaur I) jettisoned their insulation panels during flight. The Centaur II upper stage (along with all other Centaur variants) used a pressure-stabilized propellant tank design and cryogenic propellants . The two stainless steel propellant tanks were separated by

2622-478: The vehicle's roll. Compared to Atlas I , the Atlas II ;first stage was 2.7 m (8 ft 10 in) taller. The Atlas II was the last Atlas rocket to use the "stage-and-a-half" technique, where it ignited all 3 RS-56 engines at liftoff and then jettisoned the 2 RS-56-OBA side engines and their support structure during ascent. The two RS-56-OBA engines were integrated into a single unit called

2679-772: The version of the engine. The RL10 was the first liquid hydrogen rocket engine to be built in the United States, with development of the engine by Marshall Space Flight Center and Pratt & Whitney beginning in the 1950s. The RL10 was originally developed as a throttleable engine for the USAF Lunex lunar lander. The RL10 was first tested on the ground in 1959, at Pratt & Whitney 's Florida Research and Development Center in West Palm Beach, Florida . The first successful flight took place on November 27, 1963. For that launch, two RL10A-3 engines powered

2736-697: Was 3.05 m (10.0 ft) in diameter and 24.90 m (81.7 ft) long. The stage was powered by 3 RS-56 rocket engines (derived from the RS-27 main engine of the Delta ;II rocket) burning 156 t (344,000 lb) of RP-1 and liquid oxygen . The two booster engines were the RS-56-OBA variants (the complete assembly of both engines and the aft skirt was referred to as the MA-5A), with high thrust but moderate efficiency. The sustainer (center) engine

2793-502: Was conducted at the same time under the Affordable Upper Stage Engine Program (AUSEP). The RL10 has evolved over the years. The RL10B-2 that was used on the DCSS had improved performance, an extendable carbon-carbon nozzle, electro-mechanical gimbaling for reduced weight and increased reliability, and a specific impulse of 465.5 seconds (4.565 km/s). As of 2016, Aerojet Rocketdyne

2850-457: 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

2907-495: Was designed to work as part of the US Air Force's Medium Launch Vehicle II program. This version flew between 1991 and 1998. Atlas IIA was a derivative of the Atlas II designed to service the commercial launch market. The main improvement was the switch from the RL10 A-4 engine on the Centaur upper stage, increasing the stage's performance and the vehicle's payload capability. The IIA version flew between 1992 and 2002. Atlas IIAS

SECTION 50

#1732773270874

2964-425: Was largely identical to IIA, but added four Castor 4A solid rocket boosters to increase performance. These boosters were ignited in pairs, with one pair igniting on the ground, and the second igniting in the air shortly after the first pair separated. The "half-stage booster section would then drop off as usual. IIAS was used between 1993 and 2004, concurrently with IIA. Atlas (rocket family) The Atlas name

3021-538: 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 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

3078-407: Was placed into low Earth orbit on Atlas serial number 10B without an upper stage. Atlas 10B/SCORE, at 8,750 lb (3,970 kg) 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

3135-511: 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 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

3192-459: Was the RS-56-OSA variant, featuring much less thrust but higher efficiency at high altitudes than the booster engines. The vernier engines used on the first stage of the Atlas I (and all previous Atlas models) were replaced by a hydrazine -fueled roll control system on Atlas II. This system, mounted on the interstage between the first and second stages, utilized small thrusters to control

3249-568: Was working toward incorporating additive manufacturing into the RL10 construction process. The company conducted full-scale, hot-fire tests on an engine that had a printed main injector in March 2016. Another project by Aerojet Rocketdyne was an engine with a printed thrust chamber assembly in April 2017. As of 2009 , an enhanced version of the RL10 was proposed to power the Advanced Cryogenic Evolved Stage (ACES),

#873126