Atlas V first stage

The Atlas V first stage, the Common Core Booster (not to be confused with the Delta IV's Common Booster Core), is 3.8 m (12 ft) in diameter and 32.5 m (107 ft) in length. It is powered by one NPO Energomash RD-180 main engine burning 284,450 kg (627,100 lb) of liquid oxygen and RP-1. The booster operates for about four minutes, providing about 4 MN (900,000 lb_f) of thrust.^[14] Thrust can be augmented with up to five Aerojet AJ-60A or Northrop Grumman GEM 63 strap-on solid rocket boosters, each providing an additional 1.27 MN (290,000 lb_f) of thrust for 94 seconds.

The main differences between the Atlas V and earlier Atlas I and II family launch vehicles are:

• The first stage tanks no longer use stainless steel monocoque pressure stabilized "balloon" construction. The tanks are isogrid aluminum and are structurally stable when unpressurized.^[14]
• Accommodation points for parallel stages, both smaller solids and identical liquids, are built into first-stage structures.^[14]
• The "1.5 staging" technique is no longer used, having been discontinued on the Atlas III with the introduction of the Russian RD-180 engine.^[14]
• The main-stage diameter increased from 3.0 to 3.7 m (9.8 to 12.1 ft).^[15]

Centaur upper stage

The Centaur upper stage uses a pressure-stabilized propellant-tank design and cryogenic propellants. The Centaur stage for Atlas V is stretched 1.7 m (5 ft 7 in) relative to the Atlas IIAS Centaur and is powered by either one or two Aerojet Rocketdyne RL10A-4-2 engines, each engine developing a thrust of 99.2 kN (22,300 lb_f). The inertial navigation unit (INU) located on the Centaur provides guidance and navigation for both the Atlas and Centaur and controls both Atlas and Centaur tank pressures and propellant use. The Centaur engines are capable of multiple in-space starts, making possible insertion into low Earth parking orbit, followed by a coast period and then insertion into GTO.^[16] A subsequent third burn following a multi-hour coast can permit direct injection of payloads into geostationary orbit.^{[citation needed]}

As of 2006^[update], the Centaur vehicle had the highest proportion of burnable propellant relative to total mass of any modern hydrogen upper stage and hence can deliver substantial payloads to a high-energy state.^[17]

Payload fairing

Atlas V payload fairings are available in two diameters, depending on satellite requirements. The 4.2 m (14 ft) diameter fairing,^[18] originally designed for the Atlas II booster, comes in three different lengths: the original 9 m (30 ft) version and extended 10 and 11 m (33 and 36 ft) versions, first flown respectively on the AV-008/Astra 1KR and AV-004/Inmarsat-4 F1 missions. Fairings of up to 7.2 m (24 ft) diameter and 32.3 m (106 ft) length have been considered but were never implemented.^[11]

A 5.4 m (18 ft) diameter fairing, with an internally usable diameter of 4.57 m (15.0 ft), was developed and built by RUAG Space^[19] in Switzerland. The RUAG fairing uses carbon fiber composite construction and is based on a similar flight-proven fairing for the Ariane 5. Three configurations are manufactured to support the Atlas V: 20.7 m (68 ft), 23.4 m (77 ft), and 26.5 m (87 ft) long.^[19] While the classic 4.2 m (14 ft) fairing covers only the payload, the RUAG fairing is much longer and fully encloses both the Centaur upper stage and the payload.^[20]

Capabilities

Atlas V has flown in eleven configurations. While the design allows for other configurations, they have never been used and are not planned to be used. ^[42] Mass to LEO numbers are at an inclination of 28.5°.

All of the configurations use the Single Engine Centaur, except for the "N22". "N22" is used only on for Starliner missions, and uses Dual Engine Centaur

Launch system status

Launch cost

Before 2016, pricing information for Atlas V launches was limited. In 2010, NASA contracted with ULA to launch the MAVEN mission on an Atlas V 401 for approximately US$187 million.^[46] The 2013 cost of this configuration for the U.S. Air Force under their block buy of 36 launch vehicles was US$164 million.^[47] In 2015, the TDRS-M launch on an Atlas 401 cost NASA US$132.4 million.^[48]

Starting in 2016, ULA provided pricing for the Atlas V through its RocketBuilder website, advertising a base price for each launch vehicle configuration, which ranges from US$109 million for the 401 up to US$153 million for the 551.^[1] Each additional SRB adds an average of US$6.8 million to the cost of the launch vehicle. Customers can also choose to purchase larger payload fairings or additional launch service options. NASA and Air Force launch costs are often higher than equivalent commercial missions due to additional government accounting, analysis, processing, and mission assurance requirements, which can add US$30–80 million to the cost of a launch.^[49]

In 2013, launch costs for commercial satellites to GTO averaged about US$100 million, significantly lower than historic Atlas V pricing.^[50] However, in recent years^{[clarification needed]} the price of an Atlas V [401] has dropped from approximately US$180 million to US$109 million,^{[citation needed]} in large part due to competitive pressure that emerged in the launch services marketplace during the early 2010s. ULA CEO Tory Bruno stated in 2016 that ULA needs at least two commercial missions each year in order to stay profitable going forward.^[51] ULA is not attempting to win these missions on purely lowest purchase price, stating that it "would rather be the best value provider".^[52] In 2016, ULA suggested that customers would have much lower insurance and delay costs because of the high Atlas V reliability and schedule certainty, making overall customer costs close to that of using competitors like the SpaceX Falcon 9.^[53]

Historically proposed versions

In 2006, ULA offered an Atlas V Heavy option that would use three Common Core Booster (CCB) stages strapped together to lift a 29,400 kg (64,800 lb) payload to low Earth orbit.^[54] ULA stated at the time that 95% of the hardware required for the Atlas V Heavy has already been flown on the Atlas V single-core vehicles.^[11] The lifting capability of the proposed launch vehicle was to be roughly equivalent to the Delta IV Heavy,^[11] which uses RS-68 engines developed and produced domestically by Aerojet Rocketdyne.

A 2006 report, prepared by the 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).^[55] The report recommended for the U.S. Air Force and the National Reconnaissance Office (NRO) 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 United States development of an RD-180 replacement".^[56]

In 2010, ULA stated that the Atlas V Heavy variant could be available to customers 30 months from the date of order.^[11]

Atlas V PH2

In late 2006, the Atlas V program gained access to the tooling and processes for 5-meter-diameter stages used on Delta IV when Boeing and Lockheed Martin space operations were merged into the United Launch Alliance. This led to a proposal to combine the 5-meter-diameter Delta IV tankage production processes with dual RD-180 engines, resulting in the Atlas Phase 2.

An Atlas V PH2-Heavy consisting of three 5-meter stages in parallel with six RD-180s was considered in the Augustine Report as a possible heavy lifter for use in future space missions, as well as the Shuttle-derived Ares V and Ares V Lite.^[57] If built, the Atlas PH2-Heavy was projected to be able to launch a payload mass of approximately 70 t (69 long tons; 77 short tons) into an orbit of 28.5° inclination.^[57]

Booster for GX rocket

The Atlas V Common Core Booster was to have been used as the first stage of the joint US-Japanese GX rocket, which was scheduled to make its first flight in 2012.^[58] GX launches would have been from the Atlas V launch complex at Vandenberg Air Force Base, SLC-3E. However, the Japanese government decided to cancel the GX project in December 2009.^[59]

Out-licensing rejected by ULA

In May 2015, a consortium of companies, including Aerojet and Dynetics, sought to license the production or manufacturing rights to the Atlas V using the AR1 engine in place of the RD-180. The proposal was rejected by ULA.^[60]

Notable missions

The first payload, the Hot Bird 6 communications satellite, was launched to geostationary transfer orbit (GTO) on 21 August 2002 by an Atlas V 401.^[177]

On 12 August 2005, the Mars Reconnaissance Orbiter was launched aboard an Atlas V 401 launch vehicle from Space Launch Complex 41 at Cape Canaveral Air Force Station (CCAFS). The Centaur upper stage of the launch vehicle completed its burns over a 56-minute period and placed MRO into an interplanetary transfer orbit towards Mars.^[66]

On 19 January 2006, New Horizons was launched by a Lockheed Martin Atlas V 551 rocket. A third stage was added to increase the heliocentric (escape) speed. This was the first launch of the Atlas V 551 configuration with five solid rocket boosters, and the first Atlas V with a third stage.^[178]

On 6 December 2015, Atlas V lifted its heaviest payload to date into orbit – a 16,517 lb (7,492 kg) Cygnus resupply craft.^[179]

On 8 September 2016, the OSIRIS-REx Asteroid Sample Return Mission was launched on an Atlas V 411 launch vehicle. It arrived at the asteroid Bennu in December 2018 and departed back to Earth in May 2021 to arrive September 2022 at with a sample ranging from 60 grams to 2 kilograms in 2023.^[180]

The first four Boeing X-37B spaceplane missions were successfully launched with the Atlas V. The X-37B, also known as the Orbital Test Vehicle (OTV), is a reusable robotic spacecraft operated by USAF that can autonomously conduct landings from orbit to a runway.^[181] X-37B flights are launched on Atlas V's from Cape Canaveral Space Force Station in Florida. The first Vandenberg Air Force Base landing at the Space Shuttle 15,000 ft (4,600 m) runway occurred in December 2010.^[182] Landings occur at both Vandenberg and Cape Canaveral depending on mission requirements.^[181]

On 20 December 2019, the first Starliner crew capsule was launched in Boe-OFT un-crewed test flight. The Atlas V launch vehicle performed flawlessly but an anomaly with the spacecraft left it in a wrong orbit. The orbit was too low to reach the flight's destination of ISS, and the mission was subsequently cut short.

Mission success record

In its 94 launches (as of July 2022), starting with its first launch in August 2002, Atlas V has achieved a 100% mission success rate and a 98.93% vehicle success rate.^[183] This is in contrast to the industry success rate of 90%–95%.^[184]

The first anomalous event in the use of the Atlas V launch system occurred on 15 June 2007, when the engine in the Centaur upper stage of an Atlas V shut down early, leaving its payload – a pair of NROL-30 ocean surveillance satellites – in a lower than intended orbit. The cause of the anomaly was traced to a leaky valve, which allowed fuel to leak during the coast between the first and second burns. The resulting lack of fuel caused the second burn to terminate 4 seconds early.^[185] Replacing the valve led to a delay in the next Atlas V launch.^[75] However, the customer (the National Reconnaissance Office) categorized the mission as a success.^[186][187]

A flight on 23 March 2016, suffered an underperformance anomaly on the first-stage burn and shut down 5 seconds early. The Centaur proceeded to boost the Orbital Cygnus payload, the heaviest on an Atlas to date, into the intended orbit by using its fuel reserves to make up for the shortfall from the first stage. This longer burn cut short a later Centaur disposal burn.^[188] An investigation of the incident revealed that this anomaly was due to a fault in the main engine mixture-ratio supply valve, which restricted the flow of fuel to the engine. The investigation and subsequent examination of the valves on upcoming missions led to a delay of the next several launches.^[189]

Notable payloads

Retirement

In August 2021, ULA announced that they are no longer selling launches on the Atlas V and they would fulfill their 29 existing launch contracts.^[10] They made a final purchase of the RD-180 motors they needed and the last of those motors were delivered in April 2021. The last launch will occur "some time in the mid-2020s".^[10] As of January 2024^[update], twelve missions have flown since the announcement,^{[lower-alpha 2]} and 17 launches remain.