Atlas V

Atlas V is an expendable launch system and the fifth major version in the Atlas launch vehicle family. It was designed by Lockheed Martin and has been operated by United Launch Alliance (ULA) since 2006. It is used for DoD, NASA, and commercial payloads. It is America's longest-serving active rocket. After 87 launches, in August 2021 ULA announced that Atlas V would be retired, and all 29 remaining launches had been sold. , 16 launches remain. Production ceased in 2024. Other future ULA launches will use the Vulcan Centaur rocket.

Each Atlas V launch vehicle consists of two main stages. The first stage is powered by a Russian engine manufactured by Energomash and burning kerosene and liquid oxygen. The Centaur upper stage is powered by one or two American RL10 engine(s) manufactured by Aerojet Rocketdyne and burns liquid hydrogen and liquid oxygen. Strap-on solid rocket boosters (SRBs) are used in most configurations. AJ-60A SRBs were used originally, but they were replaced in November 2020 by Graphite-Epoxy Motor (GEM 63) SRBs. The standard payload fairings are 4.2 or in diameter with various lengths.

Vehicle description
The Atlas V was developed by Lockheed Martin Commercial Launch Services (LMCLS) as part of the U.S. Air Force Evolved Expendable Launch Vehicle (EELV) program and made its inaugural flight on 21 August 2002. The vehicle operates from SLC-41 at Cape Canaveral Space Force Station (CCSFS). It also operated from SLC-3E at Vandenberg Space Force Base until 2022. LMCLS continued to market the Atlas V to commercial customers worldwide until January 2018, when United Launch Alliance (ULA) assumed control of commercial marketing and sales.

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 in diameter and 32.5 m in length. It is powered by one Russian NPO Energomash RD-180 main engine burning 284450 kg of liquid oxygen and RP-1. The booster operates for about four minutes, providing about 4 MN of thrust. 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 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.
 * Accommodation points for parallel stages, both smaller solids and identical liquids, are built into first-stage structures.
 * 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.
 * The main-stage diameter increased from 3.0 to 3.7 m.

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 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. 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. A subsequent third burn following a multi-hour coast can permit direct injection of payloads into geostationary orbit.

, 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.

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

A 5.4 m diameter fairing, with an internally usable diameter of 4.57 m, was developed and built by RUAG Space 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, 23.4 m, and 26.5 m long. While the classic 4.2 m fairing covers only the payload, the RUAG fairing is much longer and fully encloses both the Centaur upper stage and the payload.

Upgrades
Many systems on the Atlas V have been the subject of upgrade and enhancement both prior to the first Atlas V flight and since that time. Work on a Fault Tolerant Inertial Navigation Unit (FTINU) started in 2001 to enhance mission reliability for Atlas vehicles by replacing the earlier non-redundant navigation and computing equipment with a fault-tolerant unit. The upgraded FTINU first flew in 2006, and in 2010 a follow-on order for more FTINU units was awarded.

In 2015, ULA announced that the Aerojet Rocketdyne-produced AJ-60A solid rocket boosters (SRBs) then in use on Atlas V would be superseded by new GEM 63 boosters produced by Northrop Grumman Innovation Systems. The extended GEM 63XL boosters will also be used on the Vulcan Centaur launch vehicle that will replace the Atlas V. The first Atlas V launch with GEM 63 boosters happened on 13 November 2020.

Human-rating certification
Proposals and design work to human-rate the Atlas V began as early as 2006, with ULA's parent company Lockheed Martin reporting an agreement with Bigelow Aerospace that was intended to lead to commercial private trips to low Earth orbit (LEO).

Human-rating design and simulation work began in earnest in 2010, with the award of US$6.7 million in the first phase of the NASA Commercial Crew Program (CCP) to develop an Emergency Detection System (EDS).

As of February 2011, ULA had received an extension to April 2011 from NASA and was finishing up work on the EDS.

NASA solicited proposals for CCP phase 2 in October 2010, and ULA proposed to complete design work on the EDS. At the time, NASA's goal was to get astronauts to orbit by 2015. Then-ULA President and CEO Michael Gass stated that a schedule acceleration to 2014 was possible if funded. Other than the addition of the Emergency Detection System, no major changes were expected to the Atlas V rocket, but ground infrastructure modifications were planned. The most likely candidate for the human-rating was the N02 configuration, with no fairing, no solid rocket boosters, and dual RL10 engines on the Centaur upper stage.

On 18 July 2011, NASA and ULA announced an agreement on the possibility of certifying the Atlas V to NASA's standards for human spaceflight. ULA agreed to provide NASA with data on the Atlas V, while NASA would provide ULA with draft human certification requirements. In 2011, the human-rated Atlas V was also still under consideration to carry spaceflight participants to the proposed Bigelow Commercial Space Station.

In 2011, Sierra Nevada Corporation (SNC) picked the Atlas V to be the booster for its still-under-development Dream Chaser crewed spaceplane. The Dream Chaser was intended to launch on an Atlas V, fly a crew to the ISS, and land horizontally following a lifting-body reentry. However, in late 2014 NASA did not select the Dream Chaser to be one of the two vehicles selected under the Commercial Crew competition.

On 4 August 2011, Boeing announced that it would use the Atlas V as the initial launch vehicle for its CST-100 crew capsule. CST-100 will take NASA astronauts to the International Space Station (ISS) and was also intended to service the proposed Bigelow Commercial Space Station. A three-flight test program was projected to be completed by 2015, certifying the Atlas V/CST-100 combination for human spaceflight operations. The first flight was expected to include an Atlas V rocket integrated with an uncrewed CST-100 capsule, the second flight an in-flight launch abort system demonstration in the middle of that year, and the third flight a crewed mission carrying two Boeing test-pilot astronauts into LEO and returning them safely at the end of 2015. These plans were delayed by many years and morphed along the way so that in the end, the first orbital test flight with no crew materialized in 2019, but it was a failure and needed to be reflown in 2022, the in-flight launch abort system test flight did not materialize, and the third flight, a manned orbital test flight with two astronauts (in the end NASA's, not Boeing's astronauts) materialized in June 2024 as Boeing Crewed Flight Test. The launch abort system was tested in 2019 in the Boeing Pad Abort Test mission but this did not take place in-flight but from the launch pad.

In 2014, NASA selected the Boeing Starliner CST-100 spacecraft as part of the Commercial Crew Program. Atlas V is the launch vehicle for Starliner. The first launch of an uncrewed Starliner, the Boeing OFT mission, occurred atop a human-rated Atlas V on the morning of 20 December 2019; the mission failed to meet goals due to a spacecraft failure, though the Atlas V launcher performed well. In 2022, an Atlas V launched an uncrewed Starliner capsule for the second time on Boe-OFT 2 mission; the mission was a success.

In June 2024, on Boe-CFT mission, Atlas V carried humans into space for the first time, launching two NASA astronauts to the ISS.

Project Kuiper
Amazon has selected the Atlas V to launch some of the satellites for Project Kuiper. Project Kuiper will offer a high-speed satellite internet constellation service. The contract signed with Amazon is for nine launches. Project Kuiper aims to put thousands of satellites into orbit. ULA is Amazon's first launch provider. Two Kuiper test satellites were launched on Atlas V in 2023 because their originally-contracted launch vehicles were not available on time. The remaining eight Atlas V Kuiper launches will each carry a full payload of Kuiper satellites. Most of the Kuiper constellation will use other launch vehicles.

Versions


Each Atlas V booster configuration has a three-digit designation.

The first digit shows the diameter (in meters) of the payload fairing and has a value of "4" or "5" for fairing launches and "N" for crew capsule launches (as no payload fairing is used).

The second digit indicates the number of solid rocket boosters (SRBs) attached to the base of the launch vehicle and can range from "0" through "3" with the 4 m fairing, and "0" through "5" with the 5 m fairing. As seen in the first image, all SRB layouts are asymmetrical.

The third digit represents the number of engines on the Centaur stage, either "1" or "2". All of the configurations use the Single Engine Centaur, except for the "N22" which is only used on Starliner crew capsule missions, and uses Dual Engine Centaur.

Atlas V has flown in eleven configurations:

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. The 2013 cost of this configuration for the U.S. Air Force under their block buy of 36 launch vehicles was US$164 million. In 2015, the TDRS-M launch on an Atlas 401 cost NASA US$132.4 million.

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. 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.

In 2013, launch costs for commercial satellites to GTO averaged about US$100 million, significantly lower than historic Atlas V pricing. However, in recent years the price of an Atlas V [401] has dropped from approximately US$180 million to US$109 million, 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. ULA is not attempting to win these missions on purely lowest purchase price, stating that it "would rather be the best value provider". 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.

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 29400 kg payload to low Earth orbit. 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. The lifting capability of the proposed launch vehicle was to be roughly equivalent to the Delta IV Heavy, which used 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). 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".

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

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.
 * Atlas V PH2:

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. If built, the Atlas PH2-Heavy was projected to be able to launch a payload mass of approximately 70 MT into an orbit of 28.5° inclination.

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. 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.
 * Booster for GX rocket:

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.
 * Out-licensing rejected by ULA:

Atlas V launches
ULA has stopped selling the Atlas V. It will fly 16 more launches.

For planned launches, see List of Atlas launches (2020–2029).

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.

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.

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.

On 6 December 2015, Atlas V lifted its heaviest payload to date into orbit – a 16517 lb Cygnus resupply craft.

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.

Five Boeing X-37B spaceplane missions were successfully launched with the Atlas V. The flights are launched on Atlas V 501s from Cape Canaveral Space Force Station in Florida. 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. The first Vandenberg Air Force Base landing at the Space Shuttle 15000 ft runway occurred in December 2010. Landings occur at both Vandenberg and Cape Canaveral depending on mission requirements.

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 100 launches (as of June 2024), starting with its first launch in August 2002, Atlas V has achieved a 100% mission success rate and a 99% vehicle success rate.

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. Replacing the valve led to a delay in the next Atlas V launch. However, the customer (the National Reconnaissance Office) categorized the mission as a success.

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. 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.

Notable payloads

 * Boeing Starliner
 * Boeing X-37
 * ELaNa
 * Geostationary Operational Environmental Satellite
 * GPS
 * Inmarsat
 * InSight
 * Juno
 * Lucy
 * Lunar Reconnaissance Orbiter
 * Lunar Crater Observation and Sensing Satellite
 * Mars Reconnaissance Orbiter
 * Curiosity
 * Perseverance and Ingenuity
 * MAVEN
 * MUOS-1 (200th Centaur upper stage launch)
 * New Horizons
 * NROL launches
 * OSIRIS-REx
 * Solar Dynamics Observatory
 * Solar Orbiter
 * Space Test Program
 * USA-212

Replacement with Vulcan
In 2014, geopolitical and U.S. political considerations because of the Russian annexation of Crimea led to an effort to replace the Russian-supplied NPO Energomash 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 U.S. rocket-engine suppliers. The results of those studies led to a decision by ULA to develop the new Vulcan Centaur launch vehicle to replace the existing Atlas V and Delta IV.

In September 2014, ULA announced a partnership with Blue Origin to develop the BE-4 LOX/methane engine to replace the RD-180 on a new first-stage booster. As the Atlas V core is designed around RP-1 fuel and cannot be retrofitted to use a methane-fueled engine, a new first stage is being developed. This booster will have the same first-stage tankage diameter as the Delta IV and will be powered by two 2400 kN thrust BE-4 engines. The engine was already in its third year of development by Blue Origin, and ULA expected the new stage and engine to start flying no earlier than 2019.

Vulcan was initially planned to use the same Centaur upper stage as on Atlas V, and later to upgrade to ACES, however ACES is no longer being pursued, and Centaur V will be used instead. It will also use a variable number of optional solid rocket boosters, called the GEM 63XL, derived from the new solid boosters planned for Atlas V.

As of 2017, the Aerojet AR1 rocket engine was under development as a backup plan for Vulcan.

The first Vulcan successfully launched on 8 January 2024.

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. 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". , twelve missions have flown since the announcement, and 17 launches remain.