Atlas V

The Atlas V first stage, the Common Core Booster (CCB), is 12.5 ft (3.8 m) in diameter and 106.6 ft (32.5 m) in length. It is powered by a single Russian RD-180 main engine burning 627,105 lb (284,450 kg) of liquid oxygen and RP-1. The booster operates for about four minutes, providing about 4 meganewtons (860,000 lbf) of thrust.[8] Thrust can be augmented with up to five Aerojet strap-on solid rocket boosters, each providing an additional 1.27 meganewtons (285,500 lbf) of thrust for 94 seconds.

The Atlas V is the newest member of the Atlas family. Compared to the Atlas III vehicle, there are numerous changes. Compared to the Atlas II, the first stage is a near-redesign. There was no Atlas IV.

The main differences between the Atlas V and earlier Atlas I and II family rockets 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.[8]
• Use of aluminum, with a higher thermal conductivity than stainless steel, requires insulation for the liquid oxygen. The tanks are covered in a polyurethane-based layer.
• Accommodation points for parallel stages, both smaller solids and identical liquids, are built into first-stage structures.[8]
• 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.[8] The RD-180 features a single turbopump feeding dual combustion chambers and nozzles burning kerosene/liquid oxygen propellants.
• As with the Atlas III, the oxygen tank is larger relative to the fuel tank to accommodate the mixture ratio of the RD-180.
• The main-stage diameter increased from 10 feet to 12.5 feet.[9]

The Centaur upper stage uses a pressure-stabilized propellant-tank design and cryogenic propellants. The Centaur stage for Atlas V is stretched 5.5 ft (1.68 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 (22,300 lbf). 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.[10] As of 2006, 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.[11]

Atlas V payload fairings are available in two diameters, depending on satellite requirements. The 4.2 meter diameter fairing,[12] originally designed for the Atlas II booster, comes in three different lengths: the original 9-meter-long version and extended 10-meter and 11-meter 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.[5]

A 5.4 meter diameter fairing (4.57 meters internally usable) was developed and built by RUAG Space[13] 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 meters long.[13] While the classic 4-meter fairing covers only the payload, the RUAG fairing is much longer and fully encloses both the Centaur upper stage and the payload.[14]

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 new Fault Tolerant Inertial Navigation Unit (FTINU) started in 2001 to enhance mission reliability for Atlas vehicles by replacing the existing non-redundant navigation and computing equipment with a fault-tolerant unit.[15] The upgraded FTINU first flew in 2006,[16] and in 2010 a follow-on order for more FTINU units was awarded.[17] Later in the decade, the FTINU was replaced with avionics common to both the Atlas V and Delta IV.

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).[18]

Human-rating design and simulation work began in earnest in 2010, with the award of US$6,700,000 in the first phase of the NASA Commercial Crew Program (CCP) to develop an Emergency Detection System (EDS).[19] As of February 2011, ULA had received an extension to April 2011 from NASA and was finishing up work on the EDS.[20]

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.[21] 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.[21]

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.[22] ULA agreed to provide NASA with data on the Atlas V, while NASA would provide ULA with draft human certification requirements.[22] In 2011, the human-rated Atlas V was also still under consideration to carry spaceflight participants to the proposed Bigelow Commercial Space Station.[23]

In 2011, Sierra Nevada Corporation (SNC) picked the Atlas V to be the booster for its still-under-development Dream Chaser crewed spaceplane.[24] The Dream Chaser was intended to launch on an Atlas V, fly a crew to the ISS, and landing horizontally following a lifting-body reentry.[24] 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 and was also intended to service the proposed Bigelow Commercial Space Station.[25][26] A three-flight test program was projected to be completed by 2015, certifying the Atlas V/CST-100 combination for human spaceflight operations.[26] The first flight was expected to include an Atlas V rocket integrated with an uncrewed CST-100 capsule,[25] the second flight an in-flight launch abort system demonstration in the middle of that year,[26] and the third flight a crewed mission carrying two Boeing test-pilot astronauts into LEO and returning them safely at the end of 2015.[26] These plans did not materialize.

In 2014, NASA selected the Boeing CST-100 space capsule as part of the CCD program after extensive delays. Atlas V is the launch vehicle of the CST-100. The first launch of an uncrewed CST-100 capsule occurred atop a human-rated Atlas V on the morning of December 20, 2019, however an anomaly with the Mission Elapsed Time clock aboard the CST-100 caused the spacecraft to enter a suboptimal orbit.[27] As a result, the CST-100 could not achieve orbital insertion to reach the International Space Station, and instead deorbited after two days.

In 2015, ULA announced that the Aerojet Rocketdyne-produced AJ-60A solid rocket boosters (SRBs) currently in use on Atlas V will 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 rocket that will replace the Atlas V.[28]

List date: August 8, 2019[31] Mass to LEO numbers are at an inclination of 28.5°. Acronyms: Single Engine Centaur (SEC), Dual Engine Centaur (DEC).

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 $187 million.[37] The 2013 cost of this configuration for the Air Force under their block buy of 36 rockets was $164 million.[38] In 2015, the TDRS-M launch on an Atlas 401 cost NASA $132.4 million.[39]

Starting in 2016, ULA provided pricing for the Atlas V through its RocketBuilder website, advertising a base price for each rocket configuration, which ranges from $109 million for the 401 up to $153 million for the 551.[1] Each additional SRB adds an average of $6.8 million to the cost of the rocket. 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 $30–$80 million to the cost of a launch.[40]

In 2013, launch costs for commercial satellites to GTO averaged about $100 million, significantly lower than historic Atlas V pricing.[41] However, in recent years the price of an Atlas V has dropped from approximately $180 million to $109 million, in large part due to competitive pressure that emerged in the launch services marketplace during the early 2010s. ULA CEO Tory Bruno has stated that ULA needs at least 2 commercial missions each year in order to stay profitable going forward.[42] ULA is not attempting to win these missions on purely lowest purchase price, stating that it "would rather be the best value provider".[43] ULA suggests that customers will 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.[44]

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 payload to low Earth orbit.[45] 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.[5] The lifting capability of the proposed rocket was to be roughly equivalent to the Delta IV Heavy,[5] which utilizes 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).[46] 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".[47]

In 2010, ULA stated that the Atlas V Heavy configuration could be available to customers 30 months from the date of order.[5]

In the mid-2000s, 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 m 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.[48] If built, the Atlas PH2-Heavy was projected to be able to launch a payload mass of approximately 70 metric tons into an orbit of 28.5° inclination.[48] Neither of the Atlas V Phase 2 proposals progressed to development work.

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.[49] GX launches would have been from the Atlas V launch complex at Vandenberg AFB, SLC-3E. However, the Japanese government decided to cancel the GX project in December 2009.[50]

In 2017, a consortium of companies, including Aerojet and Dynetics, sought license production or the manufacturing rights to the Atlas V using the AR1 engine in place of the RD-180. This proposal was declined by ULA.[51]

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 rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station. The Centaur upper stage of the rocket completed its burns over a 56-minute period and placed MRO into an interplanetary transfer orbit towards Mars[57]

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 16,517-pound (7,492 kg) Cygnus resupply craft.[148]

On 8 September 2016, the OSIRIS-REx Asteroid Sample Return Mission was launched on an Atlas V 411 rocket. It was scheduled to arrive at the asteroid Bennu in 2018 and return with a sample ranging from 60 grams to 2 kilograms in 2023.

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.[149] The first four X-37B flights were launched on Atlas V's from Cape Canaveral Air Force Station in Florida with subsequent landings taking place on the Space Shuttle 15,000-foot (4,600 m) runway located at Vandenberg Air Force Base in California.

On 20 December 2019, the first Starliner crew capsule was launched in Boe-OFT uncrewed test flight. The Atlas V carrier rocket 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.

In its 82 launches (as of February 2020), starting with its first launch in August 2002, Atlas V has had an almost perfect mission success rate. This is in contrast to the industry failure rate of 5–10%.[150] However, there have been two anomalous flights that – while still successful in their mission – prompted a grounding of the Atlas fleet while investigations determined the root cause of their problems.

The first anomalous event in the use of the Atlas V launch system occurred on June 15, 2007, when the engine in the Centaur upper stage of an Atlas V shut down early, leaving its payload – a pair of NRO L-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.[151] Replacing the valve led to a delay in the next Atlas V launch.[64] However, the customer (the National Reconnaissance Office) categorized the mission as a success.[152][153]

A flight on March 23, 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 utilizing its fuel reserves to make up for the shortfall from the first stage. This longer burn cut short a later Centaur disposal burn.[154] 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.[155]