Vulcan Centaur

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Vulcan Centaur
Vulcan logo.svg
ULA Vulcan.png
Vulcan configuration as of 2015 with sub-5.4 m Centaur
FunctionLaunch vehicle, partial reuse planned
ManufacturerUnited Launch Alliance
Country of originUnited States
Cost per launchUS$ ~82 - ~200 million (Vulcan Centaur Heavy)[1][2]
Height61.6 metres (202 ft)[3]
Diameter5.4 metres (18 ft)[4]
Mass546,700 kilograms (1,205,300 lb)
Stages2 and 0–6 boosters
Payload to Low Earth orbit (28.7°)
Mass27,200 kg (60,000 lb)[5] (Vulcan Centaur Heavy)
Payload to Geostationary transfer orbit (27.0°)
Mass14,400 kg (31,700 lb)[5] (Vulcan Centaur Heavy)
Payload to Geostationary orbit
Mass7,200 kg (15,900 lb)[5] (Vulcan Centaur Heavy)
Payload to TLI
Mass12,100 kg (26,700 lb)[5] (Vulcan Centaur Heavy)
Launch history
StatusIn construction
Launch sites
First flightJuly 2021 (planned)[7]
No. boosters0–6 [8]
Thrust2,201.7 kilonewtons (495,000 lbf)
First stage
Diameter5.4 metres (18 ft)
Engines2 × BE-4
Thrust4,900 kilonewtons (1,100,000 lbf)
Second stage – Centaur V
Diameter5.4 metres (18 ft)
Engines2 × RL-10 [10]
Thrust212 kilonewtons (48,000 lbf) [11]
Specific impulse448.5 seconds (4.398 km/s)
FuelLH2 / LOX
Second stage – ACES (proposed for mid-2020s)
Diameter5.4 metres (18 ft)
Thrust490 kilonewtons (110,000 lbf)
FuelLH2 / LOX

Vulcan Centaur is a two-stage-to-orbit heavy-lift launch vehicle under development 2014–2021 by United Launch Alliance (ULA), principally funded through National Security Space Launch (NSSL) competition and launch program, to meet the demands of the United States Air Force and US national security satellite launches.

The maiden flight is planned to take place in July 2021, launching Astrobotic Technology's Peregrine lunar lander.[12][7]

Vehicle description[edit]

Vulcan is ULA's first launch vehicle design, adapting and evolving various technologies previously developed for the Atlas V and Delta IV rockets of the USAF's EELV program. The first stage propellant tanks share the diameter of the Delta IV Common Booster Core, but will contain liquid methane and liquid oxygen propellants instead of the Delta IV's liquid hydrogen and liquid oxygen.[13]

Vulcan's upper stage is the Centaur V, an upgraded variant of the Common Centaur/Centaur III currently used on the Atlas V. A version of the RL-10 engine with an nozzle extension, the RL-10CX, will be used on the Vulcan Centaur Heavy.[3] Previous plans called for the Centaur V to be eventually upgraded with Integrated Vehicle Fluids technology to become the Advanced Cryogenic Evolved Stage (ACES), but this has now been cancelled[14]. Vulcan is intended to undergo the human-rating certification process to allow the launch of crew, such as the Boeing CST-100 Starliner or a future crewed version of the Sierra Nevada Dream Chaser spaceplane.[15]

The Vulcan booster will have a 5.4 m (18 ft) outer diameter to support the methane fuel burned by the Blue Origin BE-4 engines.[16] The BE-4 was selected to power Vulcan's first stage in September 2018 after a competition with the Aerojet Rocketdyne AR1.[17]

Zero to six[8] GEM-63XL[18] solid rocket boosters (SRB)s can be attached to the first stage in pairs,[19] providing additional thrust during the first part of the flight and allowing the six-SRB Vulcan Centaur Heavy to launch a higher mass payload than the most capable Atlas V 551 or Delta IV Heavy.[20]

Vulcan will have a 5.4 m (18 ft) diameter fairing available in two lengths. The longer fairing will be 21 m (69 ft) long, with a volume of 317 m3 (11,200 cu ft).[8][clarification needed]

Payload mass capabilities[edit]

As of November 2019, the Vulcan Centaur payload figures are as follows:[5]

Version SRBs Payload to LEO Payload to ISS Payload to polar LEO Payload to GTO Payload to GEO
Vulcan Centaur 502 0 10,600 kg (23,400 lb) 9,000 kg (20,000 lb) 8,300 kg (18,300 lb) 2,900 kg (6,400 lb) N/A
Vulcan Centaur 522 2 18,500 kg (40,800 lb) 16,100 kg (35,500 lb) 15,000 kg (33,000 lb) 7,600 kg (16,800 lb) 2,600 kg (5,700 lb)
Vulcan Centaur 542 4 23,900 kg (52,700 lb) 21,000 kg (46,000 lb) 19,500 kg (43,000 lb) 10,800 kg (23,800 lb) 4,800 kg (10,600 lb)
Vulcan Centaur 562 6 27,200 kg (60,000 lb) 25,300 kg (55,800 lb) 23,200 kg (51,100 lb) 13,600 kg (30,000 lb) 6,500 kg (14,300 lb)
Vulcan Centaur Heavy 5H2 6 27,200 kg (60,000 lb) 26,200 kg (57,800 lb) 24,000 kg (53,000 lb) 14,400 kg (31,700 lb) 7,200 kg (15,900 lb)
NSSL requirement[21] 6,800 kg (15,000 lb) 17,000 kg (37,000 lb) 8,165 kg (18,000 lb) 6,600 kg (14,600 lb)

Payload to LEO is for a 200 km (120 mi) circular orbit at 28.7 degree inclination; payload to ISS is for a 407 km (253 mi) circular orbit at 51.6 degree inclination; payload to polar LEO is for a 200 km (120 mi) circular orbit at 90 degree inclination.[5] These capabilities are driven by the need to meet USAF NSSL requirements, with room for future growth.[21] As can be seen, the direct GEO orbit is the most demanding, with Vulcan Centaur Heavy only 600 kg (1,300 lb) above the requirement.


The United Launch Alliance inherited the Lockheed-Martin Atlas V and the Boeing Delta IV launch vehicle families when the company was formed in 2006. Both were first flown in 2002.[citation needed]

By early 2014 it was clear[to whom?] that ULA would have to develop a new launch vehicle to replace its existing Atlas V fleet. The Atlas V booster uses a Russian RD-180 engine, which led to a push to replace the RD-180 with a U.S. designed and built engine during the Ukrainian crisis of 2014. Relying on foreign hardware to launch critical national security spacecraft was also seen as controversial and undesirable. Formal study contracts were issued by ULA in June 2014 to several U.S. rocket engine suppliers.[22] ULA was also facing competition from SpaceX, then seen to affect ULA's core national security market of U.S. military launches, and by July 2014 the United States Congress was debating whether to legislate a ban on future use of the RD-180.[23]

In September 2014, ULA announced that it had entered into a partnership with Blue Origin to develop the BE-4 liquid oxygen (LOX) and liquid methane (CH4) engine to replace the RD-180 on a new first stage booster. At the time, ULA expected the new booster to start flying no earlier than 2019.[24] ULA had consistently referred to Vulcan as a 'next generation launch system' into early 2015.[24][25]


On 13 April 2015, ULA CEO Tory Bruno announced the name—Vulcan—for the new launch vehicle that ULA had been planning for some time. The name was selected by an online poll. Vulcan was intended to incorporate proven technologies. ULA stated its goal was to sell the basic Vulcan for half the then-current US$164 million price of a basic Atlas V rocket. Addition of strap-on boosters for heavier payloads would increase the price.[26] The first launch was initially planned for 2019.[23]

At the time of the 2015 announcement, ULA proposed an incremental approach to rolling out the vehicle and its technologies.[13] Vulcan deployment was expected to begin with a new first stage based on the Delta IV's fuselage diameter and production process and initially expected to use two BE-4 engines, with the AR1 as an alternative. The initial second stage was planned to be the Common Centaur/Centaur III from the Atlas V, with its existing RL10 engine. A later upgrade, the Advanced Cryogenic Evolved Stage (ACES), was conceptually planned for the full development in the late 2010s to be introduced a few years after Vulcan's first flight. ULA also announced a design concept for reuse of the Vulcan booster engines, thrust structure and first stage avionics where they could be detached as a module from the propellant tanks after booster engine cutoff, with the module descending through the atmosphere under an inflatable heat shield.[27] However, neither the ACES second stage nor the SMART reuse for the first stage have become funded development projects by ULA as of 2019, even though ULA states that the "first stage propulsion module accounts for around 65% of Vulcan Centaur’s costs."[28]


Through the first several years, the ULA board of directors made quarterly funding commitments to Vulcan Centaur development.[29] As of October 2018, the US government had committed approximately US$1.2 billion in a public–private partnership to Vulcan Centaur development, with future funding being dependent on ULA securing an NSSL contract.[30]

By March 2016, the US Air Force had committed up to US$202 million of funding for Vulcan development. At that time, ULA had not yet estimated the total cost of Vulcan development, but CEO Tory Bruno noted that "new rockets typically cost $2 billion, including $1 billion for the main engine."[29] In April 2016, ULA Board of Directors member and President of Boeing's Network and Space Systems (N&SS) division Craig Cooning expressed confidence in the possibility of further USAF funding of Vulcan development.[31]

In March 2018, ULA CEO Tory Bruno said that Vulcan-Centaur had been "75 percent privately funded" up to that time.[quantify][32] In October 2018 and following a request for proposals and technical evaluation, ULA was awarded $967 million to develop a prototype Vulcan launch system as a part of the National Security Space Launch program. Two other providers, Blue Origin and Northrop Grumman Innovation Systems, were awarded $500 million and $792 million in development funding,[30] with detailed proposals and a competitive selection process to follow in 2019. The USAF's goal with the next generation of Launch Service Agreements is to get out of the business of "buying rockets" and move to acquire launch services from launch service providers, but U.S. government funding of launch vehicle development continues.[30]

Path to production[edit]

In September 2015, ULA and Blue Origin announced an agreement to expand the production capabilities of the BE-4 rocket engine then in development and test.[33]

In January 2016, ULA was designing two versions of the Vulcan first stage. The BE-4 version has a 5.4 m diameter to support the use of less-dense methane fuel.[16]

In late 2017, the upper stage was changed to the larger and heavier Centaur V, and the overall launch vehicle was renamed Vulcan Centaur.[32] The single core Vulcan Centaur will be capable of lifting "30% more" than a Delta IV Heavy,[34] meeting the NSSL requirements.[21]

In May 2018, ULA announced the selection of Aerojet Rocketdyne's RL10 engine for the Vulcan Centaur upper stage.[35] In September 2018, ULA announced the selection of the Blue Origin BE-4 engine for Vulcan's booster.[36][37]

In October 2018, the USAF released an NSSL launch service agreement with additional requirements, delaying Vulcan's initial launch to April 2021 after an earlier slip to 2020.[38][39][40]

On 8 July 2019, images of two Vulcan qualification test articles were released by CEO Tory Bruno on Twitter: the liquefied natural gas (fuel) tank[41] and thrust structure.[42] On 9 July 2019, an image of a Vulcan payload attach fitting (PAF) was released by Peter Guggenbach, the CEO of RUAG Space.[43] On 31 July 2019, two images of the mated LNG tank and thrust structure were released by CEO Tory Bruno on Twitter.[44][45]

On 2 August 2019, Blue Origin released on Twitter an image of a BE-4 engine at full power on a test stand.[46] On 6 August 2019, the first two parts of Vulcan's mobile launcher platform (MLP) were transported[47] to the Spaceflight Processing Operations Center (SPOC) near SLC-40 and SLC-41, Cape Canaveral. The MLP was fabricated in eight sections and will move at 3 mph (4.8 km/h) on existing rail dollies and stand 183 feet (56 m) tall.[48]

On 12 August 2019, ULA submitted Vulcan Centaur for phase 2 of the USAF's launch services competition. As of that time, Vulcan Centaur was on track for a 2021 launch.[49] As of February 2020, the tankage for the second operational rocket was under construction in the ULA factory in Decatur, Alabama.[50]

On 7 August 2020, the United States Space Force awarded ULA 60% of all National Security Space Launch payloads starting in 2022 through 2027.[51]

Certification flights[edit]

On 14 August 2019, it was announced that the second Vulcan certification flight will be SNC Demo-1, the first of six Dream Chaser CRS-2 flights. Launches are planned to begin in 2021 and will use the four-SRB Vulcan configuration.[52]

On 19 August 2019, it was announced that Astrobotic Technology's Peregrine lander will launch on the first Vulcan certification flight. Peregrine is intended to launch in 2021 from SLC-41 at Cape Canaveral Air Force Station.[53]

Potential upgrades[edit]

Since the formal announcement in 2015, ULA has spoken of several technologies that would extend the capabilities of the Vulcan launch vehicle. These include enhancements to the first stage——to make the most expensive components potentially reusable, and enhancements to the second stage to increase the long-term mission duration of the stage to operate for weeks or months in Earth orbit cislunar space.[28]

ACES upper stage with Integrated Vehicle Fluids[edit]

A conceptual upgrade to the upper stage of Vulcan at the time of the announcement in 2015 was the ACES upper stage,[13] which was described to be liquid oxygen (LOX) and liquid hydrogen (LH2) powered by one to four rocket engines yet to be selected, a stage that could subsequently be upgraded to include the Integrated Vehicle Fluids (IVF) technology that could allow much longer on-orbit life of the upper stage, measured in weeks rather than hours.[54][13] In the event, neither the ACES upper stage nor the IVF technology capabilities have been added to ULA's planned Vulcan capabilities for the early 2020s.[28]

SMART reuse[edit]

Also announced during the initial April 2015 unveiling was the 'Sensible Modular Autonomous Return Technology' (SMART) reuse concept. The booster engines, avionics, and thrust structure would be detached as a module from the propellant tanks after booster engine cutoff, with the module descending through the atmosphere under an inflatable heat shield. After parachute deployment, the module would be captured by a helicopter in mid-air. ULA estimated that this would reduce the cost of the first stage propulsion by 90%, and 65% of the total first stage cost.[27] Through 2020, ULA has not announced firm plans to fund and build/test this engine-reuse concept, though they stated in late 2019 that they were "still planning to eventually reuse Vulcan’s first-stage engines."[28]

Planned launches[edit]

Configuration Launch site Payloads Planned
Q2 2021[55][56] 522 SLC-41 Peregrine lander Selenocentric Astrobotic Technology
First launch
September 2021[56][57] 542 SLC-41 SNC Demo-1 LEO (ISS) NASA (CRS)
2021 and on[57] 542 SLC-41 Dream Chaser LEO (ISS) NASA (CRS)
5 more launches on contract.[57]
Q1 2022[58] TBA TBA USSF-51 TBA US Space Force
First launch for United Launch Alliance under National Security Space Launch.
Q3 2022[58] TBA SLC-41 USSF-106 / NTS-3[59] GEO US Space Force

See also[edit]


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External links[edit]