Vulcan Centaur

Vulcan is ULA's first new launch vehicle design since ULA was formed in 2006 by the merger of the launch vehicle businesses of Lockheed Martin and Boeing. It adapts and evolves technologies that were developed for the Atlas V and Delta IV rockets of the USAF's EELV program. The first-stage propellant tanks contain liquid methane and liquid oxygen propellants rather than the Delta IV's liquid hydrogen and liquid oxygen.

Vulcan's upper stage is the Centaur V, an upgraded variant of the Centaur III used on Atlas V. 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 was subsequently cancelled. At one time, ULA planned to pursue human-rating certification for Vulcan to allow the launch of crewed craft, such as the Boeing CST-100 Starliner or a future version of the Sierra Nevada Dream Chaser spaceplane.^{[needs update]}

The Vulcan booster has a 5.4 m (18 ft) outer diameter to support two Blue Origin BE-4 engines' and liquid methane fuel. In September 2018, after a competition with the Aerojet Rocketdyne AR1, the BE-4 was selected to power Vulcan's first stage.

Up to six GEM-63XL solid rocket boosters (SRB)s can be attached to the first stage in pairs, providing additional thrust during the first part of the flight and allowing the six-SRB Vulcan Centaur to launch a higher mass payload than the most capable Atlas V previously flown by the company, the Atlas V 551.

The Vulcan Centaur has a four-character designation for each configuration, in which the first character represents the first stage of the vehicle; Vulcan is designated with the letter "V". The second character shows the upper stage; Centaur is designated "C". The third character represents the number of SRBs attached to the Vulcan; "0", "2", "4" or "6". The final character represents the payload-fairing length configuration, which is indicated by "S" (Standard; 15.5 m (51 ft)) or "L" (Long; 21.3 m (70 ft)). For example, "VC6L" would represent a Vulcan first stage, a Centaur upper stage, six SRBs and a long-configuration fairing. The most powerful Vulcan Centaur will have a Vulcan first stage, a Centaur upper stage with RL10CX engines with a nozzle extension and six SRBs.

Capabilities

The payload capacity of Vulcan Centaur are as follows:

Launch system status

Payload to the ISS is for a 407 km (253 mi) circular orbit at 51.6° inclination; payload to SSO is for a 555 km (345 mi) circular orbit at 98.75° inclination; payload to MEO is for a 20,368 km (12,656 mi) circular orbit at 55° inclination; payload to GEO is for a 36,101 km (22,432 mi) circular orbit at 0° inclination; payload to GTO is for a 1800 m/s delta-V with 185 km (115 mi) perigee and 35,786 km (22,236 mi) apogee orbit at 27° inclination; payload to Molniya is for 1,203 km (748 mi) perigee and 39,170 km (24,340 mi) apogee orbit at 63.4° inclination.

These capabilities are driven by the need to meet NSSL requirements, with room for future growth.

A Vulcan Centaur with six solid rocket boosters can put 27,200 kilograms into low Earth orbit, nearly as much as the three-core Delta IV Heavy.

Background

ULA had considered a number of launch vehicle concepts in the decade since the company was formed in 2006. Various concepts for derivative vehicles based on the Atlas and Delta lines of launch vehicles they inherited from their predecessor companies were proposed, though ultimately none were built.^{[citation needed]}

In early 2014, geopolitical and US political considerations led to an effort by ULA to consider the possible replacement of the Russian-supplied RD-180 engine used on the first stage booster of the Atlas V. Events such as the Annexation of Crimea by the Russian Federation in February 2014 brought into focus that relying on foreign hardware to launch critical national security spacecraft could be undesirable. Formal study contracts were issued by ULA in June 2014 to a number of US rocket engine suppliers. ULA was also facing competition from SpaceX—then seen to affect its core national security market of US military launches—and by July 2014, Congress was debating whether to legislatively ban future use of the RD-180 engine.

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. The engine was already in its third year of development by Blue Origin, and ULA said it expected the new stage and engine to start flying as soon as 2019. Two of the 2,400-kilonewton (550,000 lbf)-thrust BE-4 engines were to be used on a new launch vehicle booster. A month later, ULA restructured company processes and its workforce with the goal of reducing costs. The company stated that the successor to Atlas V would blend existing Atlas V and Delta IV with a goal of halving the cost of the Atlas V rocket.

Announcement

In 2015, ULA announced the Vulcan rocket, proposing to incrementally replace existing vehicles with it. Vulcan deployment was expected to begin with a new first stage that was based on the Delta IV's fuselage diameter and production process, and initially expected to use two BE-4 engines or the AR1 as an alternative. The second stage was to be the existing Centaur III, already used on Atlas V. A later upgrade, the Advanced Cryogenic Evolved Stage (ACES), was planned to be introduced a few years after Vulcan's first flight. ULA also revealed a design concept for reuse of the Vulcan booster engines, thrust structure and first stage avionics, which could be detached as a module from the propellant tanks after booster engine cutoff; the module would re-enter the atmosphere behind an inflatable heat shield.

Funding

Through the first several years, the ULA board of directors made quarterly funding commitments to Vulcan Centaur development. As of October 2018^[update], the US government had committed approximately $1.2 billion in a public–private partnership to Vulcan Centaur development, with future funding pending a National Security Space Launch contract with ULA.

By March 2016, the United States Air Force (USAF) had committed up to $202 million of funding for Vulcan development. ULA had not yet estimated the total cost of development but CEO Tory Bruno noted "new rockets typically cost $2 billion, including $1 billion for the main engine".In March 2018, Bruno said the Vulcan-Centaur had been "75% privately funded" up to that point.^[quantify] In October 2018, following a request for proposals and technical evaluation, ULA was awarded $967 million to develop a prototype Vulcan launch system as part of the National Security Space Launch program.

Development, production, and testing

In September 2015, it was announced BE-4 rocket engine production would be expanded to increase production capacity for testing. The following January, ULA was designing two versions of the Vulcan first stage; the BE-4 version has a 5.4 m (18 ft) diameter to support the use of the less dense methane fuel. In late 2017, the upper stage was changed to the larger and heavier Centaur V, and the launch vehicle was renamed Vulcan Centaur. In May 2018, ULA announced the selection of Aerojet Rocketdyne's RL10 engine for the Vulcan Centaur upper stage. That September, ULA announced the selection of the Blue Origin BE-4 engine for Vulcan's first stage. In October, the USAF released an NSSL launch service agreement with new requirements, delaying Vulcan's initial launch to April 2021, after an earlier postponement to 2020.

In August 2019, the parts of Vulcan's mobile launcher platform (MLP) were transported to the Spaceflight Processing Operations Center (SPOC) near SLC-40 and SLC-41, Cape Canaveral, Florida. The MLP was fabricated in eight sections and moves at 3 mph (4.8 km/h) on rail bogies, standing 183 ft (56 m) tall. In February 2021, ULA shipped the first completed Vulcan core booster to Florida for pathfinder tests ahead of the Vulcan's debut launch. Testing continued proceeded with the pathfinder booster throughout that year.

In 2019, Vulcan Centaur's first flight was announced as the launch of Astrobotic Technology's Peregrine lunar lander. ULA declared a target launch date in early 2021. By December 2020, the launch had been delayed to 2022 due to schedule impacts of belated BE-4 main engine delivery owing to technical issues. In June 2021, Astrobotic reported that Peregrine would not be ready in time due to the COVID-19 pandemic, delaying the mission and Vulcan Centaur's first launch; further Peregrine delays put the launch of Vulcan into 2023. In March 2023, a Centaur V test stage failed during a test sequence. To address the issue, ULA made a design change to the structure of the stage, which required a new Centaur to be built for Vulcan Centaur's maiden flight. In October 2023, ULA announced they would aim for the first Vulcan Centaur launch in late December 2023.

Certification flights

On 19 August 2019, it was announced Astrobotic Technology selected ULA to launch their Peregrine lander on the first Vulcan certification flight, named Certification-1, then scheduled for 2021. Vulcan lifted off for the first time on 8 January 2024, successfully delivering the Peregrine lander on a trajectory to the Moon. It used the VC2S configuration, with two solid rocket boosters and a standard-length fairing. After payload separation following a 4-minute long trans-lunar injection burn, the Centaur upper stage was sent to a heliocentric orbit after it fired for a third time 1 hour and 18 minutes into the flight to test how it would behave in extended duration missions, such as those required to send payloads directly to geostationary orbit. While the Peregrine lander had a failure in its propulsion system shortly after separation that prevented it from landing on the Moon, Astrobotic noted that the Vulcan Centaur rocket performed without issues and there was no evidence that the failure in the spacecraft was caused by the launch.

On 14 August 2019, ULA won a commercial competition when it was announced the second Vulcan certification flight would be named SNC Demo-1, the first of seven Dream Chaser CRS-2 flights under NASA's Commercial Resupply Services program. They will use the four-SRB VC4 configuration. The SNC Demo-1 was scheduled for launch no earlier than April 2024.

After Vulcan Centaur's second certification mission, the rocket will be qualified for use on United States military missions. As of August 2020^[update], Vulcan was planned to launch ULA's awarded 60% share of National Security Space Launch payloads from 2022 to 2027, but delays occurred. The Space Force's USSF-51 launch in late 2022 had been intended to be the first national security classified mission, but in May 2021 the spacecraft was reassigned to an Atlas V to "mitigate schedule risk associated with Vulcan Centaur non-recurring design validation". For similar reasons, the Kuiper Systems prototype flight was moved to an Atlas V rocket.

After its first launch in January 2024, Vulcan encountered payload delays in the form of Dream Chaser's readiness. This led to the possibility of a mass simulator being launched in advance of the Dream Chaser launch in order for Vulcan to complete certification mandated by its contract with the Air Force. Bloomberg News reported in May 2024 that United Launch Alliance was accruing financial penalties due to delays in the military launch contracts.

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

Long-endurance upper stages

The ACES upper stage—fueled with liquid oxygen (LOX) and liquid hydrogen (LH₂) and powered by up to four rocket engines with the engine type yet to be selected—was a conceptual upgrade to Vulcan's upper stage at the time of the announcement in 2015. This stage could subsequently be upgraded to include the Integrated Vehicle Fluids technology that would allow the upper stage a much longer in-orbit life of weeks rather than hours. The ACES upper stage was eventually cancelled when in September 2020, ULA made public that the ACES development would not be continued and the Vulcan second stage would now be the Centaur V upper stage. The Centaur V is based on the Dual Engine Centaur upper stage used by the Atlas V N22 but larger and more powerful. A senior executive at ULA said the Centaur V design was also heavily influenced by ACES.

However, ULA said in 2021 that it is working to add more value to upper stages by having them perform tasks such as operating as space tugs. CEO Tory Bruno says ULA is working on upper stages with hundreds of times the endurance of those currently in use.

SMART reuse

A method of main engine reuse called Sensible Modular Autonomous Return Technology (SMART) is a proposed upgrade for Vulcan Centaur. In the concept, the booster engines, avionics, and thrust structure detach as a module from the propellant tanks after booster engine cutoff. The engine module then falls through the atmosphere protected by an inflatable heat shield. After parachute deployment, the engine section splashes down, using the heatshield as a raft. ULA estimated this technology could reduce the cost of the first stage propulsion by 90%, and 65% of the total first-stage cost. Although SMART reuse was not initially funded for development, from 2021 the higher launch cadence required to launch the Project Kuiper megaconstellation provided support for the concept's business case. Prior to 2022, ULA intended to catch the engine section using a helicopter.

Vulcan Heavy

In September 2020, ULA announced that they were carefully studying a "Vulcan Heavy" variant with three booster cores. Speculation about a new variant had been rampant for months after an image of a model of that version popped on social media. ULA CEO Tory Bruno later tweeted a clearer image of the model and said it was the subject of ongoing study.^{[needs update]}

2024

• Official ULA Vulcan page
• xTTkrxVR_20 ISPCS 2015 Keynote, Mark Peller, Program Manager of Major Development at ULA and Vulcan Program Manager discusses Vulcan, 8 October 2015, Key discussion of Vulcan is at 12:20 point in video.
• A current ULA Vulcan with 5.4 m Centaur image