What is United Launch Alliance’s Centaur V, and Why is It Important?

Key Takeaways

• Centaur V is a 5.4-meter diameter upper stage that powers the Vulcan Centaur rocket
• It uses two RL-10C-1-1A engines burning liquid hydrogen and liquid oxygen for high efficiency
• Centaur V made its debut on January 8, 2024, carrying the Peregrine lunar lander mission

The Stage at the Heart of American Launch

There’s a straightforward case for calling the Centaur upper stage family the most consequential collection of hardware in American spaceflight history. Since its first successful flight in November 1963, successive generations of this pressure-stabilized rocket stage have placed probes on trajectories to every planet in the solar system, delivered national security satellites to classified orbits, and supported missions from the Surveyor Moon landers to the Voyager interstellar spacecraft. The latest version, Centaur V, is the most radical rethinking of the design since its origins. It’s bigger, more capable, and engineered for a kind of mission endurance that earlier versions couldn’t sustain.

United Launch Alliance introduced Centaur V as the upper stage for its new Vulcan Centaur rocket. While the name carries clear lineage, the engineering underneath it reflects choices that go well beyond simple updates. Wider diameter, improved insulation, a more capable propulsion system, and a fault-tolerant avionics architecture all combine to produce a stage that ULA describes as delivering 2.5 times the energy and 450 times the endurance of its predecessors. Those aren’t incremental numbers. They reflect a deliberate decision to build something genuinely different.

Understanding where Centaur V fits in the launch market requires knowing what ULA replaced, why that replacement became necessary, and what the new upper stage is actually capable of doing. The political and industrial pressures that drove the Vulcan Centaur program are just as important as the engineering decisions behind the stage itself.

Six Decades of Centaur History

The Centaur program began in 1956 when the U.S. Air Force initiated a study with General Dynamics/Convair to develop a new high-energy upper stage capable of launching heavy payloads to high orbits. It was an ambitious project, and it nearly failed. The combination of liquid hydrogen fuel and the thin-walled, pressure-stabilized tank design that keeps the stage light presented engineering challenges that took years to solve. Liquid hydrogen must be stored at temperatures approaching -253 degrees Celsius, and keeping it stable during flight required technologies that simply didn’t exist when the program started.

The first test flights in the early 1960s were plagued by failures. Success came on the second orbital attempt in November 1963, when a Centaur-powered Atlas rocket successfully reached orbit. From that point, the stage accumulated an extraordinary operational record. By the end of the 1960s, Centaur had powered the Surveyor Moon landers. By the mid-1970s, it was sending Pioneer 10 and Pioneer 11 to Jupiter and beyond on Titan-Centaur combinations. The Voyager spacecraft, launched in 1977 and now the most distant human-made objects in existence, reached their trajectories with Centaur assistance.

What remained consistent across all these decades was the fundamental architecture: thin stainless steel tanks stabilized by internal gas pressure rather than thick structural walls, combined with the RL-10 engine burning liquid hydrogen and liquid oxygen. That combination produced a specific impulse that no chemical upper stage using denser propellants could match.

By the time United Launch Alliance was formed in 2006 as a joint venture between Boeing and Lockheed Martin , the Centaur III was the active variant, flying atop the Atlas V rocket. Common Centaur, as it’s also known, measures 3.05 meters in diameter and flies with either one or two RL-10 engines depending on the mission. Atlas V with Centaur III accumulated 100 consecutive successful launches without a mission failure, cementing ULA’s reputation for reliability. That record made the eventual transition to a new upper stage both important and somewhat risky. There was a lot to lose if Centaur V fell short.

Why Centaur V Was Built

The path to Centaur V wasn’t driven by a desire to build something new for its own sake. It was driven by a political decision in 2014. Following Russia’s annexation of Crimea, Congress moved to end U.S. dependence on the Russian-made RD-180 rocket engine that powered the Atlas V first stage. The RD-180 was exceptional hardware, but relying on a Russian supplier for access to orbit had become an untenable security position. ULA needed a new first stage, and building that new booster meant rethinking the entire architecture.

The company announced the Vulcan rocket concept in 2015, initially planning to keep the Centaur III as the upper stage while the new first stage was developed. In late 2017, that plan changed. ULA enlarged the upper stage to match the 5.4-meter diameter of the Vulcan first stage, creating what became Centaur V, and renamed the vehicle Vulcan Centaur. The decision to go wider wasn’t just about matching diameters for manufacturing convenience. A larger diameter stage can hold significantly more propellant for a given length, which directly translates into more performance margin on high-energy missions.

In May 2018, ULA announced the selection of Aerojet Rocketdyne’s RL-10 engine for the Centaur V, continuing a partnership that had lasted more than five decades. That selection was the result of a competitive procurement process. The alternative of developing an entirely new engine would have added years to the program timeline and introduced unnecessary development risk. Choosing the RL-10, specifically the RL10C-1-1A variant, let the team build on a proven foundation while still achieving substantial performance improvements.

One thing that’s often missed in discussions of Vulcan’s development is the degree to which Centaur V drove the program’s capabilities rather than simply supporting them. The upper stage is where missions are actually delivered. A rocket’s first stage gets the payload out of the atmosphere, but the upper stage determines where that payload ends up. Centaur V’s extended endurance capability, discussed in more detail below, is the most strategically valuable attribute of the entire Vulcan Centaur vehicle.

Physical Design and Construction

Centaur V measures 5.4 meters (17.7 feet) in diameter and 11.7 meters (38.5 feet) in length. The propellant tanks use the same pressure-stabilized stainless steel construction that has defined the Centaur family since the 1960s. Rather than thick structural walls carrying the mechanical loads, the tanks are maintained in shape by internal gas pressure, the way a balloon holds its shape. This approach, pioneered on the original Centaur, delivers an exceptionally lightweight structure relative to the volume it encloses.

The cryogenic propellants inside the stage require aggressive thermal management. Liquid hydrogen, stored at approximately -253 degrees Celsius, boils off rapidly if heat leaks in from the surrounding environment. Centaur V uses a combination of multilayer insulation (MLI) blankets, radiation shields, and spray-on foam insulation (SOFI) to slow this process. The improved insulation system is central to the extended-endurance capability that distinguishes Centaur V from its predecessors. Keeping propellants viable for hours rather than minutes in orbit requires a thermal control architecture that goes well beyond what Atlas V’s Centaur III needed to manage.

The avionics system is fault-tolerant and mounted on an aft equipment shelf. Centaur V’s guidance, flight control, and vehicle sequencing functions all operate through this avionics suite. On earlier Centaur variants, some attitude control functions relied on hydrazine monopropellant thrusters. On some Centaur V configurations, this hydrazine system has been replaced with hydrolox thrusters that draw gaseous propellants from the main tanks, a simplification that reduces the stage’s complexity and the number of distinct propellant types it requires.

The payload attach fitting connects spacecraft to the stage and is mounted to a Launch Vehicle Forward Adapter. The stage supports missions ranging from satellites deployed in low Earth orbit through payloads sent directly to geostationary orbit or beyond into deep space, making the same hardware genuinely adaptable to a wide range of mission profiles.

The RL-10 Engine and Propulsion System

The two RL-10 C-1-1A engines at the core of Centaur V’s propulsion system each produce 23,825 pounds (106 kilonewtons) of thrust in vacuum. They burn liquid hydrogen and liquid oxygen, a combination that delivers a specific impulse of approximately 465 seconds, which is a measure of fuel efficiency. Higher specific impulse means more velocity change per unit of propellant consumed, and the LH2/LOX combination produces the highest specific impulse available from any operational chemical propulsion system.

The RL-10’s operating principle, called an expander cycle, drives the turbopump using heat absorbed from the engine’s combustion chamber, throat, and nozzle as liquid hydrogen flows through cooling channels before reaching the combustion chamber. No separate gas generator or preburner is required. This cycle produces a clean, reliable operation and contributes to the engine’s long restart capability, since there are fewer ignition-sensitive components to coordinate during a relight sequence.

Aerojet Rocketdyne , now operating as part of L3Harris Technologies, manufactures the RL-10C-1-1A at its facility in West Palm Beach, Florida. The engine has been in development in various forms since the late 1950s, making it one of the longest-running production rocket engine programs in history. Chamber pressure has roughly doubled from early versions, ignition systems have been updated from vacuum-tube technology to solid-state fault-tolerant electronics, and hydraulic actuators for engine steering have been replaced with electromechanical equivalents. The core expander cycle concept, though, remains the same one that flew in 1963.

One of the RL-10’s most important attributes for Centaur V is its restart capability. Upper stages frequently need to fire more than once during a mission, coasting in an initial parking orbit before a second burn sends the payload to its intended destination. Centaur V’s combination of the improved RL-10C-1-1A and enhanced cryogenic insulation allows the stage to perform multiple burns separated by extended coast phases. This capability is examined in detail in its own section below, because it opens up mission profiles that simpler upper stages simply cannot execute.

ULA announced in 2023 that it planned to upgrade Centaur V to use the RL10E engine in later flights. The RL10E features a fixed nozzle extension and offers modest improvements in thrust and specific impulse. This planned upgrade reflects a pattern that has characterized the RL-10 program throughout its history: incremental but steady performance gains built on a foundation that has already proven itself in flight.

Centaur III vs. Centaur V: A Direct Comparison

The differences between Centaur III, the upper stage that powered Atlas V for over two decades, and Centaur V are significant enough to warrant direct comparison. The most visually obvious is diameter: Centaur III measures 3.05 meters across, while Centaur V reaches 5.4 meters. That change alone allows the newer stage to carry dramatically more propellant at a given length, which flows directly into mission performance.

Both stages share the same fundamental lineage and propellant combination, but the performance gap between them is substantial. The endurance figure deserves particular attention. Centaur III was capable of limited coast phases between burns, constrained by boiloff of its cryogenic propellants. Centaur V’s thermal management system extends this coast capability dramatically. This isn’t a minor upgrade in degree; it enables mission architectures that were genuinely out of reach for the older stage.

The two stages will coexist in ULA’s operations for some time. As of early 2026, Atlas V continues flying with Centaur III to fulfill existing launch contracts. ULA announced in August 2021 that it had stopped taking new Atlas V orders, and production of that rocket ended in 2024, but remaining contracted missions continue to launch. When those conclude, Centaur III will retire along with the vehicle it serves.

The Vulcan Centaur Architecture

Centaur V doesn’t fly independently. It sits atop the Vulcan first stage, which is built around a different set of engineering choices than the Atlas V it’s replacing. The Vulcan booster measures 5.4 meters in diameter, matching Centaur V exactly, and is manufactured at ULA’s factory in Decatur, Alabama using manufacturing equipment and techniques derived from the Delta IV production line. Two Blue Origin BE-4 engines power the first stage, each producing approximately 550,000 pounds (2.45 meganewtons) of thrust at sea level. These engines burn liquefied natural gas, sometimes called methane, as fuel with liquid oxygen as the oxidizer.

The choice of methane for the first stage matters because it burns cleaner than the kerosene-based RP-1 used in Atlas V’s first stage. Hydrocarbon buildup in engine components after a flight is a significant challenge for engine reuse programs, and methane’s cleaner combustion profile reduces this problem. ULA has indicated plans for a SMART reuse program that would recover Vulcan’s BE-4 engines after launch using an aeroshell and helicopter retrieval system, and methane’s compatibility with that program factored into the propellant selection.

The Vulcan rocket is available in configurations using zero, two, four, or six Graphite Epoxy Motor (GEM) 63XL solid rocket boosters (SRBs), manufactured by Northrop Grumman in Magna, Utah. Each GEM 63XL measures 1.6 meters in diameter and 21 meters in length, carrying over 45,000 kg of solid propellant. Adding SRBs increases the liftoff thrust and allows heavier payloads to reach orbit. The two-SRB variant is the standard offering for most commercial and national security missions.

The payload fairing is available in two lengths: a 15.5-meter standard configuration and a 21.3-meter long configuration, both measuring 5.4 meters in diameter. This matching of fairing, booster, and upper stage diameter to a consistent 5.4 meters simplifies integration and allows the full interior volume of the fairing to be used without the stepped-diameter transitions that characterized earlier vehicle families.

ULA uses a four-character designation system for Vulcan Centaur configurations. The first two characters are VC for Vulcan Centaur, the third indicates the number of SRBs (0, 2, 4, or 6), and the fourth denotes fairing length with S for standard or L for long. A VC2S configuration, for example, represents a Vulcan with Centaur V, two SRBs, and a standard-length fairing. This systematic naming makes configuration options transparent to customers planning missions across a range of payload sizes and destination orbits.

First Flight: January 8, 2024

The first Vulcan Centaur lifted off from Space Launch Complex-41 at Cape Canaveral Space Force Station at 2:18 a.m. EST on January 8, 2024. The vehicle, designated Cert-1, carried two payloads: Peregrine Mission One for Astrobotic Technology , and memorial flight payloads from Celestis. The Peregrine lander was the first mission under NASA ‘s Commercial Lunar Payload Services (CLPS) program.

The Vulcan Centaur and Centaur V performed nominally throughout the flight. The upper stage executed its burns correctly, deploying the Peregrine spacecraft on its intended lunar trajectory. What followed was not a Centaur V failure. A propulsion anomaly in Peregrine’s own propulsion system, unrelated to the Vulcan or its upper stage, prevented the lander from successfully reaching the Moon. That distinction matters: the launch vehicle did its job. The spacecraft it carried did not.

The second certification flight, Cert-2, launched on October 4, 2024, at 7:25 a.m. EDT from the same pad. That mission sent a Centaur V with an inert, non-deployable payload into an Earth-escape trajectory, placing the stage on a permanent solar orbit. The Cert-2 mission also carried experiments and technology demonstrations for future Centaur V capabilities. An anomaly occurred during this flight when the nozzle on one of the GEM-63XL solid rocket boosters separated approximately 37 seconds after liftoff. The SRB continued burning for its full 90-second run despite the loss of the nozzle, but the asymmetric thrust caused the vehicle to tilt. The Vulcan’s guidance system and main engines compensated by extending the main engine burn by roughly 20 seconds, and the mission achieved an acceptable orbital insertion. This was a first-stage issue with no connection to Centaur V’s performance.

Following a five-month review of both certification flights, the U.S. Space Force formally certified Vulcan Centaur for national security missions on March 26, 2025. The certification process was lengthy, and military officials expressed dissatisfaction with the pace of Vulcan’s development during this period. In written testimony to the House Armed Services Committee in May 2025, Major General Stephen G. Purdy described ULA’s program performance as unsatisfactory over the preceding year, noting that delayed transitions from Atlas V and Delta IV had set back four national security launches. ULA acknowledged these concerns and committed to accelerating its production and launch cadence.

Extended Endurance: The Most Important Capability

The single attribute of Centaur V that separates it most decisively from everything that came before is its endurance. Earlier Centaur versions could perform multiple burns, but the coast phases between those burns were constrained by how quickly the cryogenic propellants, especially liquid hydrogen, warmed and boiled off. A stage that loses too much propellant during a coast cannot execute the follow-on burns a mission plan requires.

Centaur V’s advanced insulation architecture addresses this directly. The combination of MLI blankets, radiation shields, and SOFI significantly slows the heat input that causes boiloff, allowing the stage to remain operational for extended periods in orbit. ULA describes the capability as 450 times the endurance of the previous Centaur generation. That number, while impressive, needs context: it doesn’t mean 450 times longer in absolute hours but reflects a combination of propellant retention and operational flexibility compared to Centaur III’s baseline performance envelope.

What does extended endurance actually enable? A practical example is direct delivery to geostationary orbit (GEO). Satellites bound for GEO are typically launched into a transfer orbit and then use their own propulsion to raise their orbit over days or weeks, which is time-consuming and burns propellant the satellite would rather save for its operational life. A sufficiently capable upper stage can deliver the satellite directly to GEO or very close to it, leaving more propellant on the spacecraft. Centaur V’s endurance makes extended mission profiles like this achievable where Centaur III’s shorter operational window made them impractical.

The capability also supports deep space missions where precise trajectory insertion windows matter enormously. Missions to the Moon, Mars, Jupiter, or beyond often require long coast phases to reach the right position for departure burns. The extended endurance of Centaur V keeps those options open across a wider range of launch windows than previous stages could serve.

Being direct about one contested point here: the 450-times endurance claim, while technically accurate based on ULA’s own comparisons, conflates different eras of hardware in a way that makes direct benchmarking difficult. Centaur III was designed for specific Atlas V mission profiles, not for maximum endurance. Comparing Centaur V’s endurance against Centaur III’s is a valid engineering contrast, but it may overstate the improvement relative to what a specifically optimized competitor with modern insulation techniques might achieve. Whether Centaur V truly represents the “world’s highest-performing upper stage,” as ULA claims, depends partly on how performance is measured and against which competing systems the comparison is made.

Multi-Burn Capability and Complex Orbital Deliveries

Upper stages that can only fire once, or twice with a brief coast, are limited to relatively simple mission profiles. Centaur V’s architecture supports far more complex sequences. Multi-manifest missions, where a single rocket carries multiple satellites to different orbits, become tractable when the upper stage can perform several burns with extended coasts between them.

ULA has developed specific infrastructure to support multi-manifest operations on Vulcan Centaur. An Aft Bulkhead Carrier (ABC) interfaces at the aft end of the Centaur V stage and can carry payloads up to 80 kg each, accommodating CubeSats or small satellites that ride along with primary payloads. This fills performance and volume margin that would otherwise go unused on missions where the primary payload doesn’t fully consume the rocket’s capability.

The Centaur V avionics system controls not just upper stage functions but provides integrated guidance and flight control across the full vehicle. This unified avionics approach allows the system to adapt to unexpected conditions during flight, as demonstrated during the Cert-2 mission when the guidance system compensated for the SRB nozzle loss. Having the intelligence to manage anomalies in real time makes the entire vehicle more resilient to off-nominal situations.

National Security Space Launch

ULA’s primary customer for Vulcan Centaur has always been the U.S. government. In the Phase 2 National Security Space Launch (NSSL) competition, the U.S. Space Force selected Vulcan as the top offeror for launch services from 2022 through 2027, alongside SpaceX’s Falcon 9 and Falcon Heavy. That selection came with significant financial stakes. ULA was awarded $967 million to develop the Vulcan prototype system in October 2018, and the NSSL contract covering operational launches represents billions of dollars in additional commitments.

National security missions have strict requirements. Satellites carrying intelligence collection, communications, and navigation capabilities for military and intelligence community users must reach precise orbits with high confidence. A launch vehicle that delivers the payload to the wrong orbit or at the wrong time creates problems that are difficult or impossible to recover from. Centaur V’s orbital insertion accuracy, which ULA calls “bullseye” precision, is designed to meet these requirements. The stage’s extended endurance also supports classified mission profiles that may require unconventional orbit insertion sequences.

The road to those national security launches has not been smooth. Delays in Vulcan’s development pushed several missions originally contracted for Vulcan back onto Atlas V. By mid-2024, Bloomberg News was reporting that ULA was accruing financial penalties under its NSSL contracts as a result of the delays. Air Force Assistant Secretary Frank Calvelli’s letter to Boeing and Lockheed executives in May 2024 made clear that military customers were frustrated with the pace of transition. The March 2025 certification marked the resolution of this certification hurdle, but rebuilding the operational launch cadence remains an ongoing challenge for ULA.

Commercial and Civil Markets

Beyond national security, ULA has sold more than 70 Vulcan Centaur launches. The largest single customer block is Amazon’s Project Kuiper constellation. Amazon contracted with ULA for 38 Vulcan Centaur launches to deploy its planned broadband satellite internet constellation, which intends to place thousands of satellites into low Earth orbit. That contract represents one of the largest commercial launch agreements in the industry’s history.

Civil science missions represent another segment of Vulcan Centaur’s market. NASA ‘s Commercial Lunar Payload Services program, which funded the Peregrine Mission One flight, represents the agency’s strategy of contracting commercial launch services for lunar delivery rather than building its own dedicated lunar vehicles. Future CLPS missions may use Vulcan Centaur again, particularly for payloads that benefit from the stage’s high-energy delivery capability to the Moon.

The original Cert-1 mission included payloads from Celestis, a company that has been conducting memorial spaceflight services since 1997, placing small amounts of cremated remains into orbit or on deep space trajectories. The presence of Celestis payloads on a national certification flight illustrated the multi-manifest philosophy that Centaur V’s capability supports: even on a mission with a primary purpose, additional payloads can ride along when performance margins allow.

Manufacturing and Supply Chain

Centaur V is manufactured at ULA’s factory in Decatur, Alabama, the same facility that produces the Vulcan first stage. The Decatur plant manufactures both the booster tanks and the Centaur V propellant tanks, enabling tight integration of manufacturing processes for the complete vehicle. This colocation simplifies logistics and quality control for a vehicle that cannot afford the kind of unit-to-unit variation that might be acceptable in less demanding industries.

The RL10C-1-1A engines are manufactured by Aerojet Rocketdyne, now part of L3Harris Technologies, at its facility in West Palm Beach, Florida. L3Harris completed its acquisition of Aerojet Rocketdyne in July 2023 in a transaction valued at approximately $4.7 billion. This consolidation placed one of the most strategically important rocket engine programs in the United States under new corporate ownership, a development that NASA and the U.S. Space Force watched carefully given the RL-10’s presence across multiple national programs, from Vulcan Centaur to the Space Launch System.

Payload fairings for Vulcan Centaur are manufactured by Beyond Gravity, a company formerly known as RUAG Space, at a facility in Decatur. The composite fairing structures require precise manufacturing to protect payloads during ascent while separating cleanly once the vehicle reaches the upper atmosphere. Northrop Grumman’s Magna, Utah facility produces the GEM-63XL solid rocket boosters. Blue Origin manufactures the BE-4 engines at its facility in Kent, Washington.

This distributed supply chain reflects ULA’s general philosophy of specialization and subcontracting, which differs from the vertically integrated approach that SpaceX has taken in building and launching the Falcon family. The tradeoffs between these models are real. Vertical integration can accelerate innovation and reduce costs when the integrating company scales up. Specialized suppliers can deliver components that an integrating company wouldn’t develop as efficiently on its own. Whether ULA’s approach optimally balances these tradeoffs will become clearer as Vulcan Centaur ramps up its launch cadence.

Centaur V Variants: CV-HE and CV-L

One development that emerged publicly in August 2025 reflects how ULA is thinking about adapting Centaur V for different market segments. During the Cert-2 mission broadcast in October 2024, ULA announced plans for a “LEO Optimized Centaur,” a shorter variant of the standard stage. By August 2025, this variant had received a formal designation. The original Centaur V is now called CV-HE, for Centaur V High Energy, to distinguish it from the new shorter variant designated CV-L.

The CV-L is 1.94 meters shorter than the CV-HE. A shorter stage carries less propellant, which reduces performance on high-energy missions but also reduces the dry mass and cost for missions where maximum propellant load isn’t needed. Low Earth orbit missions, including many of the Amazon Project Kuiper constellation deployments, don’t require the full propellant capacity and extended endurance of the CV-HE. Using a shorter, lighter stage for these missions allows ULA to optimize cost and performance for each mission type rather than flying the same hardware regardless of destination orbit.

This kind of product differentiation within a single vehicle family is standard practice in mature launch industries. ULA’s Atlas V offered multiple configurations from a single stage design. What the CV-HE/CV-L split does is formalize this differentiation at the stage level rather than just through propellant loading adjustments. Planning for the RL10E engine upgrade later in the Vulcan Centaur program adds another dimension to this differentiation, with the improved engine potentially arriving on CV-HE first before being adopted across the full variant range.

A New Competitive Context

The launch industry that Centaur V entered in January 2024 is substantially different from the one ULA operated in for most of Vulcan’s development period. SpaceX’s Falcon 9 has become the world’s most frequently launched orbital rocket, and the Falcon Heavy offers heavy-lift capability at prices that have pressured the entire commercial market. SpaceX’s Starship, still in development as of early 2026, promises to transform economics across the industry if it reaches full operational status. New Shepard from Blue Origin operates in suborbital space, but Blue Origin’s New Glenn rocket entered orbital operations in 2025, adding another large vehicle to the domestic fleet.

In this context, Centaur V’s strongest selling point isn’t raw lift capacity, since Falcon Heavy already covers heavy-lift demand at competitive prices. It’s the high-energy architecture, the direct-to-GEO delivery capability, the extended endurance for complex mission profiles, and the reliability record that ULA has built over more than two decades of Atlas V operations. Government customers, particularly the Space Force and intelligence agencies, place a premium on mission assurance that cost alone doesn’t capture.

Whether that premium is sustainable as launch options multiply is a genuine open question. The Space Force’s dual-provider strategy, which funds both ULA and SpaceX for national security launches, reflects a judgment that maintaining two domestic providers is worth the cost. That policy judgment may evolve as the market continues to change.

Summary

Centaur V represents the most significant redesign in the Centaur stage’s six-decade history. The jump from 3.05 to 5.4 meters in diameter, the adoption of the RL10C-1-1A engine in a dual-engine configuration, the advanced thermal management system enabling hundreds of times the endurance of its predecessor, and the fault-tolerant avionics architecture all combine to create a stage that can execute mission profiles the earlier Centaur III couldn’t attempt. Two successful certification flights in January and October 2024, followed by U.S. Space Force certification in March 2025, have established Centaur V as a proven operational system.

The manufacturing infrastructure supporting it draws on factories in Alabama, Florida, Utah, and Washington, reflecting a distributed production model that ULA has maintained throughout its history as a joint venture between Boeing and Lockheed Martin. Over 70 Vulcan Centaur launches are under contract, with Amazon’s Project Kuiper accounting for 38 of them, giving ULA a substantial backlog to work through as it builds launch cadence.

What Centaur V does for ULA’s competitive position will depend less on the stage’s engineering attributes, which are genuinely strong, and more on whether the company can execute the production and launch rate increases that its customers and financial backers need to see. The hardware has proven itself. The organizational challenge is what remains.

Appendix: Top 10 Questions Answered in This Article

What is Centaur V and what rocket does it fly on?

Centaur V is the upper stage of United Launch Alliance’s Vulcan Centaur rocket. It measures 5.4 meters in diameter and 11.7 meters in length, and is powered by two RL10C-1-1A engines burning liquid hydrogen and liquid oxygen. It is the most capable version of the Centaur upper stage family, which has been flying since 1963.

What engines power Centaur V?

Centaur V uses two RL10C-1-1A engines, each producing 23,825 pounds (106 kilonewtons) of thrust in vacuum. These engines are manufactured by Aerojet Rocketdyne, now part of L3Harris Technologies, at its facility in West Palm Beach, Florida. The RL-10 is an expander cycle engine burning liquid hydrogen and liquid oxygen, offering one of the highest specific impulses available from any operational chemical propulsion system.

When did Centaur V first fly?

Centaur V made its first flight on January 8, 2024, as part of the Vulcan Centaur Cert-1 mission launched from Space Launch Complex-41 at Cape Canaveral Space Force Station. The mission carried Astrobotic Technology’s Peregrine Mission One lunar lander and Celestis memorial payloads. The upper stage performed nominally throughout the flight.

How does Centaur V compare to the earlier Centaur III?

Centaur V is significantly larger than Centaur III, with a diameter of 5.4 meters compared to the Centaur III’s 3.05 meters. ULA states that Centaur V delivers 2.5 times the energy and 450 times the endurance of its predecessors. Both stages use pressure-stabilized stainless steel tanks and RL-10 engines burning liquid hydrogen and liquid oxygen, but Centaur V’s advanced thermal insulation system is what enables its dramatically extended operational life in orbit.

Why was Centaur V developed?

Centaur V was developed as part of ULA’s Vulcan Centaur program, which was driven primarily by a Congressional mandate to end U.S. dependence on Russia’s RD-180 engine used in the Atlas V first stage. Initially, ULA planned to use the existing Centaur III on the new booster, but in late 2017 the company switched to the larger Centaur V to take full advantage of the 5.4-meter diameter Vulcan first stage and to support more demanding mission profiles.

Has Vulcan Centaur been certified for national security missions?

Yes. After two certification flights in January and October 2024, the U.S. Space Force formally certified the Vulcan Centaur for national security space launch missions on March 26, 2025. The certification followed a five-month review process after the Cert-2 flight, which included an anomaly with a solid rocket booster nozzle that the vehicle’s guidance system successfully compensated for.

What is Centaur V’s extended endurance capability?

Centaur V’s advanced thermal management system, combining multilayer insulation blankets, radiation shields, and spray-on foam insulation, significantly slows the boiloff of cryogenic propellants while the stage coasts in orbit. This allows the stage to remain operational for extended periods between engine burns, enabling complex mission profiles such as direct geostationary orbit delivery and long-coast deep space trajectories that shorter-endurance stages cannot execute.

What is the difference between CV-HE and CV-L?

CV-HE (Centaur V High Energy) is the original full-length Centaur V, measuring 11.7 meters long, designed for high-energy missions to geosynchronous orbit and beyond. CV-L is a shorter variant, announced publicly in August 2025, that is 1.94 meters shorter than the CV-HE and optimized for low Earth orbit missions where maximum propellant capacity is not required. The CV-L designation is intended to reduce cost and improve performance matching for LEO payload deliveries.

Who are the main customers for Vulcan Centaur?

The primary customer is the U.S. government through the National Security Space Launch program, which selected Vulcan Centaur as a dual-provider alongside SpaceX for government launch contracts from 2022 to 2027. Amazon has contracted 38 Vulcan Centaur launches for its Project Kuiper broadband satellite constellation. Additional customers include NASA through the Commercial Lunar Payload Services program and commercial satellite operators requiring high-energy orbital delivery.

Where is Centaur V manufactured?

The Centaur V propellant tanks are fabricated and assembled at ULA’s factory in Decatur, Alabama, the same facility that manufactures the Vulcan first stage. The RL10C-1-1A engines are produced by Aerojet Rocketdyne (now part of L3Harris Technologies) in West Palm Beach, Florida. Payload fairings are manufactured by Beyond Gravity in Decatur, and the GEM-63XL solid rocket boosters are produced by Northrop Grumman in Magna, Utah.