What Is the BE-3PM?

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A New Engine for a New Era of Spaceflight

In the complex symphony of a rocket launch, the engines are the heart. They provide the raw power to defy gravity, and the precision to place satellites, cargo, and people exactly where they need to go. For Blue Origin, a company founded with a long-term vision for humanity’s future in space, developing its own engines has been a foundational part of its strategy. This journey has produced a family of engines, each tailored for a specific task. One of the most significant is the BE-3PM.

The BE-3PM is not an engine for the flash and thunder of liftoff. It’s an upper-stage engine, designed to operate in the vacuum of space. It’s the engine that performs the final, high-energy push to orbit. It’s set to power the second stage of Blue Origin’s heavy-lift orbital rocket, New Glenn. While its sibling, the BE-3U, gained fame by powering the reusable New Shepard rocket on suborbital flights, the BE-3PM is a different machine, built for a different and more demanding job.

Understanding the BE-3PM requires looking at its lineage, the specific challenges of orbital mechanics, and the design choices that separate it from its predecessor. It represents a different branch of engineering philosophy, one that prioritizes simplicity and reliability for the final phase of a mission. As New Glenn prepares to enter the competitive launch market, its BE-3PM engines will be responsible for delivering on its ambitious promises.

The Lineage of the BE-3 Engine Family

No rocket engine appears in isolation. Each is the result of years, sometimes decades, of research, testing, and learning from previous designs. The BE-3PM is a direct descendant of Blue Origin’s first major engine development program, the BE-3. This family’s story is central to the company’s entire incremental approach to spaceflight.

The Foundation: Blue Origin’s Propulsion Philosophy

From its founding by Jeff Bezos in 2000, Blue Origin adopted a patient, methodical, and well-funded approach to development. The company’s motto, “Gradatim Ferociter” or “Step by Step, Ferociously,” perfectly encapsulates this. Instead of immediately trying to build a massive orbital rocket, the company focused on mastering the fundamental building blocks. The most important building block is propulsion.

Developing rocket engines in-house is a massive technical and financial undertaking. It’s a capability that historically was limited to superpowers and government agencies. By choosing to build its own engines, Blue Origin ensured it would control its own destiny, pace, and technology. This vertical integration means the company isn’t reliant on outside suppliers for its most essential components.

The engine development path started small, with early thrusters and peroxide-based engines for low-altitude test vehicles. This work provided the hands-on experience needed to tackle a much more ambitious project: a throttleable, reusable, hydrogen-fueled engine. That engine would become the BE-3.

The BE-3U: Master of Reusability and Deep Throttling

The engine that most people associate with Blue Origin is the BE-3U. The “U” is often understood to mean “upper-stage,” but its primary application has been as the single engine on the New Shepard propulsion module. This is the vehicle that has flown dozens of missions, carrying scientific payloads and, more recently, tourists on brief suborbital journeys into space.

The BE-3U is a remarkable piece of engineering. It’s a turbopump-fed engine, meaning it uses powerful, high-speed turbines to force its propellants into the combustion chamber under immense pressure. This allows it to generate significant thrust from a compact package. It is also the first new liquid hydrogen engine to be developed in the United States in over a decade.

It burns liquid hydrogen (LH2) as its fuel and liquid oxygen (LOX) as its oxidizer. This combination is known as hydrolox and is one of the most efficient chemical propellants available. But the BE-3U’s most famous feature isn’t just its fuel. It’s the engine’s ability to “deep throttle.”

To power the New Shepard rocket, the BE-3U fires at its full 110,000 pounds of thrust to blast off the pad. But to land that same rocket booster vertically, the engine must re-ignite in flight and slow the vehicle for a gentle touchdown. This requires the engine to throttle down to just 20,000 pounds of thrust. This ability to vary its power output across such a wide range is known as deep throttling, and it’s exceptionally difficult to achieve. Maintaining stable combustion when the flow of propellants is reduced so drastically is a major engineering hurdle. Blue Origin’s mastery of this capability with the BE-3U was a watershed moment, proving the viability of its design and paving the way for reusable rockets.

What is Deep Throttling?

Throttling a liquid-propellant rocket engine is similar in concept to pressing the accelerator in a car, but it’s infinitely more complex. In a car, you control the flow of fuel and air. In a rocket engine, you are controlling the flow of super-cooled liquids being forced into a chamber where they combust violently at extreme temperatures and pressures.

Most rocket engines are designed to operate at a single, fixed thrust level – their “100%, full-power” setting. They are optimized for maximum efficiency at that one point. Throttling an engine requires a complex, delicate dance. The valves that control propellant flow must be precise, and the injector – the “shower head” that sprays and mixes the fuel and oxidizer – must be designed to work effectively at both high and low flow rates.

If the flow is reduced too much, the combustion can become unstable. This instability, known as “pogo” or “combustion instability,” can create vibrations strong enough to tear the engine or the entire rocket apart. The BE-3U’s ability to throttle down to less than 20% of its maximum power without losing stability is what makes it so special. This feature was essential for the gentle, propulsive landings of the New Shepard booster.

Introducing the BE-3PM: An Upper-Stage Specialist

The success of the BE-3U on New Shepard proved the engine’s core technology. But the requirements for an orbital upper stage are very different from those of a suborbital, reusable booster. This led to the development of a distinct variant: the BE-3PM.

From Suborbital Hops to Orbital Insertion

The BE-3U’s job is to push a capsule to the edge of space and then return the booster to Earth. Its total firing time is relatively short. After it has done its job, it must re-start and throttle down for landing.

An orbital upper-stage engine, like the BE-3PM, has a completely different mission. It ignites in the vacuum of space, after the massive first stage has burned all its fuel and separated. This upper stage must then accelerate the payload – a satellite, for example – from a high-altitude arc to a blistering orbital velocity of over 17,000 miles per hour.

This mission often requires not just one long burn, but multiple. The engine might fire once to get into a “parking orbit,” then shut down and coast for an hour, and then re-ignite on the other side of the planet to push the payload into its final, higher orbit, such as a geostationary transfer orbit. For this job, the BE-3U’s complex turbopumps and deep-throttling capability are not just unnecessary; they are a liability. Deep throttling isn’t needed for an expendable upper stage. The complexity of the turbopump system, with its high-speed spinning parts, introduces potential failure points for the all-important in-space restart.

The “PM” Distinction: A Shift to Pressure-Fed

This is where the BE-3PM gets its name and its unique identity. The “PM” is widely understood to stand for “Pressure-Fed, M” (with “M” possibly referring to the specific model or version). Instead of using the complex, heavy turbopumps of the BE-3U, the BE-3PM uses a pressure-fed engine cycle.

This is a much simpler design. In a pressure-fed system, the engine’s propellant tanks are pressurized with a separate, inert gas, like helium. This high-pressure gas acts like a piston, pushing the fuel and oxidizer into the combustion chamber. The concept is similar to an aerosol spray can, where a pressurized gas forces the liquid product out.

This design eliminates the entire turbopump assembly: the turbine, the pumps, the gearbox, and all the associated plumbing and sensors. This is a massive simplification. It makes the engine lighter, easier to manufacture, and, most important, more reliable. It removes the single most complex set of moving parts from the engine.

The BE-3PM is a new engine from the injector to the nozzle, optimized specifically for this pressure-fed cycle. It’s not just a BE-3U with the pumps removed. It’s a purpose-built design that leverages the same propellants (LH2/LOX) but uses a different method to get them to combust.

Why Choose a Pressure-Fed System for an Upper Stage?

The choice of a pressure-fed engine cycle is a classic engineering trade-off. It’s not “better” than a turbopump-fed engine in every situation, but it is the ideal choice for this specific application.

The primary benefit is reliability. Fewer moving parts means fewer ways for the engine to fail. When an engine needs to restart in the cold vacuum of space, hours into a mission and far from help, simplicity is the ultimate virtue.

Another benefit is cost and manufacturability. A pressure-fed engine is simpler to build and test. This aligns with Blue Origin’s goal of lowering the cost of access to space.

The main drawback of a pressure-fed system is that it requires very strong, and therefore heavy, propellant tanks. The tanks must be built to withstand the high pressure of the helium gas pushing on the propellants. This added tank weight is a penalty. In contrast, a turbopump-fed system can use much lighter tanks because the pumps are doing all the work of creating pressure.

For a first stage, this weight penalty would be a non-starter. But for an expendable upper stage, the math is different. The stage is much smaller, so the tank-weight penalty is less severe. The benefits of simplicity and high reliability for in-space restarts far outweigh the cost of slightly heavier tanks. The BE-3PM’s design shows a clear-eyed focus on optimizing the engine for its specific role.

Here is a simple comparison of the two engine variants in the BE-3 family:

The High-Energy Propellants: Liquid Hydrogen and Liquid Oxygen

Both the BE-3U and BE-3PM use the same propellant combination: liquid hydrogen (LH2) and liquid oxygen(LOX). This “hydrolox” combination is the most efficient, high-performance chemical propellant combination in common use.⁵

The “Gas Mileage” of a Rocket

A rocket’s efficiency is measured by a metric called specific impulse, or Isp. In simple terms, Isp is the “gas mileage” of a rocket engine. It measures how much thrust (push) an engine can produce for a given amount of propellant consumed over time. The higher the specific impulse, the more efficient the engine.⁶

For an upper stage like the one powered by the BE-3PM, efficiency is everything. The first stage does the “brute force” work of lifting the rocket off the ground and through the thickest part of the atmosphere. The upper stage does the “fine-tuning” work of adding velocity in space. Because the upper stage is already high up and moving fast, every ounce of propellant it uses is precious. A more efficient upper stage can deliver a heavier payload to the same orbit, or deliver the same payload to a much higher or more complex orbit.

Liquid hydrogen is the lightest element in the universe. When it combusts with liquid oxygen, its exhaust particles (which are just superheated water vapor) fly out of the engine nozzle at an extremely high velocity. This high exhaust velocity is what creates a high specific impulse. The BE-3PM is designed to maximize this efficiency, giving the New Glenn rocket a significant performance advantage for delivering payloads to their final destinations.

The Challenges of Cryogenics

While hydrolox is highly efficient, it is also notoriously difficult to work with. Both liquid hydrogen and liquid oxygen are cryogenic, meaning they must be kept at incredibly low temperatures to remain in a liquid state.

Liquid oxygen must be kept below -297°F (-183°C). It is also a powerful oxidizer that can cause many materials to combust spontaneously.

Liquid hydrogen is even more extreme. It is the coldest of all rocket fuels, needing to be stored below -423°F (-253°C), just a few degrees above absolute zero. At this temperature, it presents a host of engineering challenges.

• Boil-Off: Even with the best insulation, some of the liquid hydrogen will always absorb heat from its surroundings and “boil-off,” turning back into a gas. This is a problem for an upper stage that may need to coast for hours before its second burn. The BE-3PM and its stage must be designed to manage this boil-off.
• Leaks: Hydrogen is the smallest molecule in the universe. It can leak through seals and even pass through the microscopic pores of solid metal, a phenomenon known as hydrogen embrittlement, which can make metals brittle and weak.⁷
• Density: Liquid hydrogen is not very dense. This means it requires very large, bulky tanks to store, which is why the hydrogen tanks on rockets are always much larger than the oxygen tanks, even though more oxygen is used by weight.

Mastering these cryogenic challenges is a prerequisite for any company wanting to build high-performance upper stages. Blue Origin’s work on the BE-3U gave it extensive experience in handling LH2, and this expertise is directly applied to the BE-3PM.

The BE-3PM’s Role on the New Glenn Rocket

The BE-3PM engine does not exist in a vacuum. It was designed for one purpose: to serve as the propulsion for the second stage of the New Glenn rocket.

New Glenn’s Architecture: A Two-Stage Heavy-Lift Vehicle

New Glenn is Blue Origin’s entry into the heavy-lift orbital launch market. It’s a massive rocket, standing nearly 100 meters tall, designed to compete with the largest rockets in the world. It has two stages.

The first stage is the reusable booster.⁸ It’s powered by seven BE-4 engines, another Blue Origin product. The BE-4 is a very different engine, burning liquefied natural gas (LNG) and liquid oxygen to produce over 550,000 pounds of thrust. This booster is designed to fly back to Earth and land on a moving ship, much like its New Shepard predecessor, so it can be reused for future missions.

The second stage is expendable, meaning it is not recovered. This stage sits on top of the first stage and carries the payload. After the first stage booster separates and begins its return to Earth, the second stage ignites to continue the journey to orbit. This is where the BE-3PM engines are.

Powering the Second Stage

The job of the New Glenn second stage is to perform the orbital insertion. This stage is a high-performance vehicle in its own right. It’s powered by two BE-3PM engines.

After the first stage separates, the vacuum of space is the BE-3PM’s domain. The two engines ignite, producing a combined thrust of over 300,000 pounds. They will fire for several minutes, accelerating the stage and its payload to orbital velocity.

This stage is designed for complex missions. The BE-3PM’s ability to restart reliably is key. A typical mission to geostationary orbit, where many large communications satellites operate, might involve one burn to reach a low parking orbit. The stage would then coast for a long period, sometimes hours. Then, at the precise moment, the two BE-3PM engines would re-ignite to push the satellite into a long, elliptical transfer orbit, from which the satellite can use its own thrusters to circularize its path.

The Power of Two: Dual-Engine Configuration

The choice to use two BE-3PM engines instead of one larger engine is a significant design decision. This configuration offers several advantages.

First is “engine-out” capability. While the BE-3PM is designed for simplicity and reliability, space is an unforgiving environment. If one of the two engines should fail during the ascent, the second engine may be able to burn longer to compensate, potentially still saving the mission and delivering the payload to a usable orbit. This adds a layer of redundancy that is highly valued by customers launching multi-million dollar satellites.

Second, two engines provide a good balance of thrust and efficiency. They provide enough combined power to lift heavy payloads out of low Earth orbit, but they are still small and efficient enough to be a good match for the high-energy hydrolox propellants. This dual-engine architecture gives the New Glenn upper stage the power and flexibility to handle a wide variety of missions, from single, heavy satellites to clusters of smaller ones.

Development, Testing, and Manufacturing

Bringing a new rocket engine from a computer screen to the launch pad is an arduous process of design, fabrication, and testing. The BE-3PM has been undergoing this process for years, leveraging both NASA heritage and Blue Origin’s own state-of-the-art facilities.

A New Engine Comes to Life

The BE-3PM, while sharing a name with the BE-3U, is in many respects a new engine. Its pressure-fed cycle required a complete re-design of its components, from the injector and combustion chamber to the lightweight, expandable nozzle optimized for vacuum.

This development work takes place at Blue Origin’s expansive facilities. The company has invested heavily in creating a vertically integrated manufacturing process, allowing it to design, build, and test its engines all under its own roof.⁹ This control over the entire production chain is meant to speed up development and ensure high quality.

Rigorous Testing: From Huntsville to West Texas

An engine’s true mettle is proven on the test stand. Blue Origin has conducted extensive test campaigns for the BE-3PM. A key location for this testing has been NASA’s Marshall Space Flight Center in Huntsville, Alabama.

There, Blue Origin refurbished the historic Test Stand 4670. This stand, which once tested the engines for the Apollo program, was modified to test the BE-3U and later the BE-3PM. Testing at a NASA facility allowed the company to leverage decades of government expertise and infrastructure.

The BE-3PM has also been tested extensively at Blue Origin’s private West Texas launch and test facility. These tests involve firing the engine in a vacuum chamber to simulate the space environment. The engine is pushed to its limits, fired for its full duration, and tested for its ability to reliably restart. Each test provides critical data that engineers use to refine the design and validate its performance.

The Rise of Additive Manufacturing

A key technology that has accelerated the development of engines like the BE-3PM is additive manufacturing, more commonly known as 3D printing.

Rocket engines are filled with intricate parts. Injectors, for example, must mix propellants in precise patterns and are full of complex internal channels.¹⁰ Traditionally, these parts were made by welding or brazing dozens, or even hundreds, of individual small pieces together. This was time-consuming, expensive, and created numerous potential failure points at each weld.

With additive manufacturing, engineers can print these complex components as a single, solid piece of metal. This dramatically simplifies the supply chain, reduces manufacturing time from months to days, and creates a stronger, more reliable part. Blue Origin has aggressively adopted this technology across its engine programs, and the BE-3PM benefits from this modern manufacturing approach.

BE-3PM in the Modern Launch Market

The BE-3PM and the New Glenn rocket are entering a fiercely competitive launch market. The performance of this upper-stage engine will be a key factor in Blue Origin’s success.

Competing with a Legend: The RL10

The BE-3PM’s direct competitor is one of the most successful and legendary engines in the history of spaceflight: the Aerojet Rocketdyne RL10.

The RL10 is also a hydrolox upper-stage engine. It has been flying since the 1960s and has powered the upper stages of rockets from the Atlas and Delta families to NASA’s Space Launch System. The newest version of the RL10 powers the Centaur V upper stage for the Vulcan Centaur rocket, the primary competitor to New Glenn from the United Launch Alliance.

The BE-3PM is the new challenger, designed from a clean sheet with modern manufacturing and a different design philosophy. While the RL10 is a highly complex and incredibly efficient turbopump-fed engine, the BE-3PM counters with a pressure-fed design that bets on simplicity and reliability. This competition between two different engineering approaches for the same mission will be a major story in the launch industry.

Enabling New Glenn’s Mission Profile

The BE-3PM-powered upper stage is what gives New Glenn its versatility. The rocket is already under contract for a wide array of missions, and the BE-3PM will be responsible for the final delivery of all of them.

• Commercial Satellites: Amazon.com, a company also founded by Jeff Bezos, has booked a large number of New Glenn launches for its Project Kuiper satellite internet constellation. These missions will require the BE-3PMs to deploy large batches of satellites into precise orbits.
• National Security: The U.S. Space Force has selected New Glenn as one of its launch providers for critical national security missions. These high-value payloads require the utmost reliability, a key selling point of the BE-3PM’s simpler design.
• Interplanetary Science: NASA has also selected New Glenn to launch the ESCAPADE mission, a pair of small spacecraft that will travel to Mars to study its atmosphere. This mission requires the upper stage to perform a high-energy “trans-Mars injection” burn, flinging the spacecraft out of Earth’s orbit and onto a path to another planet.

The Future of the BE-3 Platform

The BE-3 engine family is a core asset for Blue Origin. The BE-3U continues to fly on New Shepard, gathering more data on reusability and throttling. The BE-3PM is poised to become the workhorse for the New Glenn upper stage. But the platform’s story doesn’t end there.

Blue Origin has also developed the BE-7 engine, a high-efficiency hydrolox engine designed for in-space propulsion and lunar landing. This engine will power the company’s Blue Moon lander, which is a key part of NASA’s Artemis program to return astronauts to the Moon. The lessons learned from handling cryogenic liquid hydrogen in both the BE-3U and BE-3PM are directly applicable to the development of the BE-7.

The BE-3 platform, in all its variations, represents a ladder of capabilities. The BE-3U mastered reusable, suborbital flight. The BE-3PM is designed to provide reliable, simple access to any orbit. Together, they form a deep well of expertise that Blue Origin is using to build its road to space, one step at a time.

Summary

The Blue Origin BE-3PM is a specialized liquid-propellant rocket engine that plays a vital part in the company’s orbital ambitions. As a member of the BE-3 family, it shares its efficient liquid hydrogen and liquid oxygen propellant heritage with the reusable BE-3U engine that powers New Shepard.

However, the BE-3PM is a distinct machine, purpose-built for its role on the second stage of the New Glenn rocket. It swaps the complex turbopumps of its sibling for a simpler, more reliable pressure-fed engine cycle. This design choice is a deliberate trade-off, sacrificing some weight to gain the high reliability and simple restart capability needed for an expendable upper stage that must operate in the vacuum of space.

In a dual configuration, the BE-3PM engines provides the final push to orbit for commercial, government, and scientific payloads, from Project Kuiper satellites to NASA missions to Mars. The engine is a testament to Blue Origin’s long-term, step-by-step approach, representing a critical piece of the puzzle in the company’s quest to make spaceflight a more common and accessible human endeavor.