What Is the BE-7?

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Landing Spacecraft on the Moon

The Blue Origin BE-7 is a high-performance liquid rocket engine, a specialized piece of hardware designed for a very specific and challenging task: landing spacecraft on the Moon. It is not an engine built for the raw power of launching from Earth. Instead, it is a machine of finesse, precision, and efficiency, developed to operate exclusively in the vacuum of space. The BE-7 is the powerplant behind the company’s Blue Moon (spacecraft) lander, positioning it as a key component in NASA’s plan to return astronauts to the lunar surface under the Artemis program.

This engine represents a significant modern engineering effort, combining the most efficient chemical propellants known – liquid hydrogen and liquid oxygen – with modern manufacturing techniques like additive manufacturing. Its most notable feature is its ability to “deep throttle,” meaning it can adjust its thrust over a very wide range. This capability is essential for the final, difficult moments of a lunar landing, allowing a spacecraft to gently decelerate from high orbital speeds to a soft, precise touchdown on the Moon’s hazardous, cratered terrain.

The development of the BE-7 is not just a technical exercise for Blue Origin. It is a central piece of the company’s long-term business strategy and its founder Jeff Bezos’s vision of expanding human presence into the solar system. The engine is the culmination of years of private investment, testing, setbacks, and high-stakes government competition.

A New Era of Lunar Ambition

After the Apollo program ended in 1972, human lunar exploration stopped for decades. The focus shifted to low Earth orbit with the Space Shuttle and the International Space Station. The Moon is now seen as a strategic and scientific stepping stone.

NASA’s Artemis program is the driving force behind this return. It is a multi-mission campaign to establish a long-term, sustainable human presence on and around the Moon, with the eventual goal of using those skills and technologies to send humans to Mars.

Unlike Apollo, which was a government-run endeavor, Artemis relies heavily on a new commercial model. NASA intends to buy services from private companies rather than owning and operating all the hardware itself. This approach is intended to foster innovation, reduce costs, and build a self-sustaining cislunar economy.

The most complex part of this plan is the Human Landing System (HLS). This is the vehicle that will ferry astronauts from lunar orbit (specifically, from a planned mini-space station called the Gateway) down to the Moon’s surface and back again. NASA solicited bids from private industry to develop these landers. This competition is where the BE-7 engine moved from a company project to a piece of national importance.

Blue Origin has long held lunar ambitions. The company’s vision extends to a future where millions of people live and work in space. To achieve this, the company is developing a suite of reusable vehicles. Its New Shepard rocket provides suborbital space tourism and microgravity research. The New Glenn heavy-lift rocket is designed to launch large payloads and satellites into orbit. The Blue Moon (spacecraft) lander is the logical next step: a vehicle to deliver cargo and, with the BE-7, people to the lunar surface.

Anatomy of a Lunar Lander Engine

The BE-7 is an engine defined by the unique and contradictory demands of its job. It must be simultaneously powerful enough to brake a heavy spacecraft out of orbit and gentle enough to hover and land softly. It must be highly efficient to minimize the amount of propellant it needs, yet simple and reliable enough to restart in the cold vacuum of space, far from help.

The “Hydrolox” Propellant Choice

The BE-7 is a “hydrolox” engine. This means it combines liquid hydrogen (LH2) as its fuel and liquid oxygen (LOX) as its oxidizer. This combination provides the highest specific impulse of any conventional chemical propellant.

Specific impulse is the rocket engine’s equivalent of fuel efficiency, or “miles per gallon.” A high specific impulse means the engine generates more thrust for a given amount of propellant consumed per second. When trying to land on the Moon, every kilogram of mass matters. A more efficient engine means the spacecraft can be lighter, or it can carry more payload, or it has more margin for error during landing.

This efficiency comes at a steep price. Liquid oxygen is very cold, but liquid hydrogen is far colder, needing to be stored at temperatures near absolute zero. Hydrogen is also notoriously difficult to handle. Its molecules are the smallest in the universe, allowing them to leak through seals and microscopic cracks that would contain other fluids. For a mission that may last days or weeks, preventing the cryogenic hydrogen from warming up and boiling off is a major engineering problem.

Despite these challenges, Blue Origin selected hydrolox for the BE-7. The performance gain was considered worth the complexity. This choice also aligns with a long-term vision. The Moon is now known to have significant deposits of water ice in its permanently shadowed craters. A future lunar base could theoretically “mine” this ice, use solar power to split the water (H2O) into hydrogen and oxygen through electrolysis, and then liquefy them. This would create a propellant depot on the Moon. An engine like the BE-7 is designed to one day run on fuel produced on the Moon, a concept known as in-situ resource utilization (ISRU).

The Dual-Expander Bleed Cycle

All rocket engines with turbopumps – which are needed to feed propellant into the combustion chamber at high pressure – must find a way to power those pumps. The method they use is called the engine cycle.

The BE-7 uses a dual-expander bleed cycle. This sounds complex, but the concept is elegant.

First, the super-cold liquid hydrogen fuel is pumped through small channels in the walls of the main combustion chamber and nozzle. The chamber and nozzle get incredibly hot during firing (thousands of degrees), and this process, called regenerative cooling, uses the fuel itself as a coolant to keep the engine from melting.

As the liquid hydrogen absorbs this intense heat, it flashes into a high-pressure gas. In a standard “expander cycle” engine, this hot, high-pressure gas is then routed to spin the turbines that power the turbopumps, after which it is injected into the chamber to be burned.

The BE-7’s “dual-expander bleed cycle” is a variation. It uses this hot hydrogen gas to spin the turbines for both the hydrogen pump and the liquid oxygen pump (the “dual-expander” part). After the gas has done its work spinning the turbines, a portion of it is “bled” overboard and vented into space, while the rest is sent to the combustion chamber. This approach is less efficient than a “closed” cycle that burns all its propellant, but it is mechanically simpler and more reliable. This makes it an excellent choice for an engine that must restart reliably in space.

The Key Feature: Deep Throttling

The single most important capability of the BE-7 is its deep throttling. The engine is designed to produce 10,000 pounds-force of thrust (44.5 kilonewtons). This is its 100% setting. For a lunar landing the spacecraft can’t just burn at 100% until it hits the ground. It needs fine control.

The BE-7 can throttle down to just 1,000 pounds-force of thrust, or 10% of its maximum power. This 10:1 throttle ratio is extremely difficult to achieve. A rocket engine is a continuous, balanced explosion. Changing the flow of propellants by such a large amount without the combustion becoming unstable is a major feat.

This capability is what allows the Blue Moon (spacecraft) lander to perform its entire landing sequence.

1. Braking Burn: High in lunar orbit, the BE-7 would fire at high thrust to kill the lander’s horizontal speed and begin its descent.
2. Approach Phase: As it gets closer, the engine would throttle down, allowing the lander’s navigation systems to scan the surface for a safe, flat landing spot, free of boulders or steep slopes.
3. Terminal Descent: In the final few hundred meters, the BE-7 would be throttled way down, allowing the lander to come down slowly and vertically, like a helicopter, before touching down gently on the lunar regolith.

This deep-throttling capability was pioneered by the Lunar Module Descent Engine (LMDE) during the Apollo program. The BE-7 is the modern, high-performance successor to that legacy, trading Apollo’s toxic hypergolic propellants for high-efficiency hydrolox.

Modern Manufacturing

The BE-7 is also a product of 21st-century manufacturing. Blue Origin makes extensive use of additive manufacturing, or 3D printing, to build major engine components.

Parts like the engine’s injector – a complex component that sprays and mixes the fuel and oxidizer – can be 3D-printed as a single piece. In a traditionally manufactured engine, an injector might consist of hundreds of individual parts that must be precisely machined and hand-welded together. Every weld is a potential point of failure. A printed part can be stronger, lighter, and produced much faster, with a “part count” of one. This approach simplifies the supply chain, speeds up development, and can increase overall reliability.

A Long and Winding Development Path

The BE-7 engine was not developed overnight. Its path from concept to flight hardware has been long and filled with the same challenges that face all advanced rocketry programs.

Early Testing

Blue Origin began publicly discussing the BE-7 around 2019, revealing it as the engine for its Blue Moon (spacecraft) lander. To test the engine, the company built and upgraded test stands at its remote West Texas launch facility and also secured test time at NASA facilities.

A large part of the engine’s development and qualification testing took place at NASA’s Marshall Space Flight Center (MSFC) in Alabama and at the Stennis Space Center in Mississippi. These facilities have specialized test stands that can simulate the vacuum of space, allowing engineers to hot-fire the engine and verify its performance in a flight-like environment.

The test campaign focused on three key milestones:

1. Full-Duration Burns: Firing the engine for the full amount of time it would need to for a complete lunar landing.
2. Restart Capability: Shutting the engine down and then successfully reigniting it, a process it would need to do in lunar orbit.
3. Throttling: Running the engine through its full 10:1 throttle range to prove its stability.

Blue Origin reported numerous successful tests, accumulating thousands of seconds of hot-fire time on multiple engine builds.

The 2023 Test Anomaly

The development of rocket engines is unforgiving. In June 2023, a BE-7 engine suffered a major failure during a test at the West Texas facility, resulting in an explosion that heavily damaged the test stand. No one was injured, but the event was a significant setback.

Such failures are a common, if costly, part of the development process. The engine hardware was destroyed, but the test sensors provided engineers with data on the moments leading up to the failure. Blue Origin launched an investigation to pinpoint the cause, fix the vulnerability, and implement corrective actions before resuming the test campaign. This incident highlighted the extreme difficulty of harnessing the power of liquid hydrogen.

The High-Stakes HLS Competition

The BE-7 engine became famous not just for its technology, but for its central role in a dramatic, high-stakes competition to win NASA’s Human Landing System (HLS) contract.

The First Bid: The “National Team”

In 2019, NASA asked for proposals. Blue Origin formed a “National Team,” a powerhouse partnership of legacy aerospace giants.

• Blue Origin would serve as the prime contractor and build the “Descent Element,” the main landing stage. This stage would be powered by the BE-7 engine.
• Lockheed Martin would build the “Ascent Element,” the reusable crew cabin that would lift astronauts off the Moon.
• Northrop Grumman would build the “Transfer Element,” a space tug to move the lander from a high orbit to a low lunar orbit.
• Draper would provide the guidance, navigation, and control systems.

This was a complex, three-stage lander. In April 2021, NASA announced its decision. Citing a lack of funding from Congress, the agency opted to select only one company for the initial contract: SpaceX, with its radically different Starship HLS concept.

This decision was a major blow to Blue Origin and its partners. The company filed a formal protest with the Government Accountability Office (GAO), arguing that NASA had improperly evaluated the proposals and should have either funded a second lander or re-opened the competition. The GAO reviewed the case and denied the protest.

In an unusual and controversial move, Blue Origin then sued NASA in federal court, forcing a pause on SpaceX’s work. The lawsuit failed, and the court sided with NASA. The public and political fallout was intense, but the BE-7 engine was, for the moment, left without a path to the Moon as part of the Artemis crewed program.

The Second Chance: Sustaining Lunar Development

Despite the legal battle, NASA and Congress both maintained that having a second, dissimilar lander was important for competition and redundancy. In 2022, NASA announced a new opportunity: the Sustaining Lunar Development (SLD) contract. This would fund a second lander to be used for missions following the initial SpaceX landing, beginning with Artemis V.

Blue Origin bid again, this time with a revised lander and a new team that included Lockheed Martin, Draper, Boeing, and Astrobotic Technology.

In May 2023, NASA awarded this $3.4 billion contract to the Blue Origin team. The BE-7 engine was officially back in the Artemis program.

The new “Blue Moon MK2” lander design is different from the original National Team concept. It is a single, integrated lander designed for reusability. It will be launched to a Near-Rectilinear Halo Orbit (NRHO) around the Moon, where it will be refueled by a tanker spacecraft before picking up the astronauts from the Gateway station.

For this mission, the BE-7 is even more important. It is the primary propulsion system for the lander, responsible for the entire autonomous descent and landing with astronauts on board.

The BE-7’s First Flight: The MK1 Pathfinder

Before the BE-7 is trusted to carry astronauts, it will fly on an uncrewed precursor mission. As part of NASA’s Commercial Lunar Payload Services (CLPS) initiative, Blue Origin is building a smaller, uncrewed lander called the Blue Moon Mark 1 (MK1).

This MK1 lander is designed to deliver up to 3,000 kilograms of cargo to the lunar surface. It is also powered by a single BE-7 engine. This mission will serve as a pathfinder, demonstrating the lander’s systems and the BE-7’s performance in the real lunar environment. It provides invaluable flight data and de-risk the technology before the larger, human-rated MK2 lander flies on Artemis V.

The first MK1 mission is slated to land at the lunar south pole, carrying a NASA payload designed to test the extraction of oxygen from lunar regolith – a direct test of the ISRU concept that the hydrolox BE-7 is designed to support.

Context and Comparison

The BE-7 is a modern engine, but it follows a long line of high-performance hydrolox powerplants.

The Legacy of the RL10

The most famous hydrolox engine in history is the Pratt & Whitney RL10. First developed in the late 1950s, the RL10 has been the workhorse of the American space program for over 60 years. It powered the Centaur (rocket stage) upper stage, which was responsible for sending many of NASA’s most important robotic missions on their way.

Missions launched by RL10 engines include the Surveyor landers to the Moon in the 1960s, the Viking landers to Mars, the Voyager 1 and 2 probes to the outer solar system, the Cassini-Huygens mission to Saturn, and the New Horizons probe to Pluto.

Like the BE-7, the RL10 is a hydrolox engine that uses an expander cycle. The BE-7 can be seen as a spiritual successor, taking the same high-performance principles and updating them with modern manufacturing and, most importantly, adding the deep-throttling capability required for landing.

BE-7 vs. SpaceX Raptor

The BE-7’s main contemporary is the SpaceX Raptor (rocket_engine_family) engine, which powers the Starship HLS lander. The two engines could not be more different.

• Propellant: Raptor is a “methalox” engine, using liquid methane and liquid oxygen. Methane is not as efficient as hydrogen (it has a lower specific impulse), but it is much denser and easier to handle, as it does not need to be kept as cold.
• Engine Cycle: Raptor uses a full-flow staged combustion cycle. This is a far more complex and high-pressure cycle, but it is also more powerful and efficient than the BE-7’s expander bleed cycle.
• Thrust: The BE-7 is a 10,000 lbf engine. A single Raptor engine produces over 500,000 lbf of thrust.

These differences highlight the two companies’ opposing design philosophies. The Blue Moon (spacecraft) lander is a specialized vehicle, and the BE-7 is a specialized engine custom-built for the single task of landing. Starship is an enormous, all-in-one vehicle designed for Earth launch, orbital flight, and landing, powered by dozens of the same engine. The BE-7 is a precision instrument; the Raptor is a powerhouse. Both are now tasked by NASA with landing astronauts on the Moon.

BE-7 Technical Specifications

Summary

The Blue Origin BE-7 is far more than a simple piece of machinery. It is an engine born from a specific, challenging set of requirements for a new era of lunar exploration. Its design, based on high-efficiency hydrolox propellants, a reliable expander cycle, and modern additive manufacturing, is focused on solving one of the hardest problems in spaceflight: a soft, precise landing on the Moon.

The engine’s ability to deep throttle from 10,000 pounds of thrust down to 1,000 is its defining feature, providing the fine control needed for a safe touchdown. After a long development program, including a major test failure and a dramatic, high-stakes competition for a NASA contract, the BE-7 is now slated to power the Blue Moon (spacecraft) lander.

It is scheduled to fly first on an uncrewed pathfinder mission before it fulfills its primary purpose: landing Artemis astronauts on the lunar surface. In doing so, the BE-7 represents a key bet on a future lunar economy, one where its propellant could one day be sourced from the very world it was designed to explore.