Why Methane Engines Are the Workhorse of the New Space Economy

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Not Just for SpaceX

The roar of a rocket is the sound of ambition. For decades, that sound was produced by burning either a refined kerosene or super-chilled liquid hydrogen. These propellants powered everything from the first satellites to the Apollo moon missions and the Space Shuttle. But a new sound is beginning to dominate the launchpads of the 21st century: the sound of methane.

While SpaceX‘s colossal Starship and its array of Raptor engines have brought methane into the spotlight, the shift to this fuel is a global phenomenon. From established aerospace giants to ambitious startups in the United States, China, and Europe, engineers are overwhelmingly choosing methane to power the next generation of launch vehicles. It’s not just a trend; it’s a foundational change driven by a powerful combination of performance, practicality, and a future-focused vision. Methane isn’t just another option in the toolkit; it’s becoming the go-to propellant for the growing space economy, promising cheaper access to orbit, rapid reusability, and even a path to settling other worlds. To understand why, the following reviews the fuels it’s replacing.

A Tale of Three Fuels: Kerosene, Hydrogen, and Methane

The choice of rocket fuel is a delicate balancing act. Engineers juggle performance, density, cost, and ease of handling. For over half a century, the primary choices presented a stark trade-off between practicality and raw power. The history of rocketry is a history of mastering these trade-offs, with each new fuel unlocking new capabilities.

The Old Guard: RP-1 Kerosene

The workhorse fuel of the first space age was RP-1, a highly purified form of kerosene. It’s the propellant that lifted the mighty Saturn V rockets on their way to the Moon and continues to power Russia’s venerable Soyuz launchers and SpaceX’s own Falcon 9. Its appeal is rooted in its practicality.

RP-1 is dense, which is a great quality for a rocket fuel. Because it packs a lot of energy into a small volume, the tanks that hold it don’t need to be excessively large. Smaller, lighter tanks mean more of the rocket’s lift capacity can be dedicated to the payload. It’s also stable at room temperature, making it relatively straightforward to store and handle on the ground. There’s no need for extreme refrigeration or heavily insulated tanks just to keep it from boiling away. It’s a known, reliable, and cost-effective fuel.

But RP-1 has a significant downside: it burns dirty. The long hydrocarbon chains in kerosene don’t always combust completely, especially in the fuel-rich environment inside a rocket engine. This imperfect combustion leaves behind a residue of black, sticky soot. This phenomenon, known as “coking,” coats the inside of an engine’s intricate plumbing, turbines, and combustion chamber. For an expendable rocket that flies only once, this isn’t a major problem. But for a reusable one, it’s a deal-breaker. Coking requires an engine to be painstakingly stripped down, cleaned, and refurbished after every flight – a process that is both time-consuming and expensive. It fundamentally undermines the goal of rapid and affordable reusability. Furthermore, its performance, measured by a metric called specific impulse, is good but not great, typically topping out in the range of 300-350 seconds at sea level.

The High-Performer: Liquid Hydrogen

At the other end of the spectrum is liquid hydrogen (LH2). In terms of pure efficiency, it’s the undisputed champion of chemical rocket fuels. When burned with liquid oxygen, it generates the highest specific impulse possible, often exceeding 450 seconds in the vacuum of space. It provides the most thrust for a given amount of fuel consumed per second. Its only major byproduct is water vapor, making it an exceptionally clean-burning propellant.

This high performance made it the fuel of choice for the upper stages of many powerful rockets, including the Saturn V, the Delta IV Heavy, and Europe’s Ariane family. The iconic orange external tank of the Space Shuttle was filled with liquid hydrogen and liquid oxygen to feed its three powerful main engines.

But hydrogen’s performance comes at a steep price in complexity. It is the least dense element, so even in liquid form, it takes up a massive amount of space. This necessitates enormous, lightweight fuel tanks that can add significant structural weight to a rocket. Hydrogen is also deeply cryogenic, needing to be kept at a frigid -253°C (-423°F). Maintaining this temperature requires heavy insulation and sophisticated ground support equipment. Even with the best insulation, some of the fuel inevitably “boils off” and turns to gas, which must be vented. This makes it unsuitable for long-duration missions where fuel would need to be stored for weeks or months. It also has a pesky tendency to weaken metals through a process called hydrogen embrittlement, adding another layer of engineering challenge.

The New Contender: Methane

This is where methane enters the picture, offering a “Goldilocks” solution that captures many of the benefits of both kerosene and hydrogen while minimizing their drawbacks. Methane (CH4), the primary component of natural gas, presents a compelling middle ground.

Its performance is a significant step up from kerosene, offering a higher specific impulse that allows for more efficient engines. While it can’t match the raw performance of hydrogen, it’s far denser. This means methane-fueled rockets can use smaller, lighter tanks than hydrogen vehicles, striking a better balance between the rocket’s structure and the propellant it carries.

Its handling properties are also more manageable. Methane is cryogenic, but its boiling point of -162°C (-259°F) is much “warmer” than liquid hydrogen’s. This temperature happens to be very close to that of liquid oxygen (-183°C or -297°F), the oxidizer used with all three fuels. This thermal similarity is a massive engineering advantage. It allows both the fuel and oxidizer tanks to be placed next to each other, separated by a simple common bulkhead, and to use similar insulation. This simplifies the rocket’s overall design, reducing weight and complexity.

Most importantly, methane burns cleanly. Its simple chemical structure, a single carbon atom bonded to four hydrogen atoms, means it combusts far more completely than kerosene. It produces very little to no soot, eliminating the coking problem. This single characteristic is the key that unlocks the door to true, rapid reusability. An engine that doesn’t need to be disassembled and deep-cleaned after every flight can be inspected and launched again in days or even hours, not weeks or months.

The Reusability Revolution

For most of spaceflight history, rockets were single-use machines. Imagine flying from New York to London on a Boeing 747, and then throwing the entire airplane away after it lands. The absurdity of that scenario highlights the immense cost of traditional space launch. Each rocket, a marvel of engineering costing tens or hundreds of millions of dollars, was discarded in the ocean or burned up in the atmosphere after a single flight.

The quest for reusability is about transforming that paradigm. The goal is to operate rockets more like aircraft, with most of the vehicle returning safely to be refueled and flown again. This drastically lowers the cost per launch, which in turn opens up space for countless new applications. Business models for massive satellite constellations like Starlink or Kuiper Systems are only viable with the low launch costs that reusability enables. Commercial space stations, large-scale scientific missions, and even space tourism become more feasible.

Methane is the linchpin of this revolution. While the Space Shuttle was partially reusable, its complex systems required an army of technicians and months of refurbishment between flights. Its hydrogen-fueled main engines, despite being marvels of engineering, had to be removed and completely overhauled. Kerosene engines, as noted, are functionally incompatible with rapid reuse due to coking.

Methane’s clean burn changes the equation entirely. An engine designed for reuse, like the Raptor, can theoretically fly, land, and be ready for its next mission with inspections and maintenance that are more akin to what an airliner undergoes. This is the central premise behind SpaceX’s Starship, a vehicle designed from the ground up to be fully and rapidly reusable. The ability to refly the most expensive parts of the rocket – the engines – without a complete teardown is the most important factor in slashing the cost of reaching orbit.

This vision of airline-like operations is what has captivated the entire industry. It’s not just about saving money on hardware; it’s about increasing the frequency of launches, making space access a routine and reliable service rather than a rare and monumental undertaking. And methane is the fuel that makes this vision practical.

Beyond the Burn: Methane’s Other Advantages

The benefits of methane extend beyond its clean combustion. It enables more advanced engine designs, it’s cheaper to produce, and it holds a unique potential for future deep-space exploration.

Engine Design and Performance

The chemical properties of methane make it an excellent coolant, a feature that allows for more robust and higher-performance engine designs. The pinnacle of this is the full-flow staged combustion (FFSC) cycle, used by both the SpaceX Raptor and Blue Origin‘s BE-4 engine.

To understand its significance, consider how a rocket engine works. It needs to pump huge volumes of fuel and oxidizer into a combustion chamber at extremely high pressure. This requires powerful pumps, which are driven by turbines. The question is how to power those turbines. Simpler engine designs, like the gas-generator cycle used on the Merlin engine of the Falcon 9, essentially have a small, separate rocket engine that burns a bit of propellant just to spin the turbines. The exhaust from this process is then dumped overboard, which is simple but wasteful.

More advanced staged combustion cycles improve efficiency by routing this turbine exhaust back into the main combustion chamber, so every bit of propellant is used to generate thrust. this means the turbines have to run in an environment of extremely hot, high-pressure gas, which puts immense stress on the materials.

The full-flow cycle is the most efficient and elegant solution. Instead of burning a small amount of fuel and oxidizer together to make hot gas, it sends all of the fuel through one turbine and all of the oxidizer through another. This means the turbines are driven by a large volume of single-propellant gas at much lower temperatures. This is gentler on the machinery, allowing for a longer engine life and greater reusability – all while enabling higher chamber pressures for more thrust. Methane is perfectly suited for this, as its excellent cooling properties allow it to absorb heat from the engine nozzle and other components before it goes to the turbine, further improving the cycle’s efficiency.

Cost and Availability

Compared to the alternatives, methane is cheap and abundant. RP-1 must be highly refined from crude oil to meet the strict purity standards for rocketry. Liquid hydrogen production is an energy-intensive industrial process. Methane is the main ingredient in natural gas, a widely available global commodity. Sourcing and processing it into liquid methane (often called liquefied natural gas, or LNG) is a mature, well-understood technology. This lower fuel cost, while not the largest expense in a launch, still contributes to reducing the overall price tag of getting to space. This also extends to the ground systems required. Building infrastructure for a new rocket is a major investment, and methane’s properties simplify some of those needs compared to the extreme demands of liquid hydrogen.

Destination Mars: In-Situ Resource Utilization

Perhaps the most forward-looking advantage of methane is its potential for production on Mars. This concept, known as in-situ resource utilization (ISRU), is seen as essential for any long-term human presence beyond Earth. The idea is to live off the land, making what you need from local resources instead of hauling everything from home.

The Martian atmosphere is over 95% carbon dioxide (CO2), and water ice (H2O) is known to exist in large quantities beneath the surface. Using a well-established chemical process called the Sabatier reaction, these two ingredients can be used to create rocket fuel. The process would require a sophisticated chemical plant. First, robotic systems would mine the water ice. Then, a process called electrolysis would use electricity to split the water molecules into hydrogen and oxygen. The oxygen would be stored for use as an oxidizer. The hydrogen would then be reacted with carbon dioxide from the Martian atmosphere at high temperature and pressure to produce methane (CH4) and more water. The methane is stored as fuel, and the water is recycled back into the system to produce more hydrogen and oxygen.

This capability is revolutionary. It means a spaceship like Starship could land on Mars with just enough fuel for the landing, then spend its time on the surface manufacturing a full tank of propellant for the return journey to Earth. This would all be powered by a substantial energy source, like large solar arrays or a compact nuclear reactor. Without ISRU, a Mars mission would have to carry all the fuel for the trip home, making the initial vehicle unimaginably large and expensive. The choice of methane as a fuel is a strategic bet on a future where humanity is not just visiting other worlds, but creating a self-sustaining presence there.

The Global Methalox Race

The strategic advantages of methalox (the common term for a methane and liquid oxygen propellant combination) have not gone unnoticed. What started as a bold bet by a few is now a full-blown global race, with companies of all sizes staking their future on methane-powered rockets.

American Innovators

The United States is at the forefront of this shift, with both new and established players embracing methalox.

• SpaceX: As the pioneer, SpaceX is all-in on methane with its Raptor engine and the Starship launch system. Their goal is to create a fully reusable transportation system capable of carrying humans to Mars, and their choice of methane is central to that architecture. Their relentless test-and-build campaign in South Texas has pushed methane engine technology further and faster than anyone else.
• Blue Origin: Jeff Bezos’s space company developed the powerful BE-4 engine, a direct competitor to the Raptor. The BE-4 is not only slated to power Blue Origin’s own massive, reusable New Glenn rocket but has also been selected by United Launch Alliance (ULA). ULA, a joint venture of Boeing and Lockheed Martin, is using two BE-4 engines to power the first stage of its new flagship rocket, the Vulcan Centaur. This adoption by a pillar of the old guard is one of the strongest endorsements of methane’s viability and represents a critical step for ULA in retiring its Atlas V rocket, which relied on the Russian-made RD-180 engine.
• Rocket Lab: Having already found success with its small Electron rocket, Rocket Lab is developing a much larger, fully reusable rocket named Neutron. It will be powered by their in-house Archimedes methalox engine and is designed to deploy satellite constellations with a unique, lightweight carbon composite structure.
• Relativity Space: This company is pursuing the twin goals of reusability and advanced manufacturing, aiming to 3D-print almost the entire structure of its rockets. Their first orbital attempt was with the Terran 1, the first 3D-printed rocket to fly, which used methalox engines. Their next vehicle, the fully reusable Terran R, will scale up that vision considerably, powered by a new generation of 3D-printed methalox engines.
• Stoke Space: This ambitious startup is tackling one of the hardest problems in rocketry: making a fully reusable second stage. Their innovative design uses a ring of methalox engines that double as both the primary propulsion for reaching orbit and the landing system. During reentry, propellant flows through channels in a metallic heat shield to keep it cool, a novel approach to thermal protection.

China’s Ambitions

The commercial space sector in China is developing at a breakneck pace, and its leading companies have firmly committed to methalox. This parallel development shows that the move to methane is based on sound engineering principles, not just the influence of one company.

• LandSpace: In July 2023, LandSpace achieved a major global milestone when its Zhuque-2 rocket successfully reached orbit. It was the world’s first methalox-fueled rocket to do so, beating American competitors to the punch and signaling the seriousness of China’s commercial space efforts. The rocket is powered by TQ-12 methalox engines.
• i-Space: Another leading private firm, i-Space is developing its reusable Hyperbola family of rockets, which are also based on methalox engines. They have conducted successful hop tests of their prototype stages, similar to the early tests of SpaceX’s Starship, demonstrating propulsive landing capabilities.
• Galactic Energy: This company has already reached orbit with its solid-fueled Ceres-1 rocket, but it’s developing the Pallas-1, a larger, partially reusable rocket that will also be powered by methalox engines, showing a clear strategic pivot toward the fuel.

European and Russian Efforts

Europe and Russia, home to some of the world’s most established space programs, are also moving towards methane, albeit at a more measured pace as they navigate the transition from legacy systems.

• The European Space Agency (ESA) is funding the development of the Prometheus engine, a reusable methalox engine designed to be produced at a fraction of the cost of current European engines. It’s intended to power future versions of the Ariane launch vehicle and other launchers, as Europe seeks to remain competitive in a market being reshaped by American reusability.
• Russia’s space agency, Roscosmos, has announced plans for the Amur rocket, a new reusable booster powered by methalox engines. This vehicle is envisioned as the eventual successor to the iconic Soyuz, a design that has its roots in the 1960s.

Challenges and the Road Ahead

Despite its many advantages, the transition to methane is not without its difficulties. The technology, while promising, presents its own set of engineering hurdles that the industry is actively working to overcome.

High-performance engine cycles like full-flow staged combustion are incredibly complex. The pressures and temperatures inside the engine are extreme, and managing the flow of cryogenic gases through spinning turbomachinery requires cutting-edge materials and precision manufacturing. Developing these engines is a difficult and expensive process.

Igniting methane and oxygen can also be trickier than lighting kerosene. The mixture requires a more energetic and reliable ignition source, as a failure to ignite could have catastrophic consequences. Rocket engineers have developed various solutions, from spark igniters to chemical systems, but it remains a critical phase of engine operation.

Finally, while methane’s cryogenic nature is more manageable than hydrogen’s, boil-off is still a factor. For long-duration missions in space, where propellant might need to be stored for months, mitigating this boil-off is essential. This requires developing advanced insulation, cryo-coolers, and propellant densification technologies to keep the methane liquid for as long as possible. There is also an environmental consideration. Methane is a potent greenhouse gas. While the total carbon footprint of the entire space launch industry is minuscule compared to other sectors, the release of any unburnt methane into the atmosphere is an undesirable outcome. The focus for engine designers is to achieve the highest possible combustion efficiency, ensuring that virtually all the methane is consumed inside the engine to produce thrust, not released into the air.

Summary

The global space industry is undergoing a fundamental shift in how it powers its journey to orbit. Methane has emerged as the clear propellant of choice for the new generation of launch vehicles, offering a compelling balance of high performance, operational practicality, and lower cost. Its clean-burning nature is the single most important factor enabling the development of rapidly reusable rockets, a breakthrough that promises to dramatically reduce the cost of access to space.

This is not just a story about SpaceX. From ULA‘s Vulcan to Rocket Lab‘s Neutron and the pioneering launches from Chinese firms like LandSpace, the industry has reached a consensus. The long-term potential for manufacturing methane on Mars adds another layer of strategic importance, positioning it as the fuel for humanity’s expansion into the solar system. The challenges of mastering this new technology are real, but the rewards are immense. The roar of methalox engines is set to be the defining sound of a more accessible, dynamic, and ambitious era of space exploration.

Last update on 2025-12-20 / Affiliate links / Images from Amazon Product Advertising API