Methane quietly won the second-generation launch race

For thirty years, the rocket industry's choice of propellant was settled. Most orbital-class first stages burned RP-1, a highly refined kerosene. Most upper stages burned liquid hydrogen. The alternative proposals — methane, hypergolics, solar thermal — got the same answer: kerosene for the first stage because it is dense and storable, hydrogen for the upper stage because specific impulse matters more than tank volume. That consensus broke across roughly the last decade, and it broke completely this summer. The propellant that quietly won the second-generation launch race is methane, and the working list of next-generation rockets flying or about to fly without it is now shorter than the list that uses it.

The shift nobody framed as a shift

The story of the last six months is, if you stitch the launches together, the story of a propellant category sweeping the field. SpaceX flew Starship V3 on Flight 12 in May with thirty-three Raptor 3 engines — methane — and successfully completed the mission's primary objective of deploying the Starship upper stage, though the Super Heavy booster failed its boostback burn and crash-landed in the ocean. (Source: Wikipedia, "Starship flight test 12"; USA Today, "After delays, SpaceX launches Starship V3 on mostly successful flight," May 23, 2026.) Blue Origin's New Glenn, powered by seven BE-4 methane engines, completed its first successful booster recovery on the NG-2 mission in November 2025 and has been flying steadily since. (Source: NASASpaceflight.com, "Blue Origin launches ESCAPADE on New Glenn, successfully lands first stage booster," November 13, 2025.) ULA's Vulcan — the methane-burning first stage married to a hydrogen-burning Centaur upper stage — flew its first certification mission in January 2024 and is now operational for National Security Space Launch. (Source: ULA launch archive; Wikipedia, "Vulcan Centaur.")

And then, on August 19 at 07:35 local time, LandSpace's Zhuque-3 lifted off from the Dongfeng Commercial Space Innovation Pilot Zone in northwestern China, completed its orbital insertion, and recovered the first stage on the launch site's landing zone. (Source: Ars Technica, "The floodgates are open after another Chinese company lands a reusable rocket," August 19, 2026; Space.com, "Touchdown! Private Chinese rocket aces landing on 2nd-ever flight.") It was the second Zhuque-3 flight — the first, on December 3, 2025, had reached orbit but lost the booster during the landing burn due to an "abnormal combustion" event (Source: SpaceNews, "Zhuque-3 reaches orbit on test flight, first stage lost during landing attempt," December 3, 2025) — and the recovery made LandSpace the fourth organization in history to have returned an orbital-class booster from space, after SpaceX, the China Aerospace Science and Technology Corporation's Long March 8A test in 2024, and Blue Origin. What the launches together demonstrated was the same thing: the second-generation rocket roster is, with one exception, all-methane.

The new methane roster

There are, as of this writing, six operational or near-operational orbital rockets that run primarily on methane and oxygen — methalox, in industry shorthand. They are not all the same kind of vehicle. They are not all owned by American companies. But they share a fuel.

SpaceX Starship / Super Heavy. Two methalox stages. The V3 booster runs thirty-three Raptor 3 engines, each rated at approximately 280 metric tons-force of thrust at sea level — about 22 percent more than the Raptor 2 it replaced. (Source: Wikipedia, "SpaceX Raptor," citing Musk April 2024 update; New Space Tracker, "Starship V3: Everything We Know About Flight 12.")

Blue Origin New Glenn. First stage methalox, currently expendable hydrolox upper stage. Seven BE-4 engines on the first stage, each rated at 2,800 kN (around 640,000 lbf) at sea level. (Source: Blue Origin Engines product page; ULA BE-4 fact sheet.) The BE-4 is the first oxygen-rich staged-combustion engine to fly in the United States.

ULA Vulcan Centaur. Methalox first stage, hydrolox upper stage. Two BE-4 engines below; two RL10C-1-1A engines on Centaur V, rated at 23,825 pounds (106 kN) of thrust each. (Source: ULA blog, "Centaur and the RL10: Celebrating 60 years together.") Vulcan's choice to keep hydrogen up top is the architectural exception, not the rule.

LandSpace Zhuque-3. Two methalox stages. Nine TQ-12B engines on the first stage, one TQ-15B on the second. (Source: LandSpace / Nextspaceflight.com Zhuque-3 mission page.) Vehicle length about 66 meters, lift-off mass around 550 tonnes, payload to LEO in ground-landing recovery mode approximately 12.5 tonnes. (Source: Wikipedia, "Zhuque-3"; Ars Technica, December 2025.)

Relativity Terran R. Two methalox stages; first flight targeted for the second half of 2026. Thirteen Aeon R engines on the first stage, one Aeon V on the upper. Maximum payload 23.5 tonnes to LEO reusable, 33.5 tonnes expendable. (Source: Wikipedia, "Terran R"; Relativity Space product page.)

Rocket Lab Neutron. Two methalox stages; first flight targeted for late 2026. Nine Archimedes engines on the first stage — a new methalox engine designed in-house at Rocket Lab, 3D-printed, and rated for nine-engine liftoff thrust of approximately 1.5 million pounds. (Source: Spaceflight Now, "Rocket Lab announces five-launch Neutron deal," May 7, 2026; Rocket Lab Neutron product page.)

Six vehicles. Five built by US-headquartered companies, one Chinese. Five private, one (Vulcan) jointly operated by a Boeing-Lockheed joint venture. Four are designed to land and refly the booster; one (Vulcan) is not; the sixth (New Glenn) recovers the booster but expends the upper stage. All six are committed to the same premise: methane is the right fuel for a reusable first stage that flies often.

Why methane, and not the alternatives

The case for methane rests on three engineering advantages and one strategic one.

Cleanliness. RP-1, the kerosene that Falcon 9, Soyuz, and most of the legacy fleet still burns, is a complex mixture of long-chain hydrocarbons. When it combusts, it leaves soot and residue in the engine. (Source: Stanford University PH240 project, "Methane vs. Kerosene as Rocket Fuels," 2023.) Before reuse, that did not matter. Once you start flying the same engine ten times, thirty times, the residue accumulates and limits engine life. SpaceX's Merlin 1D has demonstrated that RP-1 reuse is possible — Falcon 9 booster B1078 just completed its 30th flight on August 21 — but the inspections, X-rays, and turbine wheel replacements between flights cost time and money that a cleaner-burning fuel would not require. (Source: Spaceflight Now, B1078 30th flight mission profile, August 21, 2026.) Methane, with one carbon atom per molecule, burns cleaner and leaves less residue.

Operational temperature. Liquid hydrogen boils at -253°C and is notoriously difficult to store. Methane boils at -162°C, which is still cold but is much closer to the operational range of standard materials and seal technology. (Source: Space StackExchange, "What are the advantages and disadvantages of using either liquid hydrogen or liquid methane.") For a vehicle meant to be turned around in days rather than months, methane is far easier to handle.

Mass ratio. Hydrogen has the best specific impulse of any chemical fuel — about 450 seconds for an upper-stage engine versus around 350 for methalox — but hydrogen's very low density means a hydrogen stage needs enormous tanks. A methane-fueled rocket needs only about 25 to 30 percent more tank volume than a kerosene rocket for the same payload. (Source: SpaceAmbition Substack, "The Methane Revolution in Spaceflight: Why So Late?")

The strategic one is the reason SpaceX picked methane for Starship in the first place. Methane can be manufactured on Mars. The Sabatier reaction — carbon dioxide from the Martian atmosphere plus hydrogen, sourced from subsurface water ice, yields methane and water. (Source: NASA NTRS, "Sabatier System Design Study for a Mars ISRU Propellant Production," 2018; Wikipedia, "In situ resource utilization.") Methane is the only practical chemical propellant for which ISRU is even theoretically possible at scale. For SpaceX, the Starship fuel choice is also the Mars architecture choice.

What this means for the next decade

The propellant shift is now a settled engineering choice, and the operators that locked themselves out of it are going to have a harder time in the 2030s. Falcon 9 is the dominant Western workhorse and it still runs on RP-1 — but it is the last SpaceX vehicle that will. ULA kept hydrogen on the Centaur upper stage because Centaur V's hydrogen engine is the highest-performance upper stage ever flown for the U.S. government, and the National Security Space Launch contracts reward upper-stage performance. (Source: ULA blog, "Centaur and the RL10.") But Vulcan-successor studies are explicit about both stages running methalox. Ariane 6 and H3 will likely remain hydrolox for their entire service lives — they are not in the reuse race — but their successors, if and when they come, will face the same choice.

The corollary for observers on the ground is that the new vehicles launching over the next five years will, almost without exception, be methane-burning. From Florida, Texas, or Wallops Island, the chemistry of the booster plume is going to start looking the same: a mostly-transparent exhaust with a faint orange tint, rather than the dense black smoke of an RP-1 vehicle or the invisible exhaust of a hydrogen booster. It is a small visible detail, but it is a real-time indicator of which propellant regime the vehicle belongs to.

The methane shift is also a Mars shift, whether or not every operator using it has a Mars program. The same physics that makes methane reusable on Earth makes it the only credible choice for any long-duration deep space architecture that wants to make its own propellant at the destination. The companies that picked methane are the ones that have not closed the door on Mars ISRU. The companies that stayed on RP-1 or hydrogen have, by omission, accepted that they are building for Earth-to-orbit and not for the rest of the solar system. That choice may be perfectly rational for their business models. It is still a choice.

For amateur and hobbyist observers, the cadence of methalox launches is going to accelerate through the rest of this decade. (The launch rate finally matched the rhetoric laid out the cadence argument; the propellant choice is the part of the rhetoric that is actually true.)

If you want to follow the cadence from the ground rather than from a launch site, the DWARFLAB Dwarf 3 smart telescope is the most accessible way to actually see what is up there. Its tracking mount is designed to hold a slow-moving target like a high-altitude booster pass or a geostationary satellite.

For the broader economics and strategic context behind the propellant shift, the Wiley volume on the space economy is the most useful single reference I have found. It is not breezy, but it is the one I would hand a smart friend who wants to understand what is happening in orbit commercially and on the launch pad industrially.

For watching the actual plumes from a distance — methane burns cleaner than kerosene, hydrogen burns invisibly, RP-1 produces the iconic black smoke — a 15x70 binocular like the Celestron SkyMaster is the standard amateur recommendation.

The propellant shift is more consequential than it looks from the outside. Every vehicle on the second-generation roster is a working assumption that the future of orbital launch is reusable, frequent, and ultimately interplanetary. Methane is the one fuel that serves all three of those goals.

That's the essay for this week. Next Saturday: a closer look at the post-ISS era's commercial station transition, and why the orbital real-estate picture is going to look different by the end of next year than most observers expect.

— Atlas Renner, Editor-in-Chief, SpaceOrbitals

Atlas Renner

Editor-in-Chief · Publisher