Rocket Propellants
The fuels, oxidizers, and chemistry that power spaceflight.
Explore every rocket propellant used in spaceflight — from kerosene-based RP-1 to cryogenic liquid hydrogen and toxic hypergolics. Space Launch Live catalogs chemical properties, performance characteristics, safety data, and the engines that burn each propellant.
From RP-1 kerosene to liquid methane to solid ammonium perchlorate — explore the propellants used across modern and historic rocketry, and the trade-offs of performance, storability, toxicity, and reusability that drive each choice.
Propellant performance is measured in specific impulse (Isp) — essentially fuel efficiency, in seconds. Hydrogen-oxygen (hydrolox) tops the chart at around 450 s in vacuum (the Space Shuttle’s RS-25), but liquid hydrogen is bulky and must be kept near −253 °C, making tanks large and plumbing complex. Kerosene-oxygen (kerolox), using refined RP-1, trades some efficiency (~300 s) for high density and easy handling, which is why it powered the Saturn V’s first stage and still flies on Falcon 9. Methane-oxygen (methalox) is the new favorite of Raptor and BE-4: it lands between the two on performance, burns cleanly enough for rapid reuse, and could one day be manufactured on Mars.
Not every job wants a cryogenic fuel. Hypergolic propellants such as MMH and nitrogen tetroxide ignite the instant they touch — no igniter needed — and store for years at room temperature, which makes them the reliable choice for spacecraft thrusters, many upper stages, and Crew Dragon’s SuperDraco abort engines, despite being highly toxic. Solid propellants like ammonium-perchlorate composite (APCP) pack fuel and oxidizer into a single rubbery grain that delivers enormous thrust from a simple, storable motor — as in the Space Shuttle and SLS boosters — with the catch that, once lit, they cannot be throttled or shut down.