// PROPULSION SYSTEMS AND ENGINE TECHNOLOGY TERM
Hydrolox
Hydrolox is a high-performance rocket propellant made by combining liquid hydrogen (the fuel) and liquid oxygen (the oxidizer). This mixture provides a very powerful thrust but requires keeping the components at extremely cold, cryogenic temperatures.
TECHNICAL DEFINITION
Hydrolox is a cryogenic liquid bipropellant combination utilizing liquid hydrogen (LH2) as the fuel and liquid oxygen (LOX) as the oxidizer, notable for its high specific impulse (Isp) and clean water vapor exhaust. This high-energy propellant is critical for upper stages and core boosters on launch vehicles like the SLS, Ariane 5, and Delta IV to achieve orbital or interplanetary trajectories.
BACKGROUND
Firefly Aerospace, Inc. (Firefly) is an American aerospace firm based in Cedar Park, Texas. Firefly develops small- and medium-lift launch vehicles for commercial launches to orbit. Firefly's stated purpose is to increase access to space, similar to other private spaceflight companies.
READ MORE ON WIKIPEDIASYNONYMS & ALIASES
- LH2/LOX
- H2/O2 propellant
- cryogenic hydrogen-oxygen
- liquid hydrogen/liquid oxygen
- cryo propellant
USAGE NOTE
Due to liquid hydrogen's extremely low density, hydrolox engines require very large, well-insulated fuel tanks, which presents a significant structural design challenge.
DEVELOPERS
Organizations developing technology related to Hydrolox.
An L3Harris Technologies company, Aerojet Rocketdyne is a major American manufacturer of rocket propulsion systems. They produce the RL10 hydrolox upper stage engine and the RS-25, the former Space Shuttle main engine, now used for NASA's Space Launch System (SLS).
Founded by Jeff Bezos, Blue Origin develops rockets and spacecraft. Their BE-3PM and BE-3U engines, which power the New Shepard and the New Glenn second stage respectively, are liquid hydrogen-liquid oxygen engines. They are also developing the BE-7 hydrolox engine for lunar landers.
A joint venture between Airbus and Safran, ArianeGroup is the prime contractor for Europe's Ariane family of launchers. They develop and manufacture the Vulcain 2.1 engine for the Ariane 6 core stage and the Vinci engine for its upper stage, both of which are high-performance hydrolox engines.
The United States' space agency heavily utilizes and develops hydrolox propulsion. NASA's Marshall Space Flight Center manages the Space Launch System (SLS), the world's most powerful rocket, which uses four hydrolox RS-25 engines on its core stage. Stennis Space Center is their primary engine testing facility.
MHI is the prime contractor for Japan's flagship launch vehicles, including the H-IIA and the upcoming H3. They manufacture the LE-7A hydrolox engine for the first stage and the LE-5B-2 for the second stage, demonstrating Japan's advanced cryogenic propulsion capabilities.
India's national space agency has indigenously developed cryogenic propulsion technology. They produce the CE-20 engine, a powerful hydrolox engine that powers the upper stage of their LVM3 rocket, enabling missions to geostationary orbit and beyond.
A major American launch service provider, ULA operates rockets that rely on hydrolox propulsion. Their Delta IV Heavy uses three RS-68A engines, and the Centaur upper stage, used on both Atlas V and the new Vulcan rocket, is powered by Aerojet Rocketdyne's RL10 engine.
A British aerospace company developing the SABRE (Synergetic Air-Breathing Rocket Engine), a hybrid engine designed for single-stage-to-orbit spaceplanes. In its pure rocket mode, SABRE operates as a high-performance closed-cycle hydrolox engine.