Liquid oxygen in the context of Falcon 1

Falcon 9 is a partially reusable, two-stage-to-orbit, medium-lift launch vehicle designed and manufactured in the United States by SpaceX. The first Falcon 9 launch was on June 4, 2010, and the first commercial resupply mission to the International Space Station (ISS) launched on October 8, 2012. In 2020, it became the first commercial rocket to launch humans to orbit. The Falcon 9 has been noted for its reliability and high launch cadence, with 568 successful launches, two in-flight failures, one partial failure and one pre-flight destruction.

The rocket has two stages. The first (booster) stage carries the second stage and payload to a predetermined speed and altitude, after which the second stage accelerates the payload to its target orbit. The booster is capable of landing vertically to facilitate reuse. This feat was first achieved on flight 20 in December 2015. As of December 2, 2025, SpaceX has successfully landed Falcon 9 boosters 526 times. Individual boosters have flown as many as 31 flights. Both stages are powered by SpaceX Merlin engines, using cryogenic liquid oxygen and rocket-grade kerosene (RP-1) as propellants.

Ariane 6 is a European expendable launch system developed for the European Space Agency (ESA) and French Space Agency (CNES) and manufactured by a consortium of European companies, led by the prime contractor ArianeGroup. As part of the Ariane rocket family, it is operated by Arianespace, replacing the Ariane 5. The project's primary contributors were France (55.3%), Germany (21%) and Italy (7.6%), with the remaining work distributed among ten other participating countries.

This two-stage rocket utilizes liquid hydrogen and liquid oxygen (hydrolox) engines. The first stage features an upgraded Vulcain engine from Ariane 5, while the second uses the Vinci engine, designed specifically for this rocket. The Ariane 62 variant uses two P120C solid rocket boosters, while Ariane 64 uses four. The P120C booster is shared with Europe's other launch vehicle, and is an improved version of the P80 used on the original Vega.

The PGM-19 Jupiter was the first nuclear armed, medium-range ballistic missile (MRBM) of the United States Air Force (USAF). It was a liquid-propellant rocket using RP-1 fuel and LOX oxidizer, with a single Rocketdyne LR79-NA (model S-3D) rocket engine producing 150,000 lbf (670 kN) of thrust. It was armed with the 1.44 Mt (6.0 PJ) W49 nuclear warhead. The prime contractor was the Chrysler Corporation.

The Jupiter was originally designed by the US Army, which was looking for a highly accurate missile designed to strike enemy states such as China and the Soviet Union. The US Navy also expressed an interest in the design as an SLBM but left the collaboration to work on their solid-fuel Polaris. Jupiter retained the short, squat shape intended to fit in submarines.

Rocket propellant is used as a reaction mass ejected from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical rocket, or from an external source, as with ion engines.

Cabin pressurization is a process in which conditioned air is pumped into the cabin of an aircraft or spacecraft in order to create a safe and comfortable environment for humans flying at high altitudes. For aircraft, this air is usually bled off from the gas turbine engines at the compressor stage, and for spacecraft, it is carried in high-pressure, often cryogenic, tanks. The air is cooled, humidified, and mixed with recirculated air by one or more environmental control systems before it is distributed to the cabin.

The first experimental pressurization systems saw use during the 1920s and 1930s. In the 1940s, the first commercial aircraft with a pressurized cabin entered service. The practice would become widespread a decade later, particularly with the introduction of the British de Havilland Comet jetliner in 1949. However, two catastrophic failures in 1954 temporarily grounded the Comet worldwide. These failures were investigated and found to be caused by a combination of progressive metal fatigue and aircraft skin stresses caused from pressurization. Improved testing involved multiple full-scale pressurization cycle tests of the entire fuselage in a water tank, and the key engineering principles learned were applied to the design of subsequent jet airliners.

The Space Shuttle external tank (ET) was the component of the Space Shuttle launch vehicle that contained the liquid hydrogen fuel and liquid oxygen oxidizer. During lift-off and ascent it supplied the fuel and oxidizer under pressure to the three RS-25 main engines in the orbiter. The ET was jettisoned just over 10 seconds after main engine cut-off (MECO) and it re-entered the Earth's atmosphere. Unlike the Solid Rocket Boosters, external tanks were not re-used. They broke up before impact in the Indian Ocean (or Pacific Ocean in the case of direct-insertion launch trajectories), away from shipping lanes and were not recovered.

RP-1 (Rocket Propellant-1 or Refined Petroleum-1) and similar fuels like RG-1 and T-1 are highly refined kerosene formulations used as rocket fuel. Liquid-fueled rockets that use RP-1 as fuel are known as kerolox rockets. In their engines, RP-1 is atomized, mixed with liquid oxygen (LOX), and ignited to produce thrust. Developed in the 1950s, RP-1 is outwardly similar to other kerosene-based fuels like Jet A and JP-8 used in turbine engines but is manufactured to stricter standards. While RP-1 is widely used globally, the primary rocket kerosene formulations in Russia and other former Soviet countries are RG-1 and T-1, which have slightly higher densities.

Compared to other rocket fuels, RP-1 provides several advantages with a few tradeoffs. Compared to liquid hydrogen, it offers a lower specific impulse, but can be stored at ambient temperatures, has a lower explosion risk, and although its specific energy is lower, its higher density results in greater energy density. Compared to hydrazine, another liquid fuel that can be stored at ambient temperatures, RP-1 is far less toxic and carcinogenic.

Atlas V is an expendable launch system and the fifth major version in the Atlas launch vehicle family. It was developed by Lockheed Martin and has been operated by United Launch Alliance (ULA) since 2006. Primarily used to launch payloads for the United States Department of Defense, NASA, and commercial customers, Atlas V is the longest-serving active rocket in the United States.

Each Atlas V vehicle consists of two main stages. The first stage is powered by a single Russian-made RD-180 engine that burns kerosene and liquid oxygen. The Centaur upper stage uses one or two American-made Aerojet Rocketdyne RL10 engines that burn liquid hydrogen and liquid oxygen. Strap-on solid rocket boosters (SRBs) are used in several configurations. Originally equipped with AJ-60A SRBs, the vehicle switched to Graphite-Epoxy Motor (GEM 63) boosters beginning in November 2020, except for flights in the Boeing Starliner program. Standard payload fairings measure either 4.2 m (14 ft) or 5.4 m (18 ft) in diameter, with multiple available lengths.

Solid oxygen is the solid ice phase of oxygen. It forms below 54.36 K (−218.79 °C; −361.82 °F) at standard atmospheric pressure. Solid oxygen O₂, like liquid oxygen, is a clear substance with a light sky-blue color caused by absorption in the red part of the visible light spectrum.

Oxygen molecules have a relationship between the molecular magnetization and crystal structures, electronic structures, and superconductivity. Oxygen is the only simple diatomic molecule (and one of the few molecules in general) to carry a magnetic moment. This makes solid oxygen particularly interesting, as it is considered a "spin-controlled" crystal that displays antiferromagnetic magnetic order in the low temperature phases. The magnetic properties of oxygen have been studied extensively. At very high pressures, solid oxygen changes from an insulating to a metallic state; and at very low temperatures, it transforms to a superconducting state. Structural investigations of solid oxygen began in the 1920s and, at present, six distinct crystallographic phases are established unambiguously.

Merlin is a family of rocket engines developed by SpaceX. They are currently a part of the Falcon 9 and Falcon Heavy launch vehicles, and were formerly used on the Falcon 1. Merlin engines use RP-1 and liquid oxygen as rocket propellants in a gas-generator power cycle. The Merlin engine was originally designed for sea recovery and reuse, but since 2016 the entire Falcon 9 booster is recovered for reuse by landing vertically on a landing pad using one of its nine Merlin engines.

The injector at the heart of Merlin is of the pintle type that was first used in the Apollo Lunar Module landing engine (LMDE). Propellants are fed by a single-shaft, dual-impeller turbopump. The turbopump also provides high-pressure fluid for the hydraulic actuators, which then recycles into the low-pressure inlet. This eliminates the need for a separate hydraulic drive system and means that thrust vectoring control failure by running out of hydraulic fluid is not possible. The engine is named after Merlin (a falcon).

Vulcain is a family of European first stage rocket engines for Ariane 5 and Ariane 6. Its development began in 1988 and the first flight was completed in 1996. The updated version of the engine, Vulcain 2, was first successfully flown in 2005. Both members of the family use liquid oxygen/liquid hydrogen cryogenic fuel. The new version for Ariane 6 is called Vulcain 2.1.

Starship is a two-stage, fully reusable, super heavy-lift launch vehicle under development by American aerospace company SpaceX. Currently built and launched from Starbase in Texas, it is intended as the successor to the company's Falcon 9 and Falcon Heavy rockets, and is part of SpaceX's broader reusable launch system development program. If completed as designed, Starship would be the first fully reusable orbital rocket and have the highest payload capacity of any launch vehicle to date. As of October 13, 2025, Starship has launched 11 times, with 6 successful flights and 5 failures.

The vehicle consists of two stages: the Super Heavy booster and the Starship spacecraft, both powered by Raptor engines burning liquid methane (the main component of natural gas) and liquid oxygen. Both stages are intended to return to the launch site and land vertically at the launch tower for potential reuse. Once in space, the Starship upper stage is intended to function as a standalone spacecraft capable of carrying crew and cargo. Missions beyond low Earth orbit would require multiple in-orbit refueling flights. At the end of its mission, Starship reenters the atmosphere using heat shield tiles similar to those of the Space Shuttle. SpaceX states that its goal is to reduce launch costs by both reusing and mass producing both stages.

The Centaur is a family of rocket-propelled upper stages that has been in use since 1962. It is currently produced by United Launch Alliance (ULA) in two main versions. The 3.05 m (10 ft) diameter Centaur III (also known as the Common Centaur) serves as the second stage of the retiring Atlas V rocket, and the 5.4 m (17.7 ft) diameter Centaur V is used as the second stage of the Vulcan Centaur rocket. Centaur was the first rocket stage to use hydrolox propellant—liquid hydrogen (LH₂) and liquid oxygen (LOX)—a high-energy combination well suited for upper stages but difficult to handle because both propellants must be stored at extremely low cryogenic temperatures.

The Rocketdyne S-3D (Air Force designation LR79) was an American liquid rocket engine produced by Rocketdyne (a division of North American Aviation) between 1956 and 1961. It was a gas generator, pump-fed engine, using a liquid oxygen (LOX) and RP-1 (kerosene) propellant combination, capable of producing 134,908 pounds of thrust (600.1 kN) at sea level.

The S-3 was based on the Redstone engine, and is part of the LR79 family, used on the PGM-19 Jupiter and PGM-17 Thor missiles, and on the Juno II rocket. Other members of the LR79 engine family include: XLR71-NA-1, B-2C, XLR83-NA-1, LR79-7, S-3D, XLR89-1, MB-3-1, X-1, LR83-NA-1, H-1, LR89-5, XLR89-5, S-3, LR89-7, MB-3-J, MB-3, MB-3-3, RZ.2, H-1c, H-1b, RS-27, RS-27A R, RS-56-OBA and RS-27C.

The RS-68 (Rocket System-68) was a liquid-fuel rocket engine that used liquid hydrogen (LH₂) and liquid oxygen (LOX) as propellants in a gas-generator cycle. It was the largest hydrogen-fueled rocket engine ever flown.

Designed and manufactured in the United States by Rocketdyne (later Pratt & Whitney Rocketdyne and Aerojet Rocketdyne). Development started in the 1990s with the goal of producing a simpler, less costly, heavy-lift engine for the Delta IV launch system. Two versions of the engine have been produced: the original RS-68 and the improved RS-68A. A third version, the RS-68B, was planned for the National Aeronautics and Space Administration's (NASA) Ares V rocket before the cancellation of the rocket and the Constellation Program in 2010.

A hose, also called a hose-pipe, is a flexible hollow tube or pipe designed to carry fluids from one location to another, often from a faucet or hydrant.

Early hoses were made of leather, flax, and cotton. World War II lead to increased industrial development and the invention of synthetic rubber materials with higher chemical resistance. Modern hoses may be made of rubber, canvas, and helically wound wire. Hoses may also be made from plastics such as polyvinyl chloride and polytetrafluoroethylene. Materials such as stainless steel and polyethylene terephthalate are used for hoses capable of carrying low-temperature liquids such as liquid oxygen and liquid nitrogen.