Aestus is a

hypergolic A hypergolic propellant is a rocket propellant combination used in a rocket engine, whose components spontaneously ignite when they come into contact with each other. The two propellant components usually consist of a fuel and an oxidizer. The ...

liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...

rocket engine A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, in accordanc ...

used on an

upper stage A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''stages'', each of which contains its own engines and propellant. A ''tandem'' or ''serial'' stage is mounted on top of another stage; a ''parallel'' stage is ...

Ariane 5 Ariane 5 is a European heavy-lift space launch vehicle developed and operated by Arianespace for the European Space Agency (ESA). It is launched from the Centre Spatial Guyanais (CSG) in French Guiana. It has been used to deliver payloads int ...

family rockets for the

orbital insertion Orbit insertion is the spaceflight operation of adjusting a spacecraft’s momentum, in particular to allow for entry into a stable orbit around a planet, moon, or other celestial body. This maneuver involves either deceleration from a speed in e ...

. It features unique design of 132 coaxial injection elements causing swirl mixing of the MMH propellants with

nitrogen tetroxide Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...

oxidizer. The

pressure-fed engine The pressure-fed engine is a class of rocket engine designs. A separate gas supply, usually helium, pressurizes the propellant tanks to force fuel and oxidizer to the combustion chamber. To maintain adequate flow, the tank pressures must exceed th ...

allows for multiple re-ignitions.

Operations

Fuel and oxidizer are stored in two aluminium alloy tanks, fuel tank is spherical while oxidizer tank is enlarged due to different volumes required from engine operations. Before engine is started it is purged with helium and fuel is pressurized. Then oxidizer valve is opened in a center of injector followed by fuel injectors arranged on a chamber wall. Hypergolic propellants spontaneously ignite on contact expanding to supersonic velocities and escaping through cooled nozzle extension.

History

Aestus was developed by the Ottobrunn Space Propulsion Centre between 1988 and 1995 with first flight as an upper stage of

G flight 502 and performed as designed. The first improvements were developed between 1999 and 2002 improving the frame performance and adjusting propellant mixture ratio from 2.05 to 1.90 with a first flight on an Ariane 5 flight 518 on 26 February 2004. Ignition qualification programme preparing engine for handling new

Automated Transfer Vehicle The Automated Transfer Vehicle, originally Ariane Transfer Vehicle or ATV, was an expendable cargo spacecraft developed by the European Space Agency (ESA), used for space cargo transport in 2008–2015. The ATV design was launched to orbit fiv ...

that requires 3 ignitions per flight was completed in 2007 and flew with

Jules Verne ATV The ''Jules Verne'' ATV, or Automated Transfer Vehicle 001 (ATV-001), was a robotic cargo spacecraft launched by the European Space Agency (ESA). The ATV was named after the 19th-century French science-fiction author Jules Verne. It was launched ...

on Ariane 5 flight 528.

Aestus II / RS-72

Aestus II (also known as ''RS-72'') was a

turbopump A turbopump is a propellant pump with two main components: a rotodynamic pump and a driving gas turbine, usually both mounted on the same shaft, or sometimes geared together. They were initially developed in Germany in the early 1940s. The purpos ...

-fed version of the pressure-fed Aestus developed in a collaboration between the

Ottobrunn Space Propulsion Centre Airbus Defence and Space is the division of Airbus SE responsible for the development and manufacturing of the corporation's defence and space products, while also providing related services. The division was formed in January 2014 during the ...

and

Pratt & Whitney Rocketdyne Pratt & Whitney Rocketdyne (PWR) was an American company that designed and produced rocket engines that use liquid rocket propellants, liquid propellants. It was a division of Pratt & Whitney, a fully owned subsidiary of United Technologies Corpo ...

(

Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...

Rocketdyne Rocketdyne was an American rocket engine design and production company headquartered in Canoga Park, California, Canoga Park, in the western San Fernando Valley of suburban Los Angeles, California, Los Angeles, in southern California. The Rocke ...

at the time). It was designed for improved performance, thrust and reliability over its predecessor. Aestus II development was supported by

which provided turbopump for the engine. The first prototype variant, called RS-72 Pathfinder, successfully completed 14 tests at the

White Sands Test Facility White Sands Test Facility (WSTF) is a U.S. government rocket engine test facility and a resource for testing and evaluating potentially hazardous materials, space flight components, and rocket propulsion systems. NASA established WSTF on the Whit ...

, reaching a 60 second burn time at 100% power in May 2000.

References

{{Ariane Rocket engines using hypergolic propellant Spacecraft propulsion Rocket engines using the pressure-fed cycle