Alternative Green Propellants for Space Propulsion

ArianeGroup working areas in the field of alternative propellants for space propulsion.

Background

ArianeGroup have been actively exploring and testing non-toxic, or green propellants, as a possible replacement for hydrazine based propellants. Whilst possible hydrazine legislation is on the horizon within the European Union, non-toxic propellant alternatives offer significant economic benefits. These benefits can be further enhanced with the implementation of modern state of art technologies, such as 3D printing, for the production of dedicated green propellant rocket engines and thrusters,

As the main European supplier of space propulsion systems, ArianeGroup has a vital interest in playing an active role in the development and industrialisation of components and propulsion systems using non-toxic propellants.

Applications and Technologies

Access to space (Ariane 5, Vega, Rokot, future launchers).
Orbital propulsion (e.g. communications, geo-information, weather forecasting, navigation, space exploration).
Human space flight (e.g. ISS, Columbus, ATV).
Security and defence.
Space tourism.

Alternative green rocket propellant candidates.

Radio Frequency Ion Propulsion Flow Schematic

Currently there is no generic replacement for hydrazine with a single green propellant. Therefore, several options are being considered.

Basically the mission requirements can be divided in two areas: short term missions with a maximum of some days of operations (typically for launcher propulsion) and long term missions with lifetimes up to and beyond 15 years (satellite propulsion).

For orbital propulsion in GEO an additional trend towards an increased market share of electrical propulsion is also considered.

Alternative Propellant Working Areas

As a first priority, the replacement of monopropellant hydrazine is considered, bearing in mind that there is also a need for an alternative to the more toxic MMH used in bipropellant systems. In order to be able to select the best technology, the following alternative propellants and their impact on the different propulsion systems are amongst those under evaluation:

Ammonium Dinitramide (ADN) based propellants that successfully demonstrated space heritage on the PRISMA satellite and where ArianeGroup has a strong teaming with the Swedish Inventor company ECAPS, part of the Swedish Space Corporation Group.
Hydrogen Peroxide (H2O2) as a monopropellant and in hybrid mode.
GOX / GH2 propellants produced via water electrolysis.
Ionic liquids to replace hypergolic bipropellant's MON / MMH .
Furthermore, other technologies are being assessed as for example HAN based propellants.

Qualification of a Green Solution for a Small LEO Platform

Together with our partner ECAPS, we are currently qualifying their ADN based LMP-103S technology to be a fully exchangeable propulsion system solution for a small LEO platform.

Development of a Fully ALM manufactured H2O2 Thruster:

The Lampoldshausen centre recently completed a test series with newly developed 3D printed rocket engines. These engines are made out of only two parts and were printed in one day.

3D Printed Thruster Assembly

3D Printed Thruster

The use of 3D printing or Additive Layer Manufacturing (ALM) significantly reduces both development time and development cost. The new thruster comprises just two parts:

The injector, heat barrier and mounting interface.
The combustion chamber and the canted nozzle.

A comparable classical thruster would need 10 times as many parts with subsequent manufacturing and assembly effort.

Infrared Temperature Profile

H2O2 Hot Fire Test - 3D Printed Thruster

Advantages of ALM Technology:

Typical benefits associated with additive manufacturing include:

Cost - The more complex the part and greater the number of single parts to produce (traditional by drilling, turning or milling). Whilst reducing cost, additive layer manufacturing leads to a better buy-to-fly ratio and reduces waste and saves resources.
Schedule - Additive layer manufacturing provides the opportunity to produce parts with only one machine. Thereby, enabling the manufacturing of components within few days and so productivity can be increased.
Flexibility - By further development in handling the design process to show the options ALM technologies can provide. This offers new opportunities during the development phases in terms of design changes and alternative component configurations.

New Technologies Green Propellants