DLR is developing a reusable rocket engine for launching small satellites

Whether alone or in a constellation, small satellites weighing from just a few kilograms (nanosatellites) up to several hundred kilograms (micro- and minisatellites) are becoming increasingly technologically sophisticated and have the potential to fundamentally change the space industry.

In the coming years, hundreds of such small satellites will be carried into Earth orbit. As part of the EU project SMILE (Small Innovative Launcher for Europe), researchers from the Institute of Structures and Design at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) have developed a reusable rocket engine especially for launching such satellites, and have performed an initial series of successful trials on a test rig.

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The first hot firing test was on the high-pressure test rig of the SMILE project partner PLD Space. (courtesy: DLR)

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Central components of the rocket engine developed at the DLR Institute of Structures and Design are the 3D printed injector head and the ceramic combustion chamber. (courtesy: DLR)

Small satellite launches – Independent, flexible and cost-effective

Until now, small satellites have tended to be carried into space aboard large rockets, if there is enough room for them. The primary aim of these flights is to place large satellites in a specific orbit. Small satellites take second place as far as timing and target orbit are concerned. For this reason, 14 European research institutions and companies are working on designing an economical rocket launcher within the SMILE project. This should enable small satellites weighing up to 70 kilograms to be carried to near-Earth orbits. The project focuses on the technology required for propulsion, on-board electronics and cost-effective production.

3D printing as a success factor

The rocket engine, developed by DLR scientists specifically for this application, consists of two central components – the metal injector head and the ceramic combustion chamber. Belgian project partner 3D Systems manufactured the prototype injector out of a nickel-chromium alloy using metal 3D printing. 3D printing is an additive process. Digital design data is used to build up or rather print the desired structure in layers by depositing material. “Thanks to this relatively new manufacturing technology, we need significantly fewer parts and process steps, which speeds up the manufacturing process for the injector and reduces production costs. At the same time, we have been able to significantly reduce the mass of the components, which is always a very important factor in aerospace applications,” says Markus Kuhn, responsible for the project at the DLR Institute of Structures and Design in Stuttgart.

Combustion chamber made of high-performance ceramics

The researchers used a special high-performance material for the combustion chamber – a carbon fibre-reinforced ceramic that consists mainly of silicon carbide and was developed primarily at the DLR institute in Stuttgart. It is particularly well-suited for high-temperature applications and reliably withstands even extreme temperature changes. “Reusability was an important consideration in development. If the entire system can be used multiple times, operating costs are significantly reduced, making commercial implementation attractive to companies,” says Ilja Müller, Rocket Propulsion Systems Engineer at the Institute of Structures and Design.

First tests passed with flying colours

In hot firing tests in September 2018, the team led by DLR researcher Markus Kuhn subjected the rocket engine to an initial test run. It successfully completed a total of 18 tests at the high-pressure test bench of Spanish project partner PLD Space, with a firing time of up to 45 seconds, thereby showing very high combustion efficiency of over 90 percent. Liquid oxygen (LOx) and kerosene were used in the tests.

ESA’s space vision presented at Paris Peace Forum

ESA astronaut Claudie Haigneré attended the Paris Peace Forum this weekend, presenting the Agency’s vision for engaging humankind in multilateral cooperation for space exploration with peaceful objectives.

An initiative launched by President Macron of France, the Paris Peace Forum is an annual platform for global governance projects and was conceived as a response to tensions in the contemporary world. Taking place this year on 11-13 November, the centenary marking the end of the First World War, the event includes the attendance of over 60 international Heads of State.

Based on the belief that durable peace can only be achieved through international cooperation in several sectors, including space exploration, the Forum was an ideal opportunity to present ESA’s ‘Moon Village’ vision. This foresees a peaceful global cooperation to achieve a space landmark for humankind in 21st century, realising the potential of humankind as spacefaring species, while providing benefits and opportunities to as many people as possible on Earth.

Claudie Haigneré
Claudie Haigneré

Astronaut Claudie Haigneré said, “The question is not whether humankind will return to the Moon, but rather when and who. Our ‘Moon Village’ concept is an ambitious vision, a multi-partner open concept, it’s a step to engage all humankind, and not just separate nations, towards a component of its future.”

The Moon Village concept was introduced three years ago as a proposal for the post-International Space Station space programme. Over the last few years, plans to return to the Moon have gained interest and moved up the agendas of government, space agencies and private entrepreneurs.

A number of initiatives and missions are under way: from the US-led Lunar Orbital Platform-Gateway and Chinese plans to explore the Moon, to European initiatives conducted through ESA. All these efforts converge towards a common goal: returning to and going forward to the Moon establishing a permanent presence.

But, although international in nature, these projects still replicate to some extent the ‘competitive approach’ of earlier ventures. They lack the global approach that would maximise results, allow wider participation, inspire younger generations and further mutual understanding and cooperation.

ESA has been working to promote this approach, also reaching out to non-space potential partners and other interested parties. This is the chance to rally the whole international community around a truly global vision where, through suitable governance mechanisms, any nation can be part of the effort regardless of their actual space capability.

Claudie Haigneré said, “Mobilised together towards this new step of humankind’s expansion, let us leave aside our national divisions and rivalries. As we move from our planet Earth, our cradle, let us grasp the opportunity to think differently in terms of multilateral cooperation, peaceful objectives, and respect for diverse interests and preservation of our common interests.

“We share the values that are promoted in this forum: respect, peaceful objectives with soft leadership and inclusiveness for inspiration. The spirit of the Moon Village is not taking part in a space race or competition, but an expression of cooperation, shared responsibility and sustainability.

“It not just a temporary adventure, or a nomadic exploration, but a true sustainable endeavour, with the wish to contribute in return to a better management of our planet Earth. We want to gather high-level political will to take this tremendous opportunity to think about the future of humankind on a new basis. The generations of the 21st century will be grateful for this fascinating endeavour.”

Claudie Haigneré and Piero Messina were accompanied by ESA Director General Jan Wörner with the support of ESA astronaut Frank De Winne, Head of the European Astronaut Centre in Cologne, Germany.