Chair of Space Mobility and Propulsion
One of the greatest challenges of space travel is access to space. Powerful, reliable and environmentally friendly propulsion systems play the central role in overcoming the Earth's gravity and advancing into space beyond the limits of the atmosphere.
Currently, the competitive situation in space transportation is very dynamic. International agencies and companies are under pressure to produce, launch and operate established systems at ever lower costs. New design and production methods, system simplifications (e.g. component reduction), modular construction methods (and thus an increase in the production cadence of individual modules), as well as new operational requirements and functionalities (e.g. reuse) aim to massively reduce the cost of access to space. All these innovations need to be researched, tested and optimised for their effectiveness, reliability and safety.
Therein lies a unique opportunity: the democratisation of space and the realisation of the commercial potential of private spaceflight is highly dependent on (1) sustainable operations in space and (2) reliable and cost-effective access to space. It is therefore imperative to further intensify the commitment to the future of space transportation and to make the region a world-leading centre of forward-looking space propulsion systems. Specifically, there is an urgent need for research and testing of space propulsion systems, their components and the associated operating concepts and systems, in order to quickly bring innovative and competitive solutions to market.
Space propulsion systems are on the one hand the decisive cost factor and on the other hand the key technology that determines flexible access to space. In the field of launchers, Europe is facing major challenges as US competitors continuously renew their launch vehicle propulsion systems and continue to reduce the cost of access to space. Reusability, a means of reducing costs and increasing sustainability, relies on return strategies that usually involve powered flight. However, the rocket engines currently available in Europe are not designed for this and are unsuitable. Without losing sight of the improvement of conventional systems, the main focus of research must nevertheless be on the question of how access to space can be rethought and implemented today.
However, access to space is only one of the aspects that need to be addressed. With the increasing number of systems in space and the growing complexity of the demands placed on these systems, the operational effort required to manage and control them from the ground is also increasing.
More flexible and increasingly autonomous and intelligent systems are therefore needed. These systems must be able to independently determine and implement the best course of action algorithmically - for example, to avoid collisions with other systems. This requires technical solutions that offer operational manoeuvring strategies (analogous to "right before left") and thus take into account the increasing space traffic in the future (e.g. large satellites, small and micro satellites, rocket systems, space debris).
The diversification of space platforms and the emergence of smaller satellites, as well as the miniaturisation of key technologies such as power generators and chips, have also facilitated access to space for small and medium-sized enterprises offering innovative space-based solutions for non-space sectors. At the same time, the continuing trend towards standardisation, the best example of which is the CubeSat standard, has resulted in a large number of smaller satellites being launched and many more planned for the next decade.
However, not all technologies and subsystems have been equally developed and advanced. Although space propulsion is an important prerequisite for any space activity, the same level of innovation has not been achieved in propulsion systems, unlike other subsystems. In fact, there are not readily available commercial off-the-shelf solutions for propulsion systems for all thrust ranges needed for access to space, return from space and activities in space. Moreover, most propulsion systems in use today are either based on storable but toxic propellants or lack the necessary flexibility. For this reason, space propulsion remains a hurdle to the unfolding of a wide range of applications and activities and to the enabling of a new era of space mobility that is upon us.
From a systems perspective, the following innovations in space propulsion and space transportation will lead to further leaps in technology in the near future:
- Full autonomy and hardware-in-the-loop based on predictive health monitoring, autonomous control and maintenance of space systems and of their subsystems;
- COTS (Commercial Off The Shelf) propulsion systems using clean propellants for small satellite buses to (a) increase their business value and (b) eliminate their contribution to the space debris problem by deorbiting them at the end of their lifetime, thus contributing to collision avoidance;
- Transport, refuelling and maintenance in Earth orbit;
- Reducing the cost of electric propulsion systems, including adaptation to more conventional propellants that are more accessible and cost-effective (including air-powered systems) and increased flexibility of propulsion systems for access to space to enable return scenarios.
