Space Transportation

This research field covers the scientific investigation and development of critical technologies for the transportation between Earth, space and other celestial bodies. The focus lies on innovative chemical propulsion systems, with a world-leading expertise in the field of additively manufactured aerospike engines for thrust levels between 1 N and 30 kN.
To investigate such engines, experimental measurements are carried out on cold gas test benches as well as in hot fire tests at the institute's own engine test field. Another focus is  the development of numerical models for specific flow phenomena, such as re-entry or thrust vector control, which in turn are verified by the corresponding experimental activities.
Another research topic is the use of extraterrestrial resources. This so-called "In-Situ Resource Utilization" (ISRU) plays a central role in future space concepts and enables, for instance, the acquisition of propellant for missions on the moon or Mars. This research will not only enable the more efficient and environmentally friendly use of space, but will also enable currently unfeasible missions to explore the cosmos.
In addition, the impact of space transport systems on the environment and climate is increasingly becoming the focus of research. Understanding these influences, deriving tools for trading off design decisions and developing technologies to minimise these influences are the declared objectives of this field of research. Initial progress has already been made with the development of biodegradable thermal protection materials for re-entry systems.

Contact:
 Dr.-Ing. Christian Bach    
Head of Space Transportation

A summary of previous projects conducted by the Research Group for Space Transportation can be found here.

Recent projects

• CO-ESA (Feasibility study on high-temperature co-electrolysis for space applications)
• COMETS (Additively manufactured thermal protection systems made of ceramic and metal)
• NEDSERD (Experimental & Numerical Study on Rotating Detonation Engines)
• PARSEC (Reduction of flow separation in nozzles using quasi-DC plasma actuators)
• SLICE (Doctoral network investigating the environmental impact of rocket launches)
• SOCRATES (Solid oxide fuel cells for extraterrestrial energy generation)
• THOMAS (Concept study of an aerospike engine for extraterrestrial landing applications)
• TPRise (Feasibility study of the bio-based thermal protection material TPSea)
• TPSea2 (Development of a bio-based material for ablative thermal protection systems)

CO-ESA

The project “Co-Electrolysis and Methanation for the Production of CH₄ and O₂ in Exploration Missions” (CO-ESA) aims to advance Europe’s capabilities for human Mars exploration by developing a high-temperature solid oxide co-electrolysis system. This technology enables the simultaneous conversion of water vapour and carbon dioxide into oxygen and a syngas mixture of H₂ and CO, which can then be efficiently transformed into methane. By relying on locally available Martian resources, CO-ESA addresses one of the central challenges of future missions: the sustainable in-situ production of propellants.
Building on the success of NASA’s MOXIE experiment, which demonstrated for the first time that oxygen can be produced directly from the Martian atmosphere, CO-ESA expands this concept toward a full propellant-production chain by adding co-electrolysis and methane generation.

Funded by the European Space Agency (ESA), CO-ESA brings together key partners with complementary expertise. Fraunhofer IKTS leads the development and validation of a laboratory demonstrator to prove the feasibility of high-temperature co-electrolysis for space applications. TU Dresden contributes system-level analysis, modelling, and the evaluation of operational concepts for Mars missions, while HTW Dresden supports system definition and integration aspects. Together, the consortium assesses performance, robustness, and environmental constraints derived from ESA’s technical requirements (e.g., targeted production rates for CH₄ and O₂).
By adapting advanced solid oxide technology, widely used in terrestrial energy systems, to the unique demands of the Martian environment, CO-ESA has the potential to significantly reduce launch mass, lower mission risk, and enable a reliable supply of fuel and oxidiser on Mars. This work strengthens Europe’s strategic position in In-Situ Resource Utilisation (ISRU) and supports future crewed mission architectures that depend on local resource production.

COMETS

The project “Integrated Ceramic-Copper Thermal Protection System for Thermal Management of Reusable Launchers” (COMETS) focuses on the development of innovative thermal protection systems for reusable spacecraft. The project aims to explore material and manufacturing concepts that can withstand the extreme thermal stresses during re-entry into the atmosphere while enabling efficient heat dissipation.
COMETS is being developed in close cooperation between the Space Transportation Research Group, the University of Twente, and the Royal Netherlands Aerospace Center (NLR). A key focus is on the utilization of additive manufacturing processes (LPBF and DED), which open up new possibilities for manufacturing complex structures using multiple types of materials.
The project is investigating a multi-layer thermal protection system consisting of ceramic and metallic layers that are bonded together. The ceramic top layer has a high heat capacity and low thermal conductivity, while an underlying copper alloy dissipates any remaining residual heat and can potentially also be actively cooled. Special emphasis is placed on the interface layer between the ceramic and metal, which is intended to serve as a secure connection between the other layers.
The project is funded by the European Space Agency (ESA) under the FIRST! program.

NEDSERD

The project "Numerical and Experimental Demonstration Study for Engines using Rotating Detonation" (NEDSERD) is investigating the extent to which Rotating Detonation Engines (RDEs) can be used for space applications. RDEs use detonations as a combustion process to convert the chemical energy from fuel and oxidizer into thermal energy. Compared to conventional combustion at constant pressure, pressure-increasing detonation combustion offers a theoretical efficiency advantage that can contribute to reducing fuel consumption, increasing payload capacity, or reducing launch costs. In addition, continuous detonation enables a more compact combustion chamber and thus shorter and lighter engines. At the same time, however, there are challenges, in particular high thermal loads and ensuring reproducible and stable operation.
With this in mind, TU Dresden, together with its project partners, ArianeGroup and the Institute of Space Propulsion at the German Aerospace Center (DLR) in Lampoldshausen, is investigating the integrability of RDEs into an overall system and potential application scenarios. The focus is on hot fire campaigns and the development of a numerical model. Particular attention is being paid to the thermal loads that occur during operation at different operating points.

In an initial test campaign on an uncooled engine, several thermocouples were used to determine the heat loads along the axial direction. Based on these results, a second, scaled-up engine was designed and additively manufactured. In addition to the method already used to determine the heat flow via thermocouples, the second campaign also uses coaxial thermocouples and calorimetric measurement via the engine's cooling system. This allows two further methods for determining the heat loads during operation to be investigated. The aim of the second test campaign is to increase both the propellant mass flows and the test duration.
For the numerical analysis, a model was created to simulate the hot gas flow with a circulating detonation wave. Assuming a quasi-stationary flow, this is coupled with a simulation of the cooling channel flow and the structure of the RDE to enable predictions of the heat loads and temperature distribution that occur.
NEDSERD is funded by the Federal Ministry for Economic Affairs and Climate Protection under grant number 50RL2320.

PARSEC

The “Plasma ActuatoRs for SEparation Control in over-expanded rocket nozzles” (PARSEC) activity, funded by the European Space Agency, investigates the use of quasi-DC plasma actuators to control flow separation and reduce the associated side-loads in over-expanded nozzles. The motivation stems from the limitations of conventional bell nozzles, which must be conservatively sized to avoid severe over-expansion at lift-off, leading to reduced high-altitude performance. The project is carried out in collaboration with Politecnico di Torino, where the preliminary design and numerical analyses were completed. A subscale cold-flow experiment will be conducted within the research group for space transportation at TU Dresden to assess the effectiveness of the actuators. The planar nozzle is fed by pressurised dry air and incorporates a six-degree-of-freedom force balance for accurate side-load measurements, while the electrodes are embedded in a ceramic matrix for thermal and electrical insulation. The planar geometry also enables optical access for background-oriented Schlieren imaging. The overarching objective is to provide a proof of concept and improve the reliability of numerical simulations for larger-scale configurations.

SLICE

Space utilisation is essential for understanding climate change. At the same time, rapidly increasing launch rates create an urgent need to assess and reduce the environmental footprint of space activities themselves. The largest uncertainties in this field stem from the operational phase of launchers – from lift-off to landing or re-entry – where the highest Global Warming Potential and Ozone Layer Depletion Potential are expected. In the upper atmospheric layers, which are only reached by launch vehicles, emitted pollutants can accumulate and remain for very long periods, amplifying their impact.
SLICE addresses these knowledge gaps by offering a research and training programme that connects space engineering and climate science to close the missing elements in today’s Life-Cycle Analysis of launch systems. The network brings together 30 European partner institutions and will train 18 doctoral candidates who work across three key research areas:

• Launch Vehicle Emissions
• Atmospheric Interaction & Climate Impact
• System Analysis & Design

This work will generate actionable scientific insights and support the development of solutions to reduce greenhouse gas emissions, accelerate the European Green Deal, and enable environmentally sustainable access to space. Beyond its scientific contribution, SLICE will train a new generation of researchers who combine technical depth, environmental awareness, and the ability to work across disciplines and sectors. They will be uniquely prepared to shape the future of European space transportation — technically, environmentally, and politically.
SLICE is coordinated by TU Dresden and funded by the European Union’s Horizon Europe programme under the Marie Skłodowska-Curie grant agreement no. 101227592.

SOCRATES

The project "Solid Oxide Cell Realisation through Adaptation of Terrestrial Energy Systems" (SOCRATES) aims to revolutionize outer planets exploration by developing an innovative Solid Oxide Fuel Cell (SOFC) system using hydrocarbons and oxygen. This alternative power source addresses the challenges of energy generation in the outer solar system, leveraging the proven capabilities of SOFC technology, as demonstrated on the Perseverance Mars rover.
Financed by the European Space Agency (ESA), SOCRATES involves key partners in its development. The Fraunhofer Institute for Ceramic Technologies and Systems (IKTS) is responsible for the demonstrator's development and testing, ensuring its practical viability. Concurrently, TU Dresden manages the state-of-the-art (SOTA) aspects and investigates the utilization of residual propellants as fuel, contributing valuable insights to the project's comprehensive approach.
This collaborative effort holds the potential to redefine the landscape of outer planets exploration, providing a reliable, high-energy-density power source for future space missions in challenging environments.

THOMAS

As part of the "THrottable Oxygen Methane AeroSpike" (THOMAS) project, funded by the European Space Agency (ESA), an aerospike engine is being designed for extraterrestrial landing applications, e.g. on the moon. The engine uses oxygen and methane as propellants and is designed to provide a thrust of 20-30 kN. The aerospike engine design was chosen because, unlike conventional engines with bell nozzles, it can adapt its exhaust flow more effectively to the ambient pressure. In addition, when truncated, the overall size can be reduced while maintaining a comparable thrust. Despite the truncation, the thrust only decreases slightly, so that this difference is compensated for by the reduction in system weight. Due to the shorter overall length of the propulsion system, a corresponding landing module can be designed to be shorter and more space can be provided to payloads. Alternatively, the launcher can be kept shorter and thus lighter, which has a positive effect on launch costs. A demonstrator engine is being derived based on the design of the lander engine. Alongside the design process, numerical flow tests are carried out, the results of which are incorporated into further development. The demonstrator will then be additively manufactured from a copper alloy using the Laser Powder Bed Fusion (LPBF) process at the Fraunhofer Institute for Laser Technology (ILT). The post-processing of the demonstrator is carried out by the Fraunhofer Institute for Machine Tools and Forming Technology (IWU) with the aid of cyber-physical systems methods. Ignition and fuel atomization and mixing are being investigated by the Łukasiewicz Research Network - Institute of Aviation. The project will culminate in the demonstrator being tested at the German Aerospace Center (DLR) at the Institute of Space Propulsion in Lampoldshausen.

TPRise

The project "Thermal Protection Readiness Improvement of Sustainable Eco-materials" (TPRise) aims to further develop the disruptive, bio-based thermal protection system (TPS) “TPSea” for space applications. To this end, its technology readiness level (TRL) will be increased from TRL 4–5 to TRL 5–6 through application-oriented material adaptation, qualification, and testing. The focus is on assessing compatibility with spacecraft structures, analyzing application potential, and conducting a Life-Cycle Analysis (LCA). By using renewable resources for innovative space materials, TPSea aims to embody environmental sustainability throughout its entire life cycle – from the use of organic raw materials and biological waste materials such as wood fibers to environmentally friendly manufacturing processes and potential biodegradability or recyclability at the end of the product life cycle. TPSea material formulations are being evaluated as part of an LCA to determine and assess their environmental impact and benefits.

This project aligns with the objectives of the European Space Agency's (ESA) Agenda 2025 and Strategy 2040 and is funded through ESA's FIRST! program. These aim to minimise the environmental impact of space transportation and to strengthen Europe's autonomy, competitiveness and capacity for innovation. To ensure broad applicability and commercial relevance, the project is collaborating with space transport service providers. This enables detailed system-level requirements, operational constraints, and performance indicators for specific mission scenarios to be taken into account. This approach enables the early integration of market-oriented, sustainable material development and accelerates design iterations. It improves the market readiness of bio-based TPS solutions and takes a step towards minimising environmental impact and maximising sustainability-oriented innovations in the space sector within the framework of the project.

TPSea2

TPSea2 is a follow-up project to TPSea and focusses on the application-related investigation and feasibility of the contents identified in the TPSea project. The aim is to design an ablative Thermal Protection System (TPS) from renewable raw materials, in particular natural fibres, by developing, producing and qualifying a dimensionally stable bio-based material that meets the highest material standards. The developed bio-based TPS utilises the acceptance of a previously used material of biological origin - cork - but offers improved mechanical properties and avoids its disadvantages. This means that it can be used much more widely as a bioeconomic high-tech and can be utilised in the future as a substitute material for a more sustainable space economy. TPSea2 thus aims to establish bioeconomic principles in a prestigious industry with the highest added value - the space industry.
Within the framework of the funding guideline “Ideas competition: New Products for the Bioeconomy” in the context of the German “National Bioeconomy Strategy” the project is funded and administered by the Federal Ministry of Education and Research (BMBF, Bundesministerium für Bildung und Forschung) and the Projektträger Jülich (ptj).

Publications

All publications associated with Dr.-Ing. Christian Bach on Researchgate and the FIS of the TU Dresden

Selection of some notable publications of the Space Transportation Systems Research Group:

• Selbmann, A.; Gruber, S.; Propst, M.; Dorau, T.; Drexler, R.; Toma, F.-L.; Müller, M.; Stepien, L.; Lopez, E.; Bach, C.; Brückner, F. and Leyens, C.: Process Qualification, additive Manufacturing and Postprocessing of a Hydrogen Peroxide / Kerosene 6 kN Aerospike Breadboard Engine, Journal of Laser Applications, Volume 36, Issue 1, 2024, https://doi.org/10.2351/7.0001121.
• Maiwald, V.; Bauerfeind, M.; Fälker, S.; Westphal, B. and Bach, C.: About feasibility of SpaceX's human exploration Mars mission scenario with Starship, Nature Scientific Reports 14, 11804 (2024), https://doi.org/10.1038/s41598-024-54012-0 .
• Ziener, J.; Scheithauer, U.; Gottlieb, L.; Weingarten, S.; Joseph, A. G. and Bach, C.: Additive manufacturing of ceramic multi-material heating and ignition elements for a sustainable space access, Acta Astronautica 219 (2024) 609-617, Part of special issue ASCenSIon - Advancing Space Access Capabilities, https://doi.org/10.1016/j.actaastro.2024.03.038.
• Scheithauer, U.; Schwarzer-Fischer, E.; Sieder-Katzmann, J.; Propst, M. and Bach, C.: CerAMfacturing of a ceramic aerospike engine, Acta Astronautica 220 (2024) 197-203, Part of special issue ASCenSIon - Advancing Space Access Capabilities, https://doi.org/10.1016/j.actaastro.2024.04.017.
• Sieder-Katzmann, J.; Propst, M.; Stark, R. H.; Schneider, D.; General, S.; Tajmar, M. and Bach, C.: Surface Pressure Measurement of Truncated, Linear Aerospike Nozzles Utilising Secondary Injection for Aerodynamic Thrust Vectoring, Aerospace 2024, 11(7), 507, https://doi.org/10.3390/aerospace11070507. (selected among 76 articles as the title story for this journal issue, see https://www.mdpi.com/2226-4310/11/7)
• Lorenz, N.; Scheithauer, U.; Schwarzer-Fischer, E., Mosch, S.; Propst, M.; Sieder-Katzmann, J. and Bach, C.: Assessment of the as-sintered surfaces of ceramic components additively manufactured by Vat Photopolymerization (CerAM VPP), Open Ceramics, 2024, https://doi.org/10.1016/j.oceram.2024.100660.
• Guenther, R., Tajmar, M., Bach, C.: Wood and Wood‑Based Materials in Space Applications—A Literature Review of Use Cases, Challenges and Potential. Aerospace 2024, 11, 910. https://doi.org/10.3390/aerospace11110910.
• Scarlatella, G.; Sieder-Katzmann, J.; Propst, M.; Heutling, T.; Petersen, J.; Weber, F.; Portolani, M.; Garutti, M.; Bianchi, D.; Pastrone, D.; Ferrero, A.; Tajmar, M. and Bach, C.: RANS Simulations of Advanced Nozzle Performance and Retro-Flow Interactions for Vertical Landing of Reusable Launch Vehicles, Aerospace 2025, 12, 124, https://doi.org/10.3390/aerospace12020124
• Choi, S. M. and Bach, C.: Experimental Investigation of PWM Throttling in a 50-Newton-Class HTP Monopropellant Thruster: Analysis of Pressure Surges and Oscillations, Aerospace 2025, 12, 418, https://doi.org/10.3390/aerospace12050418.
• Lamping, T.; Petersen, J.; Giannis, K.; Lippke, M.; Wolf, S.; Propst, M.; Heutling, T.; Bach, C.; Craig, B.; Kontis, K.; Baasch, J.; Linke, S.; Stoll, E.; Hijlkema, J.; Van den Eynde, J. and Schilde, C.: Simulation of the plume-surface interaction with a manufactured landing pad, Acta Astronautica, 234, 2025, 536-547, https://doi.org/10.1016/j.actaastro.2025.05.026.