Life Cycle Assesment of Space Transportation Systems

In order to investigate the sustainability of space transportation systems across their entire life cycle – that is, design, manufacture, launch, re-use and re-entry – we carry out analyses that improve the assessment of these systems’ environmental impacts.

In order to investigate the sustainability of space transportation systems across their entire life cycle – that is, design, manufacture, launch, re-use and re-entry – we carry out analyses that improve the assessment of these systems’ environmental impacts.
Current challenges include conducting a comprehensive life-cycle assessment (LCA) of various space structures, detailed quantification of emissions during launch and re-entry, and reducing uncertainties regarding chemical interactions and physical processes involved in emissions across different layers of the atmosphere.
Using LCA methods and databases specifically tailored to space systems, as well as current and emerging simulation tools, the following aspects are investigated:

• Environmental impacts of design, development and production,
• Emissions and environmental impacts during launch,
• Emissions and environmental impacts during re-entry.

The overarching aim is to contribute to making the space sector more sustainable, given the sector’s strong growth.

Since 2021, we have been conducting research into the environmental impacts of space activities. The project began with a comprehensive literature review of the state of research at the time. This revealed that, apart from studies from the early 1990s and 2000s, very little research had been carried out to date on the environmental impacts of space activities. Using generic production datasets, various launch vehicle architectures, propellants and the effects of reusability were investigated as part of an industrial collaboration with ArianeGroup. It was found that, depending on the propellant combination used, either the production of the structure or that of the propellants has the greater impact. Reusability strategies for rocket stages can reduce the impact on most environmental indicators, depending on the return method used.

The open-source tool ‘Launch Emission Assessment Tool’ (LEAT) was developed to model emissions from space launches. It combines trajectory and emission calculations, taking into account uncertainty parameters (e.g. gravity turn, mixing ratio with the surrounding atmosphere), thereby enabling an estimate of launch emissions. In addition, the open-source tool ‘Re-entry Emission Assessment Tool’ (REAT) was developed to estimate emissions during re-entry. It analyses re-entry trajectories based on DRAMA SCARAB or DEBRISK simulations and models emissions resulting from atmospheric heating and ablation using estimates. The tool provides insights into the possible emission species and their order of magnitude. Using these tools, emission inventories for space launches and re-entries were compiled for the period 2019–2025 (Launch, Re-entry), which identify the potential emission species, their orders of magnitude and the associated uncertainties.
Both tools represent only an initial approach to emission calculation and will need to be validated by measurements and further refined in the future.

 
Durch die Arbeitsgruppe HEFDiG wurden die Forschungstätigkeiten um spektroskopische Analysen der Raketentriebwerksemissionen während Bodentests ergänzt. 

The HEFDiG working group of the IRS has expanded the research activities to include spectroscopic analyses of rocket engine emissions during ground tests.

In addition, workshops are held regularly at the University of Stuttgart, where international experts from research, industry, politics and public authorities come together to discuss knowledge gaps and measures to address them, as well as strategies for the more sustainable development of space transport systems. To date, these workshops have produced three white papers (first Whitepaper, second Whitepaper, third Whiteaper), which outline the current state of scientific knowledge and the measures required to address the research questions.

The gaps identified are now being systematically addressed as part of further research. For example, the modelling of launch and re-entry emissions (emissions calculation, particle emissions, characterisation) is being refined.
To achieve this, the aim is to implement and improve existing tools based on findings from the SLICE research network (e.g. measurement and simulation data on emissions, calculated characterisation factors).
In addition, future scenarios for the launch vehicle market are being developed to serve as a common basis.
On this basis, emission databases for launch and re-entry processes will be compiled for atmospheric simulation of current and future scenarios, and characterisation factors will be developed, particularly for emissions at high altitudes.

We also examine the chemical interaction of space-based emissions with the upper atmosphere. Our focus here is on the stratosphere and mesosphere. By analysing chemical reaction pathways, developing models to identify the resulting products, and using models to calculate climate and environmental impacts, we aim to reduce uncertainties regarding the effects of space activities. A more precise assessment of the atmospheric environmental impacts of space activities is crucial for the sustainable and safe further development of the growing space industry.