Speakers
Description
The space sector has experienced significant growth in recent years, with rocket launch rates increasing from 102 in 2019 to 329 in 2025. Given the fact that launch and re-entry operations of space transportation systems represent the only source of anthropogenic emissions in the upper atmosphere, this increase is raising concerns about respective ozone and climate effects. In recent years, there has been an increasing number of studies assessing the effects of these emissions using global Earth system models. For accurate assessments of the atmospheric effects, emission inventories that take into account the individual characteristics (trajectory, propellant, engine parameters, materials) of launches and re-entries are required.
This study addresses the general question of how launch and re-entry emissions from space transportation systems can be modeled under contemporary and expected near-future operational conditions, as well as how these emissions are currently incorporated in Earth system models and used in recent studies to assess their environmental impacts.
In the first step, results are presented that were modeled using the “Launch Emissions Assessment Tool” (LEAT) and the “Re-entry Emissions Assessment Tool” (REAT), representing all orbital space transportation missions conducted between 2019 and 2025.
It is shown that the combined LEAT–REAT framework enables the modeling of emission composition, trajectories, and altitude-dependent chemical effects of afterburning for multiple propulsion technologies and vehicle configurations. Launch vehicle trajectories are compared to data from live streams showing a good consistency for orbital launches. Emission data is compared to literature values. In comparison with previous approaches that relied on generic profiles, the new tool set captures individual flight paths, staging and fragmentation events, and vehicle-specific launch and re-entry combustion modeling. Based on this, discrepancies and uncertainties in prior emission inventories are identified. The results are then compared with natural sources, such as meteorites and other anthropogenic sources. The analysis is concluded by an assessment of uncertainties through the implementation of a systematic parameter study.
In a second step, it is investigated how emission species, which are released in different layers of the atmosphere during launch and re-entry, are incorporated in state-of-the-art chemical transport and climate models. In addition, an overview of chemical interactions between emissions and atmospheric species implemented in recent modeling studies is provided. Moreover, a chemical reaction database is presented that covers possible chemical reactions between metallic re-entry species and atmospheric species.