Researchers at The University of Manchester have developed a modeling framework that integrates collision risk into the early design of Earth-observation satellite missions.
The study, published in Advances in Space Research, addresses what the authors describe as a “space sustainability paradox” – the risk that using satellites to solve environmental and social challenges on Earth could ultimately undermine the long-term sustainability of space itself.
There are currently about 11,800 active satellites in orbit, with projections suggesting that figure could exceed 100,000 by the end of the decade. As congestion increases, so does the likelihood of collisions and the creation of long-lived space debris.
Lead author John Mackintosh, a PhD researcher at The University of Manchester, said, “By integrating collision risk into early mission design, we ensure Earth-observation missions can be planned more responsibly, balancing data quality with the need to protect the orbital environment.”
Earth-observation satellites are widely used to support the UN sustainable development goals, providing data on land use, urbanization, ecosystems and disaster response. High-resolution imaging often requires satellites to operate at lower altitudes, reducing field of view, or at higher altitudes with larger and heavier optical systems. Larger satellites face increased exposure to debris and may pose greater collision risks.
The new framework links mission requirements – such as image resolution and coverage – with satellite size, mass, constellation size and debris density in different orbital regions. This enables designers to assess trade-offs between performance and collision probability at an early stage.
Using the model, the researchers found that collision risk does not necessarily peak where debris density is highest. For a satellite delivering 0.5m resolution imagery, the highest collision probability was highest between 850km and 950km altitude above Earth – around 50km above the peak debris density.
Dr Ciara McGrath, lecturer in aerospace systems at The University of Manchester, said, “As satellite use continues to grow, our method offers a practical way to ensure that space remains safe, sustainable and usable for generations to come.”
The researchers say the framework could be expanded to include additional environmental impacts, such as debris persistence and satellite re-entry effects, to support broader sustainability assessments in future mission design.
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