Design and Performance Assessment of Very Low Earth Orbit Missions within the Framework of Responsive Space.

Kurzfassung

Very Low Earth Orbits (VLEO) represent a promising domain for future Earth Observation missions, offering significant improvements in spatial resolution, radiometric performance, and communication link budget due to their proximity to Earth. In addition, VLEO provides environmental and strategic benefits, as its self-cleaning nature prevents long-term debris accumulation and contributes to a more sustainable orbital environment. These characteristics are particularly relevant within the framework of responsive space, where rapid deployment and replacement of critical assets are essential. However, the advantages of VLEO come at the expense of major operational challenges, primarily related to atmospheric drag, orbit decay, and limited satellite lifetime. This thesis presents a comprehensive assessment of VLEO missions within the framework of responsive space, focusing on the interplay between orbital dynamics, payload performance, and constellation design. To this end, an automated simulation tool was developed to integrate analytical models and numerical propagations, enabling a systematic evaluation of orbit maintenance, fuel consumption, and revisit metrics. The analysis considers a range of satellite platforms, from CubeSats to microsatellites, and provides an example where spatial resolution improves by up to 75% compared to traditional LEO configurations. This approach allows efficient management of trade-offs between satellite lifetime, payload performance, and other mission drivers, while facilitating the comparison of different mission architectures. The results highlight the balance required between the enhanced instrument capabilities at lower altitudes and the operational constraints imposed by atmospheric drag and increased maneuvering demands. The results demonstrate that VLEO missions, when designed iteratively to integrate platform lifetime, fuel availability, and constellation sizing, can outperform traditional LEO configurations in terms of instrument performance and responsiveness, while maintaining overall mission sustainability. In particular, the feasibility of operating satellites predominantly in LEO, with periodic excursions to VLEO to take advantage of its enhanced spatial and radiometric capabilities, has been studied and validated. The outcomes provide quantitative insights that support mission design decisions, optimal constellation sizing, and satellite architecture selection, ensuring a balanced trade-off between performance benefits and operational constraints. These findings offer practical guidance for the planning of future Earth Observation constellations in VLEO. Keywords:Very Low Earth Orbit (VLEO), Responsive Space, Earth Observation, Constellation Design, Orbit Decay, Satellite Lifetime, Revisit Time, Payload Performance, Satellite Mission Design, Fuel Consumption.