Stefan-Vlad Tudor, Leaf Space S.p.A.
Giovanni Zanotti, Leaf Space S.p.A.
Stefan-Vlad Tudor, Mr., Leaf Space S.p.A.
The growing number of CubeSat and small platform being launched provides a large quantity of opportunities for various kinds of missions, from Earth observation, telecommunications, service delivery, and to scientific research. The possibilities are even wider considering formation flying or even constellation of small satellites. However, the deployment and operation of these platforms require extensive effort in defining concepts of operations and consequently the design of the dedicated ground segment. This paper examines the critical factors influencing ground segment design and satellite operations, considering the problem of selecting ground station locations to comply with the mission requirements.
The analysis addresses diverse mission requirements across various kinds of mission objectives, including Earth Observation (EO): High-resolution imaging and environmental monitoring, Telecommunications: Broadband and IoT connectivity, Scientific missions: precise positioning or pointing for payload acquisition.
Each mission type imposes unique demands on the ground segment infrastructure, such as latency requirements, data throughput, and ground station geographical distribution, based also on the orbital scenario it is posed into. We can categorize the missions also based on their orbits within the LEO orbital regime (equatorial, mid-inclination and Sun Synchronous Orbits) and the number of platforms involved which drives largely the concept of operations and the ground segment design. We can consider indeed three categories: Single Satellite missions, which involve straightforward contact allocation but may have more complex requirements; Formation Flying missions, which being orbitally clustered, pose more challenging contact allocation; Constellations, which present complex interdependencies between the satellites, also in this case requiring more complex ground contact management, such as automatically capacity allocation.
Contact management emerges thus as a fundamental component for managing increasingly complex satellite constellations. The paper discusses modeling approaches that generalize scheduling across diverse mission types, taking into account the satellite visibility and access windows, data throughput requirements, prioritization and conflict resolution within multi-satellite systems.
Different cost functions are developed then to align with mission-specific constraints, balancing also infrastructure costs.
To define the potential ground station sites, different concerns are needed, emphasizing peculiar infrastructure, regulatory, but also geopolitical limitations. Basic infrastructures needed for the ground station functioning, such as electricity, high-speed internet connectivity and security. Furthermore, the complexity to obtain authorizations for telecommunication by the national entities and the related costs is considered. Moreover, a lower risk of ground station operation associated with the political stability of the country is desired.
In order to provide a boundary to the problem, mimicking a resource-constraint scenario, cost caps for both CAPEX and OPEX are considered, ensuring financially sustainable ground segment development. Thus, the total infrastructure’s cost of ground segment is one of the selection criteria for the optimal solution
To illustrate the practical applications of the proposed framework, 3 case studies are detailed in the paper: Single Satellite SAR Mission: Operating at a low duty cycle; Scientific Formation Flight: Addressing operational constraints in no-transmission areas for a formation of two satellites; and Walker Constellation: Highlighting scheduling intricacies for a densely packed orbital configuration.
These case studies underscore the adaptability of our models across mission types and operational scenarios.
This paper provides a comprehensive approach to addressing the challenges of CubeSat mission design, from ground station selection to advanced scheduling optimization. By integrating mission requirements fulfillment, infrastructural, and economic considerations, we aim to deliver useful insights for efficient and optimal ground segment and operations design.