PAGE CONTENTS
Objectives
The goal of ESA STARS is to lay the foundation for extending the Internet into space by investigating how emerging satellite constellations and existing terrestrial networks can converge into a unified, interoperable “network of networks.”
First, the project surveys current space-based networking architectures, including operational satellite constellations, to understand how traffic is routed today and how design choices, such as inter-satellite links and reliance on ground infrastructure, affect performance, scalability, and resilience.
Second, it reviews terrestrial inter-domain routing (IDR) protocols, focusing on their applicability to highly dynamic environments such as space. This includes analysing how protocols like BGP and SCION perform under frequent and predictable topology changes caused by satellite motion, as well as identifying key limitations in convergence behaviour, scalability, and operational complexity.
Third, the project defines a set of representative use cases for space and near-space networking, capturing scenarios that benefit from persistent, global, and high-performance connectivity. These use cases provide concrete requirements for latency, availability, security, and traffic engineering across heterogeneous networks.
Finally, the requirements derived from these use cases are used to evaluate and compare existing IDR approaches, leading to a set of consolidated insights and recommendations. These form the basis for guiding the evolution of IDR towards space-capable architectures, addressing both technical and non-technical aspects, such as interoperability, security, and governance.
Benefits
Unlocking inter-domain routing (IDR) in space enables a fundamental shift from isolated satellite systems to a globally interconnected space–terrestrial Internet, where traffic can move seamlessly across constellations and borders. This transition addresses current inefficiencies, such as routing via ground gateways, and allows data to follow more direct, efficient paths in orbit, improving both performance and resource utilisation.
At its core, the benefit is the creation of a resilient, high-performance global network fabric. By enabling interconnection between multiple operators, IDR introduces path diversity and redundancy, allowing traffic to dynamically reroute across constellations in response to failures or congestion. This significantly strengthens robustness compared to today’s siloed architectures and supports critical scenarios where continuity of service is essential.
From an applications perspective, this capability underpins a wide range of emerging use cases, though their implications can be summarized succinctly:
– It improves global connectivity by extending seamless Internet access to remote and mobile users,
– Enables mission-critical and real-time operations, such as telemedicine and remote control, by ensuring low-latency and stable paths,
– Supports new space-based infrastructure, including orbital data centres and in-space services.
In addition, it provides a resilient fallback layer for terrestrial networks, allowing space systems to act as a backup backbone during major outages.
Finally, the recommendations highlight that these benefits are only achievable with coordinated evolution: adapting mature protocols such as BGP, introducing complementary mechanisms for security and path control, and establishing shared standards, governance models, and neutral interconnection points (IXP) in space.
In summary, properly enabling IDR transforms space networks into a cooperative, scalable infrastructure, delivering better performance, stronger resilience, and entirely new capabilities, while laying the foundation for a truly global Internet that extends beyond Earth.
Features
The study provides insight into routing protocols and future extensions to enable a space-earth network convergence.
Challenges
Current inter-domain routing (IDR) protocols have evolved over decades to handle random failures and relatively stable topologies in terrestrial networks, where links and peering relationships remain largely unchanged over long periods. In contrast, space-based constellations introduce inherently dynamic network conditions, where topology changes are frequent, predictable and continuous, due to orbital motion. As highlighted in the STARS study, this shift places fundamental strain on existing protocols, which must now cope with frequent link churn, rapid reconvergence requirements and scalability challenges in highly dynamic environments.
Beyond dynamics, space networking introduces new classes of challenges that are not present in terrestrial systems. Fragmentation of architectures across independent constellations, lack of interoperability standards, and the absence of established governance models complicate interconnection between operators. At the same time, limited ground-station capacity and the desire to keep traffic in space create strong incentives for direct inter-constellation routing, further increasing the need for robust and adaptable IDR mechanisms.
Additionally, global coverage means that any constellation may act as a transit network, creating a path selection and trust challenge. Operators and users must be able to control which paths traffic traverses, particularly for sensitive or policy-constrained data. This makes policy enforcement, path control, and trust mechanisms central requirements for space-based IDR, alongside traditional concerns such as convergence and scalability.
Together, these factors define the core challenge: adapting existing IDR protocols to operate reliably in a highly dynamic, multi-operator, and policy-sensitive space environment, while maintaining interoperability with the terrestrial Internet.
Plan
The project is split into 4 milestones:
1. Space constellation study.
2. Terrestrial routing protocols study.
3. Use-cases for space-based networks.
4. Final report and recommendation for space-based inter-domain routing protocols.
Current Status
The project has delivered D1 (space constellations study), the terrestrial routing protocol study (D2), the D3 deliverable of space-network use-cases and the final recommendation D4. The project was concluded in summer 2026 with an additional executive summary that provides an overview of all reports (D1-D4).
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