Evolution of Interplanetary Internet: Technology Demonstrations for Space Network Operations

As humanity ventures further into space, the limitations of traditional point-to-point communication systems become increasingly evident. The vast distances between celestial bodies introduce significant propagation delays, while space dynamics contribute to frequent link disruptions due to occlusion and asymmetric data rates. These challenges underscore the need for a robust, scalable, and flexible communication framework to support the future interplanetary internet. Delay-Tolerant Networking (DTN) is a critical technology that can address these challenges. It is designed to handle the long propagation delays and intermittent connectivity that characterize interplanetary communications. By transforming isolated, point-to-point links into a resilient and interoperable network, DTN paves the way for a Solar System Internet that can enable continuous and automated communication across vast distances in space.

This paper comprehensively surveys the most relevant demonstrations of DTN technologies in the space and aeronautical communication domains. These demonstrations, including but not limited to the following experiments, are a testament to DTN’s advancements.

DTN has proven its robustness in various environments, from its first space demonstration with the DMC-1G constellation to deep space validation in the DINET experiments. Projects like ESA’s Multi-Purpose End-To-End Robotic Operation Network (METERON) and NASA’s Lunar Laser Communications Demonstration (LLCD) further showcased DTN’s capability to control remote systems and ensure reliable data transmission over optical links. The International Space Station (ISS) has also served as a critical platform for DTN experiments, including successful video downlinks over disrupted links and internetworking with the Laser Communication Relay Demonstration (LCRD) and NASA Glenn Research Center (GRC) research aircraft. Collaborative efforts like the NASA/JAXA DRTS testing and ESA’s OPS-SAT CubeSat mission have continued to push the boundaries, demonstrating DTN’s effectiveness in actual space operations. Additionally, a CubeSat experiment (TechEd Sat-11, led by NASA GRC and Ames Research Center) leveraging commercial networks and ground tests conducted in the DTN Engineering Network further exemplifies DTN’s growing role in modern space communications.

This paper introduces a novel taxonomy that identifies gaps, challenges, and future opportunities in DTN evaluations for space by providing a comprehensive overview and comparison of these DTN demonstrations. These insights underscore DTN’s pivotal role in advancing space network operations and highlight the critical steps required to realize a fully operational interplanetary internet. As we move closer to this vision, understanding and addressing these gaps will be essential in shaping the future of space communications and ensuring the seamless integration of DTN across all levels of space exploration.