Hellas Sat (Greece) and Space Compass (Japan) have executed a Memorandum of Understanding (MoU) to establish a strategic technical and commercial framework for optical inter-satellite connectivity. The collaboration focuses on integrating the forthcoming Hellas Sat 5 geostationary (GEO) satellite with Space Compass’s planned GEO optical data-relay system to enable seamless, cross-operator interoperability.

Strategic Objectives and Infrastructure Integration Inter-Satellite Interoperability:

The partners identify cross-operator optical compatibility as a critical prerequisite for deploying next-generation, high-capacity space communications.

Hellas Sat 5 (HS5) Architecture:

The HS5 satellite is expected to play an important role in advancing space-based optical communications. Currently in the design phase, HS5 will be positioned at 39° East. It is engineered to host the European Space Agency (ESA) HydRON (High Throughput Optical Network) payload. Data Relay Capabilities: The partnership aims to validate ultra-fast laser links and ground connectivity, bridging GEO and Low Earth Orbit (LEO) systems to provide near-real-time data delivery for Earth observation missions.  By integrating the optical payload, HS5 will bridge geostationary and low earth orbit systems, enable seamless optical data relay.

Expanded Ecosystem Collaboration Regulatory & Research Alignment: Space Compass is concurrently working with ESA under a separate Memorandum of Intent to conduct feasibility studies on optical communication interoperability between their respective in-orbit demonstration programs.

Advanced Optical Payload:

In partnership with Thales Alenia Space, Hellas Sat 5 is designed to support capacities reaching the Terabit-per-second scale, a significant leap over current gigabit-scale radio frequency systems. This collaboration reinforces the transition toward a standardized, high-speed optical space network, essential for securing global digital infrastructure throughout the 2030s.

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This project is one of the initiatives of space business brand under NTT Group’s “NTT C89” and SKY Perfect JSAT.

About Space Compass:

Space Compass is a joint venture between NTT, a global Information and Communications Technology (ICT) company, and SKY Perfect JSAT Corporation, Asia’s largest satellite operator. The company was established to develop the Space Integrated Computing Network, a new multi-orbital, optical communication-based independent space infrastructure designed to address social challenges. For more information, please visit: https://space-compass.com/en/

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• SDA’s Role: The Space Development Agency is a major driver, releasing Optical Communication Terminal (OCT) Standards (covering physical & data link layers) to ensure different systems can connect.
• Kepler Network: Demonstrated Optical ISLs between its satellites using SDA-compatible terminals, forming mesh networks for data relay.
• SpaceX Starlink: Added optical links for global coverage and resiliency, testing crosslinks with other partners like York.
• Project Kuiper: Amazon’s project also successfully tested end-to-end optical links for its constellation.
• Collaborative Efforts: Companies like Space Compass, Axelspace, NEC, and ESA are working on R&D for interoperable optical networks. 

• Seamless Networks: Enables complex multi-platform, multi-orbit networks.
• Data Relay: Allows satellites to relay data for others, reducing ground station reliance.
• Standardization: Essential for different companies’ satellites to talk to each other. 

References:

https://www.skyperfectjsat.space/en/news/20251211

https://space-compass.com/en/news/000080.html

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