Space exploration is no longer a prerogative of national space agencies, it is becoming more commercialized, with U.S. and international companies working together on key programs like NASA Artemis, commercial space stations, and advances in space transportation (mainly to and from LEO). This new form of collaboration also poses new challenges when setting up data networks and avionics:
Safety and security: Humans and precious payloads need to be protected during travel, but also during their stay in space. This requires reliable solutions, qualifiable to international standards to ensure compatibility and interoperability.
Future-proofing systems: ”Orbital assets” like the Lunar Gateway that operate in space for twenty or thirty years need to not only be reliable, but also ready for expansion or modification, i.e. modular and scalable. System upgradability needs to be ensured by providing enough bandwidth in the network to add functionalities or seamlessly integrate new systems.TTTech Aerospace has been working on safe, reliable embedded networking and computing platform solutions for more than 25 years, leveraging its cross-industry technology expertise. This provides the basis for a space product portfolio that can meet the needs of current and future space programs says Bob Richards, Vice President Space at TTTech North America:
TTTech is the innovator of Deterministic Ethernet and a driving force behind the SAE AS6802 Time-Triggered Ethernet standards that are used for NASA Artemis and other international space programs. We have also worked on the European ECSS-E-ST-50-16C Time-Triggered Ethernet engineering standard for space applications, which puts us at the center of technology development. Our solutions are based on these international standards including the International Avionics System Interoperability Standards (IASIS) and thus fully interoperable and compatible across a wide range of programs and applications.”
What do NASA Orion, the Lunar Gateway, and Ariane 6 have in common?
A reliable system is composed of many components and sub-systems from different suppliers and sub-suppliers. That is why system integrators select networks built to international standards to ensure interoperability and seamless integration within the data network.
NASA’s Orion spacecraft, the Lunar Gateway, and the European launcher Ariane 6 are three active programs that unite space agencies and commercial companies from different countries and that are using mixed-criticality data networks. TTEthernet, a commercial implementation of Deterministic Ethernet is the basis of these data networks. It ensures the guaranteed real-time transmission of critical data and non-critical data within the network. The benefits are clear:
Deterministic networks are built to guarantee data transmission, which is especially important for critical command and control data, thus increasing the safety of the overall system.
Reduced system complexity, simplification of avionics and software: Data of different criticality levels can be transferred on the same network and physical medium (e.g., cable). This makes it easier and faster to create compact electronic systems, even when incorporating redundancy requirements.
Reduction in lifecycle costs: Complexity reduction and simplification play a part in reducing cost, as do easier integration and reconfiguration of system and software during the system’s lifetime.
Scalability and modularity: TTEthernet includes three different traffic classes – standard Ethernet (acc. to IEEE 802.3), rate-constrained traffic (acc. to ARINC 664 part 7), and Time-Triggered Ethernet (acc. to SAE AS6802 and ECSS-E-ST-16C) with high data transfer rates up to 1 Gbit/s. This allows the transfer of more data overall – be it command, control, payload or video data, but also allows for adding further applications or modules in the future.Mixed-criticality data networks ensure reliable, secure connectivity and enable future expansion of the network by adding new modules, sub-systems, or functionalities. (Image: TTTech)Successful implementations of TTEthernet
Bob Richards explains the range of TTTech Aerospace solutions and their applications: “TTTech Aerospace, offers products, components and box-level solutions for avionics and data networks used in human space flight (e.g., spacecraft, space station modules, and landers), space transportation (e.g., launch vehicles), and orbital infrastructure in LEO. We have been selected for a range of programs by NASA, ESA, and their commercial partners and we are proud to see that our solutions have already successfully completed their first space missions.”
NASA Orion: The first flight of a TTEthernet-based data network was in 2014, on Orion’s first test flight, the second in 2022, when Orion completed its first uncrewed mission around the Moon. TTTech Aerospace provides TTEthernet Switch and End System products for Orion and the European Service Module’s avionics backbone network. The avionics consist of a wide variety of standard and complex electronics assembled into various independent systems, each responsible for performing specific safety-critical functions. All these independent avionics sub-systems are connected to the deterministic high-performance TTEthernet network.
Ariane 6: In July 2024, the new European launch vehicle generation successfully completed its first flight. TTTech Aerospace provided radiation-hardened COTS components for the avionics networks that are considered one of the innovations of this program. The main selection criteria for these products were the reduction of software costs, higher bandwidths, and modularity. Launch vehicles only need around 100 Mbit/s for control traffic, telemetry, and video streams, but TTEthernet offers speeds up 1 Gbit/s per port and thus allows for network expansion and the introduction of new functions in the future without increasing network complexity. Modularity also played a key role in that there was no need for different network setups for Ariane 62 and Ariane 64, and the network could in future be expanded for new use cases like human space flight or with additional sub-systems without impacting the reliability of the digital backbone and the avionics system.
TTTech Aerospace has been involved in the Ariane 6 program from the initial stages, as part of a research activity funded by the European Space Agency (ESA), focusing on making communication and data transmission in the launcher safe and efficient: “We are proud to ensure fail-safe data communication in the launch vehicle with our products that are integrated into more than 50 avionics units. These sensors and electronic control systems exchange data with the control computer via the data network in Ariane 6 to operate safety-critical functions such as computing, power distribution or thrust vector actuation. We also contributed to Ariane 6 with firmware development and qualification as well as integration support,“ says Christian Fidi, General Manager, TTTech Aerospace.
Integrating a TTEthernet-based sub-system in the Ariane 6 avionics network: A practical example for extending the network and adding new functionality is the collaboration of TTTech Aerospace and Réaltra Space Systems Engineering. Together, they are developing a solution to integrate deterministic data transmission directly into the onboard camera system. The on-board cameras were already used for Ariane 6’s first flight but will for future missions be integrated into the launcher’s data network. At the core of this unit will be a compact, light-weight switch board capable of interfacing directly with the network, avoiding the need for an additional avionics unit (data bridge). It will also be suited for use in other space transportation applications.
Lunar Gateway – the new, international space hub: The International Avionics System Interoperability Standards” (IASIS) for deep space avionics applications baseline Time-Triggered Ethernet networking technology for this program, ensuring that all products and components from the commercial and space agency partners involved can be easily integrated into one common data network.
“TTTech Aerospace has been working closely with U.S. and European primes on the critical deterministic communication system for their modules for NASA’s Lunar Gateway. It is based on TTEthernet and thus open international standards that ensure seamless interoperability between the modules, visiting spacecraft, as well as landers and other vehicles,” explains Bob Richards.
The avionics backbone network on the Lunar Gateway will provide reliable high-speed data communication with built-in dual fault tolerance to increase the safety level and achieve a fail-operational system. TTTech Aerospace works with its partner Beyond Gravity Austria on the COTS products and box-level systems for Northrop Grumman’s Habitation and Logistics Outpost (HALO) and Maxar Technologies’ Power and Propulsion Element (PPE). The same type of system will also be used by Thales Alenia Space in the European contribution to the Gateway, the Lunar I-Hab and Lunar View.
However, these programs are not the only ones that TTTech Aerospace is involved in says Christian Fidi: “We are working with several international companies on new space programs, including lunar vehicles and landers. We see that there is a definite interest in deterministic, mixed-criticality networks – not just because they have proven their worth and can be produced with lead times almost as short as COTS, but also because of their benefits. Security, reliability, and modularity are key factors in every space program, and they are also at the core of TTTech Aerospace’s offering.”
Mixed-criticality digital backbone
Traditionally, spacecraft have used strictly separate data buses for control purposes, for their payloads and often for telemetry data, too. Now that even the payloads are mainly digital, engineers can build spacecraft with a single digital backbone to handle all types of data which reduces complexity and cost. This is driven by several factors. Firstly, robust electronics have become both more compact and more powerful. Secondly, Ethernet, which is widely used on Earth, can be utilized at speeds of 1 Gbit/s or more as radiation-tolerant transceivers have become available. Thirdly, the addition of determinism and redundancy management that, for example, TTEthernet provides safely and securely, prevents interference between any of the data. Finally, as the re-use of avionics systems and in particular of the ever more expensive flight software becomes a differentiating factor, so does a digital backbone which allows upgrading and extensions with limited requalification efforts. Complex spacecraft like multi-stage launch vehicles and space habitats benefit the most of course, but the adoption of Ethernet-based digital backbones in most space applications is inevitable – as are higher computing performance and increasing data rates.
TTTech has been involved in standardization efforts for deterministic data buses and networks for more than two decades. Its know-how and expertise with deterministic networking allow TTTech Aerospace to provide customers with the best solutions for their project – from the design phase, to testing, setup and implementation, to flight. TTTech Aerospace provides a portfolio that covers every step of the process and its dedicated software and systems engineering experts at its headquarters in Europe and in its North American offices support customers throughout their programs.