Syracuse-4B: Advanced French Military Communications Satellite

The Syracuse IV program was launched in 2018 by the French Ministry of Defense to develop a new-generation constellation of military communications satellites to succeed the Syracuse III system. The program initially included Syracuse 4A and 4B, with a third satellite, Syracuse 4C, planned for later. The program’s total cost was estimated at €3.6 billion, with surplus capacity intended for use by allied armed and security forces across Europe and beyond.

Advanced Technology and Capabilities

Weighing approximately 3,850 kg, Syracuse 4A became Europe’s first electrically powered military satellite. It utilizes plasma-based electric propulsion, marking a major technological breakthrough for the European space industry. This propulsion method, developed through French expertise, significantly reduces the need for onboard fuel, allowing for a larger communications payload and extended service life.

Both Syracuse 4A and Syracuse 4B are equipped with high-throughput X-band and Ka-band transponders, offering data rates between 3 to 4 Gbps—three times higher than those provided by Syracuse 3A and 3B. These satellites are also built with enhanced cybersecurity, resistance to electromagnetic pulses (EMPs), and protection against jamming. Additional features include environmental monitoring tools and the ability to perform orbital maneuvers in response to potential threats.

Launch Timeline

• Syracuse 4A was launched on October 24, 2021, aboard an Arianespace’ Ariane 5 ECA rocket from the Guiana Space Centre.
• Syracuse 4B launched on July 5, 2023, marking the final flight of the Ariane 5 rocket.
• The third satellite, Syracuse 4C, was originally scheduled for launch by 2025.

Program Adjustments and Future Plans

In April 2023, the French government announced the cancellation of Syracuse 4C, citing that the first two satellites were sufficient to meet operational requirements. The funds initially allocated for Syracuse 4C were redirected to support the development of the IRIS² European secure satellite internet constellation.

Looking ahead, the French Armed Forces will initiate development of the Syracuse V system under the 2024–2030 French Military Planning Law. This next-generation satellite constellation will be designed to replace Syracuse 4A and 4B after 2035, ensuring France maintains sovereign and secure military communications well into the future.