CSO-3 optical Earth-observation satellite successfully launched

March 6th, 2025

The CSO-3 military observation satellite has been successfully launched by Arianespace atop an Ariane 6 from Europe’s spaceport in French Guiana. Carrying a very-high resolution optical instrument built by Thales Alenia Space, the joint venture between Thales (67%) and Leonardo (33%), the satellite was developed by prime contractor Airbus Defence & Space for the French defense procurement agency DGA on behalf of the French Air and Space Force’s Space Command, with delegated oversight from the French space agency CNES.

The third and last component in the CSO system for France’s MUSIS* military program, CSO-3 will provide increased coverage and revisit capabilities to enable more effective conduct of military operations and faster crisis response.

Designed to the most stringent intelligence and defense requirements, CSO-3 is equipped with a cutting edge instrument developed by Thales Alenia Space. This instrument is the core of the mission, affording exceptional resolution and detail of Earth’s surface. Its unrivaled performance enables it to acquire imagery at extremely high resolution, even in low-light conditions and at night thanks to its infrared capabilities. Its advanced technologies include latest-generation optical systems and ultra-sensitive sensors. 

Like for the previous Helios 1, Helios 2 and Pleiades satellites, Thales Alenia Space designed strategic equipment for the CSO system, including the solar arrays, very-high-throughput image telemetry systems, and encryption/decryption modules to ensure data security and confidentiality. The company also supplied the system's telemetry, tracking and control transponders.

“The launch of CSO-3 is a major milestone for French sovereignty in space, both in terms of launch capabilities and satellite technology,” said Hervé Derrey, Thales Alenia Space CEO. “With the completion of this system, France is leading the way in optical space reconnaissance. The CSO system’s exceptional performance is based in particular on the optical instrument built by the teams at Thales Alenia Space and our industry partners. These unique skills in Europe are strategically important and demonstrate our ability to meet the new challenges facing French and European sovereignty.”