The Copernicus Sentinel‑1 mission, which delivers radar imaging for Europe’s Earth observation programme, has welcomed a new member into orbit with the successful launch of Sentinel‑1D. This satellite marks the completion of the first generation of the pioneering Sentinel‑1 constellation.

Sentinel‑1D lifted off on 4 November 2025 at 22:02 CET (18:02 local time) aboard an Ariane 6 rocket from Europe’s Spaceport in French Guiana, operated under the European Space Agency’s oversight. The heavy‑lift launcher, operating under flight VA265 with two boosters, placed the spacecraft into its planned orbit just 34 minutes after liftoff. A signal confirming the satellite’s health was received at 23:22 CET, securing another milestone for Europe’s autonomous access to space.

The Sentinel‑1 mission was originally designed as a two‑satellite system, each carrying advanced radar instruments capable of delivering imagery of Earth’s surface regardless of weather or daylight. These data streams are vital for disaster response teams, environmental monitoring agencies, maritime authorities, and climate researchers who rely on frequent updates to guide their work.

With Sentinel‑1D now in orbit, the constellation strengthens its coverage. The new satellite will operate alongside Sentinel‑1C, flying 180 degrees apart in the same orbit to maximize global data delivery. Together, they will replace Sentinel‑1A, which has served for more than 11 years, beyond its expected lifetime. Sentinel‑1B, meanwhile, was retired in August 2022 after a technical anomaly prevented further data acquisition.

Both Sentinel‑1C and Sentinel‑1D are equipped with C‑band synthetic aperture radar (SAR) instruments that capture high‑resolution images of Earth’s surface. They also carry Automatic Identification System (AIS) receivers, enhancing maritime surveillance by detecting and tracking ships. Once fully commissioned, Sentinel‑1D will provide more frequent AIS observations, including details on ship identity, location, and movement, enabling precise monitoring of maritime activity.

In addition, the satellites are compatible with Europe’s Galileo navigation system and other global positioning networks, ensuring accurate orbit determination and data reliability. This launch is a significant milestone for ESA, as it completes the Copernicus Sentinel‑1 mission. With Sentinel‑1D joining the fleet, the Copernicus programme secures continuity of radar services, reinforcing Europe’s ability to monitor environmental change, respond to emergencies, and safeguard maritime security.