Sentinel-6B Satellite Launched for Sea-Level Monitoring

The Sentinel-6B satellite lifted off aboard a SpaceX Falcon 9 rocket from Launch Complex 4 East at Vandenberg Space Force Base in central California at 9:21 p.m. PST on November 16, 2025 | Photo: NASA/Carla Thomas

The Airbus-built Sentinel-6B ocean-monitoring satellite has successfully launched from Vandenberg Space Force Base in California on Sunday. The satellite, developed under the European Union’s Copernicus earth-observation programme, is the second of two identical spacecraft designed to continue global sea-surface height measurements through at least 2030. Its predecessor, Sentinel-6 Michael Freilich, launched in 2020.

For its first year in orbit, Sentinel-6B will fly in close formation with Sentinel-6 Michael Freilich to cross-calibrate instruments and ensure continuity in data accuracy. The mission is intended to provide long-term measurements of sea-level rise, ocean circulation, and atmospheric temperature and humidity.

Alain Fauré, Head of Space Systems at Airbus, said, “The launch of this satellite will play a crucial role in advancing ongoing research while building upon the significant progress already achieved. Accurate sea-level measurements are invaluable data to help protect coastal communities and guide global climate action.”

Sentinel-6B measures sea-surface height by transmitting radar pulses and timing their return from the ocean surface, producing accuracy within a few centimetres. It will contribute to long-term datasets used for climate modelling, coastal-impact forecasting and marine weather prediction. The satellite follows a non-Sun-synchronous orbit at 1,336 kilometres with a 66-degree inclination, enabling measurements across different times of day.

Airbus-built Sentinel-6B satellite before departing to launch site | Photo: Airbus

The satellite launched aboard a SpaceX Falcon 9 rocket at 9:21 p.m. PST on 16 November. NASA confirmed contact with the spacecraft approximately 90 minutes later. Nicky Fox, associate administrator for NASA’s Science Mission Directorate, said, “Understanding tidal patterns down to the inch is critical in protecting how we use our oceans every day on Earth. Sentinel-6B will build upon the legacy of Sentinel-6 Michael Freilich by making sea level measurements that improve forecasts used by communities, businesses, and operations across the country. It also will support a safer reentry for our astronauts returning home, including crew from Artemis Moon missions.”

Simonetta Cheli, Director of ESA’s Earth Observation Programmes, said, “Collaboration between partners is key to a mission such as Sentinel-6, and my thanks go to everyone involved in developing, launching, and operating this exceptional satellite, which follows in the footsteps of the first Sentinel-6, Michael Freilich.”

The mission is a joint initiative between the European Space Agency (ESA), NASA, EUMETSAT, NOAA and CNES, under the broader Copernicus programme. Karen St. Germain, Director of NASA’s Earth Science Division, said, “Sentinel-6B will collect ocean surface observations that will inform decisions critical to coastal communities, commercial shipping and fishing, national defense, and emergency preparedness and response.”

Sentinel-6B will eventually become the official reference satellite for sea-level measurements. Dave Gallagher, Director of NASA’s Jet Propulsion Laboratory, said: “The satellite’s powerful suite of instruments will measure about 90% of Earth’s oceans down to fractions of an inch — continuing to add to a vital dataset that America and a growing global community depend on.”