Copernicus Sentinel-6B was launched on 17 November 2025, ready to continue a decades-long mission to track the height of the planet’s seas – a key measure of climate change. The satellite was carried into orbit on a Falcon 9 rocket from the Vandenberg Space Force Base in California, US.

Sentinel-6B follows in the footsteps of its predecessor, Sentinel-6 Michael Freilich, which was launched in 2020. The mission is the reference radar altimetry mission that continues the vital record of sea-surface height measurements until at least 2030.

Copernicus Sentinel-6 has become the gold standard reference mission to monitor and record sea-level rise. The mission’s main instrument is the Poseidon-4 dual-frequency (C-band and Ku-band) radar altimeter. Developed by ESA, the altimeter measures sea-surface height. It also captures the height of ‘significant’ waves as well as wind speed to support operational oceanography.