NASA and its international partners have launched Sentinel-6B, the second in a pair of ocean-monitoring satellites designed to provide high-precision sea-level and atmospheric data to support hurricane forecasting, coastal planning and maritime safety. The spacecraft lifted off aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base at 4:21 p.m. AEDT on 17 November, with first contact confirmed about 90 minutes later at 5:54 p.m. AEDT. NASA reports that all systems are functioning as expected.
Sentinel-6B, roughly the size of a full-size pickup truck, will assume the role of global reference satellite for sea-surface height measurements once its data is cross-calibrated with its predecessor, Sentinel-6 Michael Freilich. The launch continues a radar-altimetry record that has tracked changes in Earth’s oceans since the early 1990s.
The mission is a partnership between NASA, ESA, EUMETSAT and NOAA, and forms part of the European Union’s Copernicus Earth-observation program. NASA’s Jet Propulsion Laboratory supplied several of the spacecraft’s key instruments, including a microwave radiometer and radio-occultation sensors for atmospheric profiling.
Beyond measuring global and local sea-level variations, Sentinel-6B will collect data on wind speeds, wave heights, temperature and humidity. These measurements inform flood-prediction models used across the United States and contribute to decision-making for coastal infrastructure, emergency planning and maritime operations. Variations in sea-surface height also reveal warmer ocean regions, which can drive hurricane intensification and influence hazardous sea conditions for commercial shipping.
Once Sentinel-6B reaches its operational orbit — approximately 1,336 kilometres above Earth — it will fly 30 seconds behind Sentinel-6 Michael Freilich to allow precise data comparison. The older satellite will then be moved to a new orbit, leaving Sentinel-6B as the primary reference mission, circling the planet about 13 times per day.
Mission leaders from NASA and ESA highlighted the importance of long-term sea-level monitoring and the role of international cooperation in delivering climate, environmental and maritime intelligence to governments, defence agencies and commercial sectors worldwide.
