Meet Sentinel‑6B: NASA’s New Eye on the Seas

Sentinel‑6B is poised to become a cornerstone in Earth‑observation — a powerful satellite born from an international collaboration between NASA, ESA (European Space Agency), NOAA, and EUMETSAT. Scheduled to launch in November 2025, its mission is simple in concept but profound in impact: to precisely measure sea-level changes, monitor ocean dynamics, and deliver critical data that supports climate science, coastal planning, and public

Why Sentinel‑6B Matters

Sea level rise is one of the clearest indicators of climate change, but it’s also a major risk factor for coastal communities. Sentinel‑6B will continue the legacy of its twin satellite, Sentinel‑6 Michael Freilich, by providing global sea surface height observations with incredible accuracy — down to mere inches across roughly 90% of Earth’s oceans.

These measurements aren’t just scientific curiosities. They feed into models that forecast flooding, help city planners design resilient infrastructure, and support defense and commercial operations in coastal areas.

Science Under the Hood

Sentinel‑6B carries a suite of instruments built for precision and resilience:

Poseidon‑4 Radar Altimeter: This instrument sends radio pulses down to the ocean surface and measures their return time. By doing so, it can calculate sea height with extreme accuracy.

Advanced Microwave Radiometer for Climate (AMR‑C): This device measures water vapor in the atmosphere, which helps correct the radar altimeter’s readings.

GNSS‑RO (Global Navigation Satellite System – Radio Occultation): By tracking how GPS signals bend through Earth’s atmosphere, Sentinel‑6B can profile temperature, pressure, and moisture.

Precise Orbit Determination Suite: Using GNSS receivers, a laser retroreflector array (LRA), and other systems, the satellite constantly maintains and reports its orbit.

A Mission with Legacy

Sentinel‑6B is part of the Copernicus Sentinel‑6 / Jason‑CS (Continuity of Service) mission. This is not just a one-off project — it’s the latest in a decades-long series of satellites tracking sea-level rise, beginning with TOPEX/Poseidon in the early 1990s and followed by the Jason missions.

By continuing this data record, Sentinel‑6B ensures scientists have the long-term observations needed to understand how oceans respond to climate change over time.

Broader Impacts: Weather, Storms & More

Beyond sea-level monitoring, Sentinel‑6B’s data will feed into atmospheric and weather models. For example, the GNSS-RO instrument helps characterize atmospheric layers — information that improves forecasts for storms, hurricanes, and even the re-entry paths for returning spacecraft.

Improved forecasts mean better preparedness for coastal flooding and storms, helping protect communities and critical infrastructure.

Getting to Orbit

The launch plan is set: Sentinel‑6B is scheduled to lift off no earlier than Nov. 16, 2025, aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in California.

Before launch, the satellite underwent final processing at a clean facility, where engineers performed checks on its solar arrays, conducted functional tests, and prepared it for its mission.

Looking Ahead