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Image shows the Earth in the background and a metallic second stage of SpaceX separating from NASA's Sentinel-6B spacecraft

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Sentinel-6B Science

Sentinel-6B is the latest satellite in a series of spacecraft that NASA and its partners have used to measure sea levels since 1992. Their data has helped meteorologists improve hurricane forecasts, managers protect infrastructure, and coastal communities plan. 

Data from Sentinel-6B will continue a decades-long record of sea surface height, helping to improve coastal planning, protect critical infrastructure, and advance weather forecasts.

After launch, Sentinel-6B will begin the process of data cross-calibration with its predecessor, Sentinel-6 Michael Freilich, to provide essential information about Earth’s ocean. 

The twin satellites, Sentinel-6B  and Sentinel-6 Michael Freilich, constitute the Sentinel-6/Jason-CS (Continuity of Service) mission, a collaboration between NASA, ESA (European Space Agency), EUMETSAT (European Organisation for the Exploitation of Meteorological Satellites), and the National Oceanic and Atmospheric Administration (NOAA). The European Commission contributed funding support while France’s space agency CNES (Centre National d’Études Spatiales) provided technical expertise.

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‘6 Things to Know About Sentinel-6B’

Measuring sea surface height for 90% of Earth’s ocean, the mission will deliver critical sea level and ocean data to protect coastal infrastructure, improve weather forecasting, and support national defense interests and commercial activities at sea.

Artist’s concept illustration showing a gold-colored satellite at the center of the image with a black, star-filled background behind it. The Earth’s surface, blue and cloud-covered, fills the lower-left corner of the frame, from the center-left edge to the bottom-center of the frame. On the surface directly below the satellite, a spiral hurricane is visible. The satellite is shaped like a house with a peaked roof, viewed from an angle, with the pentagon-shaped front and left side side both facing the viewer. The satellite’s solar arrays form what looks like a very wide peaked roof atop the satellite, extending far beyond the side walls. Underneath the satellite, a silver cone-shaped instrument points down toward Earth. Another instrument on the front side, shaped like a silver frying pan, also faces toward Earth. In the upper right corner of the image is bright lens flare from the Sun, out of frame.

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Spacecraft

The Sentinel-6B spacecraft consists of a main satellite bus, which holds three science instruments contributed by NASA’s Jet Propulsion Laboratory in Southern California. As part of this U.S.-European mission, NASA is also contributing launch services, ground systems supporting operation of the NASA science instruments, the science data processors for two of these instruments, and support for the international ocean surface topography community. 

Satellite bus: The Sentinel-6B spacecraft was built by Airbus Defence and Space in 

Friedrichshafen, Germany. It is 19.1 feet (5.82 meters) long (including the AMR-C instrument), 7.74 feet (2.36 meters) high (including the communications antennas), and 14.28 feet (4.33 meters) wide (with solar panels deployed).

Mass: 2,623 pounds (1,190 kilograms), including onboard propellant at launch.

Power: Two fixed solar arrays, plus two deployable solar panels.

Batteries: 200-amp-hour battery consisting of 1,152 lithium-ion cells.

Instruments: Poseidon-4 synthetic aperture radar (SAR) Altimeter, Advanced Microwave Radiometer for Climate (AMR-C), Global Navigation Satellite System - Radio Occultation (GNSS-RO), and Precise Orbit Determination (POD) Package (POD).  

Sentinel-6B figure 1
Sentinel-6B contains an array of instruments to continue to measure ocean height and gather other integral information about the global ocean.
NASA/JPL-Caltech

Instruments

Poseidon-4 SAR Altimeter

The scientific heart of the mission, the Poseidon-4 synthetic aperture radar (SAR) altimeter measures the height of seawater by bouncing radar pulses off of Earth’s ocean and precisely timing how long those pulses take to travel back to the spacecraft. The instrument is also used to determine significant wave height and wind speed. 

Advanced Microwave Radiometer for Climate (AMR-C)

Water vapor affects the radar signals from the altimeter instrument, which can make the height of the water it’s measuring appear higher or lower than it actually is. The radiometer measurements of water vapor between the satellite and Earth’s surface are required to correct for this effect.  

Global Navigation Satellite System - Radio Occultation (GNSS-RO)

This instrument measures the physical properties of Earth’s atmosphere, including temperature, pressure, and water vapor content. It does so by detecting the extent to which the planet’s atmosphere refracts the radio signals from global navigation satellites as the spacecraft disappear beyond the limb of Earth.  

Precise Orbit Determination (POD) Package

Precisely determining the position of the Sentinel-6B spacecraft in orbit is of paramount importance when recording extremely small variations in sea level data (on the millimeter scale). To achieve this, Sentinel-6B carries a state-of-the-art precise orbit determination package that works in conjunction with the mission’s science instruments to accurately define its position in space and time.

The four instruments composing this package include the Doppler orbitography and Radiopositioning Integrated by Satellite (DORIS), the laser retroreflector array (LRA), the GNSS-RO, and the Global Navigation Satellite System - Precise Orbit Determination (GNSS-POD).

Featured Story

6 Things to Know From NASA About New US, European Sea Satellite

Data from Sentinel-6B will continue a decades-long record of sea surface height, helping to improve coastal planning, protect critical infrastructure,…

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Observing oceans since 1992

Learn More About Sentinel-6B and Its Predecessors

Visit the Jason-CS/Sentinel-6 program website and learn more about Sentinel-6B and its twin predecessor, Sentinel-6 Michael Freilich, which launched in November 2020 and was named in honor of the late director of NASA’s Earth Science Division.

Visit the program website for Jason-CS/Sentinel-6 — ‘Ocean Surface Topography from Space’
Image shows a fiery ignition of a SpaceX rocket carrying NASA's Sentinel-6B spacecraft.
A SpaceX Falcon 9 rocket carrying the international Sentinel-6B spacecraft lifts off from Space Launch Complex 4 East at Vandenberg Space Force Base in California on Sunday, Nov. 16, 2025. A collaboration between NASA, ESA (European Space Agency), EUMETSAT (European Organisation for the Exploitation of Meteorological Satellites), and the National Oceanic and Atmospheric Administration (NOAA), Sentinel-6B is designed to measure sea levels down to roughly an inch for about 90% of the world’s oceans.
NASA
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