Sentinel-6B: SpaceX Launches Ocean-mapping Satellite To Orbit

SpaceX launched the Sentinel-6B ocean-monitoring satellite at 0521 UTC, Monday, (Nov. 17) from Space Launch Complex 4E (SLC-4E), Vandenberg Space Force Base, California, marking the 500th orbital mission using a reused Falcon 9 first stage, highlighting the company’s advancements in reusable rocket technology.

The Falcon 9’s first-stage booster, B1097.3, completed its third flight, landing successfully at Landing Zone 4 about nine minutes after liftoff, while the satellite separated from the second stage about 57 minutes later, with the first signal received by European Space Operations Center(ESOC) via the Inuvik ground station at 0654 UTC.

The Sentinel-6B mission, a critical component of the European Copernicus climate program and NASA’s Earth observation efforts, aims to extend over 40 years of continuous sea-level measurement with high-precision data. It's a joint effort led by the European Commission, the European Space Agency (ESA), EUMETSAT, NASA, National Oceanic and Atmospheric Administration(NOAA), and French space agency, CNES, with funding from the European Commission and technical support from CNES.

"Sentinel-6B rising, extending nearly four decades of the precise sea-level record from space," NASA spokesman Derrol Nail said during the agency's launch webcast.

The satellite is designed to operate for 5.5 years after entering service, continuing the legacy of the Jason satellite series. It is the second Sentinel-6 satellite Falcon 9 will launch after delivering the Sentinel-6 Michael Freilich satellite to orbit in November 2020.

Sentinel-6B carries advanced instruments including the POSEIDON4 radar altimeter developed by ESA, Advanced Microwave Radiometer (AMR-C), GNSS POD receiver, DORIS receiver, Laser Reflector Array (LRA), and GNSS Radio Occultation (GNSS-RO) receiver.

During its first year of observations, Sentinel-6B will work with Sentinel 6 Michael Frelich, "enabling greater accuracy with precise cross-calibration between the two instruments," ESA officials wrote about the mission.

Together, the two Sentinel spacecraft will measure sea-surface height with centimeter-level precision over approximately 90% of Earth’s oceans every 10 days, providing critical data for tracking sea-level rise, ocean currents, climate change impacts and improve forecasts of wind and wave conditions.

"Monitoring sea-level rise is high on the global agenda," European Space Agency ESA officials wrote in a Sentinel-6B mission description.

"In the past 25 years, the average height of the world's oceans has risen by almost 10 cm [4 inches], according to data from Copernicus," they added. "The Copernicus Sentinel-6 mission has become the gold standard reference mission to monitor and record this key consequence of climate change."

Data from Sentinel-6B will improve weather forecasts, storm surge predictions, coastal planning, and national defense strategies by providing real-time ocean topography and environmental data.

The satellite’s data will also support NASA’s Artemis lunar missions by aiding in the development of safer reentry procedures for returning astronauts.

SpaceX highlighted the Falcon 9 reuse milestone during Monday's mission in a post on X, as did company president and chief operating officer Gwynne Shotwell.

"Congratulations to the SpaceX team on completing 500 (!!!!) missions with flight-proven rocket boosters. You’ve made the impossible possible with reusable rockets, paving the way to land huge amounts of cargo and lots of people to establish permanent human presence on the moon and beyond with Starship!" Shotwell wrote.

The fully reusable Starship is the biggest and most powerful rocket ever built. SpaceX is developing it to help get humanity to the moon and Mars, among other feats. Starship has launched 11 times to date, but those don't contribute to the 500 count; all of Starship's liftoffs so far have been suborbital test flights.