Quick Read
- SpaceX launched NASA’s Sentinel-6B satellite on November 16, 2025, from Vandenberg Space Force Base.
- Sentinel-6B will use radar to map ocean topography and collect high-resolution atmospheric temperature profiles.
- The Falcon 9 booster supporting this mission had flown twice before and was successfully recovered post-launch.
- Residents of parts of California experienced sonic booms during the launch and landing.
- Sentinel-6B continues the mission of Sentinel-6 Michael Freilich, which was launched five years earlier.
SpaceX and NASA Join Forces for Sentinel-6B Mission
On November 16, 2025, as night settled over California’s central coast, SpaceX prepared to send a new sentinel into the sky. The Sentinel-6B satellite, a collaboration between NASA and its international partners, represents a fresh chapter in Earth’s ongoing story of climate observation. With liftoff targeted for 9:21 p.m. Pacific Time from Vandenberg Space Force Base, the Falcon 9 rocket stood ready—its engines primed, its payload secure, its mission clear.
For those following the event, anticipation began an hour before launch, with a live webcast on NASA+. The Falcon 9 booster chosen for this mission was no stranger to space; it had already supported two previous Starlink launches. Now, it was set for its third flight, aiming to deliver Sentinel-6B into orbit and then return for a precision landing at Landing Zone 4, just a few miles from its launch pad.
Tracking the Launch: A Precise Countdown
Every launch is a ballet of timing and technology. At T-minus 38 minutes, the SpaceX Launch Director gave the go-ahead to start loading propellant. Rocket-grade kerosene and liquid oxygen began flowing into the Falcon 9’s tanks, feeding the engines that would soon defy gravity. Sixteen minutes before launch, the second stage was loaded with its own supply of liquid oxygen. Seven minutes to liftoff, engineers chilled the engines—a final step before the fiery climb ahead.
At T-minus one minute, computers took command, checking systems and pressurizing tanks. A final nod from the Launch Director, and the countdown continued. At zero, the engines roared to life, propelling Falcon 9 and Sentinel-6B skyward.
Within seconds, the rocket faced Max Q—the moment of peak mechanical stress. Just over two minutes in, the first stage engines shut down, and the rocket split into two. The second stage ignited, pushing the payload higher, while the first stage began maneuvers for its return to Earth. The fairing deployed, exposing Sentinel-6B to space.
Sentinel-6B: Eyes on the Ocean, Ears on the Atmosphere
Sentinel-6B is more than just a satellite; it’s an extension of humanity’s curiosity about the planet we call home. Its mission: to bounce radar signals off the ocean surface, measuring the topography of Earth’s seas with unprecedented continuity and precision. By collecting high-resolution vertical profiles of atmospheric temperature, Sentinel-6B will help scientists track changes in the climate and improve weather prediction models.
This satellite picks up where Sentinel-6 Michael Freilich left off. Launched by SpaceX in November 2020, the Michael Freilich has been a twin sibling orbiting for five years, offering critical data for oceanographers, climatologists, and meteorologists alike. Sentinel-6B is set to continue and enhance this legacy, ensuring that scientists—and policymakers—have the information they need to respond to our planet’s changing rhythms.
A Launch Heard Across California
While the focus was on the science above, the impact was felt on the ground as well. Residents in Santa Barbara, San Luis Obispo, and Ventura counties were advised they might hear one or more sonic booms as the Falcon 9 returned for landing. Depending on weather and local conditions, the sounds ranged from a distant rumble to a brief, sharp crack—a reminder that spaceflight is not just a technical feat, but a local event as well.
After separation, the first stage executed a series of burns—boostback, entry, and landing—culminating in a controlled descent onto Landing Zone 4. Meanwhile, the second stage carried Sentinel-6B onward, with two engine burns and careful deployment of the satellite nearly an hour after liftoff.
Global Implications: Why Sentinel-6B Matters
What makes Sentinel-6B truly significant is its role in monitoring global sea level rise and atmospheric changes. These measurements are central to understanding how our planet’s climate is evolving—and, by extension, how societies must adapt. Ocean topography data helps forecast storms, manage fisheries, and protect coastal infrastructure. High-resolution atmospheric profiles aid in refining climate models and predicting extreme weather.
SpaceX’s reusable rocket technology adds another layer of innovation. By recovering boosters for repeated use, the cost and environmental impact of launches decrease, making missions like Sentinel-6B more sustainable in the long run. This synergy between cutting-edge engineering and scientific ambition underscores the broader narrative: spaceflight is no longer just about reaching orbit, but about building a more informed, resilient world.
As Sentinel-6B begins its journey, it joins a growing constellation of satellites tasked with observing, measuring, and ultimately helping us understand our dynamic planet. The data it gathers will be studied for years to come, influencing everything from local weather forecasts to international climate policy.
Sentinel-6B’s launch by SpaceX is a milestone in Earth observation, blending technical precision with scientific purpose. By extending the legacy of its predecessor, it promises a clearer, more complete picture of our oceans and atmosphere—information that’s increasingly vital in an era of rapid environmental change.