SpaceX successfully launched the Sentinel-6B ocean-mapping satellite from Vandenberg Space Force Base in California early Monday, marking a major step in global efforts to track rising sea levels.The satellite lifted off aboard a Falcon 9 rocket, with NASA spokesman Derrol Nail announcing, "Sentinel-6B rising, extending nearly four decades of the precise sea-level record from space."Sentinel-6B, part of the EU's Copernicus Earth-observation program, will measure sea-surface height with high accuracy, continuing the work of its predecessor, Sentinel-6 Michael Freilich, launched in 2020. The mission is considered the global reference standard for monitoring sea-level rise -- a key indicator of climate change.According to the European Space Agency (ESA), global sea levels have risen by nearly 10 centimeters over the past 25 years, making precise long-term monitoring an international priority.The satellite carries an ESA-developed radar altimeter and a NASA microwave radiometer that measures atmospheric water vapor to improve the accuracy of sea-level readings.SpaceX confirmed that the Falcon 9's upper stage deployed Sentinel-6B about 57 minutes after launch, while the rocket's first stage returned to Vandenberg for a successful landing -- its third mission to date.