Sentinel-3B

Sentinel-3B carries four main instruments: the Ocean and Land Colour Instrument (OLCI), the Sea and Land Surface Temperature Radiometer (SLSTR), the Synthetic Aperture Radar Altimeter (SRAL), and the Microwave Radiometer (MWR). These instruments work together to measure ocean color, sea surface temperature, sea surface height, and ice surface topography with high precision. The satellite also carries a Precise Orbit Determination system using GPS and laser retroreflector.

Sentinel-3B was launched on April 25, 2018, aboard a Rockot launcher from the Plesetsk Cosmodrome in Russia. It joined its twin satellite, Sentinel-3A, which was launched two years earlier in February 2016. The two satellites fly in the same sun-synchronous orbit but are separated by 140 degrees to provide optimal global coverage.

Sentinel-3A and 3B fly in a coordinated constellation 140 degrees apart in the same sun-synchronous orbit, providing a revisit time of less than two days at the equator. Together they measure sea surface topography, sea and land surface temperature, and ocean color with global coverage. This paired configuration ensures continuous monitoring essential for operational oceanography and marine applications within the EU's Copernicus program.

Sentinel-3B's Sea and Land Surface Temperature Radiometer (SLSTR) measures sea surface temperature with accuracy better than 0.3 Kelvin, using dual-view capability that looks both nadir and forward. The instrument operates in visible, near-infrared, and thermal infrared channels, enabling temperature measurements even in partially cloudy conditions. These measurements are critical for weather forecasting, climate monitoring, and tracking phenomena like El Niño.