SpaceX Successfully Launches Sentinel-6B to Monitor Sea Levels

SpaceX successfully launched the Sentinel-6B ocean monitoring satellite early on November 17, 2025, as part of a collaborative effort between NASA and the European Space Agency. The satellite is the second in a series aimed at tracking long-term changes in sea levels, a critical indicator of climate change. The mission took off from the Vandenberg Space Force Base in California at 12:21 a.m. EST atop a Falcon 9 rocket.

The first satellite in this series, known as Sentinel-6 and named after NASA climate researcher Michael Freilich, was launched in November 2020. Both satellites are equipped with advanced cloud-penetrating radar that measures sea levels with an accuracy of about one inch. By analyzing the time it takes for radar beams to bounce back from the ocean, the Sentinel-6 satellites can also provide data on wave height and wind speeds.

This project builds upon earlier missions dating back to the early 1990s, which have created a continuous record of sea level data. Such data has consistently shown that sea levels are rising, a trend widely attributed to global warming resulting from human industrial activities.

In a pre-launch briefing, NASA officials opted not to directly reference “climate change” or “global warming,” reflecting recent governmental policies aimed at reducing the emphasis on these terms in climate research. Karen St. Germain, director of NASA’s Earth Science Division, instead highlighted the practical applications of the data collected by Sentinel-6B.

“Sentinel 6B is the latest in a line of missions stretching over three decades, keeping an uninterrupted watch over our planet’s sea surface height,” St. Germain stated. She emphasized how the data supports navigation, search and rescue operations, and industries such as commercial fishing and shipping. Furthermore, these measurements form the foundation for flood predictions related to coastal infrastructure, real estate, and energy sites along shorelines.

In addition to monitoring sea levels, Sentinel-6B is designed to measure temperature and humidity in the lower atmosphere and the stratosphere. An instrument on board will assess atmospheric effects on signals from navigation satellites.

The launch of Sentinel-6B proceeded without any issues. After liftoff, the Falcon 9 rocket’s first stage separated and returned to a landing pad at the launch site. The upper stage executed two engine firings before deploying the 2,600-pound satellite into an orbit approximately 830 miles above Earth, tilted 66 degrees to the equator. This orbital path enables the satellite to cover 90 percent of the world’s oceans.

As the satellite completes an orbit every 112 minutes, it will provide vital data to help researchers understand and predict coastal erosion and the encroachment of saltwater into inland water supplies vital for agriculture and drinking.

The development of the Sentinel-6 satellites is a joint effort involving NASA, the European Space Agency, the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), and the National Oceanic and Atmospheric Administration (NOAA). The total cost for both Sentinel-6 satellites is approximately $1 billion, with NASA contributing about $500 million and European partners providing a similar amount.

As the global community grapples with the implications of rising sea levels, the data generated by Sentinel-6B promises to play a crucial role in understanding the ongoing changes to our planet’s environment.