Sentinel-6B is an upcoming satellite designed to measure sea surface height across most of the world’s oceans. The data it collects will support various applications, including improved weather and hurricane forecasts.

Monitoring sea surface height is critical for understanding ocean dynamics and how they evolve over time. This information also plays a role in forecasting hurricane behavior, which is important given the significant economic and human impacts these storms can cause. Over the past several decades, meteorologists have improved their ability to predict both hurricane tracks and intensities. Sentinel-6B will contribute additional data to support those efforts.

Sentinel-6B is the second spacecraft in the Sentinel-6/Jason-CS (Continuity of Service) mission, a joint initiative between NASA, the European Space Agency (ESA), EUMETSAT, and the U.S. National Oceanic and Atmospheric Administration (NOAA). It will follow Sentinel-6 Michael Freilich, which launched in November 2020, continuing a data record of sea level measurements that began in 1992 through U.S.-European satellite collaboration.

One of the key factors in hurricane intensity is ocean heat. As water warms, it expands, causing a rise in sea surface height. Satellites can use this change as an indicator of ocean heat content. A deep layer of warm water supports more intense hurricane development, while a shallow layer can lead to surface cooling as storms mix the water, potentially weakening the storm.

According to Josh Willis, a project scientist at NASA’s Jet Propulsion Laboratory, sea surface height can serve as a useful proxy for subsurface ocean heat. This helps forecasters understand which parts of the ocean may support rapid intensification of hurricanes.

Mark DeMaria, a research scientist at Colorado State University, noted that sea level measurements are used in two primary ways. First, they help initialize ocean conditions in forecast models used by the National Hurricane Center. Second, they are incorporated into machine learning models that predict whether a storm may rapidly intensify — defined as a 35 mph (56 kph) or greater increase in wind speed within 24 hours.

An example of this occurred with Hurricane Milton in October 2024. The storm intensified from a Category 1 to a Category 5 between October 6 and 7, with wind speeds reaching 180 mph (289 kph), before weakening slightly before landfall in Florida. Forecast models that contributed to predicting this event used satellite sea level data, including from Sentinel-6 Michael Freilich.

Although satellite sea level data has been available since the early 1990s, it wasn’t until the 2000s that such data began to be used operationally in hurricane intensity forecasts. In 2007, a U.S. federal initiative focused on improving hurricane prediction helped move research developments into real-time forecasting systems. Since then, improvements in forecast accuracy, lead time, and reduced uncertainty have been integrated into operational tools.

Renato Molina, an economist at the University of Miami, has studied the financial implications of these forecasting improvements. He notes that better forecasts give communities more time to prepare, which can reduce damage and save billions of dollars.

While many variables contribute to hurricane forecasting, sea surface height data from satellites like Sentinel-6 Michael Freilich, and soon Sentinel-6B, remains a valuable component. DeMaria emphasized that data from both satellites and in-ocean sensors are essential and complementary.

The Sentinel-6/Jason-CS mission is a collaborative effort involving ESA, EUMETSAT, NASA, and NOAA, with support from the European Commission and technical contributions from France’s CNES.

NASA’s Jet Propulsion Laboratory contributed three instruments to each satellite: the Advanced Microwave Radiometer, the Global Navigation Satellite System – Radio Occultation, and the Laser Retroreflector Array. NASA also provides launch services, ground systems for operating the science instruments, data processing for two of those instruments, and scientific support through the Ocean Surface Topography Science Team.

Courtesy of NASA. Photo courtesy of ESA.

Falcon 9 is a reusable, two-stage rocket designed and manufactured by SpaceX for the reliable and safe transport of people and payloads into Earth orbit and beyond.

Falcon 9 is the world’s first orbital-class reusable rocket.

Stats

Completed missions: 512

Total landings: 467

Total reflights: 436

The Falcon 9 has launched 71 humans into orbit since May 2020

Specs

Height: 70 m / 229.6 ft

Diameter: 3.7 m / 12 ft

Mass: 549,054 kg / 1,207,920 lb

Payload to Low Earth Orbit (LEO): 22,800 kg / 50,265 lb

Payload to Geostationary Transfer Orbit (GTO): 8,300 kg / 18,300 lb

Payload to Mars: 4,020 kg / 8,860 lb

On January 24, 2021, Falcon 9 launched the first ride-share mission to Sun Synchronous Orbit. It was delivering a record-setting 143 satellites to space. And while this was an important mission for SpaceX in itself, it was also the moment Falcon 9 overtook United Launch Alliance’s Atlas V for the total number of consecutive successful launches.

SpaceX’s Falcon 9 had become America’s workhorse rocket, launching 31 times in 2021. It has already beaten that record this year, launching almost an average of once a week. While most of the launches deliver Starlink satellites to orbit, the company is still launching the most commercial payloads to orbit, too.

Falcon 9 is a medium-lift launch vehicle, with the capability to launch over 22.8 metric tonnes to low earth orbit. Unlike any other rocket, its first stage lands back on Earth after separating from its second stage. In part, this allows SpaceX to offer the cheapest option for most customers with payloads that need to reach orbit.

Under its ride-share program, a kilogram can be placed in a sun-synchronous orbit for a mere 1.1 million dollars, far cheaper than all other currently operating small satellite launch vehicles.

The reusability and fast booster turnaround times have made Falcon 9 the preferred choice for private companies and government agencies. This has allowed SpaceX to capture a huge portion of the launch market.

Photo courtesy of Jenny Hautmann for Supercluster.

Space Launch Complex 4 (SLC-4) at Vandenberg Space Force Base is SpaceX’s west coast launch and landing facility, with its launch pad designated SLC-4E (the eastern-most of the two areas). Originally built in the early 1960s for Atlas-Agena rockets, the pad served that rocket line until 1967, when it was taken offline and rebuilt for Titan IIID rockets. From 1971 to 1988, SLC-4E launched Titan IIID rockets, after which it was reconfigured for Titan IV missions, which continued between 1991 and 2005.

In 2011, SpaceX leased SLC-4E and spent two years rebuilding the pad for its Falcon 9 rocket. From 2013 to 2019, the pad exclusively supported Falcon 9 polar missions. However, in 2020, SpaceX began splitting polar launches between Vandenberg and Cape Canaveral, after the Air Force lifted a 51-year ban on Florida-based polar launches, previously imposed due to the risk of overflying Cuba during launch. Despite these new opportunities from Florida, SpaceX plans to continue utilizing Vandenberg, with many more launches scheduled from this location.

Photo by Supercluster

"Of Course I Still Love You" (OCISLY) is one of SpaceX’s Autonomous Spaceport Drone Ships used to recover Falcon 9 rocket boosters from the ocean. Like its sister ships, "Just Read the Instructions" (JRTI) and "A Shortfall of Gravitas" (ASOG), OCISLY plays a crucial role in SpaceX’s reusability program, which aims to make spaceflight more cost-effective and sustainable.

The name "Of Course I Still Love You" is inspired by science fiction author Iain M. Banks' Culture series, known for its imaginative and whimsical ship names. This naming theme extends to SpaceX's other drone ships.

OCISLY originally operated in the Atlantic Ocean, primarily from Cape Canaveral, Florida. It has since been retired and replaced by ASOG in the Atlantic, with its operations shifting to the Pacific Ocean.

Equipped with advanced navigation systems and thrusters for precise positioning, OCISLY featured a large landing platform designed for recovering rocket boosters at sea. It was instrumental in supporting missions where boosters couldn’t return to solid ground, enabling SpaceX to reuse rocket stages and contribute to lowering costs and improving the sustainability of space missions.