Sentinel-6B, an ocean-tracking satellite jointly developed by NASA and ESA (European Space Agency), is ready to roll out to the launch pad, packed into the payload fairing of a SpaceX Falcon 9 rocket.
Launch is targeted at 12:21 a.m. EST, Monday, Nov. 17 (9:21 p.m. PST, Sunday, Nov. 16). Once it lifts off from Vandenberg Space Force Base in California, the satellite will ride out a 57-minute sequence of events ending in spacecraft separation, when the satellite detaches from the rocket.
Then Sentinel-6B’s real work begins. Orbiting Earth every 112 minutes at 4.5 miles (7.2 kilometers) per second, the satellite will eventually take over for its twin, Sentinel-6 Michael Freilich, launched five years ago, to continue a multidecade dataset for sea level measurements from space. Those measurements, along with atmospheric data the mission gathers, will help improve public safety and city planning while protecting coastal infrastructure, including power plants and defense interests. NASA will also use the data to refine atmospheric models that support the safe re-entry of Artemis astronauts.
Here’s a closer look at what lies ahead for the satellite in the coming days.
Sentinel-6B is part of a U.S.-European mission that will continue 30-year-plus record of sea-level measurements. Its observations will help build an accurate picture of local and global sea surface heights to support storm forecasting, secure coastal infrastructure, and help optimize commercial activities, such as shipping.
Launch timeline
Measuring 19.1 feet (5.82 meters) long and 7.74 feet (2.36 meters) high (including the communications antennas), the satellite weighs in at around 2,600 pounds (1,200 kilograms) when loaded with propellant at launch.
The satellite will lift off from Space Launch Complex 4 East at Vandenberg. If needed, backup launch opportunities are available on subsequent days, with the 20-second launch window occurring about 12 to 13 minutes earlier each day.
A little more than two minutes after the Falcon 9 rocket lifts off, the main engine cuts off. Shortly after, the rocket’s first and second stages separate, followed by second-stage engine start. The reusable Falcon 9 first stage then begins its automated boost-back burn to the launch site for a powered landing. About three minutes after launch, the two halves of the payload fairing, which protected the satellite as it traveled through the atmosphere, separate and fall safely back to Earth.
The first cutoff of the second stage engine takes place approximately eight minutes after liftoff, at which point the launch vehicle and the spacecraft will be in a temporary “parking” orbit. The second stage engine fires a second time about 44 minutes later, and about 57 minutes after liftoff, the rocket and the spacecraft separate. Roughly seven minutes after that, the satellite’s solar panels deploy. Sentinel-6B is expected to make first contact with ground controllers about 35 minutes after separation (roughly an hour and a half after liftoff) — a major milestone indicating that the spacecraft is healthy.
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Science mission
Following launch operations, the team will focus on its next challenge: getting the spacecraft ready for science operations. Once in orbit, Sentinel-6B will fly about 30 seconds behind its twin, the Sentinel-6 Michael Freilich satellite. When scientists and engineers have completed cross-calibrating the data collected by the two spacecraft, Sentinel-6B will take over the role of providing primary sea level measurements while Sentinel-6 Michael Freilich will move into a different orbit. From there, researchers plan to use measurements from Sentinel-6 Michael Freilich for different purposes, including helping to map seafloor features (variations in sea surface height can reveal variations in ocean floor features, such as seamounts).
Where to find launch coverage
Launch day coverage of the mission will be available on the agency’s website, including links to live streaming and blog updates beginning no earlier than 11 p.m. EST, Nov. 16, as the countdown milestones occur. Streaming video and photos of the launch will be accessible on demand shortly after liftoff. Follow countdown coverage on NASA’s Sentinel-6B blog.
For more information about NASA’s live programming schedule, visit
More about Sentinel-6B
The Copernicus Sentinel-6/Jason-CS (Continuity of Service) mission is a collaboration between NASA, ESA, EUMETSAT (European Organisation for the Exploitation of Meteorological Satellites), and the National Oceanic and Atmospheric Administration (NOAA). The European Commission contributed funding support while France’s space agency CNES (Centre National d’Études Spatiales) provided technical expertise. The mission also marks the first international involvement in Copernicus, the European Union’s Earth Observation Programme.
A division of Caltech in Pasadena, JPL built three science instruments for each Sentinel-6 satellite: the Advanced Microwave Radiometer, the Global Navigation Satellite System - Radio Occultation, and the Laser Retroreflector Array. NASA is also contributing launch services, ground systems supporting operation of the NASA science instruments, the science data processors for two of these instruments, and support for the U.S. members of the international Ocean Surface Topography and Sentinel-6 science teams. The launch service is managed by NASA’s Launch Services Program, based at the agency’s Kennedy Space Center in Florida.