MTG-S1 commissioned and in position for weather forecasting
One year after launch, the first Meteosat Third Generation Sounder satellite, MTG-S1, is now commissioned and has been placed in its operational position in geostationary orbit at 0° longitude, and is now ready to deliver vital data to strengthen weather forecasting across Europe.
Launched on 1 July 2025, MTG-S1 is the second satellite in the Meteosat Third Generation (MTG) programme and the first of two sounder satellites. It also embarks the Copernicus Sentinel-4 instrument, bringing together two pioneering European missions on a single geostationary platform.
The Steering Committee of the Commissioning Results Review officially closed the satellite's in-orbit commissioning phase on 2 July 2026, marking the successful completion of an intensive year of testing, calibration and performance verification led by ESA, Eumetsat and European industry.
Following launch and early orbit operations, MTG-S1 was positioned in a geostationary orbit, but at 3.4°W for commissioning. Over the following twelve months, experts from ESA, Eumetsat, OHB, Thales Alenia Space, Airbus Defence and Space and numerous European partners carried out an extensive programme of functional checks, calibration activities and performance testing to verify every aspect of the satellite, its payloads and its operations.
The campaign was one of the most demanding ever undertaken for a European meteorological satellite.
Yet thanks to years of preparation, detailed rehearsals and exceptional teamwork, it progressed almost exactly according to plan, with major milestones achieved on schedule. Behind what appeared to be a remarkably smooth campaign lay countless hours of analysis, coordination and problem-solving by teams across Europe.
Commissioning is the critical phase during which a newly launched satellite, and its ground segment, are transformed into a fully characterised and trusted operational mission.
For MTG-S1, this achievement is particularly significant because, after completion of the commissioning of the system, it will introduce capabilities that Europe has never before had in geostationary orbit.
Its Infrared Sounder (IRS) is Europe's first hyperspectral sounding instrument operating from geostationary orbit. Every 30 minutes, it measures vertical profiles of atmospheric temperature and humidity over Europe, allowing meteorologists to detect atmospheric instability before severe weather develops and improving forecasts of rapidly evolving events.
MTG-S1 also hosts Copernicus Sentinel-4, the first mission dedicated to monitoring European air quality from geostationary orbit. Sentinel-4 delivers high-resolution measurements of atmospheric pollutants and aerosols, supporting environmental monitoring and public health every hour, providing information on a wide range of trace gases and pollutants to forecast and monitor air quality over Europe.
Together, the IRS and Sentinel-4's ultraviolet, visible and near-infrared spectrometer provide an unprecedented combination of meteorological and atmospheric composition measurements, strengthening weather forecasting, air-quality services and climate monitoring across Europe.
With commissioning complete, MTG-S1 has now been relocated from its commissioning position to its permanent operational orbital slot at 0° longitude, approximately 36 000 km above the equator.
From this prime geostationary vantage point, the satellite continuously observes Europe, Africa and the surrounding Atlantic Ocean. The relocation involved a carefully planned series of orbital manoeuvres to place the satellite safely and precisely into its operational position.
Now at 0° longitude, MTG-S1 joins MTG-I1 (Meteosat-12) and MSG-3 (Meteosat-10). Together, these satellites currently form Europe's operational geostationary meteorological constellation, combining the proven capabilities of Meteosat Second Generation with the next-generation imaging, lightning detection, atmospheric sounding and air-quality observations delivered by Meteosat Third Generation.
The strength of the MTG system lies in the complementary capabilities of its imager and sounder satellites. The full operational constellation will comprise two MTG-I satellites and one MTG-S satellite.
The MTG-I satellites, which embark a Flexible Combined Imager (FCI), provide more frequent observations, higher spatial resolution and additional spectral channels than its predecessor, while also carrying Europe's first Lightning Imager in geostationary orbit. MTG-S satellites add an entirely new dimension by observing the vertical structure of the atmosphere, while Sentinel-4 simultaneously monitors air quality. Together, they provide a far more complete picture of the atmosphere including how weather systems form, evolve and intensify.
With MTG-I2 currently at Europe's Spaceport in French Guiana undergoing preparations for its launch in the summer, Europe is now just one satellite away from completing the full MTG constellation. Once launched, MTG-I2 will use the 9.5° East geostationary orbital slot and provide the Rapid Scanning Service of the FCI that monitors Europe every 150 seconds.
MTG is a long-standing partnership between ESA and Eumetsat. ESA leads the development and procurement of the satellites with European industry, while Eumetsat defines user requirements, develops the ground segment, procures launch services and operates the satellites throughout their operational lifetime.
To meet more than the 20-year operational life of the mission, the full MTG system comprises six satellites, four MTG-I and two MTG-S.
The completion of the MTG-S1satellite commissioning marks a significant milestone in the overall MTG system commissioning, led by Eumetsat, which is planned to be completed by October 2026. It also signals the beginning of a new operational chapter for European meteorology. With MTG-I1 already transforming weather observation through its advanced imaging and lightning detection capabilities, MTG-S1 will add a three-dimensional view of the atmosphere together with continuous air-quality monitoring.
With the satellite handed over to Eumetsat and placed in its operational orbital slot at 0° longitude, Europe moves another step closer to realising the full potential of Meteosat Third Generation – delivering faster, richer and more precise observations from space to improve severe weather forecasting, protect lives and support better decisions for society.
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