The European Space Agency (ESA) has officially confirmed the selection of the WIVERN mission as the eleventh pioneering venture within its prestigious Earth Explorer programme. After years of meticulous planning, development, and a rigorous selection process, ESA's Member States have given the green light for the implementation of this revolutionary satellite that promises to unlock some of the most hidden secrets of Earth's atmosphere. WIVERN, whose name is an acronym for "wind velocity radar nephoscope", will be the first mission in history capable of directly measuring wind dynamics within clouds on a global scale, thus filling a critical gap in the existing satellite observation system of our planet.

A scientific breakthrough into the heart of storms

Until now, scientists have relied on indirect methods to estimate the movement of air masses within cloud systems. Existing satellites track the movement of cloud tops or water vapour in the cloud-free atmosphere, but what happens in the very centre of weather events, within dense and opaque clouds, has remained largely unknown. It is precisely this "blind spot" that represents one of the greatest challenges in modern meteorology and climatology. The WIVERN mission is designed to directly address this challenge. Its primary objective is to provide the first global and direct measurements of wind fields within clouds, which will give scientists an unprecedented insight into the internal structure and dynamics of clouds. In addition to the winds themselves, the satellite will also collect detailed profiles of water droplets, rain, snow, and ice within these systems, offering a complete three-dimensional picture of the processes that drive our weather.

Cutting-edge technology for Earth observation

At the heart of the WIVERN mission is its sophisticated main instrument: a dual-polarisation Doppler radar operating at a frequency of 94 GHz. This technologically advanced radar will perform conical scanning, which allows it to cover an impressively wide swath of 800 kilometres on the Earth's surface with each pass. The use of the 94 GHz frequency is key as it allows the signal to penetrate through dense cloud layers and accurately measure the movement of particles within them. The Doppler effect, the principle on which the radar's operation is based, will enable the precise determination of the speed at which water droplets or ice crystals are moving towards or away from the radar, thereby directly providing information on wind speed. The dual polarisation of the signal will provide additional important information about the shape and type of hydrometeors (rain, snow, ice), further enriching the dataset. Such a configuration will ensure almost daily coverage of vast areas of the planet, which is crucial for monitoring rapid changes in the atmosphere.

Improving weather forecasts and understanding the climate

The data that WIVERN will collect has enormous potential for improving our ability to predict extreme weather events. A better understanding of the internal dynamics of storm systems, such as hurricanes, cyclones, and mesoscale convective systems, will directly translate into more accurate forecasts of their intensity and trajectory. This will allow for timely warnings and better preparation of communities for potentially dangerous weather events, thereby saving lives and reducing material damage. In addition to short-term forecasts, WIVERN will also have a long-term impact on climate science. Clouds and precipitation represent one of the largest sources of uncertainty in climate models. The detailed and global data on cloud and precipitation profiles that this mission will provide will be invaluable for improving and validating these models, leading to more reliable projections of future climate change.

"The Earth Explorer missions have consistently exceeded expectations, using breakthrough technologies to provide crucial insights about our planet – from climate dynamics to ice melt and gravity," said Simonetta Cheli, Director of ESA's Earth Observation Programmes. "After a rigorous selection process, we are excited to welcome WIVERN to the Earth Explorer family and can't wait to see the revolutionary science it will deliver."

The path to selection: A long and demanding race

The selection of the WIVERN mission is the culmination of a long and highly competitive process that began back in 2020, when ESA issued a call to the scientific community for new, bold mission ideas that would push the boundaries of Earth science and satellite technology. From an initial 15 proposals, four were selected for more detailed feasibility studies. In 2023, that choice was narrowed down to just two finalists: WIVERN and CAIRT. Both concepts went through an intensive evaluation period, including the publication of detailed reports and an in-depth user consultation conference in July, where scientists had the opportunity to examine and assess each proposal in detail. The final recommendation was made by ESA's Advisory Committee for Earth Observation (ACEO), which, after a thorough evaluation, proposed WIVERN for implementation. This decision was formally confirmed by ESA's Earth Observation Programme Board on September 24, 2025.

CAIRT: A strong competitor with an important mission

The other finalist, the CAIRT (Changing-Atmosphere Infrared Tomography) mission, represented an extremely strong and scientifically relevant concept. Its goal was to collect the measurements needed for a fundamental breakthrough in understanding the links between climate change, atmospheric chemistry, and dynamics at altitudes from approximately 5 to 115 kilometres. This is the region of the atmosphere where key processes related to the ozone layer, greenhouse gas transport, and pollutants occur. "The decision was indeed very difficult. The scientific goals of the CAIRT mission are timely and important, addressing major unknowns with also significant societal benefits," pointed out Professor René Forsberg, Chairman of ACEO. Although WIVERN was recommended, the committee strongly encouraged the continuation of scientific studies and field campaigns for CAIRT, leaving the door open for possible future implementation.

Rune Floberghagen, Head of ESA's Climate Action, Sustainability and Science Department, explained the key advantages that tipped the scales in favour of the winning mission: "Ultimately, WIVERN offered the broadest range of scientific and societal applications – spanning the atmosphere, ocean, and ice – while its exceptionally wide imaging swath promised near-daily coverage of vast areas of the Earth's surface." This ability to provide frequent and global data was crucial in the final decision, ensuring that WIVERN will have the maximum impact on operational meteorology and long-term climate research.