EPS Sterna

Microsatellites to fill a gap in weather observations

Numerical weather prediction uses computer simulations of the atmosphere to model how the weather will evolve over time. Its accuracy relies, in part, on the number of microwave sounding observations that are assimilated into models to infer the temperature and humidity of the atmosphere.

Last Updated

19 January 2024

Published on

05 October 2023

The EUMETSAT Polar System – Sterna (EPS-Sterna) is a new constellation of microsatellites that will each carry a state-of-the-art microwave sounder. The initial constellation is composed of six satellites in sun-synchronous polar orbits. In only five hours or less, the microwave sounders on these satellites will make observations covering 90% of the globe.

The microwave sounder will measure energy reflected off the Earth’s surface in the microwave range of frequencies. Because it makes measurements beyond the visible range, it can provide temperature and humidity observations even when it is overcast, raining, or snowing.

EPS-Sterna will significantly improve the accuracy of numerical weather prediction models by providing data globally with unprecedented coverage and revisit time. In addition, the mission will have a large impact over the poles, where geostationary satellites have little visibility and Metop polar-orbiting satellites need longer to achieve global coverage.

EPS-Sterna will orbit the Earth in a polar orbit, complementing the observations from satellites in the EUMETSAT Polar System – Second Generation (EPS-SG), the National Oceanic and Atmospheric Administration’s Joint Polar Satellite System (JPSS), and the Chinese FengYun-3 (FY-3) system.

EUMETSAT anticipates that member states will discuss the approval of the EPS-Sterna programme in mid-2025.