As part of a new generation of modern weather satellites, MetOp-SG A1 began its journey into space on 13 August 2025 and will collect data on the atmosphere, the world's oceans and the Earth's surface around the clock. The aim is to make weather forecasts even more reliable and to better understand climate change.

MetOp SG (short for: Meteorological Operational Satellite - Second Generation) ensures the continuous availability of accurate and long-term global weather and climate data from the first MetOp weather satellites. The second-generation MetOp satellites are equipped with significantly improved data acquisition instruments. The complementary sensor technology is divided between two specialized satellites, A and B.

The European Space Agency (ESA) is developing MetOp SG A1 in collaboration with EUMETSAT (European Organisation for the Exploitation of Meteorological Satellites). Airbus Defence and Space in Germany is the prime contractor for the satellite.

Germany is making a special contribution to European weather satellite programs by providing the METimage instrument, coordinated by DLR German Space Agency

Jena-Optronik has developed and built a wide range of opto-electronic instruments and subsystems for the MetOp SG satellites, including the NIR spectrometer optics, front-end and image processing electronics, and various scanner electronics. These subsystems play a central role in fulfilling the satellite's tasks in space, particularly in image acquisition and image processing.

On board MetOp SG A1 are two instruments that are essential to the mission: the Sentinel-5 NIR spectrometer and the METimage multispectral camera, which provide different but complementary data. While the NIR spectrometer focuses on the composition of the atmosphere, METimage provides images and surface information that can be used to measure cloud and ice cover, water vapor, vegetation and even fires with high accuracy. Together, they help us understand today's weather patterns and tomorrow's climate change.

The space specialists at Jena-Optronik supply essential components for both instruments:

NIR spectrometer optics for Sentinel-5

Sentinel-5 analyses the sunlight reflected by the Earth. This is done in the near-infrared range, i.e. at a light frequency that is partially invisible to the human eye. This allows conclusions to be drawn about the composition of the air (e.g. pollutants or greenhouse gases) and the condition of plants on Earth.

A 2,700 km wide swath is used to analyze the concentration of atmospheric trace gases, which are waste products of industry and transport and contribute significantly to atmospheric pollution. Spectroscopic analysis, in this case using seven individual wavelengths in the ultraviolet to infrared spectral ranges, allows the concentration and spatial distribution patterns to be identified. Der Beitrag der Jena-Optronik ist das Spektrometer für den nahen Infrarotbereich, das sogenannte NIRSO (kurz für: Near Infrared Spectrometer Optics).

This component maps the incident light – divided into its spectral components between 685 and 775 nm – onto a sensor. In conjunction with the instrument’s other spectrometers, this allows the concentration of certain trace gases to be determined with local resolution. Furthermore, it measures the purity of the air in terms of aerosol content with a resolution of 7 km based on the amount of incident light.

Multispectral camera METimage Front End Electronic

A key instrument on board the MetOp SG A1 weather satellite is the METimage multispectral camera. It measures visible to thermal infrared light to monitor the health of vegetation and the composition of the atmosphere using a complex optical system.

Jena-Optronik supplies electronic components for METimage. Front End Electronics (FEE), i.e. the sensitive control electronics for the detectors, and the Data Formatter Module (DFM) for real-time image data pre-processing come from the Jena-based space specialists.

The video and image processing electronics from Jena cover the electro-optical conversion from the image sensor itself to the pre-processing of the image data for storage. To ensure that the image sensor can record the correct data, another module (Rotation Control Module, or RCM for short) from Jena ensures the synchronized and precise control of the scan and derotation mirrors, which guarantee continuous, high-resolution image recording and calibration of the image data via a complex scan profile.

METimage scans the Earth’s surface from an altitude of 830 km using two synchronized rotating mirrors. Each scan captures a 2560 km wide swath with a resolution of 500 m (at nadir). Each swath is captured in 20 spectral channels, ranging from the visible spectrum to the thermal infrared.

This enables analyses of water and aerosol distribution, vegetation and surface properties, ice and snow cover, surface temperatures, cloud cover, cloud type, cloud height and cloud temperature. Thanks to its ability to analyze cloud cover, METimage plays a central role on the MetOp SG A1 satellite.

All other optical instruments on MetOp SG A1 depend on the information provided on cloud coverage.

Pictures: © Florian Brill for Jena-Optronik GmbH

Disclaimer: This article was carried out under a programme of and funded by the European Space Agency. The views expressed herein can in no way be taken to reflect the official opinion of the European Space Agency.