COPERNICUS is the world's largest space-based environmental mission – Jena-Optronik’s team is proud to support this program with innovations “Made in Jena”.

 
The satellites called “Sentinel” in this unique European earth observation program have technology from Jena on board: The space-company has significant contributions to Sentinel-1 to Sentinel-6.

 
Sentinel-4, an important element for environmental and climate protection has now successfully begun its journey into space. The Sentinel-4 instruments fly on the latest geostationary weather satellite “Meteosat-Third-Generation” (MTG) to closely monitor the composition of the atmosphere and air quality over Europe.

 
The European Space Agency ESA launched the MTG-S1 satellite with Sentinel-4 on July 1st, 2025.

 
Jena-Optronik has developed, manufactured and tested several opto-electronic components for this mission. These include a telescope, a UV spectrometer (ultraviolet light), an NIR spectrometer (near infrared) and two focal plane assemblies with the image sensors.

 
"We are grateful for the trust placed in us for this project and want to thank the European Space Agency ESA as well as Airbus Defence and Space. The dedicated teams of our clients and partners were a key success factor for our own work. Jena-Optronik's #teamspace has been motivated in particular by the all-encompassing objective of the mission: to make a contribution to protecting our planet from space. With a great spirit of research, we have succeeded in exploring completely new technological horizons and delivering highly innovative satellite technology“, explains Eyk Gebhardt, Jena-Optronik’s Sentinel-4 project manager.

Pictures: © Florian Brill for Jena-Optronik GmbH

“We know what Earth is breathing”

The main objective of the Sentinel-4 mission is to record data on important trace gases and aerosols for air quality in Europe with high spatial resolution and fast repetition frequency. The special innovation of the Sentinel-4 mission is that the measurements are collected from geostationary orbit for the first time and can be therefore recorded throughout the day. This data will then be used to support the Copernicus Atmosphere Monitoring Service (CAMS), which provides globally consistent and quality-checked information on air pollution, greenhouse gases and global warming.

Copernicus is currently the most advanced geostationary meteorological satellite program, which takes climate data collection as well as a wide range of important environmental earth observations to a whole new level.

The data obtained, which is made available online and free of charge to all interested parties, can be used to create targeted environmental models that help to define and implement appropriate environmental protection measures. With the help of the data provided, the responsible authorities can immediately warn the inhabitants of Europe about possible dangers from environmental pollution and implement corresponding actions.

Insight into the technology: Innovative space optics “Made in Jena”

The spatial resolution of the entire optical system is 8 km from a distance of 36,000 km. The spectrometers operate in different wavelength ranges (in the ultraviolet 305-400 nm, in the visible 400-500 nm and in the near infrared 750-775 nm) with a spectral resolution of 0.12-0.5 nm and can therefore provide valuable information about the state of our atmosphere.

The optical system for Sentinel-4 consists of 19 lenses. Each of these lenses is unique, bonded with high precision and manufactured with micrometer accuracy. Several major technical requirements were solved during the development of these optics:

• Stress-free mounting of the lenses to ensure the optical imaging quality of the overall system
• Technological edge coating of the individual lenses to prevent stray light
• Adjustment in the µm range to realize imaging quality from 36,000 km
• Stability requirements resulting from the rocket launch and the environmental conditions prevailing in space

For optical systems that react very sensitively to temperature fluctuations, it is necessary to develop a so-called athermal design, i.e. a system that is robust to temperature fluctuations. The particular challenge is to compensate for the dependence of various materials on the coefficient of thermal expansion and the change in the refractive index. By implementing an opto-mechanical design developed and patented by Jena-Optronik, it has been possible to build an optical system that is stable over a temperature range of 20 Kelvin.

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.