ESA’s FLEX satellite uses German optics to monitor plant health

ESA’s Earth observation satellite FLEX is set to launch on 15 September 2026 from the Guiana Space Centre, carrying a suite of precision optics made in Jena, Germany. The mission will use a spectrometer that detects plant fluorescence from orbit, allowing scientists to monitor photosynthetic activity, health and stress across the planet’s vegetation.

The optics were designed and built by the Fraunhofer Institute for Applied Optics and Precision Engineering (IOF). Engineers created a silicon‑based double‑slit assembly and two high‑precision mirrors that meet the tight tolerances required for space‑borne spectroscopy. The double‑slit system improves spectral resolution, while the mirrors focus the light onto the detector with minimal distortion. This technology enables the spectrometer to capture subtle changes in chlorophyll fluorescence, a key indicator of plant health.

Data from FLEX will give researchers a new tool to track global vegetation dynamics in real time. By mapping fluorescence, scientists can identify areas of crop stress, monitor forest health, and refine models of carbon uptake. The mission also supports climate change studies and agricultural management. Once the satellite is in orbit, the spectrometer will begin continuous observations, feeding a global database that will be accessible to researchers and policymakers worldwide.