Facts and figures

Name: Fluorescence Explorer (FLEX)

Goals: To provide global measurements of vegetation fluorescence, and quantify photosynthetic activity and plant stress through fluorescence mapping. The aim is to improve our understanding of photosynthetic functioning and the health and performance of terrestrial vegetation, while generating monthly global maps at a spatial resolution of 300 m × 300 m.

Instrument: Fluorescence Imaging Spectrometer (FLORIS) which acquires data in the 500–780 nm spectral range, with a sampling of: 0.1 nm in the oxygen bands O2-A (759–769 nm) and O2-B (686–697 nm); 2.0 nm in the chlorophyll absorption band (600–677 nm) and photochemical reflectance index band (500–600 nm); 0.5–0.65 nm in the rest of the spectral range.

Satellite: The satellite is based on a small platform with recurring Myriade evolution mechanical configuration and Copernicus Sentinel-3 avionics. In orbit it measures 1.5 m x 4.9  m x 1.6 m.

Mass: 400 kg

Power: 950 W (EOL) deployable solar array with 57.6 Ah (EOL) Li-ion battery

Life: 3.5 years (plus a three-month commissioning phase) to cover at least three seasonal vegetation cycles on the northern and southern hemispheres

Launch: 2026 on a Vega-C rocket from Kourou, French Guiana

Orbit: Sun-synchronous at an altitude of 814 km and an inclination of 98.64° with a 27-day repeat cycle

Tandem: The FLEX satellite orbits 40–100 km km ahead of a Copernicus Sentinel-3 satellite, which provides additional measurements of the atmosphere and land surface

Mission control:  ESA’s European Space Operations Center (ESOC) in Darmstadt, Germany, and in coordination with EUMETSAT for tandem flight with Copernicus Sentinel-3.

Ground stations: Science data are transmitted via X-band, while telemetry, tracking and command are handled via S-band. Both links are via dedicated ground stations in Svalbard in Norway

Data: ESA’s Centre for Earth Observation (ESRIN) in Frascati, Italy

Project: Mission development and commissioning managed at ESA’s European Space research and Technology Centre (ESTEC) in Noordwijk, the Netherlands

Satellite prime contractor: Thales Alenia Space, France

Instrument contractor: Leonardo, Italy