Facts and figures

Name: Fluorescence Explorer (FLEX)

Objectives: To provide global measurements of vegetation fluorescence; to quantify photosynthetic activity and plant stress by mapping vegetation fluorescence; to advance our understanding of the functioning of the photosynthetic machinery and the actual health and performance of terrestrial vegetation; and to generate monthly global maps with a spatial resolution of 300 m × 300 m and a swath width of 150 km.

Instrument: The Fluorescence Imaging Spectrometer (FLORIS) is a high-resolution imaging spectrometer operating in pushbroom mode. It will acquire 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) bands; 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. It measures 1.5 m high x 1.2 m wide x 1.2 m long in launch configuration with the Floris instrument mounted on the top panel. There are two solar array panels on each side of the main body. When deployed in orbit this results in a total width of 5.2 m.

Mass: ~460 kg (including 140 kg instrument and 30 kg propellant)

Power: ~700 W (EOL) deployable solar array with ~40 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:  Mid-2024 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 100 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: Svalbard and Norway for science data (X-band) and Kiruna in Sweden for telemetry (S-band)

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