# FLEX (FLuorescence EXplorer)
*missions*

ESA Earth Explorer 8 mission, launch expected 2026; carries FLORIS (Fluorescence Imaging Spectrometer) operating at 500-780 nm with 0.1 nm sampling in O2-A/B bands; first mission dedicated exclusively to global SIF mapping at 300 m resolution.

## Specifications
- **operator**: esa
- **current status**: planned
- **orbit type**: LEO SSO 815 km
- **tasking supported**: false
- **planned launch**: 2026-09-01
- **swath km**: 150
- **revisit days**: 27
- **launch vehicle**: arianespace-vega-c
- **entity type**: mission
- **last verified date**: 2026-06-11
- **verified by**: agency-doc
- **claim status**: unclaimed
- **provider**: esa
- **attributes**: {"operator":"esa","current_status":"planned","orbit_type":"LEO SSO 815 km","tasking_supported":false,"summary":"ESA Earth Explorer 8 mission, launch expected 2026; carries FLORIS (Fluorescence Imaging Spectrometer) operating at 500-780 nm with 0.1 nm sampling in O2-A/B bands; first mission dedicated exclusively to global SIF mapping at 300 m resolution.","planned_launch":"2026-09-01","swath_km":150,"revisit_days":27,"launch_vehicle":"arianespace-vega-c"}
- **relevance**: in-scope

## Editorial
FLEX (FLuorescence EXplorer) is the eighth Earth Explorer mission selected by ESA, planned for launch in September 2026 on a Vega-C rocket in tandem with the Copernicus Sentinel-3C satellite. FLEX is planned to fly approximately 40 to 100 km ahead of Sentinel-3C in the same orbital plane at 815 km altitude in a sun-synchronous orbit, enabling simultaneous surface reflectance corrections using Sentinel-3 OLCI data.[^esa-flex-facts][^esa-earth-online-flex]

The mission carries the FLORIS (FLuORescence Imaging Spectrometer) instrument, a pushbroom spectrometer operating across 500 to 780 nm with 0.1 nm spectral sampling in the oxygen A-band and B-band windows used for sun-induced fluorescence (SIF) retrieval. FLORIS is planned to deliver SIF maps at 300 m spatial resolution over a 150 km swath with a 27-day revisit cycle, providing global-scale SIF measurement as an ESA Earth Explorer mission.[^esa-flex-facts][^eoportal-flex]

SIF from FLEX is intended to enable estimation of photosynthetic activity and carbon uptake across vegetation types, with applications in crop stress monitoring and ecosystem carbon cycle assessment. The satellite's planned mass is approximately 400 kg.[^esa-flex-facts]

## Compositional position
- FLEX (FLuorescence EXplorer) --[related-topic]--> crop-stress (topics)
- FLEX (FLuorescence EXplorer) --[related-topic]--> greenhouse-gas-flux (topics)
- FLEX (FLuorescence EXplorer) --[related-topic]--> co2 (topics)

## Sources
- [esa-flex-facts] | FLEX Facts and Figures - ESA | https://esa.int/Applications/Observing_the_Earth/FLEX/Facts_and_figures | tier=agency-doc | accessed=2026-06-11
- [esa-flex-mission] | FLEX mission overview - ESA | https://www.esa.int/Applications/Observing_the_Earth/FutureEO/FLEX | tier=operator-marketing | accessed=2026-06-11
- [esa-earth-online-flex] | FLEX - ESA Earth Online | https://earth.esa.int/eogateway/missions/flex | tier=agency-doc | accessed=2026-06-11
- [eoportal-flex] | FLEX (Fluorescence Explorer) - eoPortal | https://eoportal.org/web/eoportal/satellite-missions/f-missions/flex | tier=community | accessed=2026-06-11

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Source: https://eo-atlas.org/missions/flex
Maintainer: SpectraWorks B.V. (CC-BY 4.0)