FLEX (satellite)

Planned ESA Earth observation satellite

For other uses, see Flex (disambiguation).

FLEX

Mission type| Earth observing satellite
Operator| ESA
Website| https://earth.esa.int/eogateway/missions/flex
Mission duration| 3.5 years (planned)[1]
Spacecraft properties
Bus| Myriade
Manufacturer| Thales Alenia Space
Launch mass| 425 kilograms (937 lb)
Power| 700W
Start of mission
Launch date| 2026 (planned)[2]
Rocket| Vega-C
Launch site| Kourou ELV
Contractor| Arianespace
Orbital parameters
Reference system| Geocentric
Regime| Sun-synchronous
Altitude| 814 km
Inclination| 98.64°
Repeat interval| 27 days

Living Planet Programme

← BIOMASS

FORUM →

The FLuorescence EXplorer (FLEX) is a planned mission by the European Space Agency to launch a satellite to monitor the global steady-state chlorophyll fluorescence in terrestrial vegetation.[3] FLEX was selected for funding on 19 November 2015[3][4][5][6][7][8][9][10] and will be launched on a Vega C rocket from Guiana Space Centre in mid-2026 together with another Earth-observing satellite, Altius.[2][11]

## Overview

[edit]

The FLuorescence EXplorer (FLEX) mission is the eighth mission in the Earth Explorer programme, (part of ESA's Living Planet Programme). It comprises a satellite for the global monitoring of steady-state chlorophyll fluorescence in terrestrial vegetation.[12] Leaf photosynthesis releases energy not required in the biochemical process in the form of light in wavelength between 640 and 800 nanometres.[3]

After more than 70 years of basic and applied research in chlorophyll fluorescence, it is now established that fluorescence is a sensitive indicator of photosynthesis in both healthy and physiologically perturbed vegetation that can be used to monitor croplands and forests.[3]

Fluorescence is a powerful non-invasive tool to track the status, resilience, and recovery of photochemical processes, and provides important information on overall photosynthetic performance with implications for related carbon sequestration. The early responsiveness of fluorescence to atmospheric, soil and plant water balance, as well as to atmospheric chemistry and human intervention in land usage, makes it a useful biological indicator in improving the understanding of Earth system dynamics.

FLEX will encompass a three-instrument array for measurement of the interrelated features of fluorescence, hyperspectral reflectance, and canopy temperature.

ESA-developed Earth observation missions

The program will involve a space and ground-measurement program of 3-years duration and will provide data formats for research and applied science.

## Timeline

[edit]

* In November 2015, ESA has selected FLEX as the agency's eighth Earth Explorer mission.[13]
* In November 2016, ESA has selected Italian company Leonardo to build the main instrument (Floris) for the FLEX satellite.[14]
* In 2018, during the first FLEXSense campaign, the OLCI instruments of the Sentinel-3B satellite was reprogrammed to operate in a mode simulating the future cooperations with FLEX and a parallel aerial campaign used aircraft-based observations to demonstrate aspects of the Floris instrument functionality.[15]
* In January 2019, ESA has selected Thales Alenia Space as the prime contractor for the satellite and to oversee the development of the Floris instrument by Leonardo.[16]
* In summer 2019, the second FLEXSense campaign took place, with operations closely following the 2018 campaign.[15]
* In January 2022, ESA has signed a contract with Arianespace for a joint launch of FLEX and Altius on Vega C.[17]
* In December 2023, Thales Alenia Space selected the UK’s National Satellite Test Facility for the satellite's first comprehensive assembly, integration and test campaign.[18]
* In 2024, the Fraunhofer IOF in Jena was exhibiting the double-slit assembly, which it had developed for the Floris instrument, at SPIE Photonics West in San Francisco.[19]

## See also

[edit]

* List of European Space Agency programmes and missions
* Photosynthetic efficiency
* Phototroph

## References

[edit]

1. ^ "Fluorescence Explorer (FLEX) – Facts and Figures". ESA. Retrieved 3 January 2020.
2. ^ a b "ALTIUS - ESA's ozone mission". ESA. Retrieved 4 May 2024.
3. ^ a b c d Amos, Jonathan (19 November 2015). "Flex satellite will map Earth's plant glow". BBC News. Retrieved 2015-11-20.
4. ^ de Selding, Peter B. (25 September 2015). "Panel Endorses Vegetation Fluorescence Mapper for ESA's Earth Explorer Program". Spacenews. Retrieved 3 October 2015.
5. ^ Kraft, S; Del Bello, U; Bouvet, M; Drusch, M; Moreno, J (2012). "FLEX: ESA's Earth Explorer 8 candidate mission". 2012 IEEE International Geoscience and Remote Sensing Symposium. pp. 7125–7128\. doi:10.1109/IGARSS.2012.6352020. ISBN 978-1-4673-1159-5. S2CID 7603157.
6. ^ Kraft, S; Bézy, J.-L; Del Bello, U; Berlich, R; Drusch, M; Franco, R; Gabriele, A; Harnisch, B; Meynart, R; Silvestrin, P (2013). "FLORIS: Phase a status of the fluorescence imaging spectrometer of the Earth Explorer mission candidate FLEX". In Meynart, Roland; Neeck, Steven P.; Shimoda, Haruhisa (eds.). Sensors, Systems, and Next-Generation Satellites XVII. Vol. 8889\. pp. 88890T. doi:10.1117/12.2032060. S2CID 128624334.
7. ^ Drusch, Matthias; Moreno, Jose; Del Bello, Umberto; Franco, Raffaella; Goulas, Yves; Huth, Andreas; Kraft, Stefan; Middleton, Elizabeth M; Miglietta, Franco; Mohammed, Gina; Nedbal, Ladislav; Rascher, Uwe; Schuttemeyer, Dirk; Verhoef, Wout (2017). "The FLuorescence EXplorer Mission Concept—ESA's Earth Explorer 8". IEEE Transactions on Geoscience and Remote Sensing. 55 (3): 1273–1284\. Bibcode:2017ITGRS..55.1273D. doi:10.1109/TGRS.2016.2621820. S2CID 5267592.
8. ^ Stoll, M.P; Buschmann, C; Court, A; Laurila, T; Moreno, J; Moya, I (2003). "The FLEX-Fluorescence Explorer mission project: Motivations and present status of preparatory activities". IGARSS 2003. 2003 IEEE International Geoscience and Remote Sensing Symposium. Proceedings (IEEE Cat. No.03CH37477). Vol. 1\. pp. 585–587\. doi:10.1109/IGARSS.2003.1293850. ISBN 978-0-7803-7929-9. S2CID 56932583.
9. ^ Rascher, Uwe; Gioli, Beniamino; Miglietta, Franco (2008). "FLEX — Fluorescence Explorer: A Remote Sensing Approach to Quantify Spatio-Temporal Variations of Photosynthetic Efficiency from Space". Photosynthesis. Energy from the Sun. pp. 1387–1390\. doi:10.1007/978-1-4020-6709-9_299. ISBN 978-1-4020-6707-5.
10. ^ Harnisch, Bernd; Kraft, Stefan; Bézy, Jean-Loup; Drusch, Matthias; Bouvet, Marc; Del Bello, Umberto (2017). "Fluorescence imaging spectrometer concepts for the Earth explorer mission candidate flex". International Conference on Space Optics — ICSO 2012. p. 72\. doi:10.1117/12.2309086. ISBN 9781510616172. S2CID 125313615.
11. ^ "Arianespace to launch with Vega C FLEX & ALTIUS, two ESA programmes at the service of environment". Arianespace (Press release). 11 January 2022. Retrieved 11 January 2022.
12. ^ "FLEX (Fluorescence Explorer)". www.eoportal.org. Retrieved 2022-12-28.
13. ^ "New satellite to measure plant health". www.esa.int. Retrieved 2025-03-31.
14. ^ "Deal signed for FLEX's fluorescence finder". www.esa.int. Retrieved 2025-03-31.
15. ^ a b "New FLEX-related campaign datasets released - Earth Online". earth.esa.int. Archived from the original on 2024-07-11. Retrieved 2025-03-31.
16. ^ "Thales Alenia Space leads the build of photosynthesis mission". www.esa.int. Retrieved 2025-03-31.
17. ^ "Ride into space on Vega-C secured for FLEX and Altius". www.esa.int. Retrieved 2025-03-31.
18. ^ "Thales Alenia Space selects the UK's National Satellite Test Facility for FLEX satellite 1st test – SatNews". news.satnews.com. Retrieved 2025-03-31.
19. ^ "SPIE Photonics West: Fraunhofer IOF presents high-precision double slit for space spectrometer". Fraunhofer Institute for Applied Optics and Precision Engineering IOF. Retrieved 2025-04-02.

## External links

[edit]

* FLEX \- Report to ESA for mission selection
* Workshops on the FLEX mission: 2007, 2010, 2014
* FLEX Photosynthesis Study
* FLEX Bridge Study
* FLEX (Fluorescence Explorer) article on eoPortal

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