Seven organizations from seven countries
were involved in the Photosynthesis Study.
Click the logos to visit their websites.

About FLEX/Sentinel 3

FLEX will be the first mission designed to observe fluorescence by using a novel technique measuring the main part of the chlorophyll fluorescence spectrum that originates from the core of the photosynthetic machinery.  This offers the opportunity to derive the photosynthetic activity of the terrestrial vegetation layer.  Therefore, FLEX observations will provide a new possibility to assess the dynamics of actual photosynthesis through sun-induced fluorescence.  The enhanced information content from the spectrum originating from the two different photosystems offers a great advancement over current capabilities that can only detect potential photosynthesis as derived in passive reflectance measurements by conventional land surface monitoring satellites.

The FLEX mission aims to provide global maps of vegetation fluorescence, which can be converted into an indicator of photosynthetic activity.  These data would improve our understanding of how much carbon is stored in plants and their role in the carbon and water cycles.

By flying in tandem with Sentinel-3, the mission would work in combination with Sentinel's Ocean and Land Colour Instrument and Sea and Land Surface Temperature Radiometer to improve models of future atmospheric carbon dioxide concentrations.

About the European Space Agency

The European Space Agency (ESA) is Europe's gateway to space, with the mission to shape the development of Europe's space capability and ensure that investment in space delivers benefits to the citizens of Europe and the world.  ESA undertakes programmes and activities far beyond the scope of any single European country, keeping Europe at the forefront of global space activities.

For further information, please visit www.ESA.int

About Chlorophyll Fluorescence

The potential of fluorescence to serve as an early indicator of stress – that is, before damage is irreversible – is a major aspect to be considered in the exploitation of FLEX measurements, since reflectance changes often are detectable only in dramatic and/or advanced cases of physiological strain when remediation likely is too late.

To read a 50-year review of Solar-Induced Chlorophyll Fluorescence (SIF), click HERE.

About the FLEX Photosynthesis Study

This study targetted the linkage between solar-induced chlorophyll fluorescence and photosynthesis in terrestrial vegetation.  A dedicated photosynthesis model based on state-of-the-art existing modules was developed and implemented.  We also developed and tested a prototype algorithm to derive photosynthesis from FLEX tandem mission measurements.

The aim was to be able to map terrestrial photosynthesis from space by measuring vegetation fluorescence emission.  Scientific objectives of the study were:

• To assess the quality of fluorescence-derived photosynthesis data against classical optically-based methods (the fraction of absorbed photosynthetically active radiation times Light Use Efficiency).
• To address in more detail temporal and spatial scaling issues (from towers to satellite footprints).
• To identify and characterise the effects of different types of stress on fluorescence and photosynthesis (especially drought and freezing air temperatures).
• To indicate potential applications and usage of the novel fluorescence observations.

The potential of fluorescence to serve as an early indicator of stress – that is, before damage is irreversible – is a major aspect to be considered in the exploitation of FLEX measurements, since reflectance changes often are detectable only in dramatic or advanced cases of physiological strain.  Furthermore, visible plant colour does not matter to fluorescence.

The Photosynthesis Study was part of the package of parallel study activities needed for assessment of the FLEX candidate mission.

To read or download the Final Project Report, see below.

To read about the follow-up FLEX Bridge Study, click here.

You can visit the ESA FLEX Project Page by clicking HERE.

   Photosynthesis Study Project – Final Report