Photosynthesis is the only process that allows the conversion of atmospheric carbon (CO2) to organic (solid) carbon, and this process plays an essential role in climate models. This lead researchers to study the sun-induced chlorophyll fluorescence (i.e., chlorophyll fluorescence that uses the Sun as illumination source; the glow of a plant) as an indicator of photosynthetic efficiency of a region. This is interesting for scientists since its shows them things like the CO2 absorption of a forests, or the productivity of an agricultural region. The FLEX (satellite) is the upcoming satellite program by the European Space Agency designated to this type of measurements.