Fluorescence Explorer satellite mission, illustration. The satellite is shown in Earth orbit with photographs showing examples of the types of vegetation growth that it is capable of detecting. The Fluorescence Explorer (FLEX) mission is ESA's eighth Earth Explorer satellite. FLEX will provide global maps of vegetation fluorescence, which can be converted into an indicator of photosynthetic activity. This information will improve understanding of how much carbon is stored in plants and their role in the carbon and water cycles. FLEX was selected by ESA in November 2015, and is expected to be launched by 2022.