The European Space Agency (ESA) has announced plans to build and send into orbit a satellite to measure the faint glow that plants give off as they photosynthesize. The new satellite will join a series of missions that already measure and study the biological systems that control our planet. Known as the Fluorescence Explorer – or FLEX – the spacecraft will be the eighth installment in the organization's Earth Explorer missions to be given the go-ahead by ESA member states.
Expected to launch in 2022, the satellite is anticipated to yield important data on plant health, helping scientists to understand how carbon moves through ecosystems as well as how photosynthesis impacts the carbon and water cycles. It will do this by using a spectrometer to measure the faint fluorescence that plants emit when they photosynthesize. It will work in conjunction with the Copernicus Sentinel-3 satellites, which will use optical and thermal sensors to provide additional measurements.
As plants photosynthesize – turning sugar, water, and CO2 into energy – they emit tiny amounts of light. Other satellites have been able to detect this, as it radiates from vegetation in wavelengths between 640 and 800 nanometers, but FLEX will be far more sensitive to these emissions. This will allow scientists to track the health of croplands and forests, measuring if they are stressed or pushed to the limit by looking at the efficiency of the plants' photosynthesis. They hope it will help our understanding of how to feed a growing global population.
“FLEX will give us new information on the actual productivity of vegetation that can be used to support agricultural management and the development of a sustainable bioeconomy,” explains Jan Woerner, ESA’s director general, in a statement. “It will therefore help to understand our ecosystem. With the selection of the FLEX mission, ESA Member States have continued to show their determination to provide essential data to the scientific community to better understand our planet while at the same time serving society.”
The Earth Explorer missions have been running since 2009, and include a range of spacecraft measuring a variety of the Earth’s processes. GOCE, for example, looks at the Earth's gravitational field, whilst SMOS measures ocean salinity and soil moisture. Others are designed to calculate the thickness of the polar ice caps, how the wind moves around the globe, and another is effectively weighing the carbon stored in the planet’s forests.