Plants grown and sustain themselves through photosynthesis — a seemingly invisible process that converts sunlight into energy. Now, NASA scientists have developed a way to measure photosynthesis from satellites with unprecedented detail.
When plants photosynthesise, they actually re-emit some of the light they absorb as a faint but measurable glow called fluorescence. The more healthy the plant, the greater the amount of light re-emitted. Now, a team from the Goddard Space Flight centre has created maps of fluorescence that are 16 times more accurate than any that have gone before. NASA explains:
The maps were possible due to the development of a new way to identify the very faint fluorescence signal collected by the Global Ozone Monitoring Instrument 2 (GOME-2) instrument on Metop-A, a European meteorological satellite. Acquiring the measurement is complicated by the fluorescence signal mixing with that of sunlight reflected from Earth's surface and clouds, and the absorption of sunlight by gases in the atmosphere.
To identify fluorescence, Joiner and colleagues took advantage of that fact that each of these signals has its own unique spectral signature akin to a fingerprint — whether from fluorescence, Earth's surface or the atmosphere. Match the fingerprint associated with fluorescence and scientists can tease out that data from the rest of the light.
The result: higher quality images that take less time to create. Win, win. The results, of course, as well as being beautiful, are a massive help to the agricultural industry — and could even help us work out where plants could be best placed to take up our excess CO2. [NASA]