Invention:
This invention discloses a high resolution spectrometer (resolving power >20,000) that can resolve individual Fraunhofer absorption lines in the solar spectrum. When in Earth orbit the image of the surface on the entrance slit of the spectrometer is swept along perpendicular to the spacecraft motion such that the ground resolution along the slit equals the forward motion of the slit in a single integration time. The solar absorption lines are so deep that the spectrometer with its high signal to noise ratio can sense the emitted fluorescence caused by photons released during photosynthesis (1-2% of the reflected sunlight). Directly sensing plant fluorescence and therefore, sensing photosynthesis in action allows for the rapid measurement of plant health and the effects of various stressors on the fixation of carbon into the plant structure.
Background:
Plant fluorescence and the advantages of sensing it using Fraunhofer lines has been known for years, however, the challenge has been to design an instrument that can measure the faint signals in the presence of full sunlight from space orbit. Space measurements to date have used only a few solar absorption lines or an oxygen absorption band near 760 nm, which does not allow for significant clarity or area of sensing.
Applications:
- Could be used to produce global maps displaying areas of severe impact from environmental stressors like global warming, wild-fires, and poor agricultural techniques
Advantages:
Demonstrated to be superior to the state-of-the-art in theory, simulations, and using real data. Our simulation results show orders of magnitude in improvement, as compared to traditional methods. Real results from data closely replicate the performance of our simulations.
- Can identify the entire fluorescent spectrum from 650-800 nm
- Can produce a surface resolution of <4 km
- Full spectrum scanning can provide additional information about the impact of plant stresses on photosynthesis
- Can be used from space to identify much greater areas at a greater detail
