The Earth Photosynthesis Imaging Constellation: Measuring Photosynthesis with a cubesat platform

In response to NASA's Earth Venture Instrument-2 call, we proposed the Earth Photosynthesis Imaging Constellation (EPIC) mission. With EPIC, we will, for the first time, be able to provide the scientific community with global, spatially, and temporally explicit estimates of Photosynthesis, also known as Gross Primary Production (GPP) directly from satellite observations. Understanding the significance of terrestrial GPP for the global carbon, water, and energy balance, as well as its spatiotemporal dynamics is one of the key goals of Earth system science. Our proposed method is based on first principles of plant physiology and radiative transfer theory and has been demonstrated by the science team members in theoretical and experimental research. We expect EPIC to fundamentally change and improve our understanding of global photosynthesis and provide entirely new avenues for modeling and predicting Earth system behavior globally.The EPIC mission consists of four, 3-axis stabilized 6U CubeSats flown in pairs to enable multi-angle measurements. The two pairs may be launched on the same launch vehicle or on separate vehicles as necessitated by availability and destination orbits. If launched on the same vehicle, the two pairs can be spaced out via differential drag separation within a matter of months. To lower overall spacecraft costs, the CubeSats leverage existing off the shelf technologies as much as possible. Each EPIC spacecraft host an Integrated Vegetation Interferometer Spectrometer (IVIS) instrument. The highly compact IVIS consists of two primary sensors with separate, co-aligned optics: a spatial-heterodyne-spectrometer (IVIS/SHS) and hyperspectral imager (IVIS/HSI). The IVIS/HSI was specifically designed to implement a multi-angle measurement technique to determine the photosynthetic rate of vegetation (hereafter Hall-Hilker technique); the IVIS/SHS is designed to narrowly peer into a Fraunhofer line at high spectral resolution to obtain solar induced chlorophyll fluorescence (hereafter referred to as Joiner-Frankenberg technique). This paper will provide a description of the EPIC mission and science goals, details of the EPIC team, details of the science techniques to be implemented, and demonstrate how the design of the proposed EPIC CubeSat spacecraft and integrated IVIS instrument enable the proposed science at a fraction of the cost of larger systems.