Ocean Color Hyperspectral Remote Sensing With High Resolution and Low Latency-The HYPSO-1 CubeSat Mission

• Published in: IEEE transactions on geoscience and remote sensing Vol. 60; pp. 1 - 19
• Main Authors: Grotte, Mariusz E., Birkeland, Roger, Honore-Livermore, Evelyn, Bakken, Sivert, Garrett, Joseph L., Prentice, Elizabeth F., Sigernes, Fred, Orlandic, Milica, Gravdahl, J. Tommy, Johansen, Tor A.
• Format: Journal Article
• Language: English
• Published: New York IEEE 2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algal blooms; Algorithms; Coastal zone; Color; Compression; Cubesat; Eutrophication; Ground stations; High resolution; Hyperspectral imaging; HYPerspectral Smallsat for Ocean observation (HYPSO-1); Image color analysis; Image processing; Latency; Mission planning; Modular design; Ocean color; Ocean colour; onboard processing; Orbits; Pixels; Radiance; Remote sensing; Resolution; Satellite buses; Satellites; Sea measurements; Seawater; Signal to noise ratio; Small satellites; space optics; Space vehicles; Spatial discrimination; Spatial resolution; Swath width; Wavelengths
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/TGRS.2021.3080175

Sporadic ocean color events with characteristic spectra, in particular algal blooms, call for quick delivery of high-resolution remote sensing data for further analysis. Motivated by this, we present the mission design for HYPerspectral Smallsat for Ocean observation (HYPSO-1), a 6U CubeSat at 500 km orbital altitude hosting a custom-built pushbroom hyperspectral imager with wavelengths 387-801 nm at 3.33 nm bandpass and a swath width of 70 km. The imager's expected signal-to-noise ratio is characterized for typical open ocean water-leaving radiance which can be flexibly increased by binning pixels. Using geometric principles, the satellite shall execute a slew maneuver during a scan to induce greater overlap in the pixels with a goal to enable better than 100 m spatial resolution. Since high-dimensional hyperspectral data need to be transmitted over limited space-to-ground communications, we have designed a modular FPGA-based onboard image processing architecture that significantly reduces the data size without losing important spatial-spectral information. We justify the concept with a simulated scenario where HYPSO-1 first collects numerous hyperspectral images of a 40 km by 40 km coastal area in Norway and aims to immediately transfer these to nearby ground stations. Using CCSDS123 lossless compression, it takes about one orbital revolution to obtain the complete data product when considering overhead in satellite bus communications and less than 10 min without the overhead. It is shown that even better latency can be achieved with more advanced onboard processing algorithms.