Comparing a CubeSat with VIIRS: What we learned from the CUbesat MULtispectral Observing System - CUMULOS

Comparing a CubeSat with VIIRS: What we learned from the CUbesat MULtispectral Observing System - CUMULOS

CUMULOS is a three-camera remote sensing mission flown as a secondary payload on the Integrated Solar Array and Reflectarray Antenna (ISARA) 3U spacecraft. CUMULOS has the goals of researching the use of uncooled commercial infrared cameras for Earth remote sensing and demonstrating unique nighttime remote sensing capabilities in a compact CubeSat form. Three separate cameras comprise the CUMULOS payload: 1) a visible (VIS) Si CMOS camera, 2) a shortwave infrared (SWIR) InGaAs camera, and 3) a longwave infrared (LWIR) vanadium oxide microbolometer. CUMULOS operations commenced on 8 June 2018 following the successful completion of the ISARA mission, and are ongoing at the time of this writing.

Some of the unique contributions from the CUMULOS mission include: 1) operating the first CubeSat uncooled IR payloads – including the first successful flight demonstration of a CubeSat-hosted microbolometer imaging camera, 2) acquisition of science-quality nighttime lights data at 130-m resolution, 3) demonstrating the use of bright stars for on-orbit radiometric calibration of CubeSat payloads, and 4) gathering a number of simultaneous conjunction Earth images with VIIRS on S-NPP and NOAA-20. In addition, the SWIR camera served as the receiver for the first successful CubeSat laser communications crosslink pointing demonstration, at over 2000 km range. It was a highly successful multi-purpose mission.

CUMULOS remote sensing results include images of: cities at night, ship lights (including fishing vessels), oil industry gas flares, serious wildfires, volcanic activity, and daytime and nighttime clouds. The CUMULOS VIS camera has measured calibrated nightlights imagery of major cities at more than 5x the spatial resolution of VIIRS. Wildfires from the 2018 California fire season were imaged with all three cameras, and results highlight the excellent fire imaging performance that can be achieved by small sensors. The SWIR camera has exhibited extreme sensitivity to flare and fire hotspots, and was even capable of detecting airglow-illuminated nighttime cloud structures by taking advantage of the strong OH emissions within its 0.9-1.7 micron bandpass. The LWIR microbolometer has proven successful at providing cloud context imagery for our nightlights mapping experiments, can detect very large fires and the brightest flare hotspots, and can also image terrain temperature variation and urban heat islands at 300-m resolution.

CUMULOS capabilities show the potential of CubeSats and small sensors to perform several VIIRS-like nighttime missions in which wide area coverage can be traded for greater resolution over a smaller field of view. Our presentation will highlight CUMULOS performance exploring these mission areas, and comparisons to VIIRS data, especially simultaneous nadir overpass conjunction collects with S-NPP and NOAA-20. The results from the CUMULOS experiments should be useful in scaling larger, but still very small payloads for weather applications in CubeSat or SmallSat form factors. Three representative image triplets below highlight the capabilities of the extremely compact CUMULOS sensor, which fits into only 1U of spacecraft volume.