CubeSat modules for multispectral environmental imaging from polar orbit

Abstract

This paper describes an approach for addressing potential gaps in continuity of critical weather and other Earth observations begun by SeaWiFS, MODIS and MISR with single band CubeSat imagers that could be used in combination either onboard a single host satellite or in a constellation of small satellites to provide stable, high SNR multispectral measurements. These wide field of view, high SNR imagers are enabled by large format (~4000 element long) ultraviolet-near infrared focal plane assemblies and achromatic wide field of view telescopes. This new class of wide field of view pushbroom imagers offers capability to continue SeaWiFS, MODIS, MISR and, as discussed in a companion paper, DMSP OLS measurements in support of operational weather observations, Earth imaging and Earth science studies. In addition, extension of the spectral response to 350 nm enables supplementing existing and future systems with multispectral observations at near ultraviolet wavelengths of importance to aerosol and ocean color measurements. The large format size of the array and high optical quality wide field of view telescope enable an entire ~3000 km wide MODIS or VIIRS swath to be collected simultaneously by a pushbroom imaging radiometer in polar sun synchronous orbit. The increase in effective integration time made possible by a pushbroom approach versus the whiskbroom imaging approaches of AVHRR, MODIS and VIIRS enables measurements with the required SNR using a telescope aperture so small that the entire instrument can fit on a 3U CubeSat. Small single purpose imager modules like this could be used to supplement much larger systems like VIIRS by providing measurements of scientifically important bands not in VIIRS like the MODIS chlorophyll fluorescence and near-infrared water vapor bands and fill possible gaps in measurement continuity not provided by future systems or resulting from program delays.