Comparing pre- and post-launch images from the HYPSO-1 cubesat hyperspectral imager

Abstract

HYPSO-1, a 6U cubesat carrying a hyperspectral imaging payload for ocean color observation, was launched in January 2022. During the commissioning and validation phases, the satellite and payload performance were tested. The hyperspectral imager, a visible to near infrared pushbroom instrument based on a transmissive grating design and built out of commercial off-the-shelf components, was thoroughly calibrated and characterized prior to launch. During launch, however, the satellite and payload endured strong forces, and tiny movements or changes to the components, particularly the components in the optical train of the hyperspectral imager, can affect the resulting data products. Prelaunch testing showed that sub-millimeter shifts of optics spacing and component orientation resulted in measurable performance degradation. Careful on-orbit calibration and validation is therefore important to understand the data and its limitations. Here we present the observed changes in the recorded raw spectrograms between data gathered during the pre-launch calibration campaign and data from the post-launch validation campaign. Most noticeable is a spatial shift of 7 pixels, most likely due to movement of the slit, and a smudge appearing on the spectrograms at about 500 nm. In addition, an example of correction by destriping is shown to account for the spatial shift.