MERTIS - Shutterless Background Signal Removal

Abstract

MERTIS (MERcury Thermal infrared Imaging Spectrometer) is an advanced infrared remote sensing instrument that is part of the ESA mission BepiColombo to planet Mercury. The enabling technology that allows sending the first spectrometer for the thermal infrared spectral range to Mercury is an uncooled microbolometer. One of the challenges is the calibration of the instrument. Radiometric and spectroscopic breadboard models of MERTIS were used to develop proper calibration methods. In the context of the calibration we are reporting on the ongoing efforts to separate non-scene and scene signal portions from each other. The non-scene signal portion is contained in the raw image data sets and is usually the dominating signal contribution. The conventional method to measure the non-scene signal contributions using a shutter or space-view and perform a time-interpolation is compared to an approach using linear pixel-to-pixel relations in which information from the outer regions of the image matrix is used for the estimation of the non-scene signal components of the inner regions where additional scene signal components exist. The results of both methods are discussed in terms of noise or errors of the extracted scene information. The proposed method could be used without further instrument modifications offering a functional redundancy which is important to keep alive the MERTIS operation in the case of a breakdown of the mechanically stressed high-speed shutter device.