Revisiting the preprocessing procedures for elemental concentration estimation based on chemcam libs on mars rover

Abstract

The ChemCam instrument package on the Mars rover, “Curiosity”, is the first planetary instrument that employs laser-induced breakdown spectroscopy (LIBS) to determine the compositions of geological samples on another planet. However, the sampled spectra are often corrupted by various sources of interferences that would largely affect the accuracy of elemental concentration estimation. Therefore, preprocessing is essential to improve the quality of the spectra. This paper revisits the conventional preprocessing procedures where denoising is followed by continuum removal. Through comprehensive performance evaluation, we propose a new procedure that would lead to much improved estimation accuracy. First, we show that the denoising process should be conducted after continuum removal. Second, a state-of-the-art image denoising technique is adapted to the 1D domain to boost the performance of denoising. Third, an additional preprocessing step is added that effectively select the most informative spectral bands. All these approaches have largely improved the accuracy of concentration estimation with band selection being the most effective.