In-situ wavelength calibration without a calibration target: use of Fraunhofer lines after landing on planetary surface

TL;DR

This paper introduces a novel in-situ wavelength calibration method for planetary spectrometers that uses solar Fraunhofer lines in reflected spectra, eliminating the need for onboard calibration sources.

Contribution

The study proposes and validates a calibration technique based on solar Fraunhofer lines, achieving high accuracy without additional calibration hardware.

Findings

Calibration accuracy better than 0.6 cm-1

Magnesium abundance estimation more accurate than 2%

Applicable to visible Raman spectrometers in planetary exploration

Abstract

Accurate wavelength calibration is critical for qualitative and quantitative spectroscopic measurements. Many spectrometers for planetary exploration are equipped with onboard calibration sources. However, such calibration sources are not always available because planetary lander missions often have strong limitations in size and mass. In this study, we propose and validate a wavelength calibration method using solar Fraunhofer lines observed in reflective spectra. As a result, for a visible Raman spectrometer, the accuracy is better than 0.6 cm-1 in 0-4000 cm-1 range, and the magnesium abundance of olivine is estimated more accurately than 2%.