Miniaturized Laser-Induced Breakdown Spectroscopy for the in-situ analysis of the Martian surface: Calibration and quantification

Abstract

Wereport on our ongoing studies to develop Laser-Induced Breakdown Spectroscopy (LIBS) for planetary surface missions toMars and other planets andmoons, like Jupiter'smoon Europa or the Earth'smoon. Since instruments for space missions are severely mass restricted, we are developing a light-weight miniaturized close-up LIBS instrument to be installed on a lander or rover for the in-situ geochemical analysis of planetary surface rocks and coarse fines. The totalmass of the instrumentwill beâ��1 kginflight configuration.Herewe report on a systematic performance study of a LIBS instrument equipped with a prototype laser of 216 g total mass and an energy of 1.8 mJ. The LIBSmeasurementswith the prototype laser and the comparativemeasurementswith a regular 40 mJ laboratory laser were both performed under Martian atmospheric conditions. We calibrated 14 major and minor elements by analyzing 18 natural samples of certified composition. The calibration curves define the limits of detection that are N5 ppmfor the lab laser and N400 ppmfor the prototype laser, reflecting the different analyzed samplemasses ofâ��20 �¼g andâ��2 �¼g, respectively. To test the accuracywe compared the LIBS compositions, determined with both lasers, of Mars analogue rocks with certified or independently measured compositions and found agreements typically within 10â��20%. In addition we verified that dust coverage is effectively removed from rock surfaces by the laser blast. Our study clearly demonstrates that a close-up LIBS instrument (spot sizeâ��50 �¼m) will decisively enhance the scientific output of planetary lander missions by providing a very large number of microscopic elemental analyses.