Advancing LIBS for geochemical micro-mapping with lightweight prototype scanner

Kurzfassung

Understanding the geological history of planetary surfaces profits from linking the chemical composition of samples to their texture at fine scales. In the context of planetary exploration, this has been demonstrated, for example, by the mapping x-ray fluorescence instrument PIXL onboard NASA's rover Perseverance [1,2,3].

Another technique that has proven valuable for in-situ elemental analysis on the Martian surface is Laser-Induced Breakdown Spectroscopy (LIBS) [4,5,6,7]. By focusing a pulsed laser beam onto a target, a small plasma is generated whose emission spectrum yields information on major and minor elements including light elements such as H. LIBS requires no sample preparation, removes surface dust, and can be operated at standoff distances of several meters.

While the first generation of planetary in-situ LIBS instruments [4,5,6,7] were designed for point-to-point analysis at several meters, current efforts focus on developing LIBS instruments capable of resolving submillimeter heterogeneity by performing multiple LIBS measurements in a raster [8,9] at smaller working distances.

As a partner for the µLIBS development led by CNES and IRAP [8,9], DLR developed a particularly lightweight scanning unit (<130 g) to acquire dense elemental grids on geological samples at sub-millimeter resolution. The main drivers for the design were the low mass and volume budgets. The DLR scanner prototype allows for 2D scanning by using a two-axes configuration and was developed to TRL6 for Mars in 2024.

Here, we show its integration into a LIBS setup with an imager and a vacuum chamber to simulate extraterrestrial low pressure environments analog to Mars or airless bodies. The configuration of the setup is described and first measurements obtained on a natural heterogeneous rock are reported.