ChemCam obtained approximately 930,000 LIBS spectra from the surface of Mars over the course of 3700 sols (i.e., Martian days since the rover's landing) [17] and is still used almost on a daily basis. While a configuration on the rover's mast offers advantages in terms of optical access to targets at various distances up to several meters around the rover, the necessity of providing sufficient irradiance at these distances requires a powerful laser and a telescopic autofocus system. This requirement makes the instruments much larger and heavier than fixed-focus systems that measure at closer distances. ChemCam, SuperCam, and MarSCoDe weigh approximately 10 kg. For the purpose of the ARCHES project, our goal was to enhance the modular instrument and tool suite of the DLR Lightweight Rover Unit 2 (LRU2). LRU2 is equipped with a robotic arm, enabling the rover to utilize various tools and instruments in the field [18; 19; 20]. Given the arm's capability to precisely move the payload box with the LIBS instrument to the point of interest on a rock, we opted for a fixed-focus approach, where the instrument is placed in direct contact with the target of interest. This approach allowed us to design a compact and low-mass instrument with a long depth of field. The primary objective of the LIBS module is to analyze geomaterials in the field, contributing to the ongoing efforts in preparing rovers with appropriate instrumentation for the in-situ exploration of solar system bodies [20]. In addition to performing exploration tasks on Earth and beyond, including scouting for specific elements of interest for exploitation, a rover equipped with a LIBS instrument can also carry out automated observation and monitoring tasks. This includes routine measurements of rocks or soils before processing, during treatment, and after treatment [21; 22; 23]. To the best of our knowledge, no arm-mounted LIBS instrument has been developed for a rover, either for Earth or extraterrestrial applications. However, such a concept was proposed, for example, by [PERSON] et al. in 2010 [24]. The characteristics of the laser-induced plasma are significantly influenced by ambient atmospheric conditions. LIBS data obtained on a body without an atmosphere, such as the Moon, exhibit notable differences from LIBS data acquired in terrestrial atmospheric conditions or from Martian LIBS data [1; 25; 26]. The plasma's characteristics in a specific environment necessitate the adaptation of flight hardware for a particular mission, taking into account the conditions at the landing site. On Earth, the laser-induced plasma is confined by the terrestrial atmosphere, resulting in a small, spherical, and relatively long-lasting plasma. Additionally, the tail of an incoming laser pulse, which typically lasts several nanoseconds, is absorbed by the evolving plasma plume, preventing the ablation of additional material from the target that would contribute to the plasma. In the absence of ambient atmosphere and, therefore, without confinement, the laser-induced plasma typically takes on a conical shape oriented perpendicular to the surface, with only a small, very bright emitting center close to the sample. Due to the absence of confinement, the plasma expands and decays much faster compared to when confined by an atmosphere. In contrast to terrestrial ambient pressure or vacuum, the low Martian surface pressure allows for an almost ideal trade-off between a relatively high amount of ablated material and strong excitation of the plasma, resulting in a relatively large spherical plasma plume of several millimeters and intense plasma emission. To account for plasma geometry, emission, and lifetime, the optics and detector of the instrument must be designed for the specific environment in which it will be used. A LIBS instrument developed for use on Earth, therefore, differs from flight instrumentation not only in the specifics of LIBS but also in the typical requirements of space instrumentation, such as robustness.