The interest in exploring planetary bodies for scientific investigation and in situ resource utilization is ever-rising. Yet, many sites of interest are inaccessible to state-of-the-art planetary exploration robots because of the robots’ inability to traverse steep slopes, unstructured terrain, and loose soil. In addition, current single-robot approaches only allow a limited exploration speed and a single set of skills. Here, we present a team of legged robots with complementary skills for exploration missions in challenging planetary analog environments. We equipped the robots with an efficient locomotion controller, a mapping pipeline for online and postmission visualization, instance segmentation to highlight scientific targets, and scientific instruments for remote and in situ investigation. Furthermore, we integrated a robotic arm on one of the robots to enable high-precision measurements. Legged robots can swiftly navigate representative terrains, such as granular slopes beyond 25°, loose soil, and unstructured terrain, highlighting their advantages compared with wheeled rover systems. We successfully verified the approach in analog deployments at the Beyond Gravity ExoMars rover test bed, in a quarry in Switzerland, and at the Space Resources Challenge in Luxembourg. Our results show that a team of legged robots with advanced locomotion, perception, and measurement skills, as well as task-level autonomy, can conduct successful, effective missions in a short time. Our approach enables the scientific exploration of planetary target sites that are currently out of human and robotic reach.

Future human missions to the surface of the Moon and Mars will involve scientific exploration requiring new support tools to enable rapid and high quality science decision-making. Here, we describe the PANGAEA (Planetary ANalogue Geological and Astrobiological Exercise for Astronauts) Mineralogical Database developed by ESA (European Space Agency): a catalog of petrographic and spectroscopic information on all currently known minerals identified on the Moon, Mars, and associated with meteorites. The catalog also includes minerals found in the analog field sites used for ESA's geology and astrobiology training course PANGAEA, to broaden the database coverage. The Mineralogical Database is composed of the Summary Catalog of Planetary Analog Minerals and of the Spectral Archive and is freely available in the public repository of ESA PANGAEA. The Summary Catalog provides essential descriptive information for each mineral, including name (based on the International Mineralogical Association recommendation), chemical formula, mineral group, surface abundance on planetary bodies, geological significance in the context of planetary exploration, number of collected VNIR and Raman spectra, likelihood of detection using different spectral methods, and bibliographic references evidencing their detection in extraterrestrial or terrestrial analog environments. The Spectral Archive provides a standard library for planetary in-situ human and robotic exploration covering Visual-Near-Infrared reflective (VNIR) and Raman spectroscopy (Raman). To populate this library, we collected VNIR and Raman spectra for mineral entries in the Summary Catalog from open-access archives and analyzed them to select the ones with the best spectral features. We also supplemented this collection with our own bespoke measurements. Additionally, we compiled the chemical compositions for all the minerals based on their empirical formula, to allow identification using the measured abundances provided by LIBS and XRF analytical instruments. When integrated into an operational support system like ESA's Electronic Fieldbook (EFB) system, the Mineralogical Database can be used as a real-time and autonomous decision support tool for sampling operations on the Moon, Mars and during astronaut geological field training. It provides both robust spectral libraries to support mineral identification from instrument outputs, and relevant contextualized information on detected minerals.

<ul> <li><strong> </strong><strong>Introduction</strong></li> </ul> <p> </p> <p><img src="" alt="" /></p> <p>Figure 1: Rosalind Franklin rover . (a) CLUPI on the drill box (red rectangle, Image credit ESA/SEI-TJ). (b) CLUPI flight model representative (EM+) mounted in the stowed drill configuration, Image credit SEI.</p> <p>Therefore, for this scientific goal, the objective is to reconstruct topographical and 3D data from the CLUPI data, using specific CLUPI operating configurations. This project is in collaboration with the Laboratoire d’Astrophysique de Marseille (LAM, France).</p> <ul> <li><strong> </strong><strong>3D and stereo with CLUPI</strong></li> </ul> <p>CLUPI 8 configurations are linked to the drill box positions (Fig.2, Josset et al., 2017). In order to constrain the topographical data from the images acquired by CLUPI we will used the stereogrammetry method (Beyer et al., 2018). To perform that we need several images of the same geological target but with different stereo-angle (i.e. the angle between the target and CLUPI in the target repository (Fig.3)). CLUPI is a mono optics camera system. Thus, the different shots resulting in different stereo angles will come from the movement of the drill box and/or the rover itself. So, the main question of this project is how to define the optimal geometries parameters to obtain stereo images of the same target according to the 8 CLUPI operating configurations?<strong> </strong></p> <ul> <li><strong> </strong><strong>Experimentation and preliminary result</strong></li> </ul> <p>In order to simulate the operation environment of CLUPI, we are using the EM+ flight model representative in the Space Exploration Institute CLUPI science operation lab based in Microcity, Neuchâtel, Switzerland. The CLUPI EM+ is adapted on a geometric drill simulator, corresponding to the ExoMars Rover mission (Josset et al., 2017). The objectives of this experimentation are to (1) recreate the CLUPI operating configurations, (2) vary parameters such as: the angle of incidence, the working distance and the CLUPI height relative to the ground; the illumination (studied in Marslabor, University of Basel; Bontognalli et al., 2021), and (3) derived the best geometrical position of the rover in order to reconstruct topographical data (Fig.3a).</p> <p><img src="" alt="" /></p> <p>Figure 2: CLUPI eight operational configurations. (a) On the platform, (b) geological environment survey, (c) Close-up outcrops observation, (d) drilling area observation, (e) drilling operation observation, (f) Drill hole and fines observation, (g) drilled core sample observation and (h) calibration: calibration target imaging. Images credit: ESA/SEI-TJ</p> <p> </p> <p><img src="" alt="" /></p> <p>Figure 3: Experiment with the EM+. (a) Simulation of the second configuration. (b) Simulation of the second configuration after the calculated translation and rotation of the "rover", with a stereo angle (red) and the same working distance (yellow). The green and blue points correspond, respectively to the EM+ position before and after the translation/rotation.</p> <ul> <li><strong> </strong><strong>Illumination study (Basel University)</strong></li> </ul> <p>The total light and direction of incidence light plays an important role in allowing the identification of different rock textures, morphological features, and mineralogical distribution. The effect of different solar angles in relation to the target rock is studied with  CLUPI analogue camera - Canon EOS M50. The most recent results show that to identify sedimentary structures, such as cracks, laminations and other morphological features in sedimentary rocks, the lower angle of 25° of direct light is preferable (sunset conditions on Mars, Fig.4a, c). In contrast, the distribution of the minerals within the rock, the incident/direct light shall be around 70° to the rock surface (mid-day conditions on Mars, Fig.4b,d).</p> <p><img src="" alt="" /></p> <p>Figure 4. Close-up images in third configuration of basaltic tuff (A&B) and dry cracks in sedimentary rock (C&D) taken with Canon EOS M50 in Marslabor at University of Basel. (a) and (c)  direct light of the angle 25 °. (b) and (d) direct light of an angle 70 °. Each to the rock surface. The total proportion of the light was 5:1 of direct and diffused light - 5000 LUX and 1000 LUX respectively, after Bontognali et al., 2021. With a working distance of 650 mm and camera angle of 11 °. (e) and (f) are anaglyph made from basaltic tuff (a) and (b) and dry cracks in sedimentary rock with the Canon, 25° light angle and a working distance of 760 mm.</p> <ul> <li><strong> Stereo and 3D study (Space Exploration institute, Neuchâtel)</strong></li> </ul> <p>Currently, we succeed to define the optimal positions, with respect to configuration 2 and 3.  For the configuration 2, the images with different stereo angle come from a translation then a rotation of the rover (Fig.3). The stereo images from the configuration 3 come from the different drill positions. In these two cases, the calculated positions make it possible to keep the same working distance despite the movements. This point is particularly important to reconstruct the topography rigorously.</p> <p> We also reconstruct the firsts 3D anaglyphs based on the third configuration (Fig.4e, f and Fig.5).</p> <ul> <li><strong> </strong><strong>Conclusion and acknowledgment:</strong></li> </ul> <p>These study and related experiments consisting in varying the following parameters: the angle of incidence, the illumination, the working distance, the height relative to the ground, allows to faithfully reproduce the CLUPI operations configurations. These first results are promising since we succeed to define the geometrical parameters optimally to derive the topography data for 2 configurations. We will continue to investigate on the other configurations to quantify the rock morphometry recorded in the rock matrix. These steps are essential to significantly increase the science exploitation of CLUPI. The authors want to acknowledge the Swiss National Science Foundation (Subside 200021_197293/1), who is funding this project with the support of the Swiss Space Office and ESA Prodex.</p> <p><img src="" alt="" /></p> <p>Figure 5: Anaglyph of a stromatolite performed in the SEI/Lab using CLUPI Flight Model Representative in the third configuration with a working distance of 1 m and a stereo angle of 10°. Images credit: SEI.</p> <p><strong><em>References: </em></strong></p> <p>Beyer, R. A., Alexandrov, O., & McMichael, S. 2018, Earth and Space Science, 5, 537– 548.</p> <p>Bontognali, T., Meister, Y., Kuhn, B., et al., 2021, Planetary and Space Science, 208, 2021, 105355</p> <p>Bouquety, A., Sejourné, A., Costard, F., et al., 2019, Geomorphology, 334, 91</p> <p>Bouquety, A., Sejourné, A., Costard, F.,  et al., 2020, Geomorphology, 350, 106858</p> <p>Bouquety, A., Jorda, L., Groussin, O., et al. 2021, Astronomy & Astrophysics,649, A82</p> <p>Bouquety, A.,Groussin, O., Jorda, L.,  et al. 2022, Astronomy & Astrophysics: https://doi.org/10.1051/0004-6361/202142417</p> <p>Josset, J.-L., Westall, F., Hofmann,  et al., 2017. Astrobiology 17, 595–611.</p>

<p>ExoMars is an astrobiology program led by the European Space Agency, which aims to launch a rover to Oxia Planum to search for signs of past life. Although the primary goal of the mission is focused on astrobiology, there are several secondary mission objectives, such as investigating the geomorphology, aeolian and volcanic processes to better understand the evolution and paleoclimate of Mars. CLUPI (a close-up imager) will be used to acquire high-resolution images of rocks, geological outcrops, and drill cores to provide the overview on the geology of Oxia Planum. Due to the limited amount of data that can be transmitted at once from Mars, only few CLUPI images will be available daily to the science team for assessing hypotheses and decide how to program the rover of the next cycle of activities. Thus, it is curial that each CLUPI image will contain a maximum of relevant information. For this reason, we are conducting preparatory tests and simulations to identify ideal CLUPI working conditions in view of the prime mission on Mars. In this work, we specifically explored the impact that different illumination conditions (i.e., direction of the illumination axis and intensity of direct light vs diffused light) may have on the detection of textures and sedimentary structures in close-up images. We showed that by acquiring images at different type of day, under specific lighting conditions, it is possible to enhance the probability of detecting various rock textures and geological samples, which can contribute to the diverse data collection and answer main question about the geomorphology of Oxia Planum.</p>