The GeoPrep Experiment – Optimizing the Process to Select Geological Samples for A Return to Earth: The analysis of rock samples allows us to unravel the history of a terrestrial planet. This includes its accretion, the tectonic and magmatic processes that shape its interior, and the processes that shape its surface morphological features. Because rocks can store information on the conditions of planetary formation and evolution, the study of the textural, mineralogical and geochemical properties of Martian rocks will be the key for convincing evidence for the existence of a Martian biosphere and the conditions of its emergence and vanishing. During a first manned mission to Mars, the availability of on-the-ground equipment to analyze rocks in a field lab will undoubtedly be severely limited. Therefore, any strategy to comprehensively analyze rock samples from Mars will necessarily involve a return of selected samples to Earth. In order to optimize the selection process of samples to be sent back to Earth, we designed the GeoPrep experiment, which aimed to answer the question, if it is possible to set up a rock sample preparation facility in a Martian field lab using a technical and operational approach as simple as possible to produce thin sections suitable for transmitted light microscopy.

During the Amadee-24 mission, six different sedimentary rock samples were selected and prepared by the crew. At the end of the mission, one of the rock samples was also professionally prepared in a sample preparation lab for comparison.

Initial results show that the quality of the thin sections could be further improved. However, already in this first test trial, thin sections prepared by the analogue astronauts are of great quality that enables, for example, the identification of microfossils and the recognition of textural features. Based on these very positive first results, the next step should be to refine the preparation method. At the same time, the minimum quality required for sample selection with regard to specific scientific questions should be evaluated.

Source: Bastian Joachim-Mrosko¹, Jürgen Konzett¹, Daniel Sperlich¹, Dominik Jäger¹, “The GeoPrep Experiment – Optimizing the Process to Select Geological Samples for A Return to Earth”, AMADEE-24 Science Workshop Booklet 2024

¹ University of Innsbruck, Institute of Mineralogy and Petrography