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Exposure experiments of different species to space conditions are essential because real space conditions with different radiation sources like ionizing radiation, UV-radiation, X-rays, gamma-ray from even galactic radiation, vacuum and space weathering by micro-dust cannot simultaneously be simulated in parallel even in our best simulation chambers on Earth. We need results from experiments under real space conditions to enable the development of appropriate predictions about the stability of organisms and their constituent organic parts. The extremophile lichen Circinaria gyrosa is one of the selected species within the BIOMEX (Biology and Mars Experiment) experiment and in this work we compare the previous Raman results obtained in this lichen [1] with the corresponding Raman results on the lichen Xanthoparmelia hueana. Both species have been exposed to space and simulated Mars-like conditions in planetary chambers and we have studied and identified possible degradation process in different layers and biomarkers. The analysis by Raman spectroscopy of simulated Space and Mars exposed samples confirm alterations and damages of the photobiont part of the lichen and changes related to the molecular structure of whewellite. The conclusions of this work will be important to understand what are the effects to consider when biological systems are exposed to space or Mars-like conditions and to expand our knowledge of how life survives in most extreme conditions that is a prerequisite in future planetary exploration projects.Acknowledgment Support for this work was provided by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO), by the project BIOindicadores en MARTE y Espacio (BIOMARSS) (PID2019-109448RB-I00) and by INTA. References [1] M.R. Lopez Ramirez, L.G Sancho, J. P. de Vera, M. Baqué, U. Böttcher, E. Rabbow, J. Martínez-Frías, R. de la Torre Noetzel. Spectrochimica Acta, Part A. 261 (2021) 120046. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Exploration of the solar system, needs science and technology support to work at a merged way. Space platforms, such as EXPOSE, are a priority for the performance of experiments which are focused on the exploration of the limits of terrestrial life, trying to get responses to some questions, such as the 1) survival capacity of biological organisms in space, 2) the effects of space environment on no protected biological and chemical material and 3) results of degradation of organic molecules (biomarkers), that will support the interpretation of missions, such as Rosetta, ExoMars and Curiosity). Some priority scientific objectives for the next 10 years are focused on "Life and habitability" and "Biomarkers for detection of extraterrestrial life", what is belonging to the main aims of BIOMEX (Biology- and Mars Experiment, 2014-2016, ESA) [1,3], experiment performed on the exposure platform EXPOSE-R2 on board of ISS.

Exploration of the solar system is a priority research area of the AstRoMap European Astrobiology Roadmap (Horneck et al., 2015) [1], focused on various research topics, one of them is “Life and Habitability” and an other one is “Biomarkers for easy the detection of life”. Therefore “space platforms and laboratories” are necessary, such as EXPOSE, to gain more knowledment of space- and extraterrestrial habitats, eventually for human interplanetary exploration (Space, Moon, Mars, Encedalus, Titan, Europa). At the exposure platform EXPOSE-R2 on ISS (2014-2016), samples of the astrobiological model system Circinaria gyrosa gyrosa [3,4,5,6], belonging to the BIOMEX experiment [2], (Biology and Mars Experiment, ESA), were exposed during 18 months to space and to a Mars simulated environment, to study Mars habitability and resistance to space conditions. The data obtained by the investigation on biomarkers after being exposed to Mars-like conditions will support the analysis of data obtained during future instrumental detection operations in future space missions on Mars (i.e. ExoMars). After the return of the samples in June 2016, the first preliminary analysis showed a quick and complete recovery of metabolic activity of the control samples exposed to space vacuum and Mars-like atmosphere. In contrast, the samples directly exposed to extraterrestrial UV solar radiation showed slow recovery, in reference to their observed original activity. Here we expose the last results that show the biomolecular changes of the DNA analized by PCR and complementary sequencing techniques, in correlation with the previous results supporting changes in metabolic activity, and changes in viability (Electron- and fluorescence microscopy techniques), as well as in morphology/ultrastructure due to space vacuum and Mars atmosphere. Additionaly, the biogeochemical variations have been examined with spectroscopic analyses (Raman) to look for possible degradation of cell surfaces and pigments which were in contact with terrestrial rocks, and Martian analogue regolith. Moreover, differences were observed between samples irradiated with extraterrestrial UV solar radiation and samples positioned below defined as dark-control samples. These experiments will contribute to answer questions on the habitability of Mars, on the likelihood of the Lithopanspermia Hypothesis and will be of relevance for planetary protection issues.

Exploration of the solar system is a priority research area of the AstRoMap European Astrobiology Roadmap, focusing on several research topics, such as “Life and Habitability” andan other one is “Biomarkers for easy the detection of life”. Therefore, “space platforms and laboratories”, as the EXPOSE setup installed outside the ISS, are essential to gain more knowledge of spaceand planetary environments, which might be an essential basis for improvement of the robotic and human interplanetary exploration. At the exposure platform EXPOSE-R2 on the ISS (2014-2016), samples of the astrobiological model lichen Circinaria gyrosa, a specie which was exposed 18 months to space and simulated Mars-like conditions during the BIOMEX experiment (Biology and Mars Experiment, ESA), was investigated, to study Mars’ habitability and resistance to space conditions. The data obtained by this biomarker-study after being exposed to Marslike conditions will support the analysis of data obtained during future instrumental detection operations in future space missions on Mars (i.e. ExoMars or Mars 2020). N/A

Ground simulation tests are necessary for selection of the most promising biological organisms for flight experiments in Low Earth Orbit or other space destinations: Simulation of the environmental parameters of the mission, as well as of sample assembly and disassembly, need to be performed, allowing the qualification of the experiment and facilitating the post-flight analysis of the exposed biological material and thus, a deeper understanding of the individual and synergistic effects of space. This work is a presentation of the results obtained with the lichen species Circinaria gyrosa, after the Experiment Verification tests (EVT) and Space Verification tests (SVT) in the frame of the EXPOSE-R2 Mission Preflight Test Program, performed at DLR (Cologne, Germany), as part of the EXPOSE-R2 Mission Preflight Test Program. The high vitality and resistance capacity of C. gyrosa, demonstrated with the PSII values measured after reactivation in the laboratory and the CLSM (Confocal Laser Scanning Microscopy) results confirm the high survival potential of these species to space and Mars conditions, taking part of the BIOMEX experiment (Biology and Mars Experiment, EXPOSE R-2, ISS, 2016-2018) and contributing to our understanding of extremotolerance and the Lithopanspermia hypothesis.