Ákos Kereszturi

IntroductionOlympia Undae, in the north circumpolar region of Mars, is one of the largest dune fields on the planet and a key site for investigating the interaction between aeolian transport, sediment availability and local relief. Dune morphology in this region records both the regional circumpolar circulation and local perturbations caused by topographic obstacles [1,2]. In addition to its dune field, Olympia Undae contains non-impact landforms including Simple Domes (SD) and Irregular Structures (IS), which locally modify airflow and sediment redistribution [3–5] (Fig. 1). These edifices provide natural markers to analyse how topography controls dune distribution and inferred near-surface wind regime.Data and methodologyThis study focuses on the 6 Simple Domes and 5 Irregular Structures identified in Olympia Undae [3–5]. The analysis combines MOLA topography, HRSC/MOLA digital terrain models, orbital imagery, and GIS-based morphometric analysis using tools such as JMARS [3–5]. Dune distribution on and around each structure was compared with local altitude and slope in order to evaluate the topographic control on sediment accumulation and mobility.The methodology is based on a structured analysis of elevation (h) and slope (S) derived from HRSC/MOLA DEM data, organised on a spatial grid (latitude–longitude) (Fig. 2), allowing the extraction of morphometric gradients and their relationship with dune occurrence.Two diagnostic parameters are defined and applied: the critical altitude and the limiting slope. The critical altitude corresponds to the elevation above which dunes become scarce or absent and is computed from altitude gradients (dh/dx) using percentile thresholds (typically absent and identify significant topographic transitions associated with changes in wind behavior. The limiting slope represents the maximum terrain inclination allowing dune mobility and is derived from slope distributions using a similar percentile-based approach. This value is defined by identifying from which slope values of moving dunes surfaces are usually uncommon under normal conditions [5].Both parameters are calibrated using dune distribution and morphology, including crest orientation and dune type, and their spatial relationship with HRSC/MOLA-derived elevation and slope data, allowing a direct link between topographic forcing and inferred wind regime.ResultsThe results show that dune distribution around the SD and IS of Olympia Undae is markedly asymmetric and strongly controlled by local topography. As expected, dunes preferentially accumulate on low-slope flanks and sheltered sectors, whereas summit areas and more exposed sectors tend to be dune-free or to show reduced sediment cover. This confirms that the edifices locally modify near-surface airflow and sediment transport pathways [5].IS-01 is one of the catalogued Irregular Structures shown in Fig. 1 [3,4]. With an overall relief of approximately 423 m, it clearly illustrates this pattern (Fig. 3). Above an altitude of –4727.8 m, the presence of dunes decreases sharply, defining a critical threshold. The same structure shows a limiting slope of about 1.021° [5]. However, summit slopes are below 1°, indicating that the lack of dunes cannot be explained by slope alone. Instead, this is interpreted as the effect of wind interaction and turbulence over the summit, which prevents sediment accumulation, whereas the flanks favour belts of linear dunes [5].Other edifices confirm that the topographic effect is systematic, although expressed differently according to morphology. In IS-04, the calculated values are –4742.2 m for critical altitude and 1.485° for limiting slope [5]. Because of its irregular shape and internal slope variability, part of the structure remains covered by dunes. Its surface includes linear dunes aligned NW–SE, barchans in transition to barchanoids, and curved dune patterns that suggest local variations in wind intensity and direction superimposed on the dominant circumpolar flow [1,2,5] (Fig 4).The SD also records this coupling between topography and wind. In SD-01, transverse dunes, barchanoids and barchans occur on different sectors of the edifice. The main inferred wind direction is NW–SE, in agreement with the regional circumpolar circulation, while a secondary NE–SW component is indicated by oblique crests in the eastern and southern sectors [1,2,5]. The relief appears to promote sectorial sediment trapping and differential erosion.Summary and ConclusionsThe simple domes and irregular structures of Olympia Undae act as local topographic obstacles capable of reorganising dune distribution and modifying the local expression of the regional wind regime. The combined use of critical altitude and limiting slope provides a useful framework to identify where dunes can form and where sediment transport is inhibited by wind–topography interaction [5].The observed asymmetries in dune occurrence, the concentration of mobile dunes below critical thresholds, and the contrast between exposed summit areas and sediment-rich flanks indicate that local relief exerts a first-order control on aeolian redistribution at the scale of individual edifices. The results support the interpretation that dune patterns around the SD and IS of Olympia Undae can be used to infer local atmospheric circulation in the Martian polar environment [1,2,5].References[1] Ewing, R. C., Peyret, A. P. B., Kocurek, G., and Bourke, M.: Dune field pattern formation and recent transporting winds in the Olympia Undae dune field, north polar region of Mars, J. Geophys. Res. Planets, 115, E08005, 2010.[2] Rubanenko, L., Gunn, A., Pérez-López, S., Fenton, L. K., Ewing, R. C., Soto, A., and Lapôtre, M. G. A.: Global surface winds and aeolian sediment pathways on Mars from the morphology of barchan dunes, Nat. Astron., 7, 1037–1047, 2023.[3] Sánchez-Bayton, M., Herraiz,...

The activity potential of hypothetical life forms depends on a number of environmental factors beyond the Earth. The dryness of the Martian surface poses significant challenges to any hypothetic orgaism there. One possible mitigating factor is the presence of hygroscopic salts, which have the ability to absorb atmospheric water vapour and form liquid solutions (Gough et al., 2016, Martín-Torres et al., 2015 and Zorzano et al., 2009). Such brine solutions can form for several hours during the night on the Martian surface (Pál and Kereszturi, 2017). Various observations indicate that salt crystals are present in many locations on Mars, particularly near the equator (Carter et al., 2013 and Osterloo et al., 2008).However warmer daytime periods even hygroscopic salts could not keep their nighttime condensed water. Temperature fluctuations can lead to significant volume changes of such minerals. But such significant temperature fluctuations cause volumetric thermal expansion and contraction in the crystals, which can generate mechanical stress and fractures. The salt crystals of interest have been detected around the equator, within a band of about 40o, where the pronounced temperature variations occur. The average daytime maximum temperature is around 273 K, while the nighttime minimum can drop to approximately 150 K (Kuti et al., 2007).Based on the work of Drebushchak and Wallace (Drebushchak, 2020 and Wallace, 1972), we used NaCl to calculate volume change by numerical integration between 150 and 300 K. The resulting relative volume change is 1.64%, meaning that a 1 cm diameter NaCl crystal can expand by 0.16 mm during the day and contract by the same amount overnight on Mars.This process may result in a phenomenon whereby cracks in the crystal surface close during the daytime due to expansion (to inhibit H2O loss from internal voids), and reopen at night as the crystal contracts (to allow H2O migration inside.Beside dryness another important factor is UV radiation, which can cause severe damage in any organism due to Mars' thin atmosphere. According to Schuerger's measurements, a habitable environment shielded against UV would require an additional layer of dust or rock to shield against UV radiation. There is an optimal zone, approximately 3 - 4 mm below the surface, which effectively blocks radiation while still allowing enough sunlight to penetrate for photosynthesis (Marschall et al., 2012).Figure 1. Flowchart of the proposed phases in the model.Based on these parameters, salt crystals may offer potential microhabitats for microorganisms. In the evening, lower local temperatures may cause cracks in the crystals to open due to shrinkage, allowing contact with the surrounding atmosphere of the crystal’s interior. Rising relative humidity levels at night can cause hygroscopic salts to liquefy and water to seep into deeper cavities along the hygroscopic surface in the form of a microscopic liquid layer, allow wetting of the internal voids inside a crystal. As temperature rises during the day, the crystal expands and the cracks close possibly before the internal cavity fully dries out. This could allow a hypothetical organism to access liquid water throughout the day if it is situated inside such a crystal, partly similar to what has been identified in the Atacama desert on the Earth for example. Additionally, this process provides protection against UV radiation too.References:Carter, J., Poulet, F., Bibring, J.-P., Mangold, N. and Murchie, S. Hydrous minerals on Mars as seen by the CRISM and OMEGA imaging spectrometers: Updated global view. Journal of Geophysical Research: Planets, 118, 831–858, 2013.Gough, R.V., Chevrier, V. és Tolbert, M.A. Formation of liquid water at low temperatures via the deliquescence of calcium chloride: Implications for Antarctica and Mars. Planetary and Space Science, 131:79-87, 2016, doi: 10.1016/j.pss.2016.07.006.Kuti, A. and Kereszturi, A. Daily temperature fluctuation on Mars at aphelion. Workshop on Planetary Atmospheres, 2007.Martín-Torres, F.J., Zorzano, M.P., Valentín-Serrano, P., Harri, A.M., Genzer, M., Kemppinen, O., Rivera-Valentin, E.G., Jun, I., Wray, J., Madsen, M.B., Goetz, W., McEwen, A.S., Hardgrove, C., Renno, N., Chevrier, V.F., Mischna, M., Navarro- González, R., Martínez-Frías, J., Conrad, P., McConnochie, T., Cockell, C., Berger, G., Vasavada, A.R., Sumner, D. és Vaniman, D. Transient liquid water and water activity at Gale crater on Mars. Nature Geoscience, 8:357-361, 2015, doi: 10.1038/ngeo2412.Marschall, M., Dulai, S. and Kereszturi, Á. Migrating and UV screening subsurface zone on Mars as target for the analysis of photosynthetic life and astrobiology. Planetary and Space Science, 72:146–153, 2012, doi: 10.1016/j.pss.2012.06.011.Mickol, R.L., Page, J.L. and Schuerger, A.C. Magnesium sulfate salt solutions and ices fail to protect Serratia liquefaciens from the biocidal effects of UV irradiation under Martian conditions. Astrobiology, 17(5):387–400, 2017, doi: 10.1089/ast.2015.1448.Osterloo, M.M., Hamilton, V.E., Bandfield, J.L., Glotch, T.D., Baldridge, A.M., Christensen, P.R., Tornabene, L.L. and Anderson, F.S. Chloride-bearing materials in the southern highlands of Mars. Science, 319(5870):1651–1654, 2008, doi: 10.1126/science.1150690.Pál B. és Kereszturi Á. Possibility of microscopic liquid water formation at landing sites on Mars and their observational potential. Icarus, 282:84-92, 2017, doi: 10.1016/j.icarus.2016.09.006.Titov, D.V. Water vapour in the atmosphere of Mars. Advances in Space Research, 29(2):183–191, 2002, doi: 10.1016/S0273-1177(01)00568-3.Zorzano, M.P., Mateo-Martí, E., Prieto-Ballesteros, O., Osuna, S és Renno, N. Stability of liquid saline water on present day Mars. Geophysical Research Letters, 36, 2009, doi:10.1029/2009GL040315.

This study reveals the effects of artificial space-like proton irradiation on three meteorite samples that are Northwest Africa (NWA) 4560 LL3.2 and NWA 5838 H6 chondrite meteorites, as well as the Dhofar (Dho) 007 eucrite. We used low-vacuum scanning electron microscopy (LV-SEM) and Raman Spectroscopy to examine the structure and composition of olivine and pyroxene grains in the meteorites before and after the irradiation events. This article focuses on the strongest and most intense irradiation, which was performed by protons up to 12 keV with a fluence value of 10¹⁹ ions/cm² that lasted ~30 h. According to the Raman spectra, significant lattice disruption in all analyzed silicates occurred, and a more extensive amorphous, glassy layer developed under the strongest irradiation conditions. Relative to the second irradiation, peak 1 (820.0 cm⁻¹) shifts slightly negatively (–0.46 cm⁻¹) with a small FWHM increase (+0.88 cm⁻¹), while peak 2 (850.3 cm⁻¹) shifts positively in both parameters (+0.40 and +4.04 cm⁻¹) in NWA 4560 olivines. In NWA 5838 olivines, both olivine peaks (820.5 and 850.8 cm⁻¹) shift positively (+7.40 and +7.90 cm⁻¹) and broaden (+2.75 and +4.29 cm⁻¹). In Dho 007 pyroxenes, peak 1 (997.1 cm⁻¹) shifts positively (+3.01 cm⁻¹) with an FWHM decrease (−0.46 cm⁻¹), peak 2 (669.7 cm⁻¹) shifts slightly negatively (−0.75 cm⁻¹) while broadening strongly (+29.23 cm⁻¹), and peak 3 (327.7 cm⁻¹) shifts positively (+0.86 cm⁻¹) with reduced FWHM (−4.55 cm⁻¹). Three characteristic amorphous bands appear in all examined meteorite silicates, located at ~550–1000 cm⁻¹, ~1100–1700 cm⁻¹, and ~1700–1850 cm⁻¹. Olivines in NWA 4560 and NWA 5838 exhibited similar responses across all irradiation events. In contrast, Dho 007 pyroxenes showed variable compositional changes without a consistent or well-defined pattern in our SEM dataset. The Fo decrease in our experiments likely results from preferential Mg sputtering in the olivine lattice, leading to relative Fe enrichment, similar to but more pronounced than after the first irradiation. Pyroxenes exhibit a comparable response, with Fs and En increasing and Wo sharply decreasing, reflecting preferential Ca loss relative to Mg alongside Fe enrichment. Investigating these processes improves the interpretation of planetary remote sensing data and advances our understanding of planetary surface evolution, while also clarifying how surface materials respond to space environmental conditions.

Compositional and structural understanding of asteroids, especially the moderately small (and frequent) Near Earth Asteroids is important not only for science but also for possible mitigation against their any future impact. However, space weathering substantially modifies the surface infrared spectra, making it difficult to identify their composition. Laboratory tests of artificial weathering by simulated solar wind on meteorites were conducted and reviewed in this study. During the simulations, an increase in the iron content, amorphization, water loss and other structural changes were observed, which usually decreases the mechanical hardness of the very thin surface layer. Using these results, the question was formulated and evaluated here: could such surface changes influence the joint behavior of grain groups when effects driven by YORP forces modify the global shape of asteroids. Based on the evaluation, 10–100 million years of time scale changes are expected to occur both mineral structure and global asteroid shape. The related theoretical consequences and research questions are summarized here.

Water-ice occurs inside many minor bodies almost throughout the Solar System. To have an overview of the inventory of water-ice in asteroids, beside the general characteristics of their activity, examples are presented with details, including the Hilda zone and among the Trojans. There might be several extinct comets among the asteroids with only internal ice content, demonstrating the complex evolution of such bodies. To evaluate the formation of ice-hosting small objects, their migration and retention capacity by a surface covering dust layer are also overviewed to provide a complex picture of volatile occurrences. This review aims to support further work and search for sublimation-induced activity of asteroids by future missions and telescopic surveys. Based on the observed and hypothesized occurrence and characteristics of icy asteroids, future observation-related estimations were made regarding the low limiting magnitude future survey of LSST/Vera Rubin and also the infrared ice identification by the James Webb space telescope. According to these estimations, there is a high probability of mapping the distribution of ice in the asteroid belt over the next decade.

IntroductionThis decade marks our goal to return to the Moon—this time, to stay.It is therefore crucial to develop reliable and safe settlements that adequately protect astronaut’s physical and mental well-being from all possible threats that the hostile environment of extraterrestrial space presents.ArchiSpace aims to design and build sub-system prototypes (e.g., floors, walls, roofs, etc.) of human infrastructures to be built on planetary surfaces, which will be tested in analogue environments on-Earth. This project represents the first effort, to the best of our knowledge, to use a combination of environmental and geological setting analogues as a base to define architectural constraints, sketch design and prototypes to be used in future space human settlements.ArchiSpace is pioneering a new field of interdisciplinary and intersectoral research in Europe by bridging geology/space sciences and on-/off-Earth architecture. Geology/space science is crucial because the subsurface plays a fundamental role in the selection of the landing sites and the location of 'human-focused' habitats. Architecture has a key role in designing comfortable, safe and functional habitats both for on- and off-Earth applications. Our complementary partners are leaders in their respective sectors and hold the necessary know-how and/or technology level to achieve the ArchiSpace objectives. In addition, the human settlements to be developed will involve innovative low impact, low cost and light operations and ISRU materials.This sustainable planetary approach has off-Earth & on-earth implementations. The project will create, through the planned secondments, common standards, methods and prototypes for the development of space bases on Moon and Mars; which will be tested in three joint field activities (e.g., in Moroccan analogue sites).Thus, ArchiSpace promotes an innovative international, inter-sectoral and interdisciplinary research and innovation collaboration that will contribute to Europe's competitiveness and growth.Methodology:The ArchiSpace project integrates multidisciplinary expertise to develop innovative infrastructures for extreme environments (Moon, Mars, and terrestrial analogs). The methodology includes planning, designing, and constructing prototypes, leveraging planetary sciences, architecture, engineering, and advanced 3D printing techniques. The outcomes aim to support both space exploration and terrestrial applications.Researchers and architects will participate in this multi-disciplinary project through 11 Work Packages (WPs). WP1 to WP8 will focus on specific requirements of different end-user communities with a field demonstration. Several planetary and terrestrial environmental conditions and specific needs (for science, applied geotechnical and environmental aspects, architectural and design integration aspects, habitability aspects, etc.) will be modelled and examined linked to field training/test realization. The sets of data and examples produced will provide practical knowledge to additional European partners, including companies, to contribute to ESA’s and NASA’s efforts in the planning and preparation of the first human Mars mission. All researchers involved will have an opportunity to discern beyond their specific field and to perceive construction techniques in a larger framework. Using the produced innovations, WP9 to WP11 will use these in the Knowledge Transfer, Training, Dissemination and Exploitation actions.The project ArchiSpace consists of two major actions: (i) planning of the executable project integrating cross-disciplinary know-how (by applying planetary science-based methods and knowledge to Earth based locations) and (ii) the construction of subsytem prototypes (e.g., foundations, floor, wall, roof, etc) and a 3D virtual habitat. ConclusionThe outcome of the ArchiSpace project will be the realization of tangible space architecture subsystem designs, bringing the vision of sustainable human settlements into Space. This vision will position ArchiSpace as a trailblazer in the field of Space architecture, providing valuable insights and practical solutions for future Space exploration efforts. The project's unique focus on both the design of Space habitats and geological/geomorphological environmental adaptation, through Earth analogues to test and refine the project, technologies, and procedures; is expected to greatly advance our understanding of the challenges and opportunities involved in establishing human settlements on the Moon and Mars.Overall, the ArchiSpace project offers a rare opportunity to shape the future of Space architecture and contribute to Solar System exploration. The transfer of the innovative architecture designs to the market will be provided by the participating companies after the termination of this project and could be applied in Europe to low-income Earth-based communities.AcknowledgementThis project was supported by the EU HORIZON-MSCA-2023-SE-01 Grant agreement ID: 101183089.

Artificial space weathering tests on NWA 10580 CO3, NWA 11469 CO3, NWA 5838 H6, NWA 4560 LL3.2, and Dho 007 Eucrite meteorites using solar wind relevant proton irradiation were performed. The experiments revealed increased iron content, amorphization, water loss, and structural changes that typically reduce the mechanical hardness of the outermost surface layer. Results support both meteorite-asteroid linking and optimization of future infrared detector channel arrangement for cubesat asteroid missions.IntroductionArtificial space weathering tests in the laboratory of ATOMKI on meteorites using solar wind relevant proton irradiation were performed. The simulation corresponded to 10-100 million years of space weathering exposure, and the resulting changes were detected by infrared, Raman, SEM and XRD measurements before and after the irradiation actions. The aim was to better understand the modifications by surveying the sample with different methods and interpreting the results jointly. The findings are expected to support a better understanding of asteroid spectra, the linking of meteorites to source asteroids, and improved detector band localization for upcoming missions.Simulated solar wind can induce mineral amorphization, detectable by infrared (IR) spectroscopy (Demyk et al. 2004; Lantz et al. 2015) and Raman spectroscopy (Brucato et al. 2004; Demyk et al. 2004), through band shifts in silicates and compositional changes (Hapke et al. 1975). Nanophase iron-nickel particles have also been identified in CV and CO chondrites post-irradiation (Zhang et al. 2023). These effects are primarily analyzed using Fourier Transform Infrared (FTIR) spectroscopy on bulk samples (Lantz et al. 2017; Brunetto et al. 2014, 2020), and Raman spectroscopy (e.g., olivine: Lantz et al. 2017; polystyrene and olivine: Kanuchova et al. 2015). Beyond scientific interest, understanding the composition and mechanical properties of Near Earth Asteroids - potentially influenced by surface modification of grains within rubble pile structure objects - is essential for developing effective mitigation strategies and improving the spectral correlation with meteorites.MethodsThe meteorite samples (NWA 10580 CO3, NWA 11469 CO3, NWA 5838 H6, NWA 4560 LL3.2, and Dho 007 Eucrite) were irradiated with 1 keV H+ protons produced by the ECR ion source (Biri et al. 2021) at the ATOMKI institute under vacuum conditions, up to a fluence of 1017 ion/cm2. The samples were analyzed before and after irradiation actions using the following facilities. For sample analysis FTIR spectroscopy was performed using a Vertex 70 spectrometer with 32 scans in the 400–4000 cm−1 range, measured for 30 s at 4 cm−1 spectral resolution, processed using Bruker Optics’ Opus 5.5. software. Raman spectroscopy was applied using a Morphologi G3-ID instrument (Malvern Instruments; Garzanti et al. 2015) and a Kaiser Optical Systems Inc. Raman Rxn1 Spectrometer with NIR Laser Diode at 785 nm wavelength. Measurements were taken with an exposure time of 30 s at 10 mW laser power over the 150 - 1150 cm-1 range. The laser spot size was 3 μm at 50× magnification, with a spectral resolution of 1 cm−1 and a focal depth of 1.82 μm. The Scanning Electron Microscope (SEM) used was a JEOL JSM-IT700 HR, operated at a 20 keV voltage and 6 nA beam current, with a 40 s point integration time and 100 s areal integration time.ResultsA range of changes was observed in peak positions, FWHM values, and the disappearance of minor bands, indicating the following sequence of alterations during the series of irradiation and measurement sequences.Metastable phases may form ephemerally under conditions differing from those of stability, as shown by Lindsley et al. (1972) in their identification of metastable pyroxferroite related to smectites in cosmic materials, or in specific mineral-like alloys(Lilienfeld et al., 1987), where irradiation modified grain boundaries and dislocations (Chesser et al., 2024). However, such effects have rarely been explored in irradiated meteorites. Defect production occurred in the crystalline lattice during the next phase, where vacancy migration was likely influenced by temperature (Campbell et al., 2002, ). These defects could reduce band strength and increase FWHM in general. Element migration, replacement, and ion integration occurred, particularly affecting olivine composition, which changed from Fo-50–60 (Hamilton 2010) to Fo-30–35 after irradiation in Frontier Mountain 95,002 and Lancé meteorites (Brunetto et al., 2020), as well as in Tagish Lake sample following ion irradiation (Dukes et al., 2015). We also observed an increase in the Fe/Si ratio during the later stages of the tests at elevated irradiation fluence. Amorphization and mineral decomposition were characteristic of the later phase of the tests, occurring at higher levels of irradiation. Excessive defect formation and element loss or implantation were observed. In silicates, depolymerization of SiO4 tetrahedra and lattice decomposition led to the weakening, and disappearance of spectral bands. We also evaluated mineral identification possibilities using different spectral resolution, as onboard cubesats simple detectors are expected to be used for asteroid missions frequently in the near future. Spectral coarsening, achieved by artificially lowering the resolution with averaging data points, leads to flattening on a smaller scale. Smaller peaks tend to disappear quickly with the worsening resolution.Discussion and ConclusionThe experiments revealed increased iron content, amorphization, water loss, and structural changes that typically reduce the mechanical hardness of the outermost surface layer, supporting the linking of meteorites to asteroids; however, one major further step remains: the inclusion of laser-shot-simulated microscopic impact effects, resulting melting, darkening and nanophase iron formation. The...

The successful impact of the Double Asteroid Redirection Test (DART) spacecraft on Dimorphos enabled the first-ever extensive observation of a postimpact ejecta tail from a binary asteroid system. Studying the ejecta can provide insights into impact physics and asteroid composition and inform future asteroid missions. In this research, the orbital capture of the impact ejecta around the Didymos binary asteroid system is investigated. The ejecta dynamics are described using an augmented bicircular restricted four-body model, which incorporates the binary’s irregular gravity field and solar radiation pressure (SRP) acceleration. Typical periodic orbit (PO) families, including planar Lyapunov and terminator orbits, are selected as the candidates for capture analysis. The candidate POs are perturbed and backward-propagated using the invariant manifold theory, and eligible trajectories intersecting the asteroids’ surfaces are recorded. The ejecta characteristics of different POs are summarized from three principal aspects: ejection location, ejection velocity, and ejection angle. The influence of two critical factors is qualitatively assessed, including the geometry of the asteroids in the binary system and the strength of SRP acceleration. Lastly, the likelihood for the ejecta from the DART impact being transferred to candidate POs is assessed.