Introduction:  Astrochemistry is a multidisciplinary subject that allows us to investigate formation and destruction routes of molecules found in extraterrestrial environments, such as planetary atmospheres, comets or the interstellar medium (ISM) [1].

To this day, there is still a lack of knowledge concerning the chemistry of minor species, for example, there are important issues related to the presence of sulphur in the ISM, like the sulphur depletion problem [2]. Many sulphur species (H₂S, OCS, SO, S₂, SO₂ and CS₂) have been identified in the coma of the comet 67P/Churyumov-Grasimenko [3] and some have been proposed as the main carriers of S, such as H₂S and OCS, condensed in the icy mantles of interstellar dust grains.

In this contribution, we present a theoretical investigation of the reactions involving atomic sulphur, in the first electronically excited state ¹D, with water.

S(¹D) is produced by UV-induced photodissociation of precursor molecules, such as OCS [4] and CS₂ [5], which are relatively abundant in extraterrestrial environments. In. particular, OCS is among the few molecules for which a secure identification in interstellar ice has been provided [6-7].

S(¹D) + H₂O: The presence S(¹D) precursors, like OCS, on interstellar ice is documented. Therefore, if formed on the ice surface, S(¹D) will be able to react with water. According to our calculations, the reaction proceeds either by S(¹D) addition to one of the lone pairs of O or via insertion into one of the two O-H bonds. Two different intermediates can be formed: H₂OS and HOSH.

Theoretical method:  We first characterized the gas-phase potential energy surface (PES) of the reaction S(¹D) + H₂O. We then optimized the geometry of an 18-H₂O cluster ice surface at DFT level of theory. We identified several surface binding sites on the grain, based on the amount of available hydrogen bonds that engage the sulfur atom with the surface. For each identified site, we computed the binding energies of the sulfur atom in order to select the best configuration with which to investigate the catalytic effect of water molecules.

Conclusions: In this contribution we show the catalytic effect of the water ice: water molecules actively participate to the H-transfer process, reducing the energy barriers compared to the analogous gas-phase steps.

References:

[1] Caselli P. and Ceccarelli C. (2012) Astron. Astro- phys. Rev., 56, 20

[2] Vidal T. H. G. and Wakelam V. (2018) Mon. Not. R. Astron. Soc., 5575–5587, 474

[3] Hänni N. et al. (2022) Nat. Commun., 3639, 13

[4] Kim, M. H. et al. (2004) Can. J. Chem. 880-884, 82

[5] Black, G. and Jusinski, L.E. (1986) Chem. Phys. Lett., 90–92, 124

[6] Gibb E. L., et al. (2000) Astrophys. J., 347, 536

[7] Gibb E. L., et al. (2004) Astrophys. J. S. S., 35, 151

How to cite: Di Genova, G., Perrero, J., Balucani, N., Ceccarelli, C., Rosi, M., and Rimola, A.: Sulphur reactions on interstellar water ice grains , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5470, https://doi.org/10.5194/egusphere-egu24-5470, 2024.

The dust accelerator operated at the University of Colorado is used to study how the organic content of small particulates in space can be detected and identified using dust impact analyzer instruments. The Interstellar Dust Experiment (IDEX) instrument will be launched onboard the Interstellar Mapping and Acceleration Probe (IMAP) mission in 2025 and will detect and analyze the composition of hundreds or thousands of interstellar and interplanetary dust particles from Lagrange point 1. IDEX is an instrument with a large sensitive area and high mass resolution that measures the time-of-flight mass spectra of the ions generated by the hypervelocity impact of dust particles. The laboratory version of IDEX is used to collect calibration data on dust samples of known composition. Such data are required for the interpretation of future IDEX measurements, including identifying their organic content of the detected particles. A comprehensive study was performed recently on the impact ionization properties of anthracene. Measurements were made over a wide (2 - 35 km/s) impact velocity range to investigate the strong variation of the impact spectra with the energy of the impact. Such laboratory studies are also relevant to the Surface Dust Analyzer (SUDA) and DESTINY Dust Analyzer (DDA) instruments on the Europa Clipper and DESTINY+ missions, respectively. In addition, two new laboratory capabilities are in development:  A uniquely capable laboratory setup using Near Infrared (NIR) spectroscopy and Time-of-Flight (TOF) mass spectrometry will allow measuring the physical and chemical alteration of the ice surface and organic compounds due to radiation and micrometeoroid bombardment. A newly developed ice accelerator capability will be used to characterize the impact ionization or organic-bearing compounds embedded in ice particles.

How to cite: Sternovsky, Z., Mikula, B., Armes, S. P., Ayari, E., Bouwman, J., Hillier, J., Horanyi, M., Kempf, S., Postberg, F., and Srama, R.: Detecting Organics with Dust Impact Analyzer Instruments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12633, https://doi.org/10.5194/egusphere-egu24-12633, 2024.

Extraterrestrial organic compounds are predominantly examined through the analysis of natural samples delivered to Earth via meteorites [1]. The focus has largely been on carbon-rich meteorites called carbonaceous chondrites. These meteorites are believed to be remnants of asteroids and are considered the oldest solid materials accessible for laboratory analysis within our solar system. The soluble organic compounds identified within carbonaceous chondrites serve as a comprehensive record of pre-solar chemical reactions, early solar system dynamics, and transformations arising from aqueous and thermal processes on the parent bodies [2]. Understanding the extraterrestrial origins of these compounds is crucial for unraveling the origins and evolution of our solar system and to determine if carbon-rich asteroids like Bennu could have delivered prebiotic molecules to the early Earth [3].

Due to the unavoidable interaction of carbonaceous chondrites with Earth’s biosphere, analyses of the organic content in meteorites discovered on Earth often reveal different degrees of terrestrial contamination. To address the potential issue of contamination in extraterrestrial materials and to provide a sample from a known extraterrestrial source, NASA’s Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) mission delivered samples from the near-Earth asteroid (101955) Bennu to Earth on 24 September 2023 [4].

Bennu materials will be extracted in dichloromethane at NASA Goddard Space Flight Center and will be analyzed by two-dimensional gas chromatography using a LECO GC-HRT+ 4D system (GC×GC high-resolution time of flight with mass spectrometry; GC×GC-HRMS). The use of GC×GC-HRMS offers the advantage of enabling an untargeted evaluation of the soluble organic contents in these samples. Through comparisons of data collected with the same technique from carbonaceous meteorites and from samples returned by JAXA’s Hayabusa2 mission from asteroid Ryugu, there is a potential to establish parent-daughter relationships between samples collected on Earth and asteroids [5]. Analyzing the organics of Bennu will contribute to understanding the intricate history and evolution of these compounds and their precursor molecules, spanning from the molecular cloud and protosolar nebulae to planetesimal formation and parent body processing. This study will center on the GC×GC-HRMS results obtained from solvent extracts of Bennu, which should reveal a diverse array of organic species.

Acknowledgments: Supported by NASA under Award NNH09ZDA007O & Contract NNM10AA11C.

References:

[1] Simkus D. N. et al. (2019) Life 9, 47.

[2] Glavin D. P. et al. (2018) Primitive Meteorites and Asteroids, pp. 205-271.

[3] Chyba C. and Sagan C. (1992) Nature 355, 125-132.

[4] Lauretta D. S. et al. (2022) Science 377, 285-291.

[5] Aponte et al. (2023) Earth, Planets and Space 75, 28.

How to cite: Aponte, J. C., Dworkin, J. P., Elsila, J. E., Glavin, D. P., Connolly Jr., H. C., and Lauretta, D. S.: Two-Dimensional Gas Chromatography Analysis of Samples Returned from Asteroid Bennu by OSIRIS-REx  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12153, https://doi.org/10.5194/egusphere-egu24-12153, 2024.

Introduction: it is generally acknowledged that Mars’ past surface conditions were very different from what we observe today. The presence of fluvio-lacustrine morphological features and a widespread hydrous mineralogy on older surfaces indicate that water-rich conditions were common during the first billion years of the history of Mars [1]. In particular, the presence of Fe/Mg phyllosilicates on Noachian surfaces (4.1-3.7 b.y. old) indicates that aqueous alteration of the crust at that time was happening at circumneutral pH conditions [2].

The nature of Mars’ climate started to change around 3.7 b.y. ago, at the beginning of the Hesperian period (3.7-3.0 Ga), where we have indications that the environment had become drier and acidic. Evaporites, primarily sulfate-rich salts, are the major alteration mineralogy observed on Hesperian surfaces [1] and the occurrence of water-related morphologies decreased abruptly [3]. Most of the local and regional records of the stratigraphic variability induced by this major climate change event are still unclear and poorly constrained but offer valuable information for assessing the possibility for life’s origin and endurance on Mars.

Objective: we focus our investigations on the equatorial region of Mars called Meridiani Planum. This area is well-known for showing signs of a rich and varied aqueous activity spanning through the Noachian and the Hesperian. In particular, a thick sequence of layered sediments rich in sulfates and clays [4] is observed, potentially retaining key information on the climate and environment in which they deposited.

Datasets and methods: We select several areas within the northern part of Meridiani Planum which show presence of layered sediments rich in hydrous minerals. Mineralogy and stratigraphy are investigated combining spectral information from the CRISM instrument with high resolution images and DEMs from CTX and HiRISE. 

Results and discussion: Stratigraphic analysis has evidenced that sulfates (polyhydrated and monohydrated Mg sulfates) are commonly observed at the bottom of the stratigraphic sequence, while clays (Fe/Mg phyllosilicates) are deposited on top, with no evidence of tectonic-structural phenomena that could have overturned the original stratigraphic sequence. The clays observed here therefore do not belong to the Noachian units of Meridiani planum but were formed later, after the sulfates were deposited. The transition between an environment which favors abundant sulfate deposition to one that favors Fe/Mg clays is recording a climatic transition which does not follow the general clay-to-sulfate trend observed at large scales on Mars [1], implying an additional level of complexity to the geologic history of Meridiani. It is essential to assess if similar stratigraphic sequences are observed elsewhere on Mars, to define whether this phenomenon is confined to this region or is evidence of larger scale, if not global, events.

Acknowledgements: This project is partially funded by Europlanet RI20-24 GMAP project (research grant agreement No. 871149). 

References: [1] J. Bibring et al. (2006), Science, 312. [2] S. L. Murchie et al. (2009), JGR-Planets, 114 (E2). [3]  B. Hynek, et al. (2010), JGR-Planets, 115 (E9). [4] J. Flahaut et al. (2015), Icarus, 248, 269-288. 

How to cite: Baschetti, B., Tullo, A., Massironi, M., Carli, C., Altieri, F., and Breda, A.: Stratigraphy of Fe/Mg Clays and Sulfates in Meridiani Planum region: possible implications for Mars' climatic transition., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-915, https://doi.org/10.5194/egusphere-egu24-915, 2024.

Space exploration missions devoted to the detection of life have visited various celestial bodies in our Solar System, particularly Mars (1). Observations and analyses conducted by orbiters, landers and rovers provided insight into the characteristics of the Martian geology and paleoenvironment, suggesting a past aqueous process including both subsurface and surface water (ocean and lakes) (2). The water activity on Mars’ surface, billions of years ago, led to the precipitation of sulfate minerals such as kieserite, polyhydrated sulfates and hydrated gypsum (hydrous calcium sulfate, CaSO₄·2H₂O) (3), suggesting the evaporation of lakes and lacustrine systems. Once the surface of Mars started to dry out, acidic and hypersaline shallow surface waters and groundwater might have filled the ancient lake system (4).

On Earth, diverse prokaryotes live within, on the surface, or underneath the formed primary gypsum in hypersaline lakes as endolithic, epilithic, and hypolithic forms, respectively. The fast and early growth of gypsum in different geological systems allows for a rapid entombment of cells, good fossilization potential and exceptional biosignature preservation (5, 6), making it a promising target in the search for evidence of past life on Mars (7).

The kilometre thick primary lower gypsum deposits, accumulated in the Mediterranean Basin during the Messinian salinity crisis (5.97 – 5.33 Ma), revealed a well-preserved and prominent archive of diverse microbial life (8). This geological system was proposed to be a terrestrial analogue of what may have happened on Mars (9).

In this contribution, we present measurements conducted on a sample of Messinian Primary Lower Gypsum with preserved microfossils from the lower-Chelif marginal basin in northwest Algeria using our space-prototype laser ablation ionization mass spectrometer (LIMS). Previous measurements performed on microfossils preserved in ancient rock records showed that this instrument has the capability to detect biosignatures related to ancient life (10). In addition to the analyses conducted with the LIMS instrument, the sample was further investigated using optical and scanning electron microscopy. According to the observed morphology, the obtained 2D and chemical depth profiles, we established the biogenicity and syngenecity of the analysed sample material. This highlights the potential of gypsum as a possible target mineral for future in-situ space missions to search for signs of life on Mars.

References

(1). Westall F & Hickman-Lewis K. (2018). ISBN:9781315159966

(2). Carr, M. H & Head, J. W. (2003). https://doi.org/10.1029/2002je001963

(3). Gendrin, A. et al. (2005). https://doi.org/10.1126/science.1109087

(4). Squyres, S. W., et al. (2012). https://doi.org/10.1126/science.1220476

(5). Benison, K. C & Karmanocky, F. J. (2014). https://doi.org/10.1130/g35542.1

(6). Lugli, S., et al. (2010). https://doi.org/10.1016/j.palaeo.2010.07.017

(7). Schopf, J. W., et al. (2012). https://doi.org/10.1089/ast.2012.0827

(8). Natalicchio, M., et al. (2022). https://doi.org/10.1111/gbi.12464

(9). Sgavetti, M., et al. https://doi.org/10.1016/j.pss.2008.05.010

(10). Lukmanov, RA., et al. (2021). https://doi:10.1002/cem.3370

How to cite: Sellam, Y., Tulej, M., Riedo, A., Gruchola, S., Keresztes Schmidt, P., Knecht, L., Boeren, N. J., Meddane, S., and Wurz, P.: Morphological and mass spectrometric analysis of gypsum-permineralized microfossils and its implications for the search for life on Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15615, https://doi.org/10.5194/egusphere-egu24-15615, 2024.

The dominant source of methane (CH₄) on Earth is biological and thus a sign of life. Therefore, the discovery of CH₄ in the Martian atmosphere was sensational and attracted a lot of attention both within the science community and in the public. Since its discovery, we have learned that the concentration of CH₄ on Mars is very dynamic and follows an annual cycle with relatively high concentration during Martian summer and low concentration during winter. Until now the drivers behind this dynamic pattern remain enigmatic as photochemistry which stands behind most atmospheric processes on Mars is too slow to explain the rapid decline. We studied wind-driven erosion as known from dust-devils and/or sand storms and explored whether it can work as a rapid CH₄ sink. The outcome of this study will be reported in my presentation.

How to cite: Finster, K., Begnhøj, M., Nørnberg, P., Knack Jensen, S., and Thøgersen, J.: Methane a sign of life - what drives its dynamics on Mars?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3592, https://doi.org/10.5194/egusphere-egu24-3592, 2024.

Organic molecules are a major compound of icy moons and dwarf planets (Reynard & Sotin, 2023). During the accretion and differentiation of these bodies, the organics are first altered by water. The residual organics are denser than water and mix with the rocky fraction (silicates and sulfides), eventually forming a refractory core. During this step, the interior temperature is buffered by the melting temperature of ice since water is very efficient in removing interior heat. Once water and refractory compounds have been differentiated, the increase in temperature is controlled by the amount of internal heating (tidal and radioactive) and the thermal properties of the mixture of minerals and organics. Radioactive elements are present in the silicate fraction only, which implies that the heating rate decreases with increasing fraction of organics. As the temperature increases, organics are transformed into denser phases, releasing volatile species. This evolution modifies the volume and the moment of inertia (MoI) of the body. Thermo-chemical evolution models are coupled with equations of state of the different compounds, allowing the calculation of the size and the MoI as a function of time. These models are compared with observations for several icy moons (Titan, Ganymede, Europa) and dwarf planet Ceres. The initial organic fraction can then be retrieved to match the present values of size and MoI.

How to cite: Sotin, C., Delarue, C., and Reynard, B.: Role and fate of organics in the thermo chemical evolution of icy moons and dwarf planets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10133, https://doi.org/10.5194/egusphere-egu24-10133, 2024.

Magma worlds, due to their hot, extended atmospheres are readily characterized spectroscopically by ground- and space-based telescopes, such as JWST. As yet, the lack of direct observations means that the nature and composition of these planets’ atmospheres are poorly constrained.  Because the atmospheres of these planets are thought to be the result of chemical equilibrium with their interiors, their mass and composition are modulated by the solubilities of major gases in the magma. Therefore, we require a theoretical framework, informed by experimental data, to determine how volatile elements partition between the interior and atmosphere for diverse planetary compositions. Of the major gases, hydrogen is particularly important due to its cosmic abundance, significant presence during rocky planet formation if the planet forms before the nebular gas disk dissipates, and its role as an essential life-forming element. However, there is currently a lack of experimental data on hydrogen solubilities in diverse planetary magmas at the temperature, pressure and redox conditions relevant for magma worlds. To fill this gap, we performed new hydrogen solubility experiments on exoplanet melt analog materials at high temperatures (≥1400 ℃) using a 1-bar H₂-CO₂ gas-mixing furnace and an aerodynamic laser levitation furnace coupled to an FTIR spectrometer. Using FTIR spectroscopy, we determine the mechanism for hydrogen’s dissolution and its concentrations in these melts. We will present the findings of our experiments and how we can incorporate them into volatile partitioning models to determine the effect of hydrogen solubility on the atmospheric compositions of magma exoplanets. We will discuss the implications of volatile dissolution on the interior-atmosphere connection for magma planets including the early Earth.

How to cite: Thompson, M., Sossi, P., Bower, D., Petitgirard, S., Liebske, C., and Shahar, A.: Volatile Solubility Experiments on Planetary Melt Analogs and Implications for Rocky Exoplanet Interior-Atmosphere Connections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15901, https://doi.org/10.5194/egusphere-egu24-15901, 2024.

The diversity of exoplanets provides a vast range of potential environments in which liquid water can exist: atmospheres, surfaces, sub-surfaces. Therefore, many environments provide the most fundamental requirement for life as we know it from Earth and could in principle be habitable. However, the presence of water is not the only necessity for life to form, especially the presence of nutrients (C, H, N, O, P, and S) is crucial for the formation of life as we know it.

In order to further understand and constrain potentially habitable environments of diverse planets, we introduce the concept of nutrient availability to constrain the habitability of a planet. This framework is based on the concentrations of nutrient bearing molecules in the condensate and gas phase in the presence of liquid water.

Applying this concept to a diverse set of atmospheres  allows to provide constraints on the potential of surface and aerial biospheres. The atmospheric model used is a bottom-to-top equilibrium chemistry model, wich includes cloud formation. In order to cover the range of different atmospheric compositions, we investigate various different sets of element abundances and surface conditions.

We find that reduced forms of C, N, and S are commonly found at the water cloud base for a range of different compositions of the planetary surface and atmosphere - even in overall oxidised atmospheres. In our model atmospheres, the only non-CHNOS elements in the atmosphere in the surrounding of liquid water clouds are F and Cl, which are present in the form of HF and HCl. Although the CHNOS elements are present, the absence of P and metals in the atmospheres could be a limiting factor on the formation and evolution of life in aerial biospheres.

How to cite: Herbort, O., Woitke, P., Helling, C., and Zerkle, A. L.: Habitability constraints by nutrient availability in atmospheres of rocky exoplanets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20723, https://doi.org/10.5194/egusphere-egu24-20723, 2024.