SB9
Addressing these complex questions requires a multifaceted and collaborative approach. We therefore invite scientists from all backgrounds and disciplines studying carbon chemistry and its evolution, from primitive bodies to rocky planets and habitable worlds. Whether extracting organic molecules from meteorites, observing KBOs with JWST, analyzing the composition of Ceres as measured by Dawn or future missions, investigating ancient Martian lakes with rovers, simulating hydrothermal processes in asteroid parent bodies, or modeling the Venusian clouds … — all are welcome to contribute to this session to help understand the role and fate of carbon-based matter and to pave the way for future space exploration missions.
The protostellar stage is a critical phase, early in stellar evolution (less than 0.5 Myr), during which a disk of gas and dust forms, setting the chemical budget for
planet formation. However, unlike the older Class II disks, Class I protostars are deeply embedded in their natal envelopes. With the spectral range, sensitivity, and resolution of JWST-MIRI, we are now capable of characterizing these warm inner (< 10au) planet-forming regions for the first time for the young disks.
I will present new JWST-MIRI Cycle 4 observations of Class I protostars in the Ophiuchus, Taurus, and Corona Australis star-forming regions. Spectra show
a large variety of molecular emission and absorption features. We apply LTE slab models to determine the column densities and excitation temperatures of
detected species. By comparing the data with previous VLT-CRIRES observations that spectrally resolve CO emission, we can pinpoint the exact origin of the molecular emission. Only then can we assess the molecular content of the gas in the disks at the earliest stages of planet formation. I will show how we can use the fitted properties of the molecular lines to locate the emission and disentangle disks, outflows, hot corinos, and the range of excitation conditions present in each component. Preliminary results show the presence of H2O, CO2, HCN, and C2H2 species. RNO91, a Class I protostar, is particularly interesting as it is a clear example of a very prominent disk in a Class I system. Overall, our new data reveal the crucial transition between young embedded disks and mature T-Tauri disks.
How to cite: Tychoniec, L., Sellek, A., Callenbach, J., and van Dishoeck, E.: Molecular content of young disks revealed by JWST-MIRI: what is the carbon and oxygen budget available for planet formation?, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-1048, https://doi.org/10.5194/epsc2026-1048, 2026.
The interstellar medium and many Solar System bodies such as comets, meteorites, interplanetary dust particles (IDPs) and Ultracarbonaceous Antarctic Micrometeorites (UCAMMs) contain vast reservoirs of organic molecules. Laboratory analyses on these bodies have revealed that a major portion of carbon is incorporated in Insoluble Organic Matter (IOM) – a carbonaceous cross-linked macromolecular network that is resistant to demineralizing acids and organic solvents. Further analyses on IOMs from different sources also shows it exhibits extreme D/H isotopic enrichment in IOM, hinting their origin in the cold interstellar medium, where ion-molecule reaction is able to facilitate deuterium incorporation. While many laboratory works have studied the formation of organic molecules, only a handful have been characterized as analogues or precursor of IOM. In addition, the formation of IOM itself is still a fundamental question, which further necessitates laboratory works to elucidate the conditions necessary for its formation.
We thus simulate the formation of IOM precursor by co-depositing astrophysically relevant gas mixtures at 10K and heavily irradiate the interstellar ice analogues with energetic electrons, a stand-in for cosmic rays. The resulting residue is characterized with Raman spectroscopy, focusing on the D (disordered) and G (graphitic) bands that are tell-tale signatures of IOM. We find that the transformation from ice to IOM precursor requires an intermediate step by first forming medium-complexity Soluble Organic Molecules and removing precursor ice. This then involves the reirradiation of the residue left after the volatile components including water are desorbed. We hypothesize that precursor ice, in particular H2O, inhibits the growth of organic molecules to macromolecular sizes. These findings suggest that IOM formed in a heavily irradiated environment where precursors underwent an “ice-dry” cycle to remove volatile ice components.
How to cite: Zainol Abidin, A. N., Kipfer, K. A., Allen, N. M., Riebe, M. E. I., and Ligterink, N. F. W.: Synthesizing Insoluble Organic Matter Precursor with Electron Irradiation on Simple Carbon-bearing Ices, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-484, https://doi.org/10.5194/epsc2026-484, 2026.
Large trans-Neptunian objects (TNOs) such as Pluto, Eris, and Makemake exhibit increasing evidence for complex internal evolution, including differentiation, volatile transport, and potentially ongoing activity. The orbital evolution of the Eris–Dysnomia system may imply unexpectedly efficient internal dissipation (Nimmo and Brown, 2023), suggesting that some large TNOs may still host evolving interiors. Recent JWST observations provided isotopic measurements (Grundy et al., 2024) that constrain the origin of methane on the surface of Eris and Makemake as either primordial (Mousis et al., 2025) or internally produced through hydrothermal or thermogenic processes (Glein et al., 2024). Interestingly, thermal observations of Makemake reveal an anomaly (Kiss et al., 2024), the origin of which may or may not be linked to ongoing outgassing. Indeed, evidence for gaseous CH4 has been reported, making Makemake only the second trans-Neptunian object with confirmed volatile release (Protopapa et al., 2025).
One possible source of internally produced volatiles is the thermal evolution of refractory organic matter inherited from cometary building blocks. Organic molecules, which are abundant in comets (Bardyn et al., 2017), may represent a large fraction of the refractory cores of outer Solar System icy bodies (Reynard and Sotin, 2023). Following accretion, radiogenic heating progressively raises internal temperatures, driving the evolution of initially primitive insoluble organic matter toward more graphite-rich compositions through devolatilization processes (Delarue et al., 2026). Reactions such as decarboxylation, dehydration, and pyrolysis lead to the release of volatile compounds, including H2O, CO2, CH4 and N2, which may contribute to the volatile inventories observed at TNO surfaces. At the same time, the chemical evolution of the refractory material modifies key physical properties such as the H/C ratio, density, heat capacity, and thermal conductivity, thereby affecting the internal structure, cooling efficiency, and long-term evolution of these bodies.
To address this question, we are developing a coupled thermo-chemical evolution model (CRISP, Carbon-Rich Icy-worlds Simulator in Python) to investigate the long-term evolution of organic-rich interiors. The model follows the conductive thermal evolution of a differentiated refractory core composed of hydrated silicates and insoluble organic matter, heated by long-lived radiogenic isotopes. In our study, we explore how the initial proportions of silicates and refractory organics control the timing and magnitude of methane production as well as the radius evolution. For a Pluto-like body containing 30% refractory organic matter in its core, our simulations predict a contraction of the core of about 30 km. The degradation of organics and dehydration of silicates generate enough CH4 and H2O to form the equivalent of a ∼44 km thick clathrate layer, while leaving a residual free methane reservoir of ∼6×10^19 kg potentially available for long-term volatile release. These results suggest that the thermo-chemical evolution of refractory organics may play a major role in shaping the internal structure, volatile inventories, and present-day activity of large trans-Neptunian objects.
How to cite: Kervazo, M., Sotin, C., Couchevellou, S., Reynard, B., Confortini, G., Delarue, C., Guilbert-Lepoutre, A., André, V., Tobie, G., and Pinceloup, M.: The role of organics degradation in the thermo-chemical evolution of trans-Neptunian objects, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-357, https://doi.org/10.5194/epsc2026-357, 2026.
Data from Cassini-Huygens on the plume composition, and by extension the supposed composition of the Enceladus ocean, revealed a variety of organic-bearing compounds in which no amino acids were identified [1]. Given that icy moons form from small primordial bodies [2], we wondered how the primitive organic matter containing amino acids [3,4] evolved once it was accreted. This is relevant considering how the complex matrix of organic matter, minerals, and ices might evolve during the interaction with hydrothermal water circulating through the porous core of Enceladus. Among the minerals composing the building blocks of the icy moons, saponite has been detected in asteroid Ryugu and carbonaceous chondrites [5], presenting catalytic properties and a crystallographic structure that might facilitate the polymerisation of prebiotic molecules such as amino acids [5, 6].
To investigate the potential catalytic role of saponite in prebiotic chemistry in Enceladus hydrothermal system, we recreated the hydrothermal conditions (150°C, 20MPa) in an internally heated pressure vessel, in which we reacted synthetic mixtures of Fe(II)-saponite [7] incorporating organic matter obtained from a mixture of formaldehyde and glycolaldehyde, and ammonium-bearing fluids [8]. We conducted in operando analyses of Raman and Infrared spectroscopy to identify the evolution of organic matter within the aqueous mixture.
These experiments are novel in that they explore the effect of the variation of proportions of the compounds (i.e., saponite, organic, water) on their co-evolution in hydrothermal conditions. We will discuss the presence and nature of organic molecules trapped within the saponite interlayers and their potential role in catalyzing prebiotic molecules during the formation of the Enceladus ocean and their impact on its habitability potential.
[1] Khawaja et al., 2025 (https://doi.org/10.1038/s41550-025-02655-y); [2] Reynard and Sotin, 2023 (https://doi.org/10.1016/j.epsl.2023.118172); [3] Pizzarello et al., 2010 (doi: 10.1101/cshperspect.a002105); [4] Potzili et al., 2023 (https://doi.org/10.3390/life13071448); [5] Viennet et al., 2023 (https://doi.org/10.7185/geochemlet.2307); [6] Viennet et al., 2022 (https://doi.org/10.1016/j.gca.2021.12.002); [7] Noda et al., 2021 (https://doi.org/10.3390/min11111244); [8] Kebukawa et al., 2020 (https://doi.org/10.1016/j.icarus.2020.113827).
How to cite: Lévêque, P., Slodczyk, A., Champailler, R., Fukushi, K., Kebukawa, Y., and Sekine, Y.: Experimental simulation of Enceladus’ hydrothermal vents to constrain the evolution of primordial organic matter with iron-rich saponite, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-740, https://doi.org/10.5194/epsc2026-740, 2026.
The origin and chemical evolution of Saturn’s rings remain debated. Proposed formation scenarios include the disruption of an icy moon, tidal splitting of a comet, or primordial formation followed by long-term processing, including contamination by exogenous dust (Crida et al. 2019). We propose that direct intercomparison of mass spectrometer datasets could further our understanding of similarity or dissimilarity of organic matter reservoirs, even when full spectral deconvolution is not possible because of limited mass resolution and degeneracy among possible constituents. Here, we take a first step by comparing Ion and Neutral Mass Spectrometer (INMS) data (Miller et al. 2020), obtained during Cassini’s proximal orbits from material flowing from the rings into Saturn’s upper atmosphere (Waite et al. 2018), with Rosetta’s Double Focusing Mass Spectrometer (DFMS) measurements from the dusty coma of comet 67P/Churyumov-Gerasimenko (Hänni et al. 2022), as well as with laboratory spectra from irradiation experiments with astrochemical ice analogues (Javelle et al. 2025; Danger et al. 2013).
A first comparison between the averaged unit-resolution INMS spectra and rebinned DFMS spectra reveals striking similarities, including broad intensity patterns arising from a wide range of organic molecules and the prominent m/z = 91 peak associated with aromatic benzyl-bearing compounds such as toluene. Differences occur mainly at higher masses and in heteroatom-bearing regions. Some variability in fragmentation patterns between the datasets is expected, for example because the spacecraft had very different relative velocities, but remains difficult to quantify. Our preliminary analysis suggests that the equatorial ring inflow material may be related to 67P-like matter. A reference dataset of micrometeorites and/or interplanetary dust particles is needed to further constrain the various origin and evolution scenarios. Comparison with irradiated ice residue, to test a link to radiation-driven processing in these two reservoirs of organics, is ongoing. Similarity among all these organic matter reservoirs could indicate a shared history in the early Solar System.
Crida et al. Nat. Astron. (2019) 3, 967-970.
Waite et al. Science (2018) 362, eaat2382.
Miller et al. Icarus (2020) 339, 113595.
Hänni et al. Nat. Commun. (2022) 13, 3639.
Javelle et al. CommChem (2025) 8, 306.
Danger et al. GCA (2013) 118, 184-201.
How to cite: Hänni, N., Altwegg, K., Danger, G., Miller, K. E., and Rubin, M.: Comparative mass spectra analysis as a steppingstone towards a better understanding of the origin and evolution of Saturn’s rings, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-1024, https://doi.org/10.5194/epsc2026-1024, 2026.
Nitrogen, oxygen, phosphorus, and sulfur are key elements in carbon-based biochemistry, and in-situ comet missions are a unique opportunity to study these elements' prevalence in pristine organics. A milestone was ESA's Rosetta mission, which investigated comet 67P/Churyumov-Gerasimenko (hereafter 67P). The on-board high-resolution Double Focusing Mass Spectrometer (DFMS), part of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA; Balsiger et al. 2007) analyzed the chemical composition of 67P in great detail (Altwegg et al. 2019). Subsequent studies revealed a plethora of complex organic molecules reaching from pure hydrocarbons (Hänni et al. 2022), O-bearing molecules (Hänni et al. 2023), N-bearing compounds (Hänni et al. 2025) as well as dimethyl sulfide (Hänni et al. 2024). In these previous studies, the chemical species formed during the experiments were primarily identified based on signals corresponding to their molecular masses and (major) fragments produced by electron-impact in the mass spectra. However, such an approach can lead to ambiguities, as best-fitting molecules are hand-picked, introducing human bias and error propagation. In addition, isomers with similar fragmentation patterns further increase such degeneracies.
In this work, the previously acquired mass spectra will therefore be reanalyzed using a Monte Carlo-based deconvolution approach (Gautier et al. 2020) to obtain a more standardized, reproducible, and intercomparable interpretation of the chemical composition. By statistically exploring large numbers of possible combinations of candidate molecules and their associated fragmentation patterns, this method aims to disentangle overlapping contributions in the spectra and improve the identification of true molecular compounds while minimizing misassignments caused by fragmentation artifacts.
Introducing this statistical approach standardizes the analysis procedure and reduces the influence of human bias on the spectral interpretation, while also testing whether the results align with previous studies. Furthermore, the results will be compared to those reported by the Cometary Sampling and Composition Experiment (COSAC; Goesmann et al. 2007) aboard the Philae lander, where the same software was used for the deconvolution of the mass spectra (Leseigneur et al. 2022).
References:
Altwegg, K., Balsiger, H., & Fuselier, S. A. (2019). Cometary chemistry and the origin of icy solar system bodies: the view after Rosetta. Annual Review of Astronomy and Astrophysics, 57(1), 113-155.
Balsiger, H., Altwegg, K., Bochsler, P., Eberhardt, P., Fischer, J., Graf, S., ... & Wollnik, H. (2007). Rosina–Rosetta orbiter spectrometer for ion and neutral analysis. Space Science Reviews, 128(1), 745-801.
Gautier, T., Serigano, J., Bourgalais, J., Hörst, S. M., & Trainer, M. G. (2020). Decomposition of electron ionization mass spectra for space application using a Monte‐Carlo approach. Rapid Communications in Mass Spectrometry, 34(8), e8684.
Goesmann, F., Rosenbauer, H., Roll, R., Szopa, C., Raulin, F., Sternberg, R., ... & Munoz-Caro, G. (2007). COSAC, the cometary sampling and composition experiment on Philae. Space Science Reviews, 128(1), 257-280.
Hänni, N., Altwegg, K., Combi, M., Fuselier, S. A., De Keyser, J., Rubin, M., & Wampfler, S. F. (2022). Identification and characterization of a new ensemble of cometary organic molecules. Nature Communications, 13(1), 3639.
Hänni, N., Altwegg, K., Baklouti, D., Combi, M., Fuselier, S. A., De Keyser, J., ... & Wampfler, S. F. (2023). Oxygen-bearing organic molecules in comet 67P’s dusty coma: First evidence for abundant heterocycles. Astronomy & Astrophysics, 678, A22.
Hänni, N., Altwegg, K., Combi, M., Fuselier, S. A., De Keyser, J., Ligterink, N. F., ... & Wampfler, S. F. (2024). Evidence for abiotic dimethyl sulfide in cometary matter. The Astrophysical Journal, 976(1), 74.
Hänni, N., Altwegg, K., Baklouti, D., Combi, M., Fuselier, S. A., De Keyser, J., ... & Wampfler, S. F. (2025). Nitrogen-and nitrogen-oxygen-bearing organic molecules in comet 67P/Churyumov-Gerasimenko: An untargeted investigation. Astronomy & Astrophysics, 699, A135.
Leseigneur, G., Bredehöft, J. H., Gautier, T., Giri, C., Krüger, H., MacDermott, A. J., ... & Goesmann, F. (2022). ESA's Cometary Mission Rosetta—Re‐Characterization of the COSAC Mass Spectrometry Results. Angewandte Chemie International Edition, 61(29), e202201925.
How to cite: Matuszewski, F., Hänni, N., El Moudden, T., Ruben, M., Altwegg, K., and Gautier, T.: Re-characterization of complex organic molecules and their fragments in comet 67P, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-1036, https://doi.org/10.5194/epsc2026-1036, 2026.
The search for life in the Solar System hinges on measurements that planetary missions can return. Classical organic biosignatures, including molecular identity, isotopic composition, and chiral excess, require compound-specific resolution, high precision, and contamination control, and may be altered by degradation processes [e.g., 1,2]. We introduce a new class of biosignatures, based on the statistical organization of molecular assemblages [3]. Its premise is that abiotic chemistry, governed primarily by thermodynamic and kinetic constraints, tends to favor simple compounds and sparse abundance distributions [4], whereas biological systems maintain molecular distributions through metabolism, regulation, and functional demand [5]. Relative abundances within a coherent molecular family should therefore encode an origin-diagnostic imprint of chemical organization.
We quantify this imprint using the ecodiversity formalism, treating each molecular assemblage as an analog of an ecological community, with compounds as species and relative abundances defining community structure [6,7]. For each sample, we compute Hill-number diversity profiles and normalize them by sample richness to obtain evenness curves. These curves isolate abundance structure from total concentration and species count, enabling comparisons across datasets that differ in extraction protocol, analytical method, inventory size, and molecular coverage. Measurement uncertainty is propagated through the diversity calculation, and sample dissimilarities are estimated from the separation of evenness-curve distributions.
We apply this framework to a heterogeneous dataset of amino-acid assemblages spanning biological, extraterrestrial, and experimental contexts. Biotic samples include microbial biomass, sediments, hydrothermal fluids, fossil-bearing cherts, fossilized biominerals, and amber-preserved material. Abiotic samples include carbonaceous chondrites, returned asteroidal material from Ryugu and Bennu, ureilites, laboratory-prebiotic-synthesis products, and simulated ocean-world analogs [e.g., 8–10]. Despite this heterogeneity, biotic and abiotic samples occupy distinct regions of diversity space (Fig. 1a). Biotic amino-acid assemblages are more even, reflecting coordinated production of chemically diverse building blocks (Fig. 1b), whereas abiotic assemblages are sparser and more strongly dominated by low-mass species, consistent with thermodynamic and kinetic control [4]. This separation is not only visual: k-nearest-neighbor classification of the diversity space embedding yields high classification performance, with normalized Matthews correlation coefficients of approximately 90–100% across neighborhood sizes and permutation-based significance exceeding 4σ (Fig. 1c). Extensively altered samples form an intermediate group, indicating that diversity structure encodes preservation state as well as biogenicity.
We further apply the framework to fatty acids, a second molecular class central to membranes and prebiotic chemistry [11,12]. Biotic and abiotic fatty-acid assemblages are again separable, but the diversity contrast reverses. Abiotic fatty acids are more even across chain lengths, consistent with broad production pathways such as Fischer-Tropsch-type synthesis [12]. Biotic fatty acids are sparser, reflecting membrane biosynthesis, which selects restricted chain lengths and parities required for cellular function [11]. Thus, biological organization expands diversity where a broad repertoire is required, as in amino acids, and constrains it where function demands a narrower compositional range, as in membrane-forming fatty acids.
Finally, we test the persistence of the amino-acid diversity signal under space-like degradation by modeling radiolysis in Europa’s near-surface ice. Biotic and abiotic profiles are evolved under depth-dependent radiation doses and species-specific radiolytic decay constants [13,14]. The degraded biotic signal diverges from its pristine state and may briefly approach an abiotic-like profile, but remains distinguishable across depths and timescales relevant to planetary exploration until abundances become too sparse for an evenness curve to be defined.
Diversity analysis is therefore an instrument-agnostic framework for life detection. It requires only relative abundances within a coherent molecular family and can be applied to diverse measurement techniques. By capturing a statistical property of molecular organization, it provides a general, interpretable, and mission-compatible biosignature that complements existing approaches and may transcend signatures contingent on Earth-specific evolutionary history.
Figure 1. Dissimilarity analysis of evenness curves for amino-acid assemblages. (a) Multidimensional Scaling (MDS) projection of pairwise dissimilarities between evenness curves, E(q). Each point represents a sample; distances increase with statistical separation. Edges connect samples to the 25th percentile of their nearest neighbors. Markers denote inferred origin: biotic (green hexagons), abiotic (pink circles), and mixed (blue diamonds). (b) Evenness-curve distributions for four sample groups. Solid lines indicate group means; shaded regions denote one standard deviation. Each color represents the distribution of samples contained within the shaded regions of the same color in panel (a). (c) Classification performance of sample origin using k-Nearest-Neighbors (kNN) applied to pairwise dissimilarities projected onto the first two MDS axes. Three labeling schemes are evaluated: all three groups retained, and two alternatives in which the mixed group is assigned to either the biotic or abiotic class. Accuracy is reported as the normalized Matthews Correlation Coefficient (MCC), where 50% corresponds to random assignment and 100% to perfect classification. Uncertainty is estimated by bootstrapping class-balanced subsamples and recomputing kNN accuracy for each subsample. The value shown at the top right denotes the smallest permutation-based Z score across all k. It measures the deviation of the observed mean MCC from the mean under permuted class labels, using the most conservative value across the three labeling schemes.
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How to cite: Yoffe, G., Klenner, F., Sober, B., Kaspi, Y., and Halevy, I.: Diversity within organic assemblages as a biosignature, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-161, https://doi.org/10.5194/epsc2026-161, 2026.
