Mineralogy on celestial bodies is of keen and topical interest to a broad spectrum of researchers. A desired understanding of our solar system drives investigation into the structural composition of planets and moons, with an added layer of prebiotic chemical significance in potential extraterrestrial life formation.1 Titan, one of Saturn’s moons, has an atmospheric composition of nitrogen and methane. Various photo-induced ionisation and dissociation processes result in a diverse set of organic molecules forming in the atmosphere, comprising of mostly carbon, nitrogen and hydrogen.2,3 The dense and complex atmosphere of Titan is known to form crystals in the atmosphere and on the surface.4 Structures and properties of these crystals, both single and multi (cocrystal) components, has a significant influence over the composition and geological processes occurring on Titan’s surface. An understanding of organic crystals on the surface of Titan is of pressing concern, with NASA’s Dragonfly mission set to launch in 2028.
A priori prediction of crystals forming on Titan, from a structural and growth perspective provides an efficient method to build a database of likely minerals observed by future surface-landing missions. Understanding of crystal growth reveals the most likely crystal structures at Titan relevant conditions, prediction of which on Earth requires involves a rigorous experimental undertaking. Insights provided by an increased understanding of growth processes of organic crystals is not limited to the mineralogy of celestial bodies such as Titan. Growth of crystals, and the influential chemical contexts have several Earth-based applications, including the development of effective pharmaceutical polymorphs.5–7
This work utilises prediction of crystal structure, growth and properties to present crystal structures likely found on Titan. Investigation of crystal growth and mechanical properties provides foundational knowledge into the mineralogy of Titan. This serves to narrow down the wide range of potential candidates based purely on chemical composition, to a more feasible list of crystals likely observed at Titan relevant conditions. The work contained here will accelerate analysis of experimental data from upcoming interstellar probes such as Dragonfly.
References:
(1) Rahm, M.; Lunine, J. I.; Usher, D. A.; Shalloway, D. Polymorphism and Electronic Structure of Polyimine and Its Potential Significance for Prebiotic Chemistry on Titan. Proceedings of the National Academy of Sciences 2016, 113 (29), 8121–8126. https://doi.org/10.1073/pnas.1606634113.
(2) Nixon, C. A. The Composition and Chemistry of Titan’s Atmosphere. ACS Earth Space Chem. 2024, 8 (3), 406–456. https://doi.org/10.1021/acsearthspacechem.2c00041.
(3) Maynard-Casely, H. E.; Cable, M. L.; Malaska, M. J.; Vu, T. H.; Choukroun, M.; Hodyss, R. Prospects for Mineralogy on Titan. American Mineralogist 2018, 103 (3), 343–349. https://doi.org/10.2138/am-2018-6259.
(4) Thakur, A. C.; Remsing, R. C. Molecular Structure, Dynamics, and Vibrational Spectroscopy of the Acetylene:Ammonia (1:1) Plastic Co-Crystal at Titan Conditions. ACS Earth Space Chem. 2023, 7 (2), 479–489. https://doi.org/10.1021/acsearthspacechem.2c00327.
(5) Price, S. L.; Braun, D. E.; Reutzel-Edens, S. M. Can Computed Crystal Energy Landscapes Help Understand Pharmaceutical Solids? Chemical Communications 2016, 52 (44), 7065–7077. https://doi.org/10.1039/C6CC00721J.
(6) Spackman, P. R.; Walisinghe, A. J.; Anderson, M. W.; Gale, J. D. CrystalClear: An Open, Modular Protocol for Predicting Molecular Crystal Growth from Solution. Chem. Sci. 2023, 14 (26), 7192–7207. https://doi.org/10.1039/D2SC06761G.
(7) Armstrong, B.; Spackman, P. Elastic Tensors from Pairwise Energy Frameworks in Molecular Crystals. ChemRxiv 2026, 2025 (1217). https://doi.org/10.26434/chemrxiv-2025-2qh1h-v2.