1,1,2,2,- 1University College London, Space and Climate Physics, United Kingdom of Great Britain – England, Scotland, Wales (anna.parsec.22@ucl.ac.uk)
- 2Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), CNRS, France
Negative ions are emerging as key players in the chemistry of icy moon environments [1], yet their formation mechanisms remain difficult to fully constrain from space data alone. Here we present a dual approach of combining in-situ observations from the Cassini mission CAPS-ELS instrument with dedicated laboratory simulations to better understand negative ion behaviour under Enceladus-like conditions.
From the planetary perspective, we report new findings from the analysis of Cassini's Enceladus flyby E3 to build on former reports [2], focusing on the composition and chemical complexity of the plume environment. These results extend our understanding of the moon's subsurface ocean and reinforce the potential role of negative ions in forming complex organic molecules along a prebiotic chemistry pathway. We also introduce initial concepts for a next-generation instrument designed to detect and characterise negative ions in future L4 mission.
From the laboratory perspective, we present simulations performed at LATMOS designed using PAMPRE experiment [3] to reproduce Enceladus-like conditions and study negative ion formation mechanisms directly. Preliminary results demonstrate how gas composition influences ion formation in icy moon environments.
These complementary approaches highlight the power of combining planetary datasets with Earth-based laboratory experiments to unravel the chemistry of ocean worlds. We discuss how these approaches complement each other, where open questions remain and what a next generation mission would need to resolve them.
[1] Schaible, M. J. et al., A. (2024). Chapter 1: The Astrobiology Primer 3.0. Astrobiology, 24(S1):S–4–S–39.
[2] Coates, A. J. et al. (2010) ‘Negative ions in the Enceladus plume’, Icarus, 206(2), pp. 618–622. Available at: https://doi.org/10.1016/j.icarus.2009.07.013.
[3] Dubois, D. et al. (2020) ‘Positive ion chemistry in an N2-CH4 plasma discharge: Key precursors to the growth of Titan tholins’, Icarus, 338. Available at: https://doi.org/10.1016/j.icarus.2019.113437.
How to cite: Parsec-Wallis, A., Coates, A., Preston, L., Chatain, A., Nicolaou, G., Chatterjee, A., and Vettier, L.: Bridging Cassini observations and laboratory experiments to further analyse the plumes of Enceladus, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-1009, https://doi.org/10.5194/epsc2026-1009, 2026.
