Identification of Molecular Biosignatures in Antarctic Ices: Implications for Icy Moons Exploration

Enceladus and Europa are key targets for planetary exploration due to their subsurface water oceans, making them some of the most habitable places in the solar system. Onboard the Europa Clipper spacecraft, the SUrface Dust Analyzer (SUDA [1]) will provide the chemical composition of ice grains ejected by plumes and/or micrometeorite bombardment of the surface. As shown by laboratory experiments [e.g., 2,3], molecular biosignatures can be detected by SUDA or an alternative advanced mass spectrometer on an Enceladus mission [4]. Lipids in particular can provide characteristic spectral fingerprints and are considered universal biomarkers of life [5] owing to their effective membrane-forming properties even under geochemically hostile conditions and their ubiquity in all known forms of life.

The performance and calibration of SUDA-type instruments strongly relies on analogue experiments using Laser Induced Liquid Beam Ion Desorption (LILBID) - a well-established method allowing the simulation of ice grains’ impact ionization mass spectra. Many LILBID spectra have already been recorded to complement an expanding reference database [6] for e.g., Europa Clipper.Environmental samples allow for a more realistic assessment of the detection capabilities of spaceborne instruments (as compared to experiments with prepared synthetic samples of well-defined compositions). Specifically, natural ice analogues from polar locations offer some of the most realistic representations of icy moons. However, polar samples have never before been analyzed with LILBID.

Here we present the first analysis of natural ice analogues with LILBID combined with a detailed characterization of lipid biomarkers. With support from the Instituto Antártico Uruguayo, ice samples were collected from key locations in the Collins (a.k.a. Bellingshausen) glacier on King George Island, Antarctica, where several environmental conditions (including intense UV radiation, saline aerosols, low temperature) are analogous to specific processes on ocean worlds.

LILBID analysis, providing SUDA-type analogue mass spectra, were combined to data obtained from Gas Chromatography linked to Mass Spectrometry (GC-MS), Raman and IR spectroscopy. Results on icy samples containing pink microalgae revealed key fingerprints of lipids adapted to cold temperatures, and highlight a novel assessment of the detectability of lipid biomarkers from icy moon analogues with spaceborne instrumentation.

[1] S. Kempf et al., Space Sci. Rev. 221, 10 (2025); [2] M. Dannenmann et al. Astrobiology 23(1):60–75 (2023); [3] F. Klenner et al., Science Advances, 10(12), eadl0849 (2024); [4] O. Mousis et al., The Planetary Science Journal, 3(12), 268 (2022); [5] C.D. Georgiou & D.W. Deamer. Astrobiology 14(6):541–549 2014); [6] F. Klenner et al., Earth Space Sci., 9, e2022EA002313 (2022)