Hypervelocity impact mass spectrometry enables membrane phospholipid detection in ocean-world plumes
Year: 2026
Type: preprint
Abstract: Saturn's ocean moon Enceladus and Jupiter's moon Europa expel subsurface material into space, enabling direct sampling of potentially habitable ocean environments without landing on their surfaces. Previous spacecraft analyses of plume ice grains revealed salts, simple organic compounds, and degraded macromolecular material, but no unambiguous molecular biosignatures. A fundamental question is whether diagnostic components of living cells can survive hypervelocity impact ionization during spacecraft flyby sampling. Here, we demonstrate that phospholipid membranes produce distinct and diagnostic negative-ion signatures following hypervelocity impacts of nanometer-sized ice particles at velocities up to 3.7 km s⁻¹. Using artificial vesicles composed of the phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), we obtained single-particle time-of-flight mass spectra containing characteristic phosphate-derived and fatty-acid fragment ions together with higher-mass species. Assignments were supported by collision-induced dissociation measurements using high-resolution Orbitrap mass spectrometry. The persistence of these membrane-specific anions demonstrates that hypervelocity impact ionization preserves molecular signatures diagnostic of phospholipid bilayers, identifying cell membranes or their components as a detectable class of biosignatures for plume-sampling missions. Our results provide an experimental framework for interpreting complex negative-ion spectra from future ocean-world missions, including Europa Clipper and proposed Enceladus missions, and highlight the scientific value of high-resolution negative-ion impact mass spectrometry for the search for extraterrestrial life.
Source: ChemRxiv
Language: English
Subfield: Spectroscopy
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7213969776