The aim of the European Space Agency’s ExoMars rover mission is to search for potential traces of present or
past life in the swallow subsurface (2m depth) of Mars. The ExoMars rover mission relies on a suite of
analytical instruments envisioned to identify organic compounds with biological value (biomarkers) associated
with a mineralogical matrix in a highly oxidative environment. We investigated the feasibility of detecting basic
organics (linear and branched lipid molecules) with Raman laser spectroscopy, an instrument onboard the
ExoMars rover, when exposed to oxidant conditions. We compared the detectability of six lipid molecules
(alkanes, alkanols, fatty acid, and isoprenoid) before and after an oxidation treatment (15 days with hydrogen
peroxide), with and without mineral matrix support (amorphous silica rich vs. iron rich). Raman and
infrared spectrometry was combined with gas chromatography–mass spectrometry to determine detection
limits and technical constraints. We observed different spectral responses to degradation depending on the
lipid molecule and mineral substrate, with the silica-rich material showing better preservation of organic
signals. These findings will contribute to the interpretation of Raman laser spectroscopy results on cores
from the ExoMars rover landing site, the hydrated silica-enriched delta fan on Cogoon Vallis (Oxia Planum).
