Detecting Lipids on Planetary Surfaces with Laser Desorption Ionization Mass Spectrometry

Abstract

In the search for extraterrestrial life, biosignatures (e.g., organic molecules) play an important role, of which lipids are one considerable class. If detected, these molecules can be strong indicators of the presence of life, past or present, as they are ubiquitous in life on Earth. However, their detection is challenging, depending on, e.g., instrument performance, as well as the selected site. In this contribution, we demonstrate that, using laser desorption ionization mass spectrometry, detection of lipids is feasible. Using our space prototype instrument designed and built in-house, six representative lipids were successfully detected: cholecalciferol, phylloquinone, menadione, 17α-ethynylestradiol, α-tocopherol, and retinol, both as pure substances and as mixtures additionally containing amino acids or polycyclic aromatic hydrocarbons. Observed limits of detection for lipids already meet the requirements stated in the Enceladus Orbilander mission concept. The current performance of our LDI-MS system allows for the simultaneous identification of lipids, amino acids, and polycyclic aromatic hydrocarbons, using a single instrument. We therefore believe that the LDI-MS system is a promising candidate for future space exploration missions devoted to life detection.