Molecular Biosignature Detection on Ocean Worlds using a Prototype Laser-Desorption Ionisation Mass Spectrometer

Recently, it has become evident that icy moons in our solar system might constitute excellent targets for the search for life beyond Earth. Both Europa and Enceladus are of high interest for the detection of biosignatures, mainly due to the putative presence of all ingredients required to form life (as we know it), i.e., liquid water, an energy source, and the required chemical ingredients. If life is indeed present on these two bodies, molecular biosignatures may be preserved and protected from the radiative environment in the near surface ice. In situ instrumentation on board of a payload could perform compound identification and biosignature detection facilitating better limits of detection and more specific compound detection compared to spectroscopic measurements from orbit.

Several (groups of) compounds are listed as molecular biosignatures, including certain amino acids and lipids.¹ However, reliable in situ detection of molecular biosignatures is challenging. Not only does the instrumentation need to be flight-capable, it should also be sensitive enough to detect trace abundances, while simultaneously covering a high dynamic range, so as to not exclude highly abundant compounds. Additionally, instrumentation should preferably be capable of detecting many different classes of molecules and not be limited to a single compound or group of molecules.

ORIGIN (ORganics Information Gathering INstrument) is a space-prototype laser ablation ionisation mass spectrometer (LIMS) operated in desorption mode and designed for in situ detection of molecular biosignatures for space exploration missions. The simplistic and compact design make it a lightweight and robust system, which meets the requirements of space instrumentation. Currently, the setup consists of a nanosecond pulsed laser system and a miniature reflectron-type time-of-flight (RTOF) mass analyser (160 mm x Ø 60 mm). Biomolecules are desorbed and ionised by the laser pulse, after which the positive ions are separated based on their mass-to-charge ratio (TOF principle) by the mass analyser.

The molecular biosignature detection capabilities of ORIGIN have been recently demonstrated for amino acids, polycyclic hydrocarbons, and lipids ^2–4. In this contribution, our envisioned concept of going from obtained ice samples to the detection of molecular biosignatures using LIMS will be discussed. In addition, we will show results of lipid biosignature detection using ORIGIN, covering sensitivity and dynamic range², implying the future applicability for the detection of life on Icy Moons. Additionally, future projects of analogue ice studies with the ORIGIN space-prototype will be covered.

1. Hand, K. P. et al. Report of the Europa Lander Science Definition Team. (Jet Propulsion Laboratory, 2017).

2. Boeren, N. J. et al. Detecting Lipids on Planetary Surfaces with Laser Desorption Ionization Mass Spectrometry. Planet. Sci. J. 3, 241 (2022).

3. Kipfer, K. A. et al. Toward Detecting Polycyclic Aromatic Hydrocarbons on Planetary Objects with ORIGIN. Planet. Sci. J. 3, 43 (2022).

4. Ligterink, N. F. W. et al. ORIGIN: a novel and compact Laser Desorption – Mass Spectrometry system for sensitive in situ detection of amino acids on extraterrestrial surfaces. Sci. Rep. 10, 9641 (2020).