Combined Spectroscopic Analysis of Terrestrial Analogs from a Simulated Astronaut Mission Using the Laser-Induced Breakdown Spectroscopy (LIBS) Raman Sensor: Implications for Mars

Abstract

One of the primary objectives of planetary exploration is the search for signs of life (past, present, or future). Formulating an understanding of the geochemical processes on planetary bodies may allow us to define the precursors for biological processes, thus providing insight into the evolution of past life on Earth and other planets, and perhaps a projection into future biological processes. Several techniques have emerged for detecting biomarker signals on an atomic or molecular level, including laser-induced breakdown spectroscopy (LIBS), Raman spectroscopy, laser-induced fluorescence spectroscopy (LIF), and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy, each of which addresses complementary aspects of the elemental composition, mineralogy, and organic characterization of a sample. However, given the technical challenges inherent to planetary exploration, having a sound understanding of the data provided from these technologies, and how the inferred insights may be used synergistically is critical for mission success. In this work, we present an in-depth characterization of a set of samples collected during a 28-day Mars analogue mission conducted by the Austrian Space Forum in the Dhofar region of Oman. The samples were obtained under high-fidelity spaceflight conditions and by taking into account the geological context of the test site. The specimens were analyzed using the LIBS/Raman Sensor (LIRS)⁠—a prototype instrument for future exploration of Mars. We present the elemental quantification of the samples obtained from LIBS using a previously developed linear mixture model, and validated by Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS). Moreover, we provide a full mineral characterization obtained using UV Raman spectroscopy and LIF, which was verified through ATR-FTIR. Lastly, we present possible discrimination of organics in the samples using LIF and time-resolved LIF. Each of these methods yields accurate results, with low errors in their predictive capabilities of LIBS (median relative error ranging from 4.5% to 16.2%), and degree of richness in subsequent inferences to geochemical and potential biochemical processes of the samples. The existence of such methods of inference and our ability to understand the limitations thereof is crucial for future planetary missions, not only to Mars and Moon but also for future exoplanetary exploration.

Geochemical and Biological Profiles of a Quartz Stone in the Qaidam Mars Analog Using LIBS: Implications for the Search for Biosignatures on Mars

“…40,42,46,73 This study is one of the pioneering spectroscopic Qaidam investigations that combine LIBS and Raman instrumentations to survey the biotic signal of possible hypolithic communities from chemical and mineralogical profiles. 25,74,75 LIBS is a useful tool for efficiently analyzing elemental compositions of samples, especially in the context of astronomic observation. 26 Without sample preparation and homogenization, the semiquantitative technique LIBS generally does not generate as precise measures as other elemental determination technologies, such as X-ray fluorescence, atomic absorption spectroscopy, and inductively coupled plasma optical emission spectrometry.…”

“…The western Qaidam Basin is an exemplary Mars analog in accordance with its low water activity and the resultant landforms, including gravel deposition, pits, dunes, troughs, and aeolian ridges. ,,− ,− In Mars-like environments, hypolithic communities are usually acknowledged as a high-priority target for biosignature detection. ,,, This study is one of the pioneering spectroscopic Qaidam investigations that combine LIBS and Raman instrumentations to survey the biotic signal of possible hypolithic communities from chemical and mineralogical profiles. ,, …”

“…For astrobiology, LIBS becomes more useful when coupled to other techniques, mostly Raman spectroscopy , and sometimes X-ray and reflectance spectroscopy, , to integrally characterize the geochemical and mineralogical profiles as well as organic signals. , Sensitive to minor alterations in the vibrational, rotational, and low-frequency motions of chemical bonds, Raman spectra contribute to a comprehensive understanding of intramolecular structures . Raman spectroscopy and LIBS can significantly complement each other; that is, Raman is advantageous for mineral identification and organic detection but only inferable for elemental composition determination, while LIBS is excellent at elemental composition determination and potentially able to detect organic fragments and elements (e.g., C and N). − Apart from Raman spectroscopy, previous studies combined LIBS with other reflectance spectroscopy. For example, a previous study combined LIBS with IR reflectance spectroscopy to differentiate biotic and abiotic sources on Earth observed by scanning electron microscopy, indicating that the LIBS and IR spectral measures of biotic and abiotic sources could be separated by multivariate principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) …”

Novel fluorescence analysis for real-time moon mineralogy

“…XRF, PGNAA, and LIBS all provide elemental information, while Raman scattering provides information about chemical bonds and hyperspectral imaging information about chemical bonds and mineral species. SWAP (Size, Weight, And Power consumption) characteristics and knowledge required for each terrestrial task or off-world mission need to be considered carefully to select the ideal combination of sensors [16][17][18] .…”

Hybrid Raman and Laser-Induced Breakdown Spectroscopy for Food Authentication Applications

“…For example, Zhao et al [ 29 ] reported that quantifying calcium in infant formula using LIBS and Raman required two spectrometers, a 1064 nm pulsed laser for LIBS and a 532 nm continuous laser for Raman. When it comes to combined LIBS and Raman systems, the focus remains mainly on mineral analysis because the power of the LIBS modality is leveraged to its fullest in this area [ 30 , 31 ]. Finally, data processing (chemometrics) is not currently optimized when handling combined systems in various analyses.…”