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One of the primary scientific objectives in planetary exploration is analyzing the geochemistry and potential biochemistry of planetary environments and their habitability conditions, in addition to finding signs of extinct or extant life. Various spectroscopic techniques have been proposed and largely embraced by the scientific community for such analyses; however, despite the overwhelming success of these methods, it is not always well understood how they can function synergistically while complying with payload and operational constraints. Emmanuel Lalla of York University in Toronto, Ontario, Canada, as well as his co-authors, recently presented an in-depth characterization of a set of samples collected during a 28-day Mars analog mission conducted by the Austrian Space Forum in the Dhofar region of Oman. The samples were obtained under high-fidelity spaceflight conditions and by considering the geological context of the test site. The specimens were analyzed using the LIBS–Raman sensor, a prototype instrument for future exploration of Mars. Lalla spoke to Spectroscopy about this research, as well as how various methods of spectroscopic analysis can complement each other in analysis.
What inspired you to undertake this research to use a laser-induced breakdown spectroscopy (LIBS)–Raman sensor for geochemical analysis for planetary exploration as discussed in your paper (1)?
Past instruments such as ChemCam, SuperCam, and SHERLOC, while very powerful have been rather limited in scope. Each of the instruments was optimized for a specific technique. The Canadian Space Agency was looking for an integrated system that could present multiple capabilities, thus inspiring our team to develop the LIBS Raman sensor (LiRS), integrating, LIBS and ultraviolet (UV)-Raman with time-resolved capabilities. The project involved the Canadian Space Agency (CSA), the National Institute of Optics (INO), the MDA-Corporation, and York University. The final system was a three-part system featuring a multi-spectroscopic breadboard prototype that incorporates micro-laser-induced breakdown spectroscopy (μLIBS), UV-Raman spectroscopy, UV-laser-induced fluorescence (LIF), time-resolved LIF (TR-LIF), and passive reflectance spectroscopy for analysis of Martian biogeochemistry.
In what ways is a Mars analog mission limited in simulating actual Mars analysis conditions?
Earth simulated missions present several advantages compared to actual spaceflight or future real missions and by simulating the mission, we can advance and learn additional information and limitations when designing the future mission(s). In order to decrease the unknows of long-term missions, each analog mission from different institutions (NASA, ESA, OeWF) mimic certain characteristics of a possible future Martian mission. In this way, each analog mission will be of high fidelity to corresponding planetary missions which will aid in addressing engineering, psychological, scientific, and technical questions.
Furthermore, multiple simulated studies have been performed toward the development of scientific support within the context of analog Mars missions, such as MARS2013, AMADEE-15 and AMADEE-18 coordinated by the Austrian Space Forum (OeWF), Biologic Analog Science Associated with Lava Terrains (BASALT) simulated mission from NASA, and Planetary Analogue Geological and Astrobiological Exercise for Astronauts (PANGAEA) simulated mission from ESA. These missions have studied many essential aspects of planetary exploration and are part of the ongoing refinement of best practices within the Remote Science Support (RSS) framework; however, generally accepted guidelines have yet to be established. The limitations of a given simulated mission is eventually addressed by other simulated missions. As an example, the PANGAEA mission series focuses on training and preparing astronauts with a solid knowledge of the geology of Mars, the Moon, and asteroids. BASALT and AMADEE-18 carried out a platform for the detection of life through geophysical techniques, terrain tests for rovers, and increasing the situational awareness of remote support teams (such as RSS) and external experiment teams. Also, AMADEE-18 was focused on deploying analog astronauts to study a field-trial and a set of best practices and protocols for future human missions to Mars derived from previous experience.
Has planetary exploration always been of interest to you, or was it something else that attracted you to this study?
Yes, planetary exploration was always of interest. We have been working in planetary exploration for a long time, and apart from the current development of LIRS breadboard, we are involved in several on-ongoing mission like in OSIRIS-REx to Bennu (where Prof. M. G. Daly is the principal investigator of OLA), and in ESA-ExoMars (where E. Lalla is a contributor to the science of the Raman laser spectrometer). From a philosophical perspective, humans are explorers by nature and driven by our curiosity to the unknown, pushing the scientific and technical limits to the satisfaction of our imagination. In this regard, the past missions and great achievement in space exploration have been a source of inspiration for conducting our work and continuously contributing work, such as the present article to the field. Fundamentally, by visiting our planetary neighbors, we will be able to understand several questions about our solar system and origin of life: What was the origin of solar system? Where organic materials such as carbon come from? Was there ever life on Mars?
Furthermore, Robotic and Scientific missions to these planetary bodies provided reconnaissance information and scientific results about surface composition, and even returned samples to Earth for further evaluation. However, we are at a critical conjuncture as we prepare humans to re-visit the moon, and the challenge to visit an asteroid and land on Mars. In this regard, the continuous contribution to planetary exploration with Robotic mission and future human-robotic exploration will help these worthwhile pursuits.
How was your team’s approach different from previous research efforts?
Previous analyses and results combined several laboratory techniques comparable to the current research with the LiRS instrument. While those analyses provided a wealth of information around the synthesis of various techniques, they effectively simulated in situ instruments. In contrast, based on how the samples were selected, collected, returned, and analyzed, we were able to simulate, with a reasonable degree of fidelity, a sample return mission as might be expected from Mars Perseverance or OSIRIS-Rex. The synthesis of information derived from the instruments in the sample return context can be used to maximize mineralogical, petrological, and astrobiological inference in a rigorous and efficient way. Moreover, we demonstrated that combined spectroscopic methods can obtain accurate measurements, comparable to standard procedures and their laboratory equivalent. These combined measurements can contribute toward guidelines and best practices for future automatic analysis, such as the priority order for the different targets, target associations to be further investigated by the science team, and the degree of automatic guidance in current and future missions to Mars.
What were the benefits of using LIBS–Raman in this work?
LIBS-Raman is the next-generation of combined instrument for characterizing the mineralogy, bio-geo-chemical context, and possible detection of life on other planets. LIBS relies on ablating and evaporating material by focusing radiation from a pulsed laser onto the surface of a target, forming a plasma providing the sample’s elemental composition. Furthermore, the elemental information is obtained from the specific atomic transitions from the plasma. On the other hand, Raman spectroscopy has been demonstrated to be a powerful tool for the chemical and structural characterization of materials. In contrast to LIBS, Raman is a non-destructive technique that occurs when a molecule is excited by an excitation source (in modern times, a laser), and a back scattering is generated from vibration, stretching, bending or rotation from molecular bonds or crystal lattice. Furthermore, like the atomic emission lines from LIBS, the spectral bands from the molecular or crystal vibration is considered as a fingerprint. In the case of LIRS, the excitation Raman wavelength corresponds to the UV region giving many advantages over 532 nm systems like spectral separation with the fluorescence like SHERLOC. Both techniques, Raman and LIBS, share same kind of instrumentation such us the spectrometer, ICCD gated camera and optical systems. By being able to perform LIBS, UV-Raman spectroscopy, and other sequential techniques like LIF, TR-LIF and passive reflectance, LIRS can provide a set of data of elemental and mineral identification, elemental quantification, organic detection, and bio/geochemical information.
Briefly discuss your findings and their implications for the study of geochemical processes on planetary bodies and for the analysis community in general.
We have analyzed the returned samples from the AMADEE-18 mission using several modes of the LIRS instrument (UV-Raman, LIBS, LIF, and TR-LIF) with additional support from ATR-FT-IR and SEM/EDS. A principal implication of this study is the use of the sampling decision framework by which rover simulation analysis may be carried out, that is, whether to extract a sample from a given location based on the possible presence of organics and minerals, and the necessary quantity of a given sample for a specific technique. Such a decision framework informed by in situ analyses will enforce the necessity to carry out remote analyses to ensure that we can use relevant samples from the field, increasing the fidelity for ongoing and future missions and maximizing the scientific impact of sample return missions.
In addition to LIBS, Raman spectroscopy, laser-induced fluorescence (LIF) spectroscopy, time-resolved LIF (TRLIF) spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy were used in your efforts. What were the advantages and disadvantages of using these complementary analysis techniques?
Since no one technique was able to identify all mineral phases, infer the geological setting to be studied, and fully detect possible past-present biosignatures, it is important that techniques found in LiRS be complemented by other techniques to maximize the scientific output on future missions. In this regard, we made use of LIBS, Raman, LIF, TRLIF, and FT-IR, each found either on LiRS or as complementary technique on a rover, all of which cumulatively showed promise in achieving all the key scientific objectives. For example, our study revealed that combinations of synergistic instrumentation ensure precise organic detection and geological inferences can be achieved. Thus, careful selection of complementary techniques aboard a mission (such as human-rover missions) is likely to increase the probability of success.
Several examples can be cited about the combination of multi-technique instruments working in synergistic way such as Mars2020 Mission with equipped with several instruments. Of our particular interest in other mission are future results from SuperCam (providing imaging, chemical composition analysis, and mineralogy), SHERLOC (providing fine-scale imaging and uses an ultraviolet [UV] laser to determine fine-scale mineralogy and detect organic compounds), PIXL (that high resolution to determine the fine-scale elemental composition of Martian surface materials), and Mastcam-Z (that provides panoramic and stereoscopic imaging capability with the ability to zoom in). We expect that a similar synergy can be achieved with LiRS and other instruments on a future rover.
What sort of feedback did you receive on this study?
Throughout the peer-review process, the reviewers welcomed the research, mentioning that our research presents a novel contribution to planetary science, and it could be a useful example of multi-instrument spectroscopy for robust organic and mineral detection. They provided critical feedback, which made the article what it now is. Since its publication, the article has received significant attention within our scientific community and in more open platforms like ResearchGate.
What are your next steps regarding this research?
Our next step regarding this research is to continue refining the LiRS instrument since the instrument is in a bread-board configuration. The instrument is presently being used to analyze additional samples with relevance to Mars and the Moon. We are also actively working toward increasing the breadth of capabilities, namely, allowing for LiRS to conduct laser-induced molecular isotopic spectrometry, a technique by which we can estimate the age of a sample in situ. This, coupled with a recently installed nano-chamber, will allow us to conduct measurements of planetary interest under conditions like those of the planetary bodies of interest (such as similar temperatures, pressure, and atmospheres), thereby allowing us to optimize the instrument for subsequent missions.
(1) E.A. Lalla, M. Konstantinidis, E. Lymer, C.M. Gilmour, J. Freemantle, P. Such, K. Cote, G. Groemer, J. Martinez-Frias, E.A. Cloutis, and M.G. Daly, Appl. Spectrosc. 75(9), 1093–1113, 2021. doi:10.1177/00037028211016892
Emmanuel Lalla is a Research Associate at York University, where he leads and collaborates on science and technology development projects for space exploration. In 2021 he became co-PI of several projects funded by the Canadian Space Agency, where he engages in knowledge transfer activities among research institutions and industry at all technology readiness levels. He received his Ph.D. in Physics from the University of Valladolid, Spain, and worked as a researcher at several institutions in Europe before coming to Canada. He is a research collaborator of the Raman Laser Spectrometer at ExoMars Mission, currently scheduled for flight in 2022.