Raman analysis of a shocked planetary surface analogue: Implications for habitability on Mars

Abstract

The scientific aims of the ExoMars Raman laser spectrometer (RLS) include identifying biological signatures and evidence of mineralogical processes associated with life. The RLS instrument was optimised to identify carbonaceous material, including reduced carbon. Previous studies suggest that reduced carbon on the Martian surface (perhaps originating from past meteoric bombardment) could provide a feedstock for microbial life. Therefore, its origin, form, and thermal history could greatly inform our understanding of Mars' past habitability. Here, we report on the Raman analysis of a Nakhla meteorite analogue (containing carbonaceous material) that was subjected to shock through projectile impact to simulate the effect of meteorite impact. The characterisation was performed using the RLS Simulator, in an equivalent manner to that planned for ExoMars operations. The spectra obtained verify that the flightrepresentative system can detect reduced carbon in the basaltic sample, discerning between materials that have experienced different levels of thermal processing due to impact shock levels. Furthermore, carbon signatures acquired from the cratered material show an increase in molecular disorder (and we note that this effect will be more evident at higher levels of thermal maturity). This is likely to result from intense shearing forces, suggesting that shock forces within basaltic material may produce more reactive carbon. This result has implications for potential (past) Martian habitability because impacted, reduced carbon may become more biologically accessible. The data presented suggest the RLS instrument will be able to characterise the contribution of impact shock within the landing site region, enhancing our ability to assess habitability.

Tribute to Derek Long: An instant snapshot of the development of Raman spectroscopy and its application in the fields of instrumentation and methodology, solid‐state materials, cultural heritage, DFT modeling and applications in biology, microbiology, and medicine

“…Therefore, its origin, form, and thermal history could greatly inform our understanding of Mars' past habitability. The paper of McHugh et al ( Raman Analysis of a Shocked Planetary Surface Analog: Implications for Habitability on Mars , University of Leicester, UK) [ 24 ] reports on the Raman analysis of a Nakhla meteorite analog (containing carbonaceous material) that was subjected to shock through projectile impact to simulate the effect of meteorite impact. The characterization was performed using the RLS Simulator, in an equivalent manner to that planned for ExoMars operations.…”

Coherent Raman Spectroscopy of Equilibrium Phonons with Subwavenumber Resolution

“…Raman spectroscopy is a powerful technique to study vibrational motions within individual chemical bonds of molecules as well as atomic displacements in crystal lattices. The applications have spanned across broad areas of condensed matter physics, physical chemistry, chemical physics, environmental sciences, biological physics, and cell and tissue biology. − Invention of high-intensity laser sources has brought to existence coherent methods in spectroscopy with breakthrough results in quantitative characterizations of traditional and soft condensed matter. Furthermore, pulsed solid-state lasers provided a new level of opportunities in developing spectroscopic techniques with ultrafast time resolution.…”

“…Therefore, the development of the methods and different applications are of high importance for fundamental and applied sciences. Pioneering contributions in the field of coherent Raman spectroscopy demonstrated picosecond time resolutions on vibrational dynamics in liquids and solids. − More recently, coherent Raman spectroscopy techniques with time resolution down to 40 fs have been demonstrated. − Despite the progress, there are still drawbacks in the systems’ performances and further improvements could bring benefits of achieving qualitatively better results. In particular, time-domain methods in coherent Raman spectroscopy can provide high equivalent spectral resolution.…”