Raman Spectroscopy and its Role in Perseverance Rover’s SuperCam Instrument

New findings have been uncovered about the Martian environment on mineral samples, advancing our understanding of planetary evolution, according to a recent study published in Scientific Reports (1).

Planetary exploration has long depended on mineral characterization to decipher the history and composition of planets (1–3). However, understanding the processes that alter these materials on planetary surfaces is crucial for interpreting data from space missions accurately. This study, led by E. Clavé from the DLR - Institute of Optical Sensor Systems in Berlin, Germany, focuses on the first in situ observations of a known mineral target, a synthetic apatite sample, monitored on the Martian surface by the Perseverance rover's SuperCam instrument (1).

Perseverance Rover's Cruise Stage Separation. Satellite module delivers cargo to the red planet Mars | Image Credit: © alones - stock.adobe.com

SuperCam is a tool that is currently onboard the Mars2020 mission. Its purpose is to use Raman spectroscopy to analyze the crystalline state of minerals (1). Over the first 950 Martian days (sols) of the mission, the team monitored the synthetic apatite sample used as a calibration target (1). The researchers noted there was a decrease in the relative contribution of the Raman signal to the total signal. This decline indicates an alteration in the material's electronic structure, a change primarily attributed to exposure to the Martian environment (1).

One of the unique setups in their study was that the researchers replicated Martian conditions in the laboratory. By doing so, they were able to confirm that UV radiation on Mars leads to the creation of electronic defects in the mineral, thus affecting its Raman spectra (1).

Therefore, the study demonstrates that mineral alteration on Mars can occur within a matter of weeks, if not faster. This rapid alteration must be considered when analyzing mineralogical data from space missions (1). The findings highlight the need for careful interpretation of Raman and other vibrational spectroscopy data collected in situ on Mars and potentially other planetary bodies.

E. Clavé and the research team emphasized in their study that these observations are imperative for future Mars missions and the analysis of past mission data (1). Characterized by its thin atmosphere and ultraviolet (UV) radiation, the Martian surface environment is unlike the one we are used to. Because of these attributes, the Martian environment impacts the materials studied by rovers and landers differently, so it is important that scientists understand these effects which will allow them to refine their interpretations of the geological history and surface processes on Mars (1).

In their study, the research team emphasized the importance of continuous monitoring and calibration of scientific instruments on space missions (1). By observing the changes in the calibration targets over time, researchers can account for environmental effects and ensure the accuracy of their measurements. This approach is vital for the success of ongoing and future missions aimed at exploring Mars and other planetary bodies.

As planetary exploration continues to push the boundaries of our knowledge, studies like this remind us of the complex interplay between environmental conditions and the materials we study on other worlds (1). This knowledge is essential for accurately reconstructing the history and natural changes of Mars over time, ultimately bringing us closer to unraveling the mysteries of our solar system.

References

(1) Clave, E.; Beyssac, O.; Bernard, S.; et al. Radiation-Induced Alteration of Apatite on the Surface of Mars: First In Situ Observations with SuperCam Raman Onboard Perseverance. Sci. Rep. 2024, 14, 11284. DOI: 10.1038/s41598-024-61494-5

(2) Spectroscopy Staff, Advancing Hydrogen Detection on Airless Planetary Bodies through Laser-Induced Breakdown Spectroscopy. Spectroscopy. Available at: https://www.spectroscopyonline.com/view/advancing-hydrogen-detection-on-airless-planetary-bodies-through-laser-induced-breakdown-spectroscopy (accessed 2024-06-11).

(3) Pilorget, C.; Fernando, J. Quantifying the Minerals Abundances on Planetary Surfaces Using Vis–NIR Spectroscopy, What Uncertainties Should We Expect? General Results and Application to the Case of Phyllosilicates and Carbonates on Mars. Icarus 2021, 365, 114498. DOI: 10.1016/j.icarus.2021.114498