Multi spectral investigation of volcanic deposits in Vulcano, Italy, and the PETRAS campaign/summer school

Abstract

The volcanic settings of the Aeolian Islands, Italy, offer access to various types of volcanic terrains, with diverse morphology and mineralogy. The current signs of volcanic activity on the island of Vulcano, whose last eruption is dated to 1890, include e.g. the presence of large fumarole fields on ground and underwater. The dry landscape and easy access to layers of older and more recent volcanic material, in addition to the possibility of investigating secondary minerals, make this site a very promising analogue for the Moon, Mars, Venus and other planetary environments. For instance, the active and acidic fumarolic sites provide extreme acid alteration conditions of volcanic deposits, which also have been a key process at local and regional scales throughout Martian geologic history. For these reasons, Vulcano is a remarkable training site to test instruments, rovers, or data processing techniques for planetary exploration and has a high astrobiological potential pertaining to the questions of life detection, using spectroscopy techniques, and habitability, looking at microbial colonization in extreme environments. Since 2019, we combined three different field instruments to investigate volcanic deposits: a portable visible and near infrared spectro-radiometer, a portable LIBS (laser-induced breakdown spectroscopy) instrument, and a portable Raman system; thus, combining mineralogical, elemental and molecular information. This combination significantly improved the characterization of the spectral properties of the volcanic deposits in the study area and therefore offered a more comprehensive view into their alteration processes. In short, LIBS, or any instrument solving the elemental composition of the rocks, is essential to study the composition of lava rocks and to distinguish between different types, while VIS-NIR and Raman spectrometers are powerful tools for the detection, discrimination and characterization of alteration and hydrothermally formed minerals. In parallel to the field campaigns, and building on previous editions going on since 2015, the PETRAS Summer school (Planetology, Exploration, Terrestrial analogs, Robotics, Astrobiology and, Spectroscopy) was launched in 2024. PETRAS involves volcanologists, geophysicists, astrobiologists, electronic/mechanical engineers and computer scientists to provide a 360-degree vision of the different skills needed by the planetary sciences community. Results on the combination of VIS-NIR, LIBS, and Raman will be presented, showing the complementarity of the techniques, and lessons learned from the field campaigns, especially on the alignment of measurements. Data processing techniques are also in focus to help in the interpretation of the results (Stephan et al. under review). Finally, a brief overview of the recent and current PETRAS campaigns/summer school will be presented to show the unique multi-disciplinary aspects and opportunities for young researchers as well as different research groups interested in all aspects of planetary exploration from science to technology, outreach, and dissemination.