Infrared spectroscopy on various kinds of primitive fine-grained silicate material: Deciphering the nature of protoplanetary nebula dust components

• Applicant: Aelita Girich, Ph.D.
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 527070235

Recent spectacular space missions (e.g., to asteroids Ryugu and Bennu) have drastically encouraged planetary research, but they have also shown that direct collection of soil samples on both planetary and small bodies of the Solar System is still accompanied by great difficulties. Therefore, remote sensing techniques, especially infrared (IR) spectroscopy, remain a priority. An extensive database is needed to accurately interpret the spectra obtained from these missions. One such database (the IRIS spectral database) is currently being developed at the Institut für Planetologie at the Westfälische Wilhelms-Universität Münster. In the proposed project, a systematic infrared spectroscopic study will be carried out, for the first time, on various kinds of primitive fine-grained silicate materials that occur in different types of meteorites (in particular, in the carbonaceous chondrites of different groups, namely CI, CM, CV, CO, CR, CK) as well as in different textural units of the Krymka (LL3.1) unequilibrated ordinary chondrite. Complex structural, mineralogical and chemical studies of the selected samples will be conducted for a reliable interpretation of the obtained IR spectral data. This research, in particular for CI and CM chondrites, is especially relevant now that the Hayabusa2 (JAXA) spacecraft with asteroid Ryugu samples has returned. Also, the OSIRIS-REx (NASA) spacecraft will soon return samples from asteroid Bennu, in September 2023. Spectroscopic observations of both C-group asteroids suggest that these are most similar to CM, or heated CI and CM chondrites. The primitive fine-grained silicate matter found in meteorites is one of the most interesting materials being studied recently, since these components can be considered as probable relics of the dust component of the early protoplanetary nebula. Fine-grained silicate material has been found in different textural units of carbonaceous and unequilibrated ordinary chondrites. It has been found to occur in various parageneses (enriched or depleted in phyllosilicates, iron sulfides, Fe,Ni metal, and magnetite), and/or with different degrees of shock-metamorphic transformation or alteration. The main aims of this work are (a) to understand the nature and degree of heterogeneity of the protoplanetary nebula dust; (b) to determine the influence of various structural, mineralogical and chemical factors (e.g., enrichment or depletion in phyllosilicates, iron sulfides, Fe,Ni metal and magnetite; the degree of shock metamorphism and/or aqueous alteration) on the IR spectra of the primitive fine-grained silicate materials in carbonaceous and unequilibrated ordinary chondrites; and (c) to expand the IR spectra database for the remote sensing of cosmic bodies (in particular asteroids and comets).

• DFG Programme: WBP Position