Mass Spectrometry Analysis of the Molecular Complexity of Soluble Organic Matter from a Fragment of the Asteroid Bennu

5-6 months in 2027, flexible dates

Context: Carbonaceous chondrites, primitive objects in the Solar System, contain up to 4% carbon by weight, primarily in organic form. The precursors of this organic matter, partially inherited from the interstellar medium and/or synthesized in the protoplanetary disk, may have undergone modifications during secondary weathering processes that occurred on their asteroidal parent body. From an experimental standpoint, a distinction is made between the soluble organic fraction (SOM, in water and organic solvents) and the insoluble organic fraction (IOM, in acids). These two fractions differ in their abundance, molecular structure, and chemical composition. The soluble organic fraction, which is of interest for this internship, is composed of a very wide variety of organic molecules. Recent analyses of samples from the asteroids Ryugu and Bennu—brought back by the Hayabusa2 (JAXA) and OSIRIS-REx (NASA) missions, respectively, have confirmed the abiotic origin and remarkable diversity of these soluble compounds in asteroid samples that avoided atmospheric entry and for which interactions with the Earth’s environment are minimized.

Internship Objectives: The focus of this internship will be on analyzing the SOM of a Bennu grain. The student will first be tasked with conducting a systematic and comparative analysis of the molecular diversity of 15 carbonaceous chondrites (9 CM, 3 CI, 3 CR) measured using an ultra-high-resolution mass spectrometer (FT-ICR 18T). Significant methodological development work (using Bruker’s DataAnalysis software and Python code) has already been carried out to enable the molecular characterization of polar compounds. During this internship, we will focus on analyzing the data acquired for nonpolar molecules, for which the processing methods will need to be adapted. We will then acquire and process the same datasets for the SOM from a Bennu grain, which is already available in the laboratory. The results obtained will be interpreted by comparison with the existing dataset, as the chondrites studied cover a wide range of degrees of secondary alteration (aqueous alteration, heating, impacts). If time permits during the internship, additional analyses of the elemental composition (%N and %C) and isotopic composition (δ¹⁵N and δ¹³C) of a series of CI chondrites may be conducted. The internship will take place at IPAG (Université Grenoble Alpes, CNRS), with a few-day assignment at the CARMeN laboratory (Université de Rouen Normandie, INSA Rouen Normandie, CNRS).

To apply: send a CV (including the previous research internship(s) and name of supervisors), and a copy of master grades at veronique.vuitton[at]univ-grenoble-alpes.fr and lydie.bonal[at]univ-grenoble-alpes.fr.