Sprecher
Beschreibung
We present here a review of the state of the art in non-targeted high resolution analysis of the soluble organic fraction of various meteorites; these include carbonaceous chondrites as well as achondrites and ordinary chondrites in the light of the analysis of the sample return missions HAYABUSA2 and OSIRIS ReX.
Understanding the origin and evolution of organic matter, is linked to observation derived astrochemistry (telescopic observations) and the laboratory wet chemical analysis of return objects and meteorites. The molecular composition and diversity of non-terrestrial organic matter in carbonaceous chondrites was studied by means of both, targeted and non-targeted chemical analytical approaches, leading to new molecular insights. Targeted chemical analyses are hypothesis-driven and are largely focused on molecules of biological/prebiotic interest. In a non-targeted approach, all analytes are globally profiled within the analytical possibilities without biased or constrained hypothesis in order to gain comprehensive information. We review in this presentation the state of the art in using non-targeted high resolution organic spectroscopy.
Ultrahigh-resolving analytics, like high field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and nuclear magnetic resonance spectroscopy (NMR), represent a powerful tool to allow insights into the holistic complex compositional space to tens of thousands of different molecular compositions and functional groups and likely millions of diverse structures. This could be observed in solvent extracts of pristine carbonaceous meteorites, and suggests that interstellar chemistry is extremely active and rich. Since then we studied the chemical composition of thousands of individual components out of complex organic mixtures, as accessed in the solvent-accessible organic fraction, extracted under mild conditions, from diversely-classified and heated meteorites.
We described that heteroatomic organic molecules play an important role in the description of non-terrestrial chemical evolution. The thermally and shock-stressed Chelyabinsk (LL5) showed high number of nitrogen counts within CHNO molecular formulas, especially in the melt region. This match of the organic molecular profile with the petrologic character could be also observed for Novato (L6), Braunschweig (L6) and the latest German fall Stubenberg (LL6). Additionally, the extremely thermally altered Sutter’s mill (C-type) reflects a loss in the organic diversity, but an increase in the polysulphur domain, as compared to other CM2-analyzed falls. The increase of polynitrogen and polysulphur compounds could be simulated in laboratory experiments by heating Murchison (CM2). Recently we reported the discovery of a previously unrecognized chemical class, dihydroxymagnesium carboxylates, [(HO)2MgO2CR]−, gained from non-terrestrial meteoritic analyses. These thermostable compounds might have contributed to the stabilization of organic molecules on a geological time scale, which emphasizes their potential astrobiological relevance. The resulted extreme richness in chemical diversity analyzed in meteorites offers information on the meteoritic parent body history and help in expanding our knowledge or astrochemistry towards higher molecular masses and complex molecular structures.
The sample from the near-Earth carbonaceous asteroid (162173) Ryugu collected by the Hayabusa2 spacecraft did not see any terrestrial alteration and could be analyzed in the context of carbonaceous meteorites SOM. The analysis of soluble molecules of Ryugu samples collected by the Hayabusa2 spacecraft shine light on an extremely high molecular diversity on the C-type asteroid. Sequential solvent extracts of increasing polarity in hexane, dichloromethane, methanol and water of Ryugu samples were analyzed using ultrahigh resolution mass spectrometry with complementary ionization methods and structural information confirmed by nuclear magnetic resonance spectroscopy and interpreted in the light of the knowledge rised on meteoritic organic matter.
