Showing papers by "Uwe J. Meierhenrich published in 2015"

Organic compounds on comet 67P/Churyumov-Gerasimenko revealed by COSAC mass spectrometry

Abstract: Comets harbor the most pristine material in our solar system in the form of ice, dust, silicates, and refractory organic material with some interstellar heritage. The evolved gas analyzer Cometary Sampling and Composition (COSAC) experiment aboard Rosetta’s Philae lander was designed for in situ analysis of organic molecules on comet 67P/Churyumov-Gerasimenko. Twenty-five minutes after Philae’s initial comet touchdown, the COSAC mass spectrometer took a spectrum in sniffing mode, which displayed a suite of 16 organic compounds, including many nitrogen-bearing species but no sulfur-bearing species, and four compounds—methyl isocyanate, acetone, propionaldehyde, and acetamide—that had not previously been reported in comets.

Aldehydes and sugars from evolved precometary ice analogs: Importance of ices in astrochemical and prebiotic evolution

Abstract: Evolved interstellar ices observed in dense protostellar molecular clouds may arguably be considered as part of precometary materials that will later fall on primitive telluric planets, bringing a wealth of complex organic compounds. In our laboratory, experiments reproducing the photo/thermochemical evolution of these ices are routinely performed. Following previous amino acid identifications in the resulting room temperature organic residues, we have searched for a different family of molecules of potential prebiotic interest. Using multidimensional gas chromatography coupled to time-of-flight mass spectrometry, we have detected 10 aldehydes, including the sugar-related glycolaldehyde and glyceraldehyde—two species considered as key prebiotic intermediates in the first steps toward the synthesis of ribonucleotides in a planetary environment. The presence of ammonia in water and methanol ice mixtures appears essential for the recovery of these aldehydes in the refractory organic residue at room temperature, although these products are free of nitrogen. We finally point out the importance of detecting aldehydes and sugars in extraterrestrial environments, in the gas phase of hot molecular clouds, and, more importantly, in comets and in primitive meteorites that have most probably seeded the Earth with organic material as early as 4.2 billion years ago.

Molecular chirality in meteorites and interstellar ices, and the chirality experiment on board the ESA cometary Rosetta mission.

Abstract: Life, as it is known to us, uses exclusively L-amino acid and D-sugar enantiomers for the molecular architecture of proteins and nucleic acids. This Minireview explores current models of the original symmetry-breaking influence that led to the exogenic delivery to Earth of prebiotic molecules with a slight enantiomeric excess. We provide a short overview of enantiomeric enhancements detected in bodies of extraterrestrial origin, such as meteorites, and interstellar ices simulated in the laboratory. Data are interpreted from different points of view, namely, photochirogenesis, parity violation in the weak nuclear interaction, and enantioenrichment through phase transitions. Photochemically induced enantiomeric imbalances are discussed more specifically in the topical context of the "chirality module" on board the cometary Rosetta spacecraft of the ESA. This device will perform the first enantioselective in situ analyses of samples taken from a cometary nucleus.

Comets And Their Origin: The Tools To Decipher A Comet

Abstract: Foreword Professor Michael F. A'Hearn Foreword Professor Gerhard A. Schwehm Preface Part I Comets and Their Origin 1. Introduction 2. The Formation of Comets 3. Astrochemistry: Water and Organic Molecules in Comets 4. The Asymmetry of Life Part II The Rosetta Mission - Rendezvous With a Comet 5. The Rosetta Cometary Mission: Launch and Target Comet 6. On the Way to Comet 67P/Churyumov-Gerasimenko 7. Rosetta's Rendezvous With the Comet 8. Conclusions and Outlook

Anisotropy-Guided Enantiomeric Enhancement in AlanineUsing Far-UV Circularly Polarized Light

Abstract: All life on Earth is characterized by its asymmetry – both the genetic material and proteins are composed of homochiral monomers. Understanding how this molecular asymmetry initially arose is a key question related to the origins of life. Cometary ice simulations, l-enantiomeric enriched amino acids in meteorites and the detection of circularly polarized electromagnetic radiation in star-forming regions point to a possible interstellar/protostellar generation of stereochemical asymmetry. Based upon our recently recorded anisotropy spectra g(λ) of amino acids in the vacuum-UV range, we subjected amorphous films of racemic 13C-alanine to far-UV circularly polarized synchrotron radiation to probe the asymmetric photon-molecule interaction under interstellar conditions. Optical purities of up to 4 % were reached, which correlate with our theoretical predictions. Importantly, we show that chiral symmetry breaking using circularly polarized light is dependent on both the helicity and the wavelength of incident light. In order to predict such stereocontrol, time-dependent density functional theory was used to calculate anisotropy spectra. The calculated anisotropy spectra show good agreement with the experimental ones. The European Space Agency’s Rosetta mission, which successfully landed Philae on comet 67P/Churyumov-Gerasimenko on 12 November 2014, will investigate the configuration of chiral compounds and thereby obtain data that are to be interpreted in the context of the results presented here.

Molekülchiralität in Meteoriten und interstellarem Eis und das Chiralitätsexperiment an Bord der Kometenmission Rosetta der ESA

Abstract: Das uns bekannte Leben kontrolliert den ausschlieslichen Gebrauch von L-Aminosaure- und D-Zucker-Enantiomeren zum molekularen Aufbau von Proteinen und Nukleinsauren. In diesem Kurzaufsatz wird aktuellen Modellen zum Symmetriebruch in Biomolekulen nachgegangen, die den Transport erdauserer prabiotischer Molekule umfassen. Der Kurzaufsatz stellt Enantiomerenuberschusse dar, wie sie in extraterrestrischen Korpern wie Meteoriten und simuliertem interstellarem Eis nachgewiesen wurden. Die Daten werden aus verschiedenen Blickwinkeln, wie der Photochirogenese, der Paritatsverletzung durch die Schwache Wechselwirkung sowie durch Enantiomerenanreicherungen durch Phasenubergange interpretiert. Im aktuellen Kontext des Chiralitatsmoduls an Bord der Kometensonde Rosetta der ESA, die erstmals enantioselektive In-situ-Messungen an Proben eines Kometenkerns durchfuhrt, wird die photochemisch induzierte “chirale Asymmetrie” genauer diskutiert werden.

Behavior of Multiclass Pesticide Residue Concentrations during the Transformation from Rose Petals to Rose Absolute

Abstract: This study investigates the concentrations of 54 multiclass pesticides during the transformation processes from rose petal to concrete and absolute using roses spiked with pesticides as a model. Th...

Molecular Chirality in Meteorites and Interstellar Ices, and the Chirality Experiment on Board the ESA Cometary Rosetta Mission

Abstract: Life, as it is known to us, uses exclusively L-amino acid and D-sugar enantiomers for the molecular architecture of proteins and nucleic acids. This Minireview explores current models of the original symmetry-breaking influence that led to the exogenic delivery to Earth of prebiotic molecules with a slight enantiomeric excess. We provide a short overview of enantiomeric enhancements detected in bodies of extraterrestrial origin, such as meteorites, and interstellar ices simulated in the laboratory. Data are interpreted from different points of view, namely, photochirogenesis, parity violation in the weak nuclear interaction, and enantioenrichment through phase transitions. Photochemically induced enantiomeric imbalances are discussed more specifically in the topical context of the "chirality module" on board the cometary Rosetta spacecraft of the ESA. This device will perform the first enantioselective in situ analyses of samples taken from a cometary nucleus.