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A polished slice the Allende meteorite disclosing the included chondrules. Chondrules are silicate and metal droplets which date back to the period when the Solar System formed. The chondrules cooled on a timescale of minutes and later stuck together with other minerals to form chondrites.
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The astrobiological relevance of carbonaceous chondrites is reviewed. It is argued that the primitive meteorites called carbonaceous chondrites provide a unique source of information about the materials and conditions in the Solar System during the earliest phases of its history, and its subsequent evolution. Presolar dust grains extracted from the...
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... relevant information about the early conditions in the Solar System can be obtained by considering the millimeter- to centimeter-sized chondrules and calcium-aluminum-rich inclusions (CAIs) within the carbonaceous chondrites. The chondrules and the CAIs are at present the oldest Solar System material known. The CAIs can be seen on Fig. 1 and 2 as ”white spots”, while the chondrules are easily seen in Fig. 2 and 3, as spherical inclusions. The chondrules, the CAIs and the micron- and smaller-scale matrix particles appear to have been the major solid constituents of the Solar nebular, at least inside Jupiter’s orbit. Their formation and assembly into chondrites provides strong constraints on processes occurring during the earliest phases of the Solar System formation. Chondrules with relict unmelted grains or igneous rims record multiple melting events. They consist of ferromagnesian silicate particles. There are two main types of chondrules, type I which are poor in FeO and volatiles and type II which are FeO rich and have approximately Solar composition. The abundance of chondrules in the chondrite meteorites implies that melting of small particles was a common phenomenon in the early Solar System (Hewins, 1997). Understanding chondrule formation therefore has potential astrophysical and/or planetary significance. Chondrules are currently believed to have formed 2-3 Myr after the CAIs (Hewins, 1997). However, recently Bizzarro et al. (2004) reported that chondrule formation processes recorded by the Allende and other chondrites could have persisted for 2-3 Myr starting contemporaneously with CAI formation in the early Solar System. This finding is consistent with both the X-wind model (Shu et al. , 2001) or shock wave models (Boss and Durisen, 2005) as an explanation for chondrule formation. Alternatively, chondrule formation could be reconciled with an origin as ejecta from colliding planetesimals in the accretion disk (Sanders, 1996), providing that accumulation and melting of asteroids occurred < 0.2 Myr after CAI formation. Since the study by Bizzarro et al. (2004) indicates recurrent formation of chondrules over nearly 3 Myr it could indicate that a number of distinct processes and/or heat sources were involved in the formation history of these ...
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Abstract Understanding the processes involved in the evolution of organic matter in the early Solar System requires extensive experimental work. The scientifically valuable carbonaceous chondrites are principal targets for organic analyses, but these meteorites are rare. Meteoritic analog materials available in larger quantities, on which experimen...
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... This leads to a hypothesis that at least a part of the chemical stockpiles required for the generation of life on the Earth may have come from the ISM through comets and meteoroids. Detection of many amino acids and other biological and pre-biotic molecules in the comets, meteoroids, and ISM gives support to this hypothesis (Lawless 1973;Marvin 1983;Sephton 2002;Cecchi-Pestellini et al. 2004;Andersen & Haack 2005;Duvernay et al. 2014a). Some of the interstellar chemical species are precursors of the most fundamental building blocks of the terrestrial's biology (viz. ...
Aminomethanol is an important precursor of interstellar glycine. A two-step formation pathway has been proposed for aminomethanol in interstellar ice via reaction between CH+, NH3 mixed water ice and OH radical. The ice model is build using cluster approach that employs one NH3 and eleven water molecules to simulate NH3 mixed water ice. Density functional theory at B2PLYPD/6-311++G(2d, p) level of theory is utilized to explore the proposed pathway. Our proposed pathway is found to be very efficient in the ice owing to the low entrance barrier of ca. 1.443 kcal mol−1. It is also observed that CH2NH+2 is the starting reactant in our proposed root for aminomethanol, thus, if discussed formation root is applicable, the abundance of CH2NH+2 is a direct indicator for the presence of aminomethanol.
... Although none of the amino acids has been found in the ISM to date, their presence is expected because most of the molecules involved in the amino acid synthesis (particularly Strecker synthesis) have been already observed in the ISM in the past few decades. Several research groups around the world are looking for the various other possible roots for the amino acid synthesis (Woon, 2002, Cecchi-Pestellini et al., 2004Andersen and Haack, 2005;Chiaramello et al., 2005;Mita et al., 2005;Lattelais, Ellinger and Zanda, 2007). ...
The formation mechanism of linear and isopropyl cyanide (hereafter n-PrCN and i-PrCN, respectively) in the interstellar medium (ISM) has been proposed from the reaction between some previously detected small cyanides/cyanide radicals and hydrocarbons/hydrocarbon radicals. n-PrCN and i-PrCN are nitriles therefore, they can be precursors of amino acids via Strecker synthesis. The chemistry of i-PrCN is especially important since it is the first and only branched molecule in ISM, hence, it could be a precursor of branched amino acids such as leucine, isoleucine, etc. Therefore, both n-PrCN and i-PrCN have significant astrobiological importance. To study the formation of n-PrCN and i-PrCN in ISM, quantum chemical calculations have been performed using density functional theory at the MP2/6-311++G(2d,p)//M062X/6-311+G(2d,p) level. All the proposed reactions have been studied in the gas phase and the interstellar water ice. It is found that reactions of small cyanide with hydrocarbon radicals result in the formation of either large cyanide radicals or ethyl and vinyl cyanide, both of which are very important prebiotic interstellar species. They subsequently react with the radicals CH2 and CH3 to yield n-PrCN and i-PrCN. The proposed reactions are efficient in the hot cores of SgrB2 (N) (where both n-PrCN and i-PrCN were detected) due to either being barrierless or due to the presence of a permeable entrance barrier. However, the formation of n-PrCN and i-PrCN from the ethyl and vinyl cyanide always has an entrance barrier impermeable in the dark cloud; therefore, our proposed pathways are inefficient in the deep regions of molecular clouds. It is also observed that ethyl and vinyl cyanide serve as direct precursors to n-PrCN and i-PrCN and their abundance in ISM is directly related to the abundance of both isomers of propyl cyanide in ISM. In all the cases, reactions in the ice have smaller barriers compared to their gas-phase counterparts.
... Dicarboxylic acids have been found also in carbonaceous chondrites (Andersen and Haack 2005;Briscoe and Moore 1993), meteorites associated to the primitive asteroids; and hence could give information about chemical and mineralogical composition of the early Solar System. ...
... The returned samples will undergo to laboratory tests, which will give insights aboutthe origin of planetary materials, the early Solar System formation processes and the organic and volatile substances in a primitive asteroid, focusing on the connection between these materials and biogenic molecules. Andersen and Haack (2005) and Briscoe and Moore (1993) proposed that complex organic molecules (Amino acids, Nucleobases and Carboxylic acids) contained in carbonaceous chondrites have been able to triggering the prebiotic synthesis of biochemical compounds in the early Earth. The VISTA (Volatile In Situ Thermogravimetry Analyser) μ-Thermogravimeter (Fig. 2) is included in the MarcoPolo-R scientific package ) and is based on PCM's. ...
Piezoelectric Crystal Microbalances (PCM’s) are widely used to study the chemical processes involving volatile compounds in any environment, such as condensation process. Since PCM’s are miniaturized sensor, they are very suitable for planetary in situ missions, where can be used to detect and to measure the mass amount of astrobiologically significant compounds, such as water and organics. This work focuses on the realization and testing of a new experimental setup, able to characterize volatiles which can be found in a planetary environment. In particular the enthalpy of sublimation of some dicarboxylic acids has been measured. The importance of dicarboxylic acids in planetology and astrobiology is due to the fact that they have been detected in carbonaceous chondritic material (e.g. Murchinson), among the most pristine material present in our Solar System. In this work, a sample of acid was heated in an effusion cell up to its sublimation. For a set of temperatures (from 30 °C to 75 °C), the deposition rate on the PCM surface has been measured. From these measurements, it has been possible to infer the enthalpy of sublimation of Adipic acid, i.e. ΔH = 141.6 ± 0.8 kJ/mol and Succinic acid, i.e. ΔH = 113.3 ± 1.3 kJ/mol. This technique has so demonstrated to be a good choice to recognise a single compound or a mixture (with an analysis upstream) even if some improvements concerning the thermal stabilization of the system will be implemented in order to enhance the results’ accuracy. The experiment has been performed in support of the VISTA (Volatile In Situ Thermogravimetry Analyzer) project, which is included in the scientific payload of the ESA MarcoPolo-R mission study.
... Moreover, even though a role that mineral surfaces and/or cosmic dust [6] [7] can play as a friendly base environment to develop the processes involved in organic chemistry has been widely recognized, relatively few studies have been conducted to identify and explain, at the molecular level, the catalytic effects [8] [9] [10]. Nearly 50 years ago, Bernal and Goldschmidt [8] independently proposed that clay minerals could have played an important role in prebiotic chemistry and the origin of life. ...
... For example, the C in the Tagish Lake meteorite is divided largely between organic C (2.49 to 2.57 wt%) and carbonates (2.69 wt%), with 1634 ppm of nanodiamonds and 8 ppm of SiC (Grady et al. 2002). Interest in the organic C stems largely from its potential to reveal information about prebiotic chemical evolution (Andersen and Haack 2005;Cody and Alexander 2005;Pizzarello 2006). Much is known regarding the identities and structures of the organic materials Cody and Alexander 2005;Garvie and Buseck 2004;Pizzarello et al. 2001;Sephton 2002). ...
Abstract— Transmission electron microscopic (TEM) and electron energy-loss spectroscopic (EELS) study of the Ivuna and Orgueil (CI), and Tagish Lake (C2 ungrouped) carbonaceous chondrite meteorites shows two types of C-clay assemblages. The first is coarser-grained (to 1 μm) clay flakes that show an intense O K edge from the silicate together with a prominent C K edge, but without discrete C particles. Nitrogen is common in some clay flakes. Individual Orgueil and Tagish Lake meteorite clay flakes contain up to 6 and 8 at% C, respectively. The C K-edge spectra from the clays show fine structure revealing aromatic, aliphatic, carboxylic, and carbonate C. The EELS data shows that this C is intercalated with the clay flakes. The second C-clay association occurs as poorly crystalline to amorphous material occurring as nanometer aggregates of C, clay, and Fe-O-rich material. Some aggregates are dominated by carbonaceous particles that are structurally and chemically similar to the acid insoluble organic matter. The C K-edge shape from this C resembles that of amorphous C, but lacking the distinct peaks corresponding to aliphatic, carboxylic, and carbonate C groups. Nanodiamonds are locally abundant in some carbonaceous particles. The abundance of C in the clays suggest that molecular speciation in the carbonaceous chondrites is partly determined by the effects of aqueous processing on the meteorite parent bodies, and that clays played an important role. This intricate C-clay association lends credence to the proposal that minerals were important in the prebiotic chemical evolution of the early solar system.
... Astrobiologically , it is important to note that: a) carbonaceous chondrites are the closest spectral analogs available in laboratory of the carbonaceous asteroids that impacted the Earth during the Hadean eon [7]; b) most of the extraterrestrial carbon accreted by Earth is carried by the 40,000 tons of ≈ 0.2 mm micrometeorites [8], as well micron-sized interplanetary dust particles (IDPs), that enter the atmosphere every year. Petrological and geochemical studies carried out on micrometeorites indicate that the majority are carbonaceous [9,10], and c) according to [11], the abundance, compositional types and diversity of amino acids, sugars and other molecules discovered in carbonaceous chondrites support the possibility that these meteorites could have seeded our planet, with extraterrestrial organics required for the origin of life. ...
... Carbonaceous chondrites are primitive and undifferentiated meteorites that include different clans and groups (CI, CM, CR, CB, CO, CV, CH, CK, C ungrouped)[11]. Most carbonaceous chondrites consist of spherical glasslike chondrules [12,13], embedded in a fine-grained groundmass. The chondrules and the CAIs (calciumaluminum-rich inclusions) are at present the oldestknown material that formed in the solar nebula [14]. ...
... The search for amino acids in meteorites began in the 1960s. Since then, around 70 amino acids have been identified in meteorites among the 159 possible C2 to C7 isomers [11,16,27,28]. Kvenvolden et al. [29] identified five protein and two non-protein amino acids and four of the protein amino acids were racemic. ...
A brief overview of astrobiologically relevant organic species detected in small solar system bodies, in partic-ular meteorites, is provided. Such organic molecules, however, are only a minor component of the carbon in these objects. Many of them, like amino acids, proba-bly the most interesting family of molecules for astro-biology, have not yet been detected in the interstellar medium. Most of the carbon is present as the so-called macromolecular organic material, both in meteorites and interplanetary dust particles. We show that material is analogous to hydrogenated amorphous carbon, a hydro-carbon widely studied by chemists. A form of hydro-genated amorphous carbon is also observed in grains to-ward the diffuse interstellar medium, and even in Seyfert 2 galaxies, although with different chemical properties. Therefore, in our attempt to trace the evolution of car-bonaceous matter as the local interstellar cloud collapsed leading to the formation of the solar nebula, we focus on the study of an ubiquitous form of carbon, namely hydro-genated amorphous carbon.
Bringing together the latest scientific advances and some of the most enduring subtle philosophical puzzles and problems, this book collects original historical and contemporary sources to explore the wide range of issues surrounding the nature of life. Selections ranging from Aristotle and Descartes to Sagan and Dawkins are organised around four broad themes covering classical discussions of life, the origins and extent of natural life, contemporary artificial life creations and the definition and meaning of 'life' in its most general form. Each section is preceded by an extensive introduction connecting the various ideas discussed in individual chapters and providing helpful background material for understanding them. With its interdisciplinary perspective, this fascinating collection is essential reading for scientists and philosophers interested in astrobiology, synthetic biology and the philosophy of life.
The formation mechanism of linear and isopropyl cyanide (hereafter n-PrCN and i-PrCN, respectively) in the interstellar medium (ISM) has been proposed from the reaction between some previously detected small cyanides/cyanide radicals and hydrocarbons/hydrocarbon radicals. n-PrCN and i-PrCN are nitriles therefore, they can be precursors of amino acids via Strecker synthesis. The chemistry of i-PrCN is especially important since it is the first and only branched molecule in ISM, hence, it could be a precursor of branched amino acids such as leucine, isoleucine, etc. Therefore, both n-PrCN and i-PrCN have significant astrobiological importance. To study the formation of n-PrCN and i-PrCN in ISM, quantum chemical calculations have been performed using density functional theory at the MP2/6-311++G(2d,p)//M062X/6-311+G(2d,p) level. All the proposed reactions have been studied in the gas phase and the interstellar water ice. It is found that reactions of small cyanide with hydrocarbon radicals result in the formation of either large cyanide radicals or ethyl and vinyl cyanide, both of which are very important prebiotic interstellar species. They subsequently react with the radicals CH2 and CH3 to yield n-PrCN and i-PrCN. The proposed reactions are efficient in the hot cores of SgrB2 (N) (where both n-PrCN and i-PrCN were detected) due to either being barrierless or due to the presence of a permeable entrance barrier. However, the formation of n-PrCN and i-PrCN from the ethyl and vinyl cyanide always has an entrance barrier impermeable in the dark cloud; therefore, our proposed pathways are inefficient in the deep regions of molecular clouds. It is also observed that ethyl and vinyl cyanide serve as direct precursors to n-PrCN and i-PrCN and their abundance in ISM is directly related to the abundance of both isomers of propyl cyanide in ISM. In all the cases, reactions in the ice have smaller barriers compared to their gas-phase counterparts.
The Quest for a Universal Theory of Life - by Carol E. Cleland September 2019
Cambridge Core - History of Astronomy and Cosmology - The Quest for a Universal Theory of Life - by Carol E. Cleland
