Meteorites and the Origin of Life

A special issue of Life (ISSN 2075-1729). This special issue belongs to the section "Astrobiology".

Deadline for manuscript submissions: closed (31 March 2018) | Viewed by 48616

Special Issue Editor


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Guest Editor
Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
Interests: organic chemistry; meteorite analysis; astrobiology; space missions; life detection instrumentation

Special Issue Information

Dear Colleagues,

In 1969, a large carbon-rich meteorite fell near the town of Murchison, Victoria, Australia, and was found to contain extraterrestrial amino acids, nucleobases, carboxylic acids, sugar acids and other organic molecules found in life. Studies over the past five decades have shown that these organics are common in a wide variety of carbonaceous chondrites, bolstering the theory that exogenous delivery may have been crucial to the origin of life on Earth. The discovery of large L-amino acid and D-sugar acid enrichments in some meteorites provides important clues to their formation and potential contribution to the origin of homochirality in life. Asteroids, comets and their fragments, including meteorites, micrometeorites and interplanetary dust particles, impact the Earth with ~40 million kg of material each year, with a much higher flux during the heavy bombardment period ~4.5 to 3.8 billion years ago. Research has shown that simple organic molecules derived from the interstellar medium and protosolar nebula were processed in the meteorite parent body forming more complex mixtures. This organic material can survive large impacts and impact-generated hydrothermal systems on the early Earth may have provided habitats where life originated and evolved. Some scientists argue that the contribution of organics from extraterrestrial sources is too low for meteorites alone to be responsible for the emergence of life. However, these samples provide the only record of early Solar System chemistry prior to the emergence of life. This Special Issue aims to bring together what we have learned from meteorite analyses, laboratory analog experiments and models about prebiotic chemistry, chiral asymmetry, and the potential role of exogenous delivery and large meteor impacts in the origin of life on Earth.

Dr. Daniel P Glavin
Guest Editor

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Keywords

  • Meteorites Micrometeorites
  • Astrochemistry
  • Exogenous delivery and impacts
  • Prebiotic organics
  • Chiral asymmetry
  • Origin of homochirality

Published Papers (7 papers)

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Research

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15 pages, 3249 KiB  
Article
Caveats to Exogenous Organic Delivery from Ablation, Dilution, and Thermal Degradation
by Chris Mehta, Anthony Perez, Glenn Thompson and Matthew A. Pasek
Life 2018, 8(2), 13; https://doi.org/10.3390/life8020013 - 12 May 2018
Cited by 15 | Viewed by 4928
Abstract
A hypothesis in prebiotic chemistry argues that organics were delivered to the early Earth in abundance by meteoritic sources. This study tests that hypothesis by measuring how the transfer of organic matter to the surface of Earth is affected by energy-dissipation processes such [...] Read more.
A hypothesis in prebiotic chemistry argues that organics were delivered to the early Earth in abundance by meteoritic sources. This study tests that hypothesis by measuring how the transfer of organic matter to the surface of Earth is affected by energy-dissipation processes such as ablation and airbursts. Exogenous delivery has been relied upon as a source of primordial material, but it must stand to reason that other avenues (i.e., hydrothermal vents, electric discharge) played a bigger role in the formation of life as we know it on Earth if exogenous material was unable to deliver significant quantities of organics. For this study, we look at various properties of meteors such as initial velocity and mass of the object, and atmospheric composition to see how meteors with different initial velocities and masses ablate. We find that large meteors do not slow down fast enough and thus impact the surface, vaporizing their components; fast meteors with low masses are vaporized during entry; and meteors with low velocities and high initial masses reach the surface. For those objects that survive to reach the surface, about 60 to >99% of the mass is lost by ablation. Large meteors that fragment are also shown to spread out over increasingly larger areas with increasing mass, and small meteors (~1 mm) are subjected to intense thermal heating, potentially degrading intrinsic organics. These findings are generally true across most atmospheric compositions. These findings provide several caveats to extraterrestrial delivery models that—while a viable point source of organics—likely did not supply as much prebiotic material as an effective endogenous production route. Full article
(This article belongs to the Special Issue Meteorites and the Origin of Life)
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22 pages, 1845 KiB  
Article
Comet Pond II: Synergistic Intersection of Concentrated Extraterrestrial Materials and Planetary Environments to Form Procreative Darwinian Ponds
by Benton C. Clark and Vera M. Kolb
Life 2018, 8(2), 12; https://doi.org/10.3390/life8020012 - 11 May 2018
Cited by 10 | Viewed by 5367
Abstract
In the “comet pond” model, a rare combination of circumstances enables the entry and landing of pristine organic material onto a planetary surface with the creation of a pond by a soft impact and melting of entrained ices. Formation of the constituents of [...] Read more.
In the “comet pond” model, a rare combination of circumstances enables the entry and landing of pristine organic material onto a planetary surface with the creation of a pond by a soft impact and melting of entrained ices. Formation of the constituents of the comet in the cold interstellar medium and our circumstellar disk results in multiple constituents at disequilibrium which undergo rapid chemical reactions in the warmer, liquid environment. The planetary surface also provides minerals and atmospheric gases which chemically interact with the pond’s organic- and trace-element-rich constituents. Pond physical morphology and the heterogeneities imposed by gravitational forces (bottom sludge; surface scum) and weather result in a highly heterogeneous variety of macro- and microenvironments. Wet/dry, freeze/thaw, and natural chromatography processes further promote certain reaction sequences. Evaporation concentrates organics less volatile than water. Freezing concentrates all soluble organics into a residual liquid phase, including CH3OH, HCN, etc. The pond’s evolutionary processes culminate in the creation of a Macrobiont with the metabolically equivalent capabilities of energy transduction and replication of RNA (or its progenitor informational macromolecule), from which smaller organisms can emerge. Planet-wide dispersal of microorganisms is achieved through wind transport, groundwater, and/or spillover from the pond into surface hydrologic networks. Full article
(This article belongs to the Special Issue Meteorites and the Origin of Life)
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Review

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29 pages, 4230 KiB  
Review
Monosaccharides and Their Derivatives in Carbonaceous Meteorites: A Scenario for Their Synthesis and Onset of Enantiomeric Excesses
by George Cooper, Andro C. Rios and Michel Nuevo
Life 2018, 8(3), 36; https://doi.org/10.3390/life8030036 - 27 Aug 2018
Cited by 14 | Viewed by 7156
Abstract
Carbonaceous meteorites provide the best glimpse into the solar system’s earliest physical and chemical processes. These ancient objects, ~4.56 billion years old, contain evidence of phenomena ranging from solar system formation to the synthesis of organic compounds by aqueous and (likely) low-temperature photolytic [...] Read more.
Carbonaceous meteorites provide the best glimpse into the solar system’s earliest physical and chemical processes. These ancient objects, ~4.56 billion years old, contain evidence of phenomena ranging from solar system formation to the synthesis of organic compounds by aqueous and (likely) low-temperature photolytic reactions. Collectively, chemical reactions resulted in an insoluble kerogen-like carbon phase and a complex mixture of discrete soluble compounds including amino acids, nucleobases, and monosaccharide (or “sugar”) derivatives. This review presents the documented search for sugars and their derivatives in carbonaceous meteorites. We examine early papers, published in the early 1960s, and note the analytical methods used for meteorite analysis as well as conclusions on the results. We then present the recent finding of sugar derivatives including sugar alcohols and several sugar acids: The latter compounds were found to possess unusual “d” enantiomeric (mirror-image) excesses. After discussions on the possible roles of interstellar grain chemistry and meteorite parent body aqueous activity in the synthesis of sugar derivatives, we present a scenario that suggests that most of Earth’s extraterrestrial sugar alcohols (e.g., glycerol) were synthesized by interstellar irradiation and/or cold grain chemistry and that the early solar disk was the location of the initial enantiomeric excesses in meteoritic sugar derivatives. Full article
(This article belongs to the Special Issue Meteorites and the Origin of Life)
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16 pages, 903 KiB  
Review
The Nitrogen Heterocycle Content of Meteorites and Their Significance for the Origin of Life
by Zita Martins
Life 2018, 8(3), 28; https://doi.org/10.3390/life8030028 - 11 Jul 2018
Cited by 45 | Viewed by 5785
Abstract
Carbonaceous chondrites are very primitive meteorites that are rich in carbon. They contain many soluble organic compounds, including nitrogen heterocycles. These play a crucial role in present-day living organisms as they are components of the genetic material and of the co-factors of enzymes. [...] Read more.
Carbonaceous chondrites are very primitive meteorites that are rich in carbon. They contain many soluble organic compounds, including nitrogen heterocycles. These play a crucial role in present-day living organisms as they are components of the genetic material and of the co-factors of enzymes. This review outlines the nitrogen heterocycle content of carbonaceous meteorites. The potential mechanisms of formation of these molecules are also described. Measurements of the compound-specific carbon and hydrogen isotopic compositions are mentioned as a way of establishing the origin of the nitrogen heterocycles detected in meteorites. Full article
(This article belongs to the Special Issue Meteorites and the Origin of Life)
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31 pages, 1809 KiB  
Review
Data-Driven Astrochemistry: One Step Further within the Origin of Life Puzzle
by Alexander Ruf, Louis L. S. D’Hendecourt and Philippe Schmitt-Kopplin
Life 2018, 8(2), 18; https://doi.org/10.3390/life8020018 - 1 Jun 2018
Cited by 29 | Viewed by 8927
Abstract
Astrochemistry, meteoritics and chemical analytics represent a manifold scientific field, including various disciplines. In this review, clarifications on astrochemistry, comet chemistry, laboratory astrophysics and meteoritic research with respect to organic and metalorganic chemistry will be given. The seemingly large number of observed astrochemical [...] Read more.
Astrochemistry, meteoritics and chemical analytics represent a manifold scientific field, including various disciplines. In this review, clarifications on astrochemistry, comet chemistry, laboratory astrophysics and meteoritic research with respect to organic and metalorganic chemistry will be given. The seemingly large number of observed astrochemical molecules necessarily requires explanations on molecular complexity and chemical evolution, which will be discussed. Special emphasis should be placed on data-driven analytical methods including ultrahigh-resolving instruments and their interplay with quantum chemical computations. These methods enable remarkable insights into the complex chemical spaces that exist in meteorites and maximize the level of information on the huge astrochemical molecular diversity. In addition, they allow one to study even yet undescribed chemistry as the one involving organomagnesium compounds in meteorites. Both targeted and non-targeted analytical strategies will be explained and may touch upon epistemological problems. In addition, implications of (metal)organic matter toward prebiotic chemistry leading to the emergence of life will be discussed. The precise description of astrochemical organic and metalorganic matter as seeds for life and their interactions within various astrophysical environments may appear essential to further study questions regarding the emergence of life on a most fundamental level that is within the molecular world and its self-organization properties. Full article
(This article belongs to the Special Issue Meteorites and the Origin of Life)
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21 pages, 3709 KiB  
Review
Insights into Abiotically-Generated Amino Acid Enantiomeric Excesses Found in Meteorites
by Aaron S. Burton and Eve L. Berger
Life 2018, 8(2), 14; https://doi.org/10.3390/life8020014 - 12 May 2018
Cited by 39 | Viewed by 9947
Abstract
Biology exhibits homochirality, in that only one of two possible molecular configurations (called enantiomers) is used in both proteins and nucleic acids. The origin of this phenomenon is currently unknown, as nearly all known abiotic mechanisms for generating these compounds result in equal [...] Read more.
Biology exhibits homochirality, in that only one of two possible molecular configurations (called enantiomers) is used in both proteins and nucleic acids. The origin of this phenomenon is currently unknown, as nearly all known abiotic mechanisms for generating these compounds result in equal (racemic) mixtures of both enantiomers. However, analyses of primitive meteorites have revealed that a number of amino acids of extraterrestrial origin are present in enantiomeric excess, suggesting that there was an abiotic route to synthesize amino acids in a non-racemic manner. Here we review the amino acid contents of a range of meteorites, describe mechanisms for amino acid formation and their potential to produce amino acid enantiomeric excesses, and identify processes that could have amplified enantiomeric excesses. Full article
(This article belongs to the Special Issue Meteorites and the Origin of Life)
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11 pages, 835 KiB  
Review
The Prevailing Catalytic Role of Meteorites in Formamide Prebiotic Processes
by Raffaele Saladino, Lorenzo Botta and Ernesto Di Mauro
Life 2018, 8(1), 6; https://doi.org/10.3390/life8010006 - 22 Feb 2018
Cited by 18 | Viewed by 4426
Abstract
Meteorites are consensually considered to be involved in the origin of life on this Planet for several functions and at different levels: (i) as providers of impact energy during their passage through the atmosphere; (ii) as agents of geodynamics, intended both as starters [...] Read more.
Meteorites are consensually considered to be involved in the origin of life on this Planet for several functions and at different levels: (i) as providers of impact energy during their passage through the atmosphere; (ii) as agents of geodynamics, intended both as starters of the Earth’s tectonics and as activators of local hydrothermal systems upon their fall; (iii) as sources of organic materials, at varying levels of limited complexity; and (iv) as catalysts. The consensus about the relevance of these functions differs. We focus on the catalytic activities of the various types of meteorites in reactions relevant for prebiotic chemistry. Formamide was selected as the chemical precursor and various sources of energy were analyzed. The results show that all the meteorites and all the different energy sources tested actively afford complex mixtures of biologically-relevant compounds, indicating the robustness of the formamide-based prebiotic chemistry involved. Although in some cases the yields of products are quite small, the diversity of the detected compounds of biochemical significance underlines the prebiotic importance of meteorite-catalyzed condensation of formamide. Full article
(This article belongs to the Special Issue Meteorites and the Origin of Life)
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