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1.
Nano Lett ; 21(19): 8135-8142, 2021 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-34529916

RESUMO

Iron and its alloys have made modern civilization possible, with metallic meteorites providing one of the human's earliest sources of usable iron as well as providing a window into our solar system's billion-year history. Here highest-resolution tools reveal the existence of a previously hidden FeNi nanophase within the extremely slowly cooled metallic meteorite NWA 6259. This new nanophase exists alongside Ni-poor and Ni-rich nanoprecipitates within a matrix of tetrataenite, the uniaxial, chemically ordered form of FeNi. The ferromagnetic nature of the nanoprecipitates combined with the antiferromagnetic character of the FeNi nanophases gives rise to a complex magnetic state that evolves dramatically with temperature. These observations extend and possibly alter our understanding of celestial metallurgy, provide new knowledge concerning the archetypal Fe-Ni phase diagram and supply new information for the development of new types of sustainable, technologically critical high-energy magnets.


Assuntos
Meteoroides , Ligas , Humanos , Ferro , Imãs , Transição de Fase
2.
Orig Life Evol Biosph ; 51(3): 185-213, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34279769

RESUMO

How life arose on the primitive Earth is one of the biggest questions in science. Biomolecular emergence scenarios have proliferated in the literature but accounting for the ubiquity of oxidized (+ 5) phosphate (PO43-) in extant biochemistries has been challenging due to the dearth of phosphate and molecular oxygen on the primordial Earth. A compelling body of work suggests that exogenous schreibersite ((Fe,Ni)3P) was delivered to Earth via meteorite impacts during the Heavy Bombardment (ca. 4.1-3.8 Gya) and there converted to reduced P oxyanions (e.g., phosphite (HPO32-) and hypophosphite (H2PO2-)) and phosphonates. Inspired by this idea, we review the relevant literature to deduce a plausible reduced phospholipid analog of modern phosphatidylcholines that could have emerged in a primordial hydrothermal setting. A shallow alkaline lacustrine basin underlain by active hydrothermal fissures and meteoritic schreibersite-, clay-, and metal-enriched sediments is envisioned. The water column is laden with known and putative primordial hydrothermal reagents. Small system dimensions and thermal- and UV-driven evaporation further concentrate chemical precursors. We hypothesize that a reduced phospholipid arises from Fischer-Tropsch-type (FTT) production of a C8 alkanoic acid, which condenses with an organophosphinate (derived from schreibersite corrosion to hypophosphite with subsequent methylation/oxidation), to yield a reduced protophospholipid. This then condenses with an α-amino nitrile (derived from Strecker-type reactions) to form the polar head. Preliminary modeling results indicate that reduced phospholipids do not aggregate rapidly; however, single layer micelles are stable up to aggregates with approximately 100 molecules.


Assuntos
Meteoroides , Fósforo , Planeta Terra , Fosfatos , Fosfolipídeos
3.
Astrobiology ; 21(11): 1350-1362, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34314603

RESUMO

Laser-induced fluorescence spectroscopy is a useful laboratory and in situ technique for planetary exploration, with applications in biosignature detection and the search for life on Mars. However, little work has been completed on the utility of fluorescence spectroscopy techniques on asteroid relevant material. In preparation for asteroid sample return missions such as NASA's OSIRIS-REx and JAXA's Hayabusa2, we conducted UV time resolved laser-induced fluorescence spectroscopy (TR-LIF) analysis of 10 amino acids, all of which have been found in the carbonaceous meteorites Murchison and Allende. We present the calculation of decay rates of each amino acid (1.55-3.56 ns) and compare with those of relevant homogeneous minerals (15-70 ns). Moreover, we demonstrate a linear relationship between calculated lifetimes and elemental abundance of nitrogen and carbon (p < 0.025). The quantitative and qualitative fluorescence analyses presented in this work will lead to more reliable identification of organic material within meteorites and asteroids in a time-efficient, minimally destructive way.


Assuntos
Meteoroides , Aminoácidos , Exobiologia , Lasers , Espectrometria de Fluorescência
4.
J Chromatogr A ; 1652: 462343, 2021 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-34174716

RESUMO

Analysis of organic matter extracted from meteorites showed that solar system objects present an important molecular diversity. To improve our understanding of such organic matter, new analytical technologies must be developed. The present study displays the first experiments using a GC-FT-Orbitrap-MS to decipher the molecular diversity observed in experiments simulating the evolution of cometary ices. The proposed analytical strategy focuses on the analysis of 110 volatile organic compounds (VOC) with mainly 1 to 6 carbon atoms generated in such cometary ice analogs. Electron ionization (EI) and chemical ionization (CI) modes with methane (CH4) or ammonia (NH3) were optimized and compared. Those developments maximized the intensity of molecular, protonated or deprotonated ions, and improved high-resolution molecular formula unambiguous identification: EI mode is too energetic to provides there detection, while it is not the case in CI mode. Particularly, NH3 as a reagent gas improves amine identification in positive mode (PCI), and esters, alcohols, carbonyls, amides, carboxylic acids and nitriles in negative mode (NCI). The combination of both EI and CI mass spectrum analysis improves molecular identification, thanks to the detection of molecular, deprotonated or protonated ion of highest intensity and fragment formula assignments. The EI and NCI NH3 combination allows formula assignments up to 94% of our database with limit of detection up to 7 ppm. This procedure has been validated for untargeted GC-FT-Orbitrap-MS analysis of VOC coming from the processing of cometary ice analogs.


Assuntos
Meteoroides , Compostos Orgânicos Voláteis , Elétrons , Cromatografia Gasosa-Espectrometria de Massas , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/isolamento & purificação
5.
Nature ; 593(7859): 349-350, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-34012077
6.
Int J Mol Sci ; 22(7)2021 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-33800543

RESUMO

Viroids are non-coding circular RNA molecules with rod-like or branched structures. They are often ribozymes, characterized by catalytic RNA. They can perform many basic functions of life and may have played a role in evolution since the beginning of life on Earth. They can cleave, join, replicate, and undergo Darwinian evolution. Furthermore, ribozymes are the essential elements for protein synthesis of cellular organisms as parts of ribosomes. Thus, they must have preceded DNA and proteins during evolution. Here, we discuss the current evidence for viroids or viroid-like RNAs as a likely origin of life on Earth. As such, they may also be considered as models for life on other planets or moons in the solar system as well as on exoplanets.


Assuntos
Origem da Vida , RNA Catalítico/genética , RNA Viral/genética , Ribossomos/genética , Viroides/genética , Replicação Viral , Animais , Inativação Gênica , Teste de Complementação Genética , Humanos , Meteoroides , Conformação de Ácido Nucleico , Doenças das Plantas/virologia , Interferência de RNA , Ribossomos/química , Simbiose , Viroses/metabolismo
7.
Astrobiology ; 21(8): 940-953, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33857382

RESUMO

The martian meteorite ALH 84001 formed before ∼4.0 Ga, so it could have preserved information about habitability on early Mars and habitability since then. ALH 84001 is particularly important as it contains carbonate (and other) minerals that were deposited by liquid water, raising the chance that they may have formed in a habitable environment. Despite vigorous efforts from the scientific community, there is no accepted evidence that ALH 84001 contains traces or markers of ancient martian life-all the purported signs have been shown to be incorrect or ambiguous. However, the meteorite provides evidence for three distinct episodes of potentially habitable environments on early Mars. First is evidence that the meteorite's precursors interacted with clay-rich material, formed approximately at 4.2 Ga. Second is that igneous olivine crystals in ALH 84001 were partially dissolved and removed, presumably by liquid water. Third is, of course, the deposition of the carbonate globules, which occurred at ∼15-25°C and involved near-neutral to alkaline waters. The environments of olivine dissolution and carbonate deposition are not known precisely; hydrothermal and soil environments are current possibilities. By analogies with similar alteration minerals and sequences in the nakhlite martian meteorites and volcanic rocks from Spitzbergen (Norway), a hydrothermal environment is favored. As with the nakhlite alterations, those in ALH 84001 likely formed in a hydrothermal system related to a meteoroid impact event. Following deposition of the carbonates (at 3.95 Ga), ALH 84001 preserves no evidence of habitable environments, that is, interaction with water. The meteorite contains several materials (formed by impact shock at ∼3.9 Ga) that should have reacted readily with water to form hydrous silicates, but there is no evidence any formed.


Assuntos
Marte , Meteoroides , Carbonatos , Meio Ambiente Extraterreno , Minerais
8.
Astrobiology ; 21(6): 741-756, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33885329

RESUMO

In Earth's deep continental subsurface, where groundwaters are often isolated for >106 to 109 years, energy released by radionuclides within rock produces oxidants and reductants that drive metabolisms of non-photosynthetic microorganisms. Similar processes could support past and present life in the martian subsurface. Sulfate-reducing microorganisms are common in Earth's deep subsurface, often using hydrogen derived directly from radiolysis of pore water and sulfate derived from oxidation of rock-matrix-hosted sulfides by radiolytically derived oxidants. Radiolysis thus produces redox energy to support a deep biosphere in groundwaters isolated from surface substrate input for millions to billions of years on Earth. Here, we demonstrate that radiolysis by itself could produce sufficient redox energy to sustain a habitable environment in the subsurface of present-day Mars, one in which Earth-like microorganisms could survive wherever groundwater exists. We show that the source localities for many martian meteorites are capable of producing sufficient redox nutrients to sustain up to millions of sulfate-reducing microbial cells per kilogram rock via radiolysis alone, comparable to cell densities observed in many regions of Earth's deep subsurface. Additionally, we calculate variability in supportable sulfate-reducing cell densities between the martian meteorite source regions. Our results demonstrate that martian subsurface groundwaters, where present, would largely be habitable for sulfate-reducing bacteria from a redox energy perspective via radiolysis alone. We present evidence for crustal regions that could support especially high cell densities, including zones with high sulfide concentrations, which could be targeted by future subsurface exploration missions.


Assuntos
Marte , Meteoroides , Planeta Terra , Meio Ambiente Extraterreno , Hidrogênio
9.
Astrobiology ; 21(6): 718-728, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33798393

RESUMO

Life is pervasive on planet Earth, but whether life is ubiquitous in the Galaxy and sustainable over timescales comparable to stellar evolution is unknown. Evidence suggests that life first appeared on Earth more than 3.77 Gyr ago, during a period of heavy meteoric bombardment. Amino acids, the building blocks of proteins, have been demonstrated to exist in interstellar ice. As such, the contribution of space-generated amino acids to those existing on Earth should be considered. However, detection of space amino acids is challenging. In this study, we used analytical data from several meteorites and in situ measurements of the comet 67P/Churyumov-Gerasimenko collected by the Rosetta probe to evaluate the detectability of alanine by ultraviolet spectropolarimetry. Alanine is the second-most abundant amino acid after glycine and is optically active. This chirality produces a unique signature that enables reliable identification of this amino acid using the imprint of optical rotatory dispersion (ORD) and circular dichroism (CD) in the ultraviolet spectrum (130-230 nm). Here, we show that the ORD signature could be detected in comets by using ultraviolet spectropolarimetric observations conducted at middle size space observatories. These observations can also provide crucial information for the study of sources of enantiomeric imbalance on Earth.


Assuntos
Aminoácidos , Meteoroides , Alanina , Glicina , Estereoisomerismo
10.
Astrobiology ; 21(5): 605-612, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33684326

RESUMO

Mars was habitable in its early history, but the consensus is that it is quite inhospitable today, in particular because its modern climate cannot support stable liquid water at the surface. Here, we report the presence of magmatic Fe/Mg clay minerals within the mesostasis of the martian meteorite NWA 5790, an unaltered 1.3 Ga nakhlite archetypal of the martian crust. These magmatic clay minerals exhibit a vesicular texture that forms a network of microcavities or pockets, which could serve as microreactors and allow molecular crowding, a necessary step for the emergence of life. Because their formation does not depend on climate, such niches for emerging life may have been generated on Mars at many periods throughout its history, regardless of the stability or availability of liquid water at the surface.


Assuntos
Marte , Meteoroides , Argila , Meio Ambiente Extraterreno , Minerais
12.
Astrobiology ; 21(4): 413-420, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33784199

RESUMO

Formaldehyde (FA) is an important precursor in the abiotic synthesis of major biomolecules including amino acids, sugars, and nucleobases. Thus, spontaneous formation of prebiotic FA must have been crucial for the chemical origin of life. The frequent impacts of meteorites and asteroids on Hadean Earth have been considered one of the abiotic synthetic processes of organic compounds. However, the impact-induced formation of FA from CO2 as the major atmospheric constituent has not been confirmed yet. This study investigated the formation of FA in impact-induced reactions among meteoritic minerals, bicarbonate, gaseous nitrogen, and water to simulate the abiotic process experimentally. Products were analyzed with ultra-high-performance liquid chromatography/tandem mass spectrometry and powder X-ray diffraction techniques. The results show the formation of FA and oxidation of metallic iron to siderite in the impact shock experiments. This indicates that this important prebiotic molecule was also synthesized by impacts of iron-bearing meteorites/asteroids on the Hadean oceans. The impact events might have generated spatially and temporally FA-enriched localized environments. Moreover, the impact-induced synthesis of FA may have also occurred on Noachian Mars given the presence of liquid water and a CO2-N2-rich atmosphere on the planet.


Assuntos
Meteoroides , Atmosfera , Planeta Terra , Formaldeído , Água
13.
J Proteome Res ; 20(2): 1444-1450, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-33078610

RESUMO

Method development is one of the objectives of the astrophysical community for characterizing the organic matter in objects of the solar system. In this context, we report on the development of an enzyme-catalyzed stereoselective hydrolysis, inspired by the proteomics discipline, which has enabled the indirect detection of peptide sequences in extraterrestrial samples. A proof of concept has been performed on a Murchison extract. We show that our approach can successfully highlight l- and d-amino acids involved in peptide bonds. While we show that some d-amino acids must have been involved in peptide bonds, we cannot at this stage conclude on the indigenous or exogenous nature of these biopolymers. However, our strategy constitutes the first step toward direct UPLC-MS evidence of peptide sequences in extraterrestrial samples. It should thus contribute to deepening knowledge on the molecules available in the solar system, hence providing new clues about their chemical history, especially on Earth.


Assuntos
Meteoroides , Cromatografia Líquida , Meio Ambiente Extraterreno , Peptídeos , Proteômica , Espectrometria de Massas em Tandem
14.
Molecules ; 25(23)2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-33265981

RESUMO

The building blocks of life, amino acids, are believed to have been synthesized in the extreme conditions that prevail in space, starting from simple molecules containing hydrogen, carbon, oxygen and nitrogen. However, the fate and role of amino acids when they are subjected to similar processes largely remain unexplored. Here we report, for the first time, that shock processed amino acids tend to form complex agglomerate structures. Such structures are formed on timescales of about 2 ms due to impact induced shock heating and subsequent cooling. This discovery suggests that the building blocks of life could have self-assembled not just on Earth but on other planetary bodies as a result of impact events. Our study also provides further experimental evidence for the 'threads' observed in meteorites being due to assemblages of (bio)molecules arising from impact-induced shocks.


Assuntos
Aminoácidos/química , Planeta Terra , Substâncias Macromoleculares/química , Meteoroides , Origem da Vida
15.
Proc Natl Acad Sci U S A ; 117(37): 22649, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32913062
16.
Astrobiology ; 20(11): 1377-1388, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32985898

RESUMO

Over 200 molecules have been detected in multiple extraterrestrial environments, including glycolaldehyde (C2(H2O)2, GLA), a two-carbon sugar precursor that has been detected in regions of the interstellar medium. Its recent in situ detection on the nucleus of comet 67P/Churyumov-Gerasimenko and through remote observations in the comae of others provides tantalizing evidence that it is common on most (if not all) comets. Impact experiments conducted at the Experimental Impact Laboratory at NASA's Johnson Space Center have shown that samples of GLA and GLA mixed with montmorillonite clays can survive impact delivery in the pressure range of 4.5 to 25 GPa. Extrapolated to amounts of GLA observed on individual comets and assuming a monotonic impact rate in the first billion years of Solar System history, these experimental results show that up to 1023 kg of cometary GLA could have survived impact delivery, with substantial amounts of threose, erythrose, glycolic acid, and ethylene glycol also produced or delivered. Importantly, independent of the profile of the impact flux in the early Solar System, comet delivery of GLA would have provided (and may continue to provide) a reservoir of starting material for the formose reaction (to form ribose) and the Strecker reaction (to form amino acids). Thus, comets may have been important delivery vehicles for starting molecules necessary for life as we know it.


Assuntos
Acetaldeído/análogos & derivados , Meteoroides , Origem da Vida , RNA/química , Acetaldeído/química , Meio Ambiente Extraterreno , Sistema Solar
17.
Clin Dermatol ; 38(4): 485-488, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32972607

RESUMO

Many factors affect the health and physiology of human skin, with some of them arising from outer space. This contribution explores four celestial influences on the skin: (1) the sun's ultraviolet light, which has both beneficial and deleterious dermatologic effects, (2) meteorite injuries, (3) possible lunar effects on the body's health, and (4) cosmic radiation as a risk factor for skin cancer and pregnancy-related complications. Some of these extraterrestrial influences on skin health have taken on added significance as human beings increasingly spend more time at higher altitudes in aircraft, spaceships, and space stations.


Assuntos
Radiação Cósmica/efeitos adversos , Neoplasias Cutâneas/etiologia , Pele/lesões , Pele/efeitos da radiação , Luz Solar/efeitos adversos , Raios Ultravioleta/efeitos adversos , Aeronaves , Altitude , Dermatite de Contato/etiologia , Feminino , Humanos , Masculino , Meteoroides , Lua , Gravidez , Complicações na Gravidez/etiologia
18.
Astrobiology ; 20(9): 1121-1149, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32876492

RESUMO

The conditions, timing, and setting for the origin of life on Earth and whether life exists elsewhere in our solar system and beyond represent some of the most fundamental scientific questions of our time. Although the bombardment of planets and satellites by asteroids and comets has long been viewed as a destructive process that would have presented a barrier to the emergence of life and frustrated or extinguished life, we provide a comprehensive synthesis of data and observations on the beneficial role of impacts in a wide range of prebiotic and biological processes. In the context of previously proposed environments for the origin of life on Earth, we discuss how meteorite impacts can generate both subaerial and submarine hydrothermal vents, abundant hydrothermal-sedimentary settings, and impact analogues for volcanic pumice rafts and splash pools. Impact events can also deliver and/or generate many of the necessary chemical ingredients for life and catalytic substrates such as clays as well. The role that impact cratering plays in fracturing planetary crusts and its effects on deep subsurface habitats for life are also discussed. In summary, we propose that meteorite impact events are a fundamental geobiological process in planetary evolution that played an important role in the origin of life on Earth. We conclude with the recommendation that impact craters should be considered prime sites in the search for evidence of past life on Mars. Furthermore, unlike other geological processes such as volcanism or plate tectonics, impact cratering is ubiquitous on planetary bodies throughout the Universe and is independent of size, composition, and distance from the host star. Impact events thus provide a mechanism with the potential to generate habitable planets, moons, and asteroids throughout the Solar System and beyond.


Assuntos
Planeta Terra , Evolução Química , Meio Ambiente Extraterreno/química , Meteoroides , Origem da Vida , Fenômenos Geológicos
19.
Astrobiology ; 20(8): 964-976, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32783564

RESUMO

Measurements of the isotopic abundances in meteoritic amino acids have found enhancements of 2H/H, 15N/14N, and 13C/12C in the amino acids in the meteorites studied. We show that they are consistent with the processing of the constituents of the meteorites by electron antineutrinos that would be expected from a core-collapse supernova or neutron-star merger. Using theoretical electron antineutrino cross-sections, we are able to predict these isotopic ratio variations depending on the time-integrated antineutrino flux at the site where the amino acids were processed.


Assuntos
Aminoácidos/química , Elétrons , Evolução Química , Meio Ambiente Extraterreno/química , Meteoroides , Aminoácidos/isolamento & purificação , Estereoisomerismo
20.
Astrobiology ; 20(9): 1109-1120, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32749859

RESUMO

Delivery of water and organics by asteroid and comet impacts may have influenced prebiotic chemistry on the early Earth. Some recent prebiotic chemistry experiments emphasize hydrogen cyanide (HCN) as a feedstock molecule for the formation of sugars, ribonucleotides, amino acids, and lipid precursors. Here, we assess how much HCN originally contained in a comet would survive impact, using parametric temperature and pressure profiles together with a time-dependent chemistry model. We find that HCN survival mainly depends on whether the impact is hot enough to thermally decompose H2O into reactive radicals, and HCN is therefore rather insensitive to the details of the chemistry. In the most favorable impacts (low impact angle, low velocity, small radius), this temperature threshold is not reached, and intact delivery of HCN is possible. We estimate the global delivery of HCN during a period of Early and Late Heavy Bombardment of the early Earth, as well as local HCN concentrations achieved by individual impacts. In the latter case, comet impacts can provide prebiotically interesting HCN levels for thousands to millions of years, depending on properties of the impactor and of the local environment.


Assuntos
Planeta Terra , Evolução Química , Cianeto de Hidrogênio/química , Meteoroides , Origem da Vida , Meio Ambiente Extraterreno/química
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