A simple method for the determination of the porosity and tortuosity of meteorites with ultrasound

Abassi, Dris El; Ibhi, Abderrahmane; Faiz, Bouazza; Aboudaoud, Idris

doi:10.1088/1742-2132/10/5/055003

Cited by 16 publications

(9 citation statements)

References 16 publications

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“…We found no systematic influence on the density results from the variable numbers of scans needed to acquire the complete volumes when analyzing sample masses of 30–360 g. The measured densities of fragments from the Tamdakht and Huaxi meteorites are consistent with previous density measurements on smaller fragments, performed by El Abassi et al. () and Li et al. (), respectively, which suggest that the bulk density data presented here are accurate.…”

Section: Discussionsupporting

confidence: 88%

Radionuclide activities in recent chondrite falls determined by gamma‐ray spectrometry: Implications for terrestrial age estimates

Rosén

Hofmann

Sivers

et al. 2019

Meteorit & Planetary Scien

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Radionuclide activities were measured in the low-background gamma-ray spectrometry facility GeMSE in eight meteorite falls (Lost City, Tamdakht, Huaxi, Boumdeid, Xining, Kamargaon, Degtevo, and Ouidiyat Sbaa) and two finds (SaU 606 and M€ urtschenstock) to evaluate the use of radionuclides for terrestrial age estimates. Results indicate that these meteorites were all derived from small-(r < 25 cm) to medium-sized (r < 65 cm) meteoroids. Short-lived 48 V (t 1/2 = 16.0 d) and 51 Cr (t 1/2 = 27.7 d) were only detected in Oudiyat Sbaa (EH), while 7 Be (t 1/2 = 53.1 d) was also detected in Degtevo (H) and Kamargaon (L), in agreement with reported fall dates. The 22 Na/ 26 Al activity ratio in Huaxi agrees with the previously reported short cosmic-ray exposure age of this meteorite while 22 Na/ 26 Al in Kamargaon likely records a complex exposure history. Bayesian statistical analysis verifies the detection of very low activities of 44 Ti (t 1/2 = 60 a) in the relatively large H chondrites (>100 g) Degtevo, Huaxi, Tamdakht, Lost City, and SaU 606. Additionally, large samples from Oudiyat Sbaa (EH) and Kamargaon (L) gave positive detections. For H chondrite target compositions, detected 44 Ti(Fe+Ni)/ 26 Al averaged 0.055 AE 0.013. Activities of 22 Na and 54 Mn in SaU 606 show that this meteorite fell between July and September 2012, making SaU 606 the second recent fall from Oman identified using gamma-ray spectrometry. The upper activity limit of 22 Na in the M€ urtschenstock meteorite shows that it fell prior to 1999 and is not related to a bolide observation in 2015. M€ urtschenstock shows 137 Cs~109 higher than previously determined in Oman meteorites, likely due to Chernobyl fallout.

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Section: Discussionsupporting

confidence: 88%

Radionuclide activities in recent chondrite falls determined by gamma‐ray spectrometry: Implications for terrestrial age estimates

Rosén

Hofmann

Sivers

et al. 2019

Meteorit & Planetary Scien

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“…Results show that measurements of the porosity using our method are similar to the ultrasound measurements presented in [7]. The calculated porosities of the two meteorite specimens are low (13.41 % for Aubrite and 11.02 % for Bra chinite).…”

Section: B Results For 3d Porosity Imagessupporting

confidence: 73%

“…Consolmagno et al [5], [6] used the ideal gas pycnometry which yields accurate total porosity values. Recently in [7], the porosity of meteorites has been determined from reflection coefficient measurements using ultrasonic waves. However, it gives no indication of 3 ISTO, 4 PRISME, Polytech'OrLeans University of Orleans B. P. 6744, Orleans, France the location or structure of the porosity in terrestrial and extraterrestrial rocks.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the meteorites porosity by X-ray tomography and 3D image processing

Riad

Ibhi

Douzi

et al. 2014

2014 Second World Conference on Complex Systems (WCCS)

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In recent years an interest has emerged in the fields of meteoritic sciences such as X-ray Computed To mog raphy (CT), which is a nondestructive method that produces three-dimensional (3D) images of the internal features of rock specimens. To analyze the characteristics of meteorites, it is critical that the elements constituting can be distinguished. The use of X-ray CT and various 3D image processing techniques can isolate the porosity from the meteorite materials. The porosity is an essential element for the characterization of meteorites. Two samples of achondrite meteorites (Aubrite and Brachinite)with variable alteration and shock histories were examined. The 3D images were acquired with a high resolution CT scanner (Nanotom Phoenix). The isotropic voxel size is 3.6 Mm. We found that the size and structure of porosity varies with the degree of alteration and shock loading experienced by the materials.

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“…Tortuosities of chondritic meteorites have an average value of 1.45 [71], and the empirical exponent m for carbonaceous meteorites might be similar to that of nearshore sediments with a value of 2 [68].…”

Section: Appendix A: Advection and Diffusion Modelmentioning

confidence: 99%

“…The free water diffusion coefficient, D0, represents the unobstructed diffusion of a species, the porosity factor, φ, represents the void fraction of the medium, the constrictivity factor, δ, represents the bottleneck effect due to small pore diameters, and the tortuosity factor, τ , represents the restiction in diffusive flow due to curves in the pores. Estimates of these factors, and the empirical exponent, m, for carbonaceous IDPs and meteorites are, D0 = 4×10 −10 m 2 s −1 , φ = 0.25, δ = 1, τ = 1.45, and m = 2 [68][69][70][71] The degenerate WLP models used for these calculations correspond to a hot early Earth at 65…”

Section: Appendix A: Advection and Diffusion Modelmentioning

confidence: 99%

Origin of the RNA world: The fate of nucleobases in warm little ponds

Pearce

Pudritz

Semenov

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

170

222

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Prior to the origin of simple cellular life, the building blocks of RNA (nucleotides) had to form and polymerize in favourable environments on the early Earth. At this time, meteorites and interplanetary dust particles delivered organics such as nucleobases (the characteristic molecules of nucleotides) to warm little ponds whose wet-dry cycles promoted rapid polymerization. We build a comprehensive numerical model for the evolution of nucleobases in warm little ponds leading to the emergence of the first nucleotides and RNA. We couple Earth's early evolution with complex prebiotic chemistry in these environments. We find that RNA polymers must have emerged very quickly after the deposition of meteorites (< a few years). Their constituent nucleobases were primarily meteoritic in origin and not from interplanetary dust particles. Ponds appeared as continents rose out of the early global ocean but this increasing availability of "targets" for meteorites was offset by declining meteorite bombardment rates. Moreover, the rapid losses of nucleobases to pond seepage during wet periods, and to UV photodissociation during dry periods means that the synthesis of nucleotides and their polymerization into RNA occurred in just one to a few wet-dry cycles. Under these conditions, RNA polymers likely appeared prior to 4.17 billion years ago.Significance: There are currently two competing hypotheses for the site at which an RNA world emerged: hydrothermal vents in the deep ocean and warm little ponds. Because the former lacks wet and dry cycles, which are well known to promote polymerization (in this case, of nucleotides into RNA), we construct a comprehensive model for the origin of RNA in the latter sites. Our model advances the story and timeline of the RNA world by constraining the source of biomolecules, the environmental conditions, the timescales of reaction, and the emergence of first RNA polymers.Keywords: life origins | astrobiology | planetary science | meteoritics | RNA worldOne of the most fundamental questions in science is how life first emerged on the Earth. Given its ubiquity in living cells and its ability to both store genetic information and catalyze its own replication, RNA probably formed the basis of first life [1]. RNA molecules are made up of sequences of 4 different nucleotides, the latter of which can be formed through reaction of a nucleobase with a ribose and a reduced phosphorous (P) source [2,3]. The evidence suggests that first life appeared earlier than 3.7 Gyr ago (Ga) [4,5] and thus the RNA world would have developed on a violent early Earth undergoing meteoritic bombardment at a rate of ∼1-1000 ×10 12 kg/yr [6], which is approximately 8-11 orders of magnitude greater than today [7]. At this time, the atmosphere was dominated by volcanic gases, and dry land was scarce as continents were rising out of the global ocean. [8,9], the answer to these questions are largely unknown.As to the sources of nucleobases, the early Earth's atmosphere was likely dominated by CO 2 , N 2 , SO 2 , and H 2 O [10...

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A simple method for the determination of the porosity and tortuosity of meteorites with ultrasound

Cited by 16 publications

References 16 publications

Radionuclide activities in recent chondrite falls determined by gamma‐ray spectrometry: Implications for terrestrial age estimates

Radionuclide activities in recent chondrite falls determined by gamma‐ray spectrometry: Implications for terrestrial age estimates

Investigation of the meteorites porosity by X-ray tomography and 3D image processing

Origin of the RNA world: The fate of nucleobases in warm little ponds

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