Physical properties of the stone meteorites: Implications for the properties of their parent bodies

Flynn, G. J.; Consolmagno, G. J.; Brown, Peter; Macke, R. J.

doi:10.1016/j.chemer.2017.04.002

Cited by 146 publications

(173 citation statements)

References 121 publications

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“…Ordinary chondrite falls have quite large porosities of 11–15% (Wasson ) with an average range of 8–9.5% (Flynn et al. ). Ordinary chondrite finds have porosities of 2.8–5.8% (Macke ).…”

Section: Discussionmentioning

confidence: 99%

“…Due to differences in mineralogy (e.g., amount and types of metal) and physical properties (e.g., density, porosity), thermal conductivity of meteorites varies significantly. Published thermal conductivity data on meteorites whose porosity has been determined are particularly rare (Flynn et al 2018). Consequently, measured thermal diffusivity values have been used to determine thermal conductivity values of ordinary chondrites (Matsui and Osako 1979;Yomogida and Matsui 1983).…”

Section: Thermal Propertiesmentioning

confidence: 99%

“…Published thermal conductivity data on meteorites whose porosity has been determined are particularly rare (Flynn et al. ). Consequently, measured thermal diffusivity values have been used to determine thermal conductivity values of ordinary chondrites (Matsui and Osako ; Yomogida and Matsui ).…”

Section: Introductionmentioning

confidence: 99%

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Thermal and porosity properties of meteorites: A compilation of published data and new measurements

Soini

Kukkonen

Kohout

et al. 2020

Meteorit & Planetary Scien

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We report direct measurements of thermal diffusivity and conductivity at room temperature for 38 meteorite samples of 36 different meteorites including mostly chondrites, and thus almost triple the number of meteorites for which thermal conductivity is directly measured. Additionally, we measured porosity for 34 of these samples. Thermal properties were measured using an optical infrared scanning method on samples of cm‐sizes with a flat, sawn surface. A database compiled from our measurements and literature data suggests that thermal diffusivities and conductivities at room temperature vary largely among samples even of the same petrologic and chemical type and overlap among, for example, different ordinary chondrite classes. Measured conductivities of ordinary chondrites vary from 0.4 to 5.1 W m−1 K−1. On average, enstatite chondrites show much higher values (2.33–5.51 W m−1 K−1) and carbonaceous chondrites lower values (0.5–2.55 W m−1 K−1). Mineral composition (silicates versus iron‐nickel) and porosity control conductivity. Porosity shows (linear) negative correlation with conductivity. Variable conductivity is attributed to heterogeneity in mineral composition and porosity by intra‐ and intergranular voids and cracks, which are important in the scale of typical meteorite samples. The effect of porosity may be even more significant for thermal properties than that of the metal content in chondrites.

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Section: Discussionmentioning

confidence: 99%

Section: Thermal Propertiesmentioning

confidence: 99%

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Thermal and porosity properties of meteorites: A compilation of published data and new measurements

Soini

Kukkonen

Kohout

et al. 2020

Meteorit & Planetary Scien

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“…Finally, the diurnal skin depth (i.e., the approximate depth at which the amplitude of the thermal wave is attenuated by a factor of 1/e) for a 200 J m −2 K −1 s −1/2 thermal inertia surface is also shown in Figure as a thick gray line. The skin depth is calculated by

δ = \frac{TI}{ρ c_{p}} \sqrt{\frac{P}{π} .}

The rotation period, P , for Bennu is 15,466 s (Lauretta et al, ), thermal inertia, TI, is assumed at 200 J m −2 K −1 s −1/2 , specific heat, c p , is 750 J kg −1 K −1 (Biele et al, ), and bulk density, ρ , is estimated as a function of k m , using the average of two models by Henke et al () and Flynn et al (; see Methods section in Grott et al, 2019), assuming a grain density of 2,960 kg m −3 (Flynn et al, ) and a regolith macroporosity of 0.40.…”

Section: Discussionmentioning

confidence: 99%

“…Two reference k m values are displayed with vertical lines/bars: the Cold Bokkeveld (CM2) meteorite (Opeil et al, 2010) and the Ryugu boulder examined by the MARA radiometer data . Model input values: macroporosity = 0.40; specific heat = 750 J kg −1 K −1 (a); particle density is a function of thermal conductivity, using the average of two models (b, c) for meteorite thermal conductivity versus microporosity and assuming an average CM grain density = 2,960 kg m The rotation period, P, for Bennu is 15,466 s , thermal inertia, TI, is assumed at 200 J m −2 K −1 s −1/2 , specific heat, c p , is 750 J kg −1 K −1 (Biele et al, 2019), and bulk density, ρ, is estimated as a function of k m , using the average of two models by Henke et al (2016) and Flynn et al (2018; see Methods section in Grott et al, 2019), assuming a grain density of 2,960 kg m −3 (Flynn et al, 2018) and a regolith macroporosity of 0.40.…”

Section: /2019je006100mentioning

confidence: 99%

Full‐Field Modeling of Heat Transfer in Asteroid Regolith: 1. Radiative Thermal Conductivity of Polydisperse Particulates

et al. 2020

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Characterizing the surface material of an asteroid is important for understanding its geology and for informing mission decisions, such as the selection of a sample site. Diurnal surface temperature amplitudes are directly related to the thermal properties of the materials on the surface. We describe a numerical model for studying the thermal conductivity of particulate regolith in vacuum. Heat diffusion and surface‐to‐surface radiation calculations are performed using the finite element (FE) method in three‐dimensional meshed geometries of randomly packed spherical particles. We validate the model for test cases where the total solid and radiative conductivity values of particulates with monodisperse particle size frequency distributions (SFDs) are determined at steady‐state thermal conditions. Then, we use the model to study the bulk radiative thermal conductivity of particulates with polydisperse, cumulative power law particle SFDs. We show that for each polydisperse particulate geometry tested, there is a corresponding monodisperse geometry with some effective particle diameter that has an identical radiative thermal conductivity. These effective diameters are found to correspond very well to the Sauter mean particle diameter, which is essentially the surface area‐weighted mean. Next, we show that the thermal conductivity of the particle material can have an important effect on the radiative component of the thermal conductivity of particulates, especially if the particle material conductivity is very low or the spheres are relatively large, owing to non‐isothermality in each particle. We provide an empirical correlation to predict the effects of non‐isothermality on radiative thermal conductivity in both monodisperse and polydisperse particulates.

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Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu

Grott

Biele

Michel

et al. 2020

Preprint

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• Ryugu's large bulk porosity is distributed between intrinsic boulder microporosity and macroporosity due to void spaces in-between boulders. • We use the boulder size-frequency distribution as observed on the surface together with mixing models to estimate Ryugu's macroporosity. • We find that macroporosity is 16±3 %, indicating that Ryugu's large bulk porosity of close to 50 % is governed by microporosity.

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Physical properties of the stone meteorites: Implications for the properties of their parent bodies

Cited by 146 publications

References 121 publications

Thermal and porosity properties of meteorites: A compilation of published data and new measurements

Thermal and porosity properties of meteorites: A compilation of published data and new measurements

Full‐Field Modeling of Heat Transfer in Asteroid Regolith: 1. Radiative Thermal Conductivity of Polydisperse Particulates

Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu

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