Ablation of Meteoroids

Бронштен, В. А.

doi:10.1007/978-94-009-7222-3_4

Cited by 5 publications

(7 citation statements)

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“…Regarding oriented forms, it is striking that the meteorites in Fig. 1 A-C (22). The similarity of such angles to that of the cone carved in our erosion experiments (Fig.…”

Section: Discussionsupporting

confidence: 69%

“…Much early work aimed to link the overall conical shape as well as surface features to the flows present (ref. 22 and references therein), and laboratory experiments on the ablation of plastic bodies fixed within supersonic airflow revealed the formation of a conical nose directed into the flow (32). This shape is thereafter retained as the windward face recedes.…”

mentioning

confidence: 94%

“…A particularly splendid example is a meteor or "shooting star" (19,20), which involves the hypersonic flight motions of a meteoroid that are coupled to its reshaping due to aerodynamic heating, vaporization, melting, and removal of surface material (21)(22)(23)(24). When this process of ablation incompletely consumes a meteoroid, the resulting meteorite collected on Earth, its shape, and fusion crust of resolidified material give clues to its flight history (25)(26)(27)(28).…”

mentioning

confidence: 99%

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The role of shape-dependent flight stability in the origin of oriented meteorites

Amin

Huang

et al. 2019

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

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The atmospheric ablation of meteoroids is a striking example of the reshaping of a solid object due to its motion through a fluid. Motivated by meteorite samples collected on Earth that suggest fixed orientation during flight—most notably the conical shape of so-called oriented meteorites—we hypothesize that such forms result from an aerodynamic stabilization of posture that may be achieved only by specific shapes. Here, we investigate this issue of flight stability in the parallel context of fluid mechanical erosion of clay bodies in flowing water, which yields shapes resembling oriented meteorites. We conduct laboratory experiments on conical objects freely moving through water and fixed within imposed flows to determine the dependence of orientational stability on shape. During free motion, slender cones undergo postural instabilities, such as inversion and tumbling, and broad or dull forms exhibit oscillatory modes, such as rocking and fluttering. Only intermediate shapes, including the stereotypical form carved by erosion, achieve stable orientation and straight flight with apex leading. We corroborate these findings with systematic measurements of torque and stability potentials across cones of varying apex angle, which furnish a complete map of equilibrium postures and their stability. By showing that the particular conical form carved in unidirectional flows is also posturally stable as a free body in flight, these results suggest a self-consistent picture for the origin of oriented meteorites.

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“…Regarding oriented forms, it is striking that the meteorites in Fig. 1 A-C (22). The similarity of such angles to that of the cone carved in our erosion experiments (Fig.…”

Section: Discussionsupporting

confidence: 69%

mentioning

confidence: 94%

mentioning

confidence: 99%

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The role of shape-dependent flight stability in the origin of oriented meteorites

Amin

Huang

et al. 2019

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

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“…Ablation of planetesimal fragments < 1 km may deliver the bulk of the solids needed to form the satellites. For objects in that size range, the heat transfer coefficient C H ∼ 0.1 may be reasonably obtained from observations of terrestrial meteorites (Bronshten 1983). The rate at which energy is transferred to the planetesimal per unit area is given by E ∼ 0.5C H ρv 3 , where ρ is the gas density, v is the speed of the planetesimal through the gas, and some planetesimal flattening (which increases its cross section) takes place (e.g., Zahnle 1992;Chyba et al 1993).…”

Section: Thermal Ablation Of Disk Crossersmentioning

confidence: 79%

“…For this reason, we leave development of a more detailed ablation model for later work, and we employ the classic approach of Bronshten with minor modifications. We calculate the amount of material ablated by solving coupled equations of motion and ablation (Bronshten 1983) for a planetesimal of mass m which is assumed for simplicity to cross the circumplanetary disk perpendicular to the disk plane:…”

Section: Thermal Ablation Of Disk Crossersmentioning

confidence: 99%

Deciphering the origin of the regular satellites of gaseous giants – Iapetus: The Rosetta ice-moon

Mosqueira

Estrada

Charnoz

2010

Icarus

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Ever since their discovery the regular satellites of Jupiter and Saturn have held out the promise of providing an independent set of observations with which to test theories of planet formation. Yet elucidating their origin has proven elusive. Here we show that Iapetus can serve to discriminate between satellite formation models. Its accretion history can be understood in terms of a two-component gaseous subnebula, with a relatively dense inner region, and an extended tail out to the location of the irregular satellites, as in the SEMM model of Mosqueira and Estrada (2003a,b). Following giant planet formation, planetesimals in the feeding zone of Jupiter and Saturn become dynamically excited, and undergo a collisional cascade. Ablation and capture of planetesimal fragments crossing the gaseous circumplanetary disks delivers enough collisional rubble to account for the mass budgets of the regular satellites of Jupiter and Saturn. This process can result in rock/ice fractionation as long as the make up of the population of disk crossers is non-homogeneous, thus offering a natural explanation for the marked compositional differences between outer solar nebula objects and those that accreted in the subnebulae of the giant planets. For a given size, icy objects are easier to capture and to ablate, likely resulting in an overall enrichment of ice in the subnebula. Furthermore, capture and ablation of rocky fragments become inefficient far from the planet for two reasons: the gas surface density of the subnebula is taken to drop outside the centrifugal radius, and the velocity of interlopers decreases with distance from the planet. Thus, rocky objects crossing the outer disks of Jupiter and Saturn never reach a temperature high enough to ablate either due to melting or vaporization, and capture is also greatly diminished there. In contrast, icy objects crossing the outer disks of each planet ablate due to the melting and vaporization of water-ice. Consequently, our model leads to an enhancement of the ice content of Iapetus, and to a lesser degree those of Titan, Callisto and Ganymede, and accounts for the (non-stochastic) compositions of these large, low-porosity outer regular satellites of Jupiter and Saturn. For this to work, the primordial population of planetesimals in the Jupiter-Saturn region must be partially differentiated, so that the ensuing collisional cascade produces an icy population of 1 m size fragments to be ablated during subnebula crossing. We argue this is likely because the first generation of solar nebula ∼ 10 km planetesimals in the Jupiter-Saturn region incorporated significant quantities of 26 Al. This is the first study successfully to provide a direct connection between nebula planetesimals and subnebulae mixtures with quantifiable and observable consequences for the bulk properties of the regular satellites of Jupiter and Saturn, and the only explanation presently available for Iapetus' low density and ice-rich composition.

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The electrical effects of micrometeoroids entering the terrestrial atmosphere at different speeds

Mendis

Maravilla

2010

J. Plasma Phys.

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Micrometeoroids entering the terrestrial atmosphere lead to two important related electrical effects. One is the electrification of the upper atmosphere along their paths and the other is the electrical charging of the micrometeoroids themselves. In this brief note we will emphasize the central role of the initial encounter speed of the incoming micrometeoroid, showing how it changes the altitude profiles of electron production and electrical charging, not just quantitatively but also qualitatively. We will discuss the underlying reasons for this, as well as their importance in meteor studies.

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Ablation of Meteoroids

Cited by 5 publications

References 0 publications

The role of shape-dependent flight stability in the origin of oriented meteorites

The role of shape-dependent flight stability in the origin of oriented meteorites

Deciphering the origin of the regular satellites of gaseous giants – Iapetus: The Rosetta ice-moon

The electrical effects of micrometeoroids entering the terrestrial atmosphere at different speeds

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