Interpretation of Wild 2 dust fine structure: Comparison of Stardust aluminum foil craters to the three‐dimensional shape of experimental impacts by artificial aggregate particles and meteorite powders

Kearsley, A. T.; Burchell, M. J.; Price, M. C.; Graham, G. A.; Wozniakiewicz, P. J.; Cole, M. J.; Foster, N. J.; Teslich, Nick E.

doi:10.1111/j.1945-5100.2009.tb01188.x

Cited by 32 publications

(56 citation statements)

References 72 publications

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“…However, because Stardust foil surfaces present only a planar section through complex 3‐D, polygonal crystal shapes (flattened by rolling during foil fabrication) it is also not possible for us to make a simple judgement as to the proximity of a particular crater to all possibly significant grain boundaries (which may lie beneath). So far, we have found no evidence of a wider range of crater morphology in our smallest (∼500 nm) impactor shots; this is in contrast to the wide range of shape seen in the smaller Stardust craters (see below) which we have attributed to complex internal structures with Wild 2 dust grains (Kearsley et al. 2009).…”

Section: Resultscontrasting

confidence: 84%

“…(2008a) that such particles comprise a small proportion of the total cometary dust mass remains valid. Evidence from crater depth profiles (Kearsley et al. 2008a, 2008b, 2009) also indicates that the density of most of the larger particles was relatively high, and they should not be considered as highly porous, of low density, and hence low mass contributors.…”

Section: Discussionmentioning

confidence: 99%

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Comet 81P/Wild 2: The size distribution of finer (sub‐10 μm) dust collected by the Stardust spacecraft

Price

Kearsley

Burchell

et al. 2010

Meteorit & Planetary Scien

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Abstract-The fluence of dust particles <10 lm in diameter was recorded by impacts on aluminum foil of the NASA Stardust spacecraft during a close flyby of comet 81P ⁄ Wild 2 in 2004. Initial interpretation of craters for impactor particle dimensions and mass was based upon laboratory experimental simulations using projectiles less than >10 lm in diameter and the resulting linear relationship of projectile to crater diameter was extrapolated to smaller sizes. We now describe a new experimental calibration program firing very small monodisperse silica projectiles (470 nm-10 lm) at approximately 6 km s )1. The results show an unexpected departure from linear relationship between 1 and 10 lm. We collated crater measurement data and, where applicable, impactor residue data for 596 craters gathered during the postmission preliminary examination phase. Using the new calibration, we recalculate the size of the particle responsible for each crater and hence reinterpret the cometary dust size distribution. We find a greater flux of small particles than previously reported. From crater morphology and residue composition of a subset of craters, the internal structure and dimensions of the fine dust particles are inferred and a ''maximumsize'' distribution for the subgrains composing aggregate particles is obtained. The size distribution of the small particles derived directly from the measured craters peaks at approximately 175 nm, but if this is corrected to allow for aggregate grains, the peak in subgrain sizes is at <100 nm.

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Section: Resultscontrasting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Comet 81P/Wild 2: The size distribution of finer (sub‐10 μm) dust collected by the Stardust spacecraft

Price

Kearsley

Burchell

et al. 2010

Meteorit & Planetary Scien

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“…Case II has a radius, bulk density and albedo of 130 m, 1000 kg m −3 and 0.04, respectively. If we assume the solid component (both the nucleus and the dust) to have specific density similar to that found for the dust particles of comet Wild 2, ∼3400 kg m −3 (Kearsley et al 2009), we can constrain the initial ice abundances for the thermal evolution calculations (see Prialnik et al 2008). These values are taken as 0.05 and 0.5 (with corresponding initial porosities of 0.01 and 0.3) for Case I and Case II, respectively.…”

Section: Thermal Modelmentioning

confidence: 99%

P/2010 a2 Linear

Hainaut

Kleyna

Sarid

et al. 2012

A&A

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Comet P/2010 A2 LINEAR is an object on an asteroidal orbit within the inner main belt, therefore a good candidate for membership with the main belt comet family. It was observed with several telescopes (ESO New Technology Telescope, La Silla, Chile; Gemini North, Mauna Kea, Hawaii; University of Hawaii 2.2 m, Mauna Kea, Hawaii) from 14 Jan. until 19 Feb. 2010 in order to characterize and monitor it and its very unusual dust tail, which appears almost fully detached from the nucleus; the head of the tail includes two narrow arcs forming a cross. No evolution was observed during the span of the observations. Observations obtained during the Earth orbital plane crossing allowed an examination of the out-of-plane 3D structure of the tail. The immediate surroundings of the nucleus were found dust-free, which allowed an estimate of the nucleus radius of 80-90 m, assuming an albedo p = 0.11 and a phase correction with G = 0.15 (values typical for S-type asteroids). A model of the thermal evolution indicates that such a small nucleus could not maintain any ice content for more than a few million years on its current orbit, ruling out ice sublimation dust ejection mechanism. Rotational spin-up and electrostatic dust levitations were also rejected, leaving an impact with a smaller body as the favoured hypothesis. This is further supported by the analysis of the tail structure. Finston-Probstein dynamical dust modelling indicates the tail was produced by a single burst of dust emission. More advanced models (described in detail in a companion paper), independently indicate that this burst populated a hollow cone with a half-opening angle α ∼ 40 • and with an ejection velocity v max ∼ 0.2 m s −1 , where the small dust grains fill the observed tail, while the arcs are foreshortened sections of the burst cone. The dust grains in the tail are measured to have radii between a = 1-20 mm, with a differential size distribution proportional to a −3.44±0.08 . The dust contained in the tail is estimated to at least 8 × 10 8 kg, which would form a sphere of 40 m radius (with a density ρ = 3000 kg m −3 and an albedo p = 0.11 typical of S-type asteroids). Analysing these results in the framework of crater physics, we conclude that a gravity-controlled crater would have grown up to ∼100 m radius, i.e. comparable to the size of the body. The non-disruption of the body suggest this was an oblique impact.

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“…The two-stage light gas gun (LGG) is used to study impacts on materials commonly used on space vehicles [1][2][3] The Kent LGG shown in Fig. 1, fires small projectiles (micron to mm size) at speeds from 1 km/s to 8.4 km/s.…”

Section: Introductionmentioning

confidence: 99%

Fiber optic interrogation systems for hypervelocity and low velocity impact studies

Jackson

Cole

2011

Photonic Sens

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Abstract:The aim of this project was to develop non-contact fiber optic based displacement sensors to operate in the harsh environment of a "light gas gun" (LGG), which can "fire" small particles at velocities ranging from 1 km/s8.4 km/s. The LGG is used extensively for research in aerospace to analyze the effects of high speed impacts on materials. Ideally the measurement should be made close to the center of the impact to minimize corruption of the data from edge effects and survive the impact. We chose to develop a non-contact "pseudo" confocal intensity sensor, which demonstrated resolution comparable with conventional polyvinylidene fluoride (PVDF) sensors combined with high survivability and low cost. A second sensor was developed based on "fiber Bragg gratings" (FBG) to enable a more detailed analysis of the effects of the impact, although requiring contact with the target the low weight and very small contact area of the FBG had minimal effect on the dynamics of the target. The FBG was mounted either on the surface of the target or tangentially between a fixed location. The output signals from the FBG were interrogated in time by a new method. Measurements were made on carbon fiber composite plates in the LGG and on low velocity impact tests. The particle momentum for the low velocity impact tests was chosen to be similar to that of the particles used in the LGG.

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Interpretation of Wild 2 dust fine structure: Comparison of Stardust aluminum foil craters to the three‐dimensional shape of experimental impacts by artificial aggregate particles and meteorite powders

Cited by 32 publications

References 72 publications

Comet 81P/Wild 2: The size distribution of finer (sub‐10 μm) dust collected by the Stardust spacecraft

Comet 81P/Wild 2: The size distribution of finer (sub‐10 μm) dust collected by the Stardust spacecraft

P/2010 a2 Linear

Fiber optic interrogation systems for hypervelocity and low velocity impact studies

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