The dust coma of comet P/Halley: measurements on the Vega-1 and Vega-2 spacecraft

Simpson, J. A.; Rabinowitz, D.; Tuzzolino, A. J.; Ksanfomality, L. V.; Sagdeev, R. Z.

doi:10.1007/978-3-642-82971-0_128

Cited by 27 publications

(36 citation statements)

References 6 publications

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“…Closer in to the nucleus, but still at distances of 100,000 to 200,000 km, the DUCMA instrument on board both VEGA spacecraft detected non-Poissonian clustering of particles, described as 'dust packets' (Simpson et al, 1987). This was later confirmed by studying large-distance, low-mass particle detections of the SP-1 experiment (Simpson et al, 1989).…”

Section: Dynamics Of Particulates Within the Dust Comamentioning

confidence: 79%

Physical Properties of Cometary Dust

McDonnell

Lamy²,

Pankiewicz

1991

International Astronomical Union Colloquium

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ABSTRACT. Prior to the 1986 apparition of comet Halley, all attempts to determine the physical properties of cometary dust were limited to remote observations and the analysis of various particles captured by the Earth's atmosphere. The in situ measurements made by the three spacecraft that passed within 10,000 km of the nucleus provided the first opportunity to investigate both the full size-range of particles and the complete process of dust production. Information on composition is derived through mass spectra and the scattering and emission of light from the grains, whilst the dynamics of the dust coma can be modeled from the three separate sets of measurements made over a period of eight days.

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Section: Dynamics Of Particulates Within the Dust Comamentioning

confidence: 79%

Physical Properties of Cometary Dust

McDonnell

Lamy²,

Pankiewicz

1991

International Astronomical Union Colloquium

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“…Clusters of coma dust particles were observed in previous space missions to comets: in the coma of comet 1P/Halley (Simpson et al 1987), 81P/Wild , and 9P/Tempel (Economou et al 2013). Large variations in the dust flux of 67P are reported by GIADA, which detected several "dust showers", that is, from tens to hundreds of particles arriving in a few seconds Della Corte et al 2015).…”

Section: Discussionmentioning

confidence: 91%

Dust particle flux and size distribution in the coma of 67P/Churyumov-Gerasimenko measured in situ by the COSIMA instrument on board Rosetta

Merouane

Zaprudin

Stenzel

et al. 2016

A&A

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Context. The COmetary Secondary Ion Mass Analyzer (COSIMA) on board Rosetta is dedicated to the collection and compositional analysis of the dust particles in the coma of 67P/Churyumov-Gerasimenko (67P). Aims. Investigation of the physical properties of the dust particles collected along the comet trajectory around the Sun starting at a heliocentric distance of 3.5 AU. Methods. The flux, size distribution, and morphology of the dust particles collected in the vicinity of the nucleus of comet 67P were measured with a daily to weekly time resolution. Results. The particles collected by COSIMA can be classified according to their morphology into two main types: compact particles and porous aggregates. In low-resolution images, the porous material appears similar to the chondritic-porous interplanetary dust particles collected in Earth's stratosphere in terms of texture. We show that this porous material represents 75% in volume and 50% in number of the large dust particles collected by COSIMA. Compact particles have typical sizes from a few tens of microns to a few hundreds of microns, while porous aggregates can be as large as a millimeter. The particles are not collected as a continuous flow but appear in bursts. This could be due to limited time resolution and/or fragmentation either in the collection funnel or few meters away from the spacecraft. The average collection rate of dust particles as a function of nucleo-centric distance shows that, at high phase angle, the dust flux follows a 1/d 2 comet law, excluding fragmentation of the dust particles along their journey to the spacecraft. At low phase angle, the dust flux is much more dispersed compared to the 1/d 2 comet law but cannot be explained by fragmentation of the particles along their trajectory since their velocity, indirectly deduced from the COSIMA data, does not support such a phenomenon. The cumulative size distribution of particles larger than 150 µm follows a power law close to r −0.8±0.1 , confirming measurements made by another Rosetta dust instrument Grain Impact Analyser and Dust Accumulator (GIADA). The cumulative size distribution of particles between 30 µm and 150 µm has a power index of −1.9 ± 0.3. The excess of dust in the 10-100 µm range in comparison to the 100 µm-1 mm range together with no evidence for fragmentation in the inner coma, implies that these particles could have been released or fragmented at the nucleus right after lift-off of larger particles. Below 30 µm, particles exhibit a flat size distribution. We interprete this knee in the size distribution at small sizes as the consequence of strong binding forces between the sub-constitutents. For aggregates smaller than 30 µm, forces stronger than Van-der-Waals forces would be needed to break them apart.

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“…Showers of particles were observed during previous comet flybys ( Simpson et al 1987;Rabinowitz 1988;Green et al 2004), when the spacecraft speed was orders of magnitude larger than the dust speed. This makes the size of the dust clusters associated with these flyby showers orders of magnitude larger than those observed by GIADA.…”

Section: The Observationsmentioning

confidence: 96%

Density and Charge of Pristine Fluffy Particles From Comet 67p/Churyumov–gerasimenko

Fulle

Corte

Rotundi

et al. 2015

ApJ

140

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The Grain Impact Analyzer and Dust Accumulator (GIADA) instrument on board ESA's Rosetta mission is constraining the origin of the dust particles detected within the coma of comet 67 P/Churyumov-Gerasimenko (67P). The collected particles belong to two families: (i) compact particles (ranging in size from 0.03 to 1 mm), witnessing the presence of materials that underwent processing within the solar nebula and (ii) fluffy aggregates (ranging in size from 0.2 to 2.5 mm) of sub-micron grains that may be a record of a primitive component, probably linked to interstellar dust. The dynamics of the fluffy aggregates constrain their equivalent bulk density to <1 kg m −3 . These aggregates are charged, fragmented, and decelerated by the spacecraft negative potential and enter GIADA in showers of fragments at speeds <1 m s −1 . The density of such optically thick aggregates is consistent with the low bulk density of the nucleus. The mass contribution of the fluffy aggregates to the refractory component of the nucleus is negligible and their coma brightness contribution is less than 15%.

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The dust coma of comet P/Halley: measurements on the Vega-1 and Vega-2 spacecraft

Cited by 27 publications

References 6 publications

Physical Properties of Cometary Dust

Physical Properties of Cometary Dust

Dust particle flux and size distribution in the coma of 67P/Churyumov-Gerasimenko measured in situ by the COSIMA instrument on board Rosetta

Density and Charge of Pristine Fluffy Particles From Comet 67p/Churyumov–gerasimenko

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