Comet 67p/Churyumov–gerasimenko: Close-Up on Dust Particle Fragments

Abstract

The COmetary Secondary Ion Mass Analyser instrument on board ESAʼs Rosetta mission has collected dust particles in the coma of comet 67P/Churyumov-Gerasimenko. During the early-orbit phase of the Rosetta mission, particles and particle agglomerates have been imaged and analyzed in the inner coma at distances between 100 km and 10 km off the cometary nucleus and at more than 3 AU from the Sun. We identified 585 particles of more than 14 μm in size. The particles are collected at low impact speeds and constitute a sample of the dust particles in the inner coma impacting and fragmenting on the targets. The sizes of the particles range from 14 μm up to submillimeter sizes and the differential dust flux size distribution is fitted with a power law exponent of −3.1. After impact, the larger particles tend to stick together, spread out or consist of single or a group of clumps, and the flocculent morphology of the fragmented particles is revealed. The elemental composition of the dust particles is heterogeneous and the particles could contain typical silicates like olivine and pyroxenes, as well as iron sulfides. The sodium to iron elemental ratio is enriched with regard to abundances in CI carbonaceous chondrites by a factor from ∼1.5 to ∼15. No clear evidence for organic matter has been identified. The composition and morphology of the collected dust particles appear to be similar to that of interplanetary dust particles.

Cometary dust: the diversity of primitive refractory grains

“…Na probably is not associated with a silicate component because Na is not co-located with Si [16]. Thus, the lack of Si rules out Kool particles as Rosetta ’s Na-rich material since Kool particles have olivine and pyroxene.…”

Dust evolution, a global view: III. Core/mantle grains, organic nano-globules, comets and surface chemistry

“…The Comet 67P refractory grains directly analysed with the COmetary Secondary Ion Mass Analyzer (COSIMA) dust particle instrument onboard Rosetta appear to be somewhat reminiscent of IDPs in that they contain olivine and pyroxene silicates, iron sulfides but no clear evidence for organic matter [146]. The latter result must be due to a limited sampling because we know from the Stardust results, from IDPs and other Rosetta instrument measurements that comets contain significant amounts of organic matter.…”

Prognostic Value of Cardiovascular Magnetic Resonance and Single-Photon Emission Computed Tomography in Suspected Coronary Heart Disease: Long-Term Follow-up of a Prospective, Diagnostic Accuracy Cohort Study

“…Study of the aerogel keystones has allowed a thorough 52 laboratory chemical and mineralogical characterisation of the particles (Frank, et al, 2014, 53 Stephan, et al, 2008). Rosetta currently analyses in situ the composition, morphology and 54 optical properties of particles released by comet 67P Churyumov-Gerasimenko 55 (Hilchenbach, et al, 2016). A caveat to these close-to-source studies is that a particular 56 comet is only a sample among a population of millions.…”