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The DESTINY+(Demonstration and Experiment of Space Technology for INterplanetary voYage with Phaethon fLyby and dUst Science) Dust Analyser (DDA) is a state-of-the-art dust telescope for the in situ analysis of cosmic dust particles. As the primary scientific payload of the DESTINY+ mission, it serves the purpose of characterizing the dust environment within the Earth-Moon system, investigating interplanetary and interstellar dust populations at 1 AU from the Sun and studying the dust cloud enveloping the asteroid (3200) Phaethon. DDA features a two-axis pointing platform for increasing the accessible fraction of the sky. The instrument combines a trajectory sensor with an impact ionization time-of-flight mass spectrometer, enabling the correlation of dynamical, physical and compositional properties for individual dust grains. For each dust measurement, a set of nine signals provides the surface charge, particle size, velocity vector, as well as the atomic, molecular and isotopic composition of the dust grain. With its capabilities, DDA is a key asset in advancing our understanding of the cosmic dust populations present along the orbit of DESTINY+. In addition to providing the scientific context, we are presenting an overview of the instrument's design and functionality, showing first laboratory measurements and giving insights into the observation planning. This article is part of a theme issue 'Dust in the Solar System and beyond'.

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Early-generation in situ dust detectors in near-Earth space have reported the occurrence of clusters of sub-micron dust particles that seemed unrelated to human spaceflight activities. In particular, data from the impact ionization detector onboard the HEOS-2 satellite indicate that such swarms of particles occur throughout the Earth's magnetosphere up to altitudes of 60 000 km-far beyond regions typically used by spacecraft. Further account of high-altitude clusters has since been given by the GEO-deployed GORID detector, however, explanations for the latter have so far only been sought in GEO spaceflight activity. This perspective piece reviews dust cluster detections in near-Earth space, emphasizing the natural swarm creation mechanism conjectured to explain the HEOS-2 data-i.e. the electrostatic disruption of meteoroids. Highlighting this mechanism offers a novel viewpoint on more recent near-Earth dust measurements. We further show that the impact clusters observed by both HEOS-2 and GORID are correlated with increased geomagnetic activity. This consistent correlation supports the notion that both sets of observations stem from the same underlying phenomenon and aligns with the hypothesis of the electrostatic breakup origin. We conclude that the nature of these peculiar swarms remains highly uncertain, advocating for their concerted investigation by forthcoming dust science endeavours, such as the JAXA/DLR DESTINY+ mission. This article is part of the theme issue 'Dust in the Solar System and beyond'.

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Micrometeorites are estimated to represent the main part of the present flux of extraterrestrial matter found on the Earth's surface and provide valuable samples to probe the interplanetary medium. Here, we describe large and representative collections of micrometeorites currently available to the scientific community. These include Antarctic collections from surface ice and snow, as well as glacial sediments from the eroded top of nunataks-summits outcropping from the icesheet-and moraines. Collections extracted from deep-sea sediments (DSS) produced a large number of micrometeorites, in particular, iron-rich cosmic spherules that are rarer in other collections. Collections from the old and stable surface of the Atacama Desert show that finding large numbers of micrometeorites is not restricted to polar regions or DSS. The advent of rooftop collections marks an important step into involving citizen science in the study of micrometeorites, as well as providing potential sampling locations over all latitudes to explore the modern flux. We explore their strengths of the collections to address specific scientific questions and their potential weaknesses. The future of micrometeorite research will involve the finding of large fossil micrometeorite collections and benefit from recent advances in sampling cosmic dust directly from the air. This article is part of the theme issue 'Dust in the Solar System and beyond'.

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Phenanthrene is the simplest example of a polycyclic aromatic hydrocarbon (PAH). Herein, we exploit its relatively low melting point (101 °C) to prepare microparticles from molten phenanthrene droplets by conducting high-shear homogenization in a 3:1 water/ethylene glycol mixture at 105 °C using poly(N-vinylpyrrolidone) as a non-ionic polymeric emulsifier. Scanning electron microscopy studies confirm that this protocol produces polydisperse phenanthrene microparticles with a spherical morphology: laser diffraction studies indicate a volume-average diameter of 25 ± 21 µm. Such projectiles are fired into an aluminum foil target at 1.87 km s-1 using a two-stage light gas gun. Interestingly, the autofluorescence exhibited by phenanthrene aids analysis of the resulting impact craters. More specifically, it enables assessment of the spatial distribution of any surviving phenanthrene in the vicinity of each crater. Furthermore, these phenanthrene microparticles can be coated with an ultrathin overlayer of polypyrrole, which reduces their autofluorescence. In principle, such core-shell microparticles should be useful for assessing the extent of thermal ablation that is likely to occur when they are fired into aerogel targets. Accordingly, polypyrrole-coated microparticles were fired into an aerogel target at 2.07 km s-1. Intact microparticles were identified at the end of carrot tracks and their relatively weak autofluorescence suggests that thermal ablation during aerogel capture did not completely remove the polypyrrole overlayer. Thus, these new core-shell microparticles appear to be useful model projectiles for assessing the extent of thermal processing that can occur in such experiments, which have implications for the capture of intact PAH-based dust grains originating from cometary tails or from plumes emanating from icy satellites (e.g., Enceladus) in future space missions.

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Molecular clouds (MCs) in space are the birthplace of various molecular species. Chemical reactions occurring on the cryogenic surfaces of cosmic icy dust grains have been considered to play important roles in the formation of these species. Radical reactions are crucial because they often have low barriers and thus proceed even at low temperatures such as ∼10 K. Since the 2000s, laboratory experiments conducted under low-temperature, high-vacuum conditions that mimic MC environments have revealed the elementary physicochemical processes on icy dust grains. In this review, experiments conducted by our group in this context are explored, with a focus on radical reactions on the surface of icy dust analogues, leading to the formation of astronomically abundant molecules such as H2, H2O, H2CO, and CH3OH and deuterium fractionation processes. The development of highly sensitive, non-destructive methods for detecting adsorbates and their utilization for clarifying the behavior of free radicals on ice, which contribute to the formation of complex organic molecules, are also described.

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INTRODUCTION: Recent observations indicate that the Universe is not transparent but partially opaque due to absorption of light by ambient cosmic dust. This implies that the current cosmological model valid for the transparent universe must be modified for the opaque universe. OBJECTIVES: The paper studies a scenario of the evolution of the Universe when the cosmic opacity steeply rises with redshift, because the volume of the Universe was smaller and the cosmic dust density was higher in the previous epochs. In this case, the light-matter interactions become important, because cosmic opacity produces radiation pressure that counterbalances gravitational forces. METHODS: The radiation pressure due to cosmic opacity is evaluated and incorporated into the Friedmann equations, which describe cosmic dynamics. The equations are based on the conformal FLRW metric and are consistent with observations of the cosmological redshift as well as time dilation. Using astronomical observations of basic cosmological parameters, the solution of the modified Friedmann equations is numerically modelled. RESULTS: The presented model predicts a cyclic expansion/contraction evolution of the Universe within a limited range of scale factors with no Big Bang. The redshift of the Universe with the minimum volume is about 15-17. The model avoids dark energy and removes several fundamental tensions of the standard cosmological model. In agreement with observations, the modified Friedmann equations predict the existence of very old mature galaxies at high redshifts and they do not limit the age of stars in the Universe. The new model is consistent with theory of cosmic microwave background as thermal radiation of cosmic dust. CONCLUSION: The paper demonstrates that considering light-matter interactions in cosmic dynamics is crucial and can lead to new cosmological models essentially different from the currently accepted ΛCDM model.

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Interstellar dust particles were discovered in situ, in the solar system, with the Ulysses mission's dust detector in 1992. Ever since, more interstellar dust particles have been measured inside the solar system by various missions, providing insight into not only the composition of such far-away visitors, but also in their dynamics and interaction with the heliosphere. The dynamics of interstellar (and interplanetary) dust in the solar/stellar systems depend on the dust properties and also on the space environment, in particular on the heliospheric/astrospheric plasma, and the embedded time-variable magnetic fields, via Lorentz forces. Also, solar radiation pressure filters out dust particles depending on their composition. Charge exchanges between the dust and the ambient plasma occur, and pick-up ions can be created. The role of the dust for the physics of the heliosphere and astrospheres is fairly unexplored, but an important and a rapidly growing topic of investigation. This review paper gives an overview of dust processes in heliospheric and astrospheric environments, with its resulting dynamics and consequences. It discusses theoretical modeling, and reviews in situ measurements and remote sensing of dust in and near our heliosphere and astrospheres, with the latter being a newly emerging field of science. Finally, it summarizes the open questions in the field.

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Silicon is present in interstellar dust grains, meteorites and asteroids, and to date thirteen silicon-bearing molecules have been detected in the gas-phase towards late-type stars or molecular clouds, including silane and silane derivatives. In this work, we have experimentally studied the interaction between atomic silicon and hydrogen under physical conditions mimicking those at the atmosphere of evolved stars. We have found that the chemistry of Si, H and H2 efficiently produces silane (SiH4), disilane (Si2H6) and amorphous hydrogenated silicon (a-Si:H) grains. Silane has been definitely detected towards the carbon-rich star IRC+10216, while disilane has not been detected in space yet. Thus, based on our results, we propose that gas-phase reactions of atomic Si with H and H2 are a plausible source of silane in C-rich AGBs, although its contribution to the total SiH4 abundance may be low in comparison with the suggested formation route by catalytic reactions on the surface of dust grains. In addition, the produced a-Si:H dust analogs decompose into SiH4 and Si2H6 at temperatures above 500 K, suggesting an additional mechanism of formation of these species in envelopes around evolved stars. We have also found that the exposure of these dust analogs to water vapor leads to the incorporation of oxygen into Si-O-Si and Si-OH groups at the expense of SiH moieties, which implies that, if this type of grains are present in the interstellar medium, they will be probably processed into silicates through the interaction with water ices covering the surface of dust grains.

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Polyaromatic hydrocarbons (PAHs) are found throughout the universe. The ubiquity of these organic molecules means that they are of considerable interest in the context of cosmic dust, which typically travels at hypervelocities (>1 km s-1) within our solar system. However, studying such fast-moving micrometer-sized particles in laboratory-based experiments requires suitable synthetic mimics. Herein, we use ball-milling to produce microparticles of anthracene, which is the simplest member of the PAH family. Size control can be achieved by varying the milling time in the presence of a suitable anionic commercial polymeric dispersant (Morwet D-425). These anthracene microparticles are then coated with a thin overlayer of polypyrrole (PPy), which is an air-stable organic conducting polymer. The uncoated and PPy-coated anthracene microparticles are characterized in terms of their particle size, surface morphology, and chemical structure using optical microscopy, scanning electron microscopy, laser diffraction, aqueous electrophoresis, FT-IR spectroscopy, Raman microscopy, and X-ray photoelectron spectroscopy (XPS). Moreover, such microparticles can be accelerated up to hypervelocities using a light gas gun. Finally, studies of impact craters indicate carbon debris, so they are expected to serve as the first synthetic mimic for PAH-based cosmic dust.

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The solar system formed from interstellar dust and gas in a molecular cloud. Astronomical observations show that typical interstellar dust consists of amorphous (a-) silicate and organic carbon. Bona fide physical samples for laboratory studies would yield unprecedented insight about solar system formation, but they were largely destroyed. The most likely repositories of surviving presolar dust are the least altered extraterrestrial materials, interplanetary dust particles (IDPs) with probable cometary origins. Cometary IDPs contain abundant submicron a-silicate grains called GEMS (glass with embedded metal and sulfides), believed to be carbon-free. Some have detectable isotopically anomalous a-silicate components from other stars, proving they are preserved dust inherited from the interstellar medium. However, it is debated whether the majority of GEMS predate the solar system or formed in the solar nebula by condensation of high-temperature (>1,300 K) gas. Here, we map IDP compositions with single nanometer-scale resolution and find that GEMS contain organic carbon. Mapping reveals two generations of grain aggregation, the key process in growth from dust grains to planetesimals, mediated by carbon. GEMS grains, some with a-silicate subgrains mantled by organic carbon, comprise the earliest generation of aggregates. These aggregates (and other grains) are encapsulated in lower-density organic carbon matrix, indicating a second generation of aggregation. Since this organic carbon thermally decomposes above ∼450 K, GEMS cannot have accreted in the hot solar nebula, and formed, instead, in the cold presolar molecular cloud and/or outer protoplanetary disk. We suggest that GEMS are consistent with surviving interstellar dust, condensed in situ, and cycled through multiple molecular clouds.

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Recent measurements by the Imaging Ultraviolet Spectrograph (IUVS) instrument on NASA's Mars Atmosphere and Volatile EvolutioN mission show that a persistent layer of Mg+ ions occurs around 90 km in the Martian atmosphere but that neutral Mg atoms are not detectable. These observations can be satisfactorily modeled with a global meteoric ablation rate of 0.06 t sol-1, out of a cosmic dust input of 2.7 ± 1.6 t sol-1. The absence of detectable Mg at 90 km requires that at least 50% of the ablating Mg atoms ionize through hyperthermal collisions with CO2 molecules. Dissociative recombination of MgO+.(CO2)n cluster ions with electrons to produce MgCO3 directly, rather than MgO, also avoids a buildup of Mg to detectable levels. The meteoric injection rate of Mg, Fe, and other metals-constrained by the IUVS measurements-enables the production rate of metal carbonate molecules (principally MgCO3 and FeCO3) to be determined. These molecules have very large electric dipole moments (11.6 and 9.2 Debye, respectively) and thus form clusters with up to six H2O molecules at temperatures below 150 K. These clusters should then coagulate efficiently, building up metal carbonate-rich ice particles which can act as nucleating particles for the formation of CO2-ice clouds. Observable mesospheric clouds are predicted to occur between 65 and 80 km at temperatures below 95 K and above 85 km at temperatures about 5 K colder.

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This review presents our understanding of cometary dust at the end of 2017. For decades, insight about the dust ejected by nuclei of comets had stemmed from remote observations from Earth or Earth's orbit, and from flybys, including the samples of dust returned to Earth for laboratory studies by the Stardust return capsule. The long-duration Rosetta mission has recently provided a huge and unique amount of data, obtained using numerous instruments, including innovative dust instruments, over a wide range of distances from the Sun and from the nucleus. The diverse approaches available to study dust in comets, together with the related theoretical and experimental studies, provide evidence of the composition and physical properties of dust particles, e.g., the presence of a large fraction of carbon in macromolecules, and of aggregates on a wide range of scales. The results have opened vivid discussions on the variety of dust-release processes and on the diversity of dust properties in comets, as well as on the formation of cometary dust, and on its presence in the near-Earth interplanetary medium. These discussions stress the significance of future explorations as a way to decipher the formation and evolution of our Solar System.

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There are four known sources of dust in the inner solar system: Jupiter Family comets, asteroids, Halley Type comets, and Oort Cloud comets. Here we combine the mass, velocity, and radiant distributions of these cosmic dust populations from an astronomical model with a chemical ablation model to estimate the injection rates of Na and Fe into the Earth's upper atmosphere, as well as the flux of cosmic spherules to the surface. Comparing these parameters to lidar observations of the vertical Na and Fe fluxes above 87.5 km, and the measured cosmic spherule accretion rate at South Pole, shows that Jupiter Family Comets contribute (80 ± 17)% of the total input mass (43 ± 14 t d-1), in good accord with Cosmic Background Explorer and Planck observations of the zodiacal cloud.

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Organics are observed to be a significant component of cosmic dust in nearly all environments were dust is observed. In many cases only remote telescope observations of these materials are obtainable and our knowledge of the nature of these materials is very basic. However, it is possible to obtain actual samples of extraterrestrial dust in the Earth's stratosphere, in Antarctic ice and snow, in near-Earth orbit, and via spacecraft missions to asteroids and comets. It is clear that cosmic dust contains a diverse population of organic materials that owe their origins to a variety of chemical processes occurring in many different environments. The presence of isotopic enrichments of D and 15N suggests that many of these organic materials have an interstellar/protosolar heritage. The study of these samples is of considerable importance since they are the best preserved materials of the early Solar System available.

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The size and velocity distribution of cosmic dust particles entering the Earth's atmosphere is uncertain. Here we show that the relative concentrations of metal atoms in the upper mesosphere, and the surface accretion rate of cosmic spherules, provide sensitive probes of this distribution. Three cosmic dust models are selected as case studies: two are astronomical models, the first constrained by infrared observations of the Zodiacal Dust Cloud and the second by radar observations of meteor head echoes; the third model is based on measurements made with a spaceborne dust detector. For each model, a Monte Carlo sampling method combined with a chemical ablation model is used to predict the ablation rates of Na, K, Fe, Mg, and Ca above 60 km and cosmic spherule production rate. It appears that a significant fraction of the cosmic dust consists of small (<5 µg) and slow (<15 km s-1) particles.

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The solar wind (SW), composed of predominantly ∼1-keV H(+) ions, produces amorphous rims up to ∼150 nm thick on the surfaces of minerals exposed in space. Silicates with amorphous rims are observed on interplanetary dust particles and on lunar and asteroid soil regolith grains. Implanted H(+) may react with oxygen in the minerals to form trace amounts of hydroxyl (-OH) and/or water (H2O). Previous studies have detected hydroxyl in lunar soils, but its chemical state, physical location in the soils, and source(s) are debated. If -OH or H2O is generated in rims on silicate grains, there are important implications for the origins of water in the solar system and other astrophysical environments. By exploiting the high spatial resolution of transmission electron microscopy and valence electron energy-loss spectroscopy, we detect water sealed in vesicles within amorphous rims produced by SW irradiation of silicate mineral grains on the exterior surfaces of interplanetary dust particles. Our findings establish that water is a byproduct of SW space weathering. We conclude, on the basis of the pervasiveness of the SW and silicate materials, that the production of radiolytic SW water on airless bodies is a ubiquitous process throughout the solar system.