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Beginning some 30,000 years ago, nine of our Paleolithic ancestors painted their unique hands on the walls of Altamira Cave in Cantabria, Spain – an act of communication by the community, for the community. We present a proof-of-concept for the Altamira Comet, a 21st century work that expresses the evolution of this gesture in our digital age: we all go. The Altamira Comet invites everyone on Earth to participate, individually and uniquely, through our contemporary society's iconic representation of identity: the selfie. Everyone's selfies will be cast as microscopic low relief golden busts, frozen into a ball of ice, and deployed into heliocentric orbit as a sublimating comet, embodying millions of individual humans from around the world. The proof-of-concept is a vial of five million discrete selfie sculptures in solution, using computer vision, electron-beam lithography and high-vacuum deposition to fabricate each selfie the size of a grain of cosmic dust. We also discuss plans to deploy the comet using an off-the-shelf CubeSat deployer and to scale the work to support a goal of at least one billion global participants. • Space art in the form of a comet. • Global art that invites everyone on Earth to participate. • Inspired by prehistoric hand art on the walls of Altamira Cave. • Multidisciplinary art combining computer vision, e-beam lithography, comets and CubeSats. [ABSTRACT FROM AUTHOR]

[Display omitted] • An alternative scenario of the evolution of the Universe is proposed. • The absorption of light by cosmic dust causes opacity that counterbalances gravitational forces. • The theory predicts cyclic model of the expansion and contraction of the Universe. • The maximum redshift of the Universe is about 15–17. • The proposed model removes some tensions of the standard cosmological model. 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. 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. 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. 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. 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. [ABSTRACT FROM AUTHOR]

Cosmic dust transports information about the composition and evolution of distant realms over space and time. Dust sources may be in our local neighbourhood, such as the surfaces of moons and small bodies, or further away, in the galactic environment. The interior of moons like Io or Enceladus are well known dust sources in our solar system. Dust grains are therefore like probes, giving us the opportunity to investigate these objects at a distance. Thus, a new field of activity has been born: Dust Astronomy. The ultimate tool for Dust Astronomy is a dust observatory which was never been flown so far. Until today, all our knowledge is based on smaller individual dust detectors flown on various interplanetary spacecraft. Recently, a new generation of dust telescopes, which can be combined to a full dust observatory, became available. The scientific goal of such an observatory is to characterise our micrometeoroid environment with high precision and sensitivity and to record an inventory of various dust populations from asteroidal, cometary and interstellar dust sources. Two competitive studies on a Dust Astronomy mission were performed as part of a master's course, including mission analysis and spacecraft design. The goal was to demonstrate the feasibility of an observatory reaching the main asteroid belt with a minimum spacecraft mass using electric propulsion. Additional secondary payloads supporting the primary objective were selected as well. The results prove that small probes with less than 700 kg mass are capable of placing an array of dust telescopes deep in the asteroid belt, leading to a huge leap in Dust Astronomy and our knowledge about the local dust environment. • First presentation of feasibility studies for a dust observatory between Earth and asteroid belt. • A dust observatory is a tool for dust astronomy and studies interplanetary and interstellar dust fluxes in our solar system. • The observatories reach the asteroid belt within 7 years using electric propulsion. • Two full mission studies were performed by a small satellite project. [ABSTRACT FROM AUTHOR]

A coordinated TEM and NanoSIMS isotopic imaging study of microtome sections of three anhydrous interplanetary dust particles (IDPs) revealed a diverse collection of primitive materials having disparate origins and histories. Presolar silicate grains that likely originated in asymptotic giant branch (AGB) stars were present in each IDP at abundances ranging from 140 (+320/-120) ppm to 2000 (+4600/-1700) ppm. A unique compound presolar grain was identified that consisted of a crystalline spinel core and amorphous silicate mantle having heterogeneous Fe content. This compound grain traces the changing conditions in the circumstellar region during condensation and is the first identified presolar spinel in an IDP. A presolar SiC grain, also rare in IDPs, was found to be enriched in 13C, 14N, and 28Si, consistent with mainstream SiC that originated in ∼ solar metallicity AGB stars. We determine presolar spinel and presolar SiC abundances of 760 (+1700/-630) ppm and 190 (+440/-160) ppm, respectively, in the individual IDPs. Two elongate whisker-like enstatite grains and one platy enstatite were found to have near-terrestrial O isotopic compositions (δ18O = -17 – 18 ‰) and show chemical evidence of equilibrium condensation from a high temperature gas. Two highly 16O-rich silicates with near-solar O isotopic compositions (δ18O = -79 ‰ and -83 ‰) were also identified and may represent the primordial dust reservoir. These silicates were crystalline equilibrated aggregates. The wide range of isotopic compositions observed in these silicate grains suggests they condensed from isotopically diverse reservoirs in the protoplanetary disk in different locations and/or times. The 16O-rich grains likely condensed in the inner solar system and were subsequently transported to the outer solar system, while grains having terrestrial O isotopic compositions likely condensed from the gas phase in the terrestrial planet forming region or beyond. The IDPs showed bulk 15N enrichments (δ15N = 15 – 129 ‰) and contained 15N-rich hotspots up to 1150 ‰, consistent with the presence of molecular cloud material. IDPs U2015D21 and W7013E17 had bulk O isotopic compositions that were offset from the carbonaceous chondrite anhydrous minerals line by ∼ 10 ‰ to more 17O-rich compositions. This 17O enrichment cannot be explained by the observed abundance of 17O-rich presolar grains in these particles and the source remains unknown. IDP W7027E6 had an unusual isotopically heavy bulk O isotopic composition (δ17,18O = 40 ‰, Δ17O = 19 ‰). W7027E6 lacked hydrous phases and was therefore not likely altered by isotopically heavy primordial water. We propose that the high temperature mineral assemblage in W7027E6 condensed in the inner solar system from an 16O-poor reservoir that existed prior to O isotope homogenization in the early nebula and was subsequently transported to the outer solar system. [ABSTRACT FROM AUTHOR]

• Oxygen isotope ratios represent a robust tool for the identification of precursor signatures in Cr-spinel, with a ratio of 1 carbonaceous chondritic particles out of 10 micrometeorites. • The first Cr-Spinel bearing Antarctic micrometeorite related to R chondrites is identified. • Cr-spinel grains may undergo chemical modification at various stages during their evolution. • Cr-spinel minerals recovered from sediments represent a valid proxy to trace events related to ordinary chondrite-like materials, but cannot be used as sole indicator to estimate the composition of the general extraterrestrial flux. Each year, approximately 5000 tons of extraterrestrial material reaches the Earth's surface as micrometeorites, cosmic dust particles ranging from 10 to 2000 μm in size. These micrometeorites, collected from diverse environments, mainly deep-sea sediments, Antarctic ice, snow and loose sediments, and hot deserts, are crucial in understanding our Solar System's evolution. Chrome-rich spinel (Cr-spinel) minerals have gained attention as proxies for studying the extraterrestrial flux in sedimentary deposits, because these robust minerals occur, in various extraterrestrial materials, with compositions characteristic of their parent bodies. A total of 27 Cr-spinel bearing micrometeorites within the size range of 185–800 μm, were identified from approximately 6000 micrometeorites from the Transantarctic Mountains (n = 23) and the Sør Rondane Mountains (n = 4), in Antarctica, containing Cr-spinel (8–120 μm), were examined in this study for geochemical composition and high-precision oxygen isotope ratios to assess alteration and identify potential parent bodies. Oxygen isotopes in the micrometeorite groundmass and in Cr-spinel grains reveal a predominance of ordinary chondritic precursors, with only 1 in 10 micrometeorites containing Cr-spinel minerals showing a carbonaceous chondritic signature. This may be further confirmed by an elevated Al content (> 12 wt% Al 2 O 3) in Cr-spinel from specific carbonaceous chondrite types, but a more extensive dataset is required to establish definitive criteria. The first Cr-spinel bearing particle, in an Antarctic micrometeorite, that can be linked to R-chondrites based on oxygen isotopes, has been documented, demonstrating the potential for R-chondrites as a source of chrome-rich spinels. The study also highlights the potential for chemical modifications and alteration processes that Cr-spinel minerals may undergo during their time on the parent body, atmospheric entry, and terrestrial residence. In the context of the broader micrometeorite flux, the results align with previous findings, showing a consistent contribution of micrometeorites containing Cr-spinel minerals related to ordinary chondrites over the past 2 to 4 million years. This is however a small fraction (∼ 1 %) of the total micrometeorite flux. The study further confirms that Cr-spinel minerals recovered from sedimentary deposits serve as valuable proxies for tracking events related to ordinary chondritic or achondritic materials. However, it is emphasized that Cr-spinel minerals alone cannot serve as exclusive indicators of the overall extraterrestrial flux, especially during periods dominated by carbonaceous chondritic dust in the inner Solar System. To comprehensively understand the complete extraterrestrial flux, additional proxies are needed to trace dust-producing events associated with various Solar System objects. The intricate nature of Cr-spinel compositions, and the potential for alteration processes emphasize the need for further research to refine our understanding of these extraterrestrial markers. [ABSTRACT FROM AUTHOR]

• Hypervelocity impact flash is reported on thin Kapton films at speeds up to 5 km s −1. • The flashes from two layers of film provide a time of flight and hence projectile speed. • The accuracy of the speed is good to 1%. The impact flash from hypervelocity impact on thin (12.5 µm) Kapton film was observed. The projectile sizes ranged from 0.1 to 1 mm, with speeds from 2 to 5 km s−1 and penetrated the Kapton intact, leaving holes the same size as the projectile (to within measurement errors). The flash intensity (normalised to impactor mass) scaled with impact speed to the power 5.5. However, the data also suggest that at constant speed the intensity scales with the area of the hole in the Kapton and not the projectile mass (i.e. with some property of the target and not as a function of the projectile energy or momentum). Using two layers of Kapton, it was possible to construct a Time of Flight (TOF) system, which used the time of the onset of the flash in each layer to produce flight speeds accurate to within typically 1%. When compared to the projectile speed pre-impact, there was no indication of projectile deceleration during passage through the Kapton film. In addition, when PVDF acoustic sensors were placed on the Kapton film, they exhibited an electromagnetic "pick-up" signal from the impact of projectile on the Kapton, confirming suspicions of signal interference from past work with acoustic sensors. The ability of the light flash to provide accurate impact timing signals suggests the TOF system would be suitable for use as a cosmic dust or debris impact detector in space (e.g. Low Earth Orbit). [ABSTRACT FROM AUTHOR]

As part of the space experiment "Test", a roll of cotton cloth fixed on the outer surface of the International Space Station for more than 10 years was delivered to the Earth in September 2019. The elemental composition of two fragments of the cloth, contaminated and clean, was determined using instrumental neutron activation analysis at the IBR-2 reactor. Along with 19 elements (Mg, Al, Cl, Ca, Ti, Cr, Mn, Fe, Co, Ni, Zn, Rb, Sr, Ag, Sb, Ba, Sm) determined on both fragments of the cloth, additional 20 elements (Na, Si, Sc, Cu, As, Se, Br, Mo, Zr, Cd, I, La, Ce, Eu, Ta, W, Re, Ir, Th, and U) were determined only on the contaminated fragment. The morphology of the rolled cotton cloth was characterized using Scanning Electron Microscopy. Gama and liquid beta spectroscopy were applied to measure the radioactivity of the cloth fragments. Possible sources of the determined chemical elements deposited on the cloth were discussed. • The content of 39 elements was determined in cotton cloth fixed on the outer surface of the International Space Station. • Cosmic dust and micrometeorites can be considered primarily sources of element deposition on the cloth. • The unidentified beta-active nuclides with maximum emission energy of no more than 60 keV were identified. [ABSTRACT FROM AUTHOR]

• A model dust detector payload is described for deployment near the Moon. • An ideal lunar platform would be the proposed Lunar Gateway. • The payload has active and passive components. • It would measure dust identifying the cometary, asteroidal and interstellar fluxes. The decade of the 2020s promises to be when humanity returns to space beyond Earth orbit, with several nations trying to place astronauts on the Moon, before going further into deep space. As part of such a programme, NASA and partner organisations, propose to build a Deep Space Gateway in lunar orbit by the mid-2020s. This would be visited regularly and offer a platform for science as well as for human activity. Payloads that can be mounted externally on the Gateway offer the chance to, amongst other scientific goals, monitor and observe the dust flux in the vicinity of the Moon. This paper looks at relevant technologies to measure dust which will impact the exposed surface at high speed. Flux estimates and a model payload of detectors are described. It is predicted that the flux is sufficient to permit studies of cometary vs. asteroidal dust and their composition, and to sample interstellar dust streams. This may also be the last opportunity to measure the natural dust flux near the Moon before the current, relatively pristine environment, is contaminated by debris, as humanity's interest in the Moon generates increased activity in that vicinity in coming decades. [ABSTRACT FROM AUTHOR]

Detection of areas of increased density of cosmic dust in near-Earth space is important from both theoretical and practical points of view. To continue our explication of the phenomenon of appearance-disappearance of the Kodylewski dust clouds, we consider dynamics of charged dust particles in the small vicinity of Lagrange libration point. The masses of particles are comparable to the masses of protons and electrons. These particles induce a self-consistent electric as well as a self-consistent gravitational fields. As a result, we obtain an existence of periodically changing stable configuration of an ensemble of the charged particles. It should be taken into account when planning space missions. [ABSTRACT FROM AUTHOR]

Recent observations using the Wind and Ulysses spacecrafts and the Solar Occultation For Ice Experiment (SOFIE) during the period between 2007 and 2020 indicate a total cosmic dust influx at Earth ranging from 22 to 32 tonnes per day. Much is still unclear about the formation, evolution, and propagation of this cosmic dust throughout our Solar System, as well as the transport and chemical interaction of such particles within our own atmosphere. Studying meteoroids, which are particles small and fast enough to ablate in the Earth's upper atmosphere producing meteor plasma detectable by meteor radars, offers an opportunity to better understand these processes. While meteor radars provide a powerful tool to detect meteoroids, they are limited to detecting particles that produce a sufficient amount of plasma within the instrument's field-of-view, and thus most of their trajectory remains undetected. In this work, we report a novel methodology, using new polarization measurements as well as two state-of-the art models, to determine the pre-atmosphere dynamical characteristics of the detected particles, before they suffer any significant ablation or deceleration. We present the results for 20 meteor detection case studies, and find that for the majority of particles, at least 80% (typically 95%) of the particle mass has already been lost at the time of detection. In addition, while all particles experienced deceleration by the time of detection, this was typically small (≤ 4% of their initial velocity). Future work will implement this new methodology to automatically determine the initial mass and velocities of individual meteors. This will help provide more precise meteor orbits and characterization of parent source populations, as well as the identification of potential interstellar particles. • Meteoroids offer tool to better understand processes within Earth's upper atmosphere. • Meteor radars provide powerful detection tool but have detection limits. • Much of particle's trajectory remains undetected — initial mass and velocity unknown. • Methodology utilizes new polarization measurements and two state-of-the-art models. • Determines pre-atmosphere dynamical parameters prior to significant ablation. [ABSTRACT FROM AUTHOR]

"You realise that the Earth is nothing but accumulated cosmic dust having formed a rock that is encompassed by a flimsy, fragile atmosphere. To grasp this, I needed the view out of the window." German ESA Astronaut Alexander Gerst's perspective on Earth was changed sustainably by the view from the International Space Station (ISS) onto our home planet. It is possible to give pupils a very similar perspective within the means of public education due to the availability of Earth Observation data from the ISS. However, the data can be put to more educational use than providing a taste of the overview effect. Applying common remote sensing methods and modern teaching concepts to EO (Earth Observation) data from the National Aeronautics and Space Administration (NASA) High Definition Earth Viewing experiment, teaching modules for several STEM (Science, Technology, Engineering, and Mathematics) subjects could be implemented successfully. Building on this success, more ISS EO sensors are being implemented in teaching materials and new media techniques are explored. The more recent addition to the material pool are smartphone apps using Augmented Reality (AR) with which the pupils can experiment on their own. These apps are developed in a partial What You See Is What You Get (WYSIWYG) application development system called Unity with the Vuforia extension, the latter allowing the use of printed images as reference markers for AR. Complex theoretical topics can be visualised in 3-dimensional (3D) animations or turned into inexpensive, easy digital experiments. The app "The Earth-Moon System" applies this with experiments on the effects of changes in the distance between Earth and Moon and a 3D animation on the barycentre between two celestial bodies. Development of such apps is feasible for researchers to visualise their data even with no prior app development knowledge. • AR apps for smartphones are suitable for digital education in STEM subjects. • An AR app was created to teach about gravitational effects and Kepler laws. • Digital experiments include a tide simulation, Moon position, distortion, and shadow. • The app balances limited smartphone computing resources and scientific accuracy. • Preliminary tests show interest and understanding in previously indifferent pupils. [ABSTRACT FROM AUTHOR]

The JAXA/ISAS spacecraft DESTINY+ will be launched to the active asteroid (3200) Phaethon in 2022. Among the proposed core payload is the DESTINY+ Dust Analyzer (DDA) which is an upgrade of the Cosmic Dust Analyzer flown on the Cassini spacecraft to Saturn (Srama et al., 2011). We use two up-to-date computer models, the ESA Interplanetary Meteoroid Engineering Model (IMEM, Dikarev et al., 2005a, c), and the interstellar dust module of the Interplanetary Meteoroid environment for EXploration model (IMEX;Sterken et al. 2013; Strub et al., 2019) to study the detection conditions and fluences of interplanetary and interstellar dust with DDA. Our results show that a statistically significant number of interplanetary and interstellar dust particles will be detectable with DDA during the 4-years interplanetary cruise of DESTINY+. The particle impact direction and speed can be used to descriminate between interstellar and interplanetary particles and likely also to distinguish between cometary and asteroidal particles. [ABSTRACT FROM AUTHOR]

Abstract Silicate minerals such as "Mg-Fe-Si-O" compounds, are found in asteroids, planets, and cosmic dust grains in the interstellar medium. As the silicate dust grains traverse regions of space, they are irradiated by energetic ions, such as alpha particles, which can modify the crystalline phase of the mineral dust. Silicate dust grain analogues were synthesized using multiple low energy (<60 keV) ion (Fe−, Mg−, O−) implantations into a silicon wafer. The low energy ion beam as-implanted samples were cut into several smaller sections. Some of these low-energy as-implanted samples were further irradiated with a 600 keV helium ion beam at varying current densities (ions/unit area/unit time) and subsequent furnace annealed at 1000 °C temperature in Ar gas environment. The crystalline phases of the post annealed samples were monitored and reported as a function of current densities using x-ray diffraction (XRD). The XRD results showed an increase in the crystalline phases of olivine by the high-energy helium ion irradiation processing with a beam of current density of 500 nA/cm2. This work is relevant for space weathering processes as well as solid material evolution in astrophysical environments, especially asymptotic giant branch stars with an oxygen rich outflow. [ABSTRACT FROM AUTHOR]

Abstract The Beagle family is a C-type subgroup of the Themis family, in the outer main belt. Previous works suggested that it could be younger than 20 Myr and a possible source for the dust in the i ≃ 1.4 ∘ α zodiacal dust band. Here we took advantage of a much larger database for Beagle family members to revisit previous age estimates of this group. Standard dating techniques based on the family V-shape or on Monte Carlo methods of Yarkovsky and YORP mobility suggest that i) there might be a dichotomy for the inner and outer part of the Beagle family, which may be either two separate families or the product of an anisotropic ejection velocity field and that ii) the age of the possibly younger outer part of the Beagle family should be 35 − 35 + 65 Myr. The past convergence of Beagle longitude of the node is compatible with a family age of ≃ 14 Myr, when (1678) Glarona is used as a reference orbit. Without further information on Beagle members spin states, however, only very lower limits on the family age can be currently obtained when the Yarkovksy force is accounted for. Highlights • The Beagle family is a sub-family of the larger Themis asteroid group. • It is a possible source for the dust in the i ∼ 1.4° α zodiacal dust band. • Here we obtained improved age estimates of this group. • There might be a dichotomy for the inner and outer part of the Beagle family. • The past convergence of Beagle longitude of the node suggests an age of ∼14 Myr. [ABSTRACT FROM AUTHOR]

Abstract This study explores the petrology of five giant (>400 μm) hydrated fine-grained micrometeorites from the Transantarctic Mountain (TAM) micrometeorite collection. For the first time, the extent and mechanisms of aqueous alteration in unmelted cosmic dust are evaluated and quantified. We use a range of criteria, previously defined for use on hydrated chondrites, including phyllosilicate fraction, matrix geochemistry and micro textures. Collectively, these micrometeorites represent ∼2.22 mm2 of intensely altered hydrated chondritic matrix (with petrologic subtypes of <1.2 in the scheme of Howard et al. (2015)) and reveal a range of alteration styles. Two particles are found to contain pseudomorphic chondrules with thick fine-grained rims, while another micrometeorite contains several aqueously altered CAIs. Their outlines range from well-defined to indistinct, demonstrating that the advanced stages of aqueous alteration progressively remove evidence of coarse-grained components. The remaining two micrometeorites entirely lack coarse-grained components but are similarly altered. Thus, the combined chondrule-to-matrix ratio among these giant micrometeorites is extremely low (6.45 area%), and significantly below the average ratio found in typical CM or CR chondrites (∼20%, Weisberg et al., 2006). Our findings are consistent with previous analyses from smaller Antarctic micrometeorites, which suggest that chondrules (and CAIs) derived from hydrated carbonaceous chondrite parent bodies are underrepresented among the micrometeorite flux, even when considering contributions from coarse-grained micrometeorites. Therefore, to explain the relative paucity of anhydrous material, we propose that the flux of fine-grained micrometeorites is primarily derived from intensely aqueously altered, primitive C-type asteroids, which have lost the majority of their refractory coarse-grained components by replacement with secondary phyllosilicate minerals. [ABSTRACT FROM AUTHOR]

Abstract The Dust Coordinate Sensor (DCS) is a dual detector instrument located on the beamline of the 3 MV hypervelocity dust accelerator at the University of Colorado Institute for Modeling Plasma, Atmospheres and Cosmic Dust (IMPACT). This instrument non-destructively measures the three-dimensional trajectories of charged, hypervelocity (3–8 km/s), micron-sized dust particles in flight by utilizing the image charge induced on grids of wire electrodes. Where previous peak detection was typically limited to dust particles carrying charges > ∼ 100 fC, new signal processing techniques developed for DCS allow for effective trajectory measurements on particles carrying charges as small as 6 fC. The new signal processing also effectively eliminates false signal detections completely. The position measurements are matched by timestamp to the charge and velocity for each launched dust particle. Verification of the system was performed with independent impact location measurements on a target placed in the beamline. These measurements agree to within 1 mm2 of the predicted locations using DCS trajectories. This study demonstrates the capability of the instrument including new processing methods. Precise trajectory measurement along the beamline enables new options for instrument calibration, scientific experiments, and improvement of the accelerator performance. [ABSTRACT FROM AUTHOR]

Abstract Three body dynamics problems in the system of Earth-Moon are crucial for Space navigation safety. The existence of the stable periodic solutions, capturing the Lagrange libration points of the Earth-Moon system, under gravitational perturbation of the Sun is under investigation taking into account the light pressure of the Sun. A family of periodical orbits, which rises from the periodic solutions, is obtained. The probability of formation of cosmic dust clouds in these zones is estimated. Highlights • Stable periodic orbits of dust particles in the Earth-Moon-Sun system are obtained. • Light pressure influence on the particles of different sizes is studied. • Probability of dust clouds formation is investigated by means of Liouville equation. [ABSTRACT FROM AUTHOR]

Impact ionisation mass spectrometry enables the composition of cosmic dust grains to be determined in situ by spacecraft-based instrumentation. The proportion of molecular ions in the impact plasma is a function of the impact velocity, making laboratory calibration vital for the interpretation of the mass spectra, particularly at the low velocities typical of lunar or asteroid encounters. Here we present an analysis of laboratory impact ionisation mass spectra from primarily low (<15 km s −1 ) velocity impacts of both olivine and magnesite-dominated particles onto the SUrface Dust Mass Analyzer (SUDA) laboratory mass spectrometer. The cation mass spectra show characteristic peaks due to their constituent elements, with Mg, Al, Si, C, Ca, O and Fe frequently present. Contaminant species from the conductive coating process (B, Na, K, C, Pt) also occur, at varying frequencies. Possible saponite or talc inclusions in the magnesite particles are revealed by the presence of Si, Fe, Ca and Al in the magnesite mass spectra. Magnesium is clearly present at the lowest impact velocities (3 km s −1 ), at which alkali metals were presumed to dominate. Peaks attributed to very minor amounts of water or hydroxyl present in the grains are also seen at low velocities in both cation and anion mass spectra, demonstrating the feasibility of impact ionisation mass spectrometry in identifying hydrated or hydrous minerals, during very low velocity encounters or with very low abundances of water or hydroxy groups, in the impinging grains. Velocity thresholds for the reliable identification of the major elements within the magnesite and olivine cation spectra are presented. Additionally, relative sensitivity factors for Mg (5.1), Fe (1.5) and O (0.6) with respect to Si, in the olivine particles, at impact speeds >19 km s −1 , were found to be very similar to those previously determined for orthopyroxene-dominated particles, despite different target and projectile materials. This confirms that quantitative analyses of mineral dust grain composition in space is viable despite initially poorly-constrained mineralogy. [ABSTRACT FROM AUTHOR]

Gas to Dust Ratio (GDR) indicates the mass ratio of interstellar gas to dust. It is widely adopted that the GDR in our Galaxy is 100∼150. We choose three typical star forming regions to study the GDR: the Orion molecular cloud — a massive star forming region, the Taurus molecular cloud — a low-mass star forming region, and the Polaris molecular cloud — a region with no or very few star formation activities. The mass of gas only takes account of the neutral gas, i.e. only the atomic and molecular hydrogen, because the amount of ionized gas is very small in a molecular cloud. The column density of atomic hydrogen is taken from the high-resolution and high-sensitivity all-sky survey EBHIS (Effelsberg-Bonn HI Survey). The CO J = 1 →0 line is used to trace the molecular hydrogen, since the spectral lines of molecular hydrogen which can be detected are rare. The intensity of CO J = 1 →0 line is taken from the Planck all-sky survey. The mass of dust is traced by the interstellar extinction based on the 2MASS (Two Micron All Sky Survey) photometric database in the direction of anti-Galactic center. Adopting a constant conversion coefficient from the integrated intensity of the CO line to the column density of molecular hydrogen, X CO = 2.0 × 10 20 cm −2 · (K · km/s) −1 , the gas to dust ratio N (H)/ A V is calculated, which is 25, 38, and 55 (in units of 10 20 cm −2 · mag −1 ) for the Orion, Taurus, and Polaris molecular clouds, respectively. These values are significantly higher than the previously obtained average value of the Galaxy. Adopting the WD01 interstellar dust model (when the V-band selective extinction ratio is R V = 3.1), the derived GDRs are 160, 243, and 354 for the Orion, Taurus, and Polaris molecular clouds, respectively, which are apparently higher than 100∼150, the commonly accepted GDR of the diffuse interstellar medium. The high N (H)/ A V values in the star forming regions may be explained by the growth of dust in the molecular clouds because of either the particle collision or accretion, which can lead to the reduction of extinction efficiency per unit mass in the V band, rather than the increase of the GDR itself. [ABSTRACT FROM AUTHOR]

Nearby galaxies are particularly relevant laboratories to study dust evolution due to the diversity of physical conditions they harbor and to the wealth of data at our disposal. In this paper, we review several recent advances in this field, mainly based on Herschel observations. We first discuss the problems linked with our ignorance of grain emissivities, and show that it can be constrained in some cases. New models are starting to incorporate these constraints. We then present methodological issues encountered when fitting spectral energy distributions, leading to biases in derived dust properties, and some attempts to solve them. Subsequently, we review studies scrutinizing dust evolution: (i) from a global point of view, inferring long term cosmic dust evolution; (ii) from a local point of view, looking for indices of dust processing in the ISM. [ABSTRACT FROM AUTHOR]

We report the discovery of fossil micrometeorites from Late Cretaceous chalk. Seventy-six cosmic spherules were recovered from Coniacian ( 87 ± 1 Ma ) sediments of the White Chalk Supergroup. Particles vary from pristine silicate and iron-type spherules to pseudomorphic spherules consisting of either single-phase recrystallized magnetite or Fe-silicide. Pristine spherules are readily identified as micrometeorites on the basis of their characteristic mineralogies, textures and compositions. Both magnetite and silicide spherules contain dendritic crystals and spherical morphologies, testifying to rapid crystallisation of high temperature iron-rich metallic and oxide liquids. These particles also contain spherical cavities, representing weathering and removal of metal beads and irregular cavities, representing vesicles formed by trapped gas during crystallization; both features commonly found among modern Antarctic Iron-type (I-type) cosmic spherules. On the basis of textural analysis, the magnetite and Fe-silicide spherules are shown to be I-type cosmic spherules that have experienced complete secondary replacement during diagenesis (fossilization). Our results demonstrate that micrometeorites, preserved in sedimentary rocks, are affected by a suite of complex diagenetic processes, which can result in disparate replacement minerals, even within the same sequence of sedimentary beds. As a result, the identification of fossil micrometeorites requires careful observation of particle textures and comparisons with modern Antarctic collections. Replaced micrometeorites imply that geochemical signatures the extraterrestrial dust are subject to diagenetic remobilisation that limits their stratigraphic resolution. However, this study demonstrates that fossil, pseudomorphic micrometeorites can be recognised and are likely common within the geological record. [ABSTRACT FROM AUTHOR]

The mesospheric metal layers are formed by the vaporization of high-speed cosmic dust particles as they enter the Earth's upper atmosphere. We show that the downward fluxes of these metal atoms, induced locally by waves and turbulence, are related in a straightforward way to the meteoric influxes of the metals, their chemical losses and their advective transport by the large-scale vertical and horizontal motions associated with the meridional circulation system. Above the peak of the metal layers where chemical losses and large-scale vertical motions are small, the wave-induced flux is insensitive to changes in local wave activity. If the downward transport velocity increases, because wave activity increases, then in response, the metal densities will decrease to maintain a constant vertical flux. By fitting the theoretical Na flux profile to the annual mean vertical flux profile measured during the night at the Starfire Optical Range, NM, we derive improved estimates for the global influxes of both Na and cosmic dust. The mean Na influx is 22,500±1050 atoms/cm 2 /s, which equals 389±18 kg/d for the global input of Na vapor. If the Na composition of the dust particles is identical to CI chondritic meteorites (4990 ppm by mass), then the global influx of cosmic dust is 176±38 t/d. If the composition is identical to ordinary chondrites (7680 ppm), the global dust influx is 107±22 t/d. [ABSTRACT FROM AUTHOR]

Analogues have been developed and characterised for both interplanetary dust and meteoric smoke particles. These include amorphous materials with elemental compositions similar to the olivine mineral solid solution series, a variety of iron oxides, undifferentiated meteorites (chondrites) and minerals which can be considered good terrestrial proxies to some phases present in meteorites. The products have been subjected to a suite of analytical techniques to demonstrate their suitability as analogues for the target materials. [ABSTRACT FROM AUTHOR]

Europa is one of the icy moons of Jupiter and the possibility of an ocean of liquid water beneath its icy crust makes it one of the most fascinating destinations for exploration in the solar system. NASA's Europa Multiple Flyby Mission (EMFM, formerly Europa Clipper) is slated to visit the icy moon in a timeframe near the year 2022 to study the habitability of Europa. CubeSats carried along by the primary mission can supplement the measurements made, at a relatively low cost, and with the added benefits of involving students at universities in this challenging endeavor. Further, such a mission holds the key to extending the applicability of CubeSats to interplanetary missions. In this paper, we present the design of the Europa Radiation and Dust Observation Satellite (ERDOS), a 3U CubeSat designed to be deployed by the Europa Multiple Flyby Mission to carry out measurements of the radiation and dust environment, before impacting Europa's surface. We present a detailed design for a CubeSat-based secondary mission, and discuss the science goals that may be accomplished by such a mission. Further, we discuss results from a comprehensive analysis of various engineering challenges associated with an interplanetary CubeSat mission, such as radiation shielding and thermal environment control. Our results show that a short duration CubeSat-based flyby mission is feasible when the CubeSat is carried on board the primary mission until the Jovian system is reached. Such a flyby mission can provide important supplementary information to the primary mission about Europa's environment at a closer range and lead to a substantial increase in scientific knowledge about surface processes on Europa. [ABSTRACT FROM AUTHOR]

The classical theory of grain nucleation suffers from both theoretical and predictive deficiencies. We strive to alleviate these deficiencies in our understanding of dust formation and growth by utilizing an atomistic model of nucleation. Carbon cluster geometries are determined with a set of global minimization algorithms. Using density functional theory, the binding energies of carbon clusters from n =2 to n =99 are then calculated. These energies are used to calculate the critical size and nucleation rate of carbon clusters. We find that the critical cluster size is largely determined by the changes in geometry of the clusters. Clusters with size n =27 and n =8, roughly corresponding to the transition from ring-to-fullerene geometry and chain-to-ring geometry respectively, are the critical sizes across the range of temperature and saturation where nucleation is significant. In contrast to the classical theory, nucleation is enhanced at low-temperatures, and suppressed at high temperatures. These results will be applied to a modified chemical evolution code using results from supernova simulations. [ABSTRACT FROM AUTHOR]

Impact ionization of high-velocity cosmic dust particles has been used as a basic principle for dust detectors in space for many decades. It has provided optimum means to gain insight into the dust environment in the solar system. The Ulysses Dust Detector System provided for the first time impact ionization-based detection of interstellar dust (ISD) in the solar system and discovered surprisingly heavy ISD particles with sizes up to a few microns. Studies based on astronomical observations of the local interstellar medium, on the other hand, suggested a much smaller upper limit of around 0.25 ​μm (silica) or 1 ​μm (graphite) for the size distribution of ISD particles. Therefore, it has been suggested that low-density fluffy dust particles may mimic the impact signals of heavier compact particles. In this work, we discuss a series of impact experiments that have been performed at the Heidelberg dust accelerator facility with the Cosmic Dust Analyzer flight spare unit, to compare the high-velocity impact ionization properties of compact and hollow silicate particles, and carbon aerogel particles with each other and with literature data. The experiments indicate differences in the collected total amount of impact charges and how quickly the charges are collected, between impacts from compact particles and their non-compact counterparts. The results of this first study suggest that fluffy particles generate less ions upon impact than their compact counterparts, opposite to the suggested explanation for the heavy ISD particles. Data from the performed impact experiments indicate that a secondary process (e.g. secondary impacts from ejecta or more target material ionization) could be the main cause for the observed differences. These results imply that the previously detected heavy ISD particles may be real. We identify the key problems with the performed dust experiments and advise that future impact ionization instruments should additionally be calibrated with improved low-density fluffy dust particles that better represent the properties of cosmic dust particles. • Shows new results for impact ionization experiments with non-compact dust particles. • Secondary ionization processes may depend on particle structure and density. • Impact ejecta and target ionization are candidates for relevant secondary processes. • Large and porous in situ interstellar dust particles might likely be real. [ABSTRACT FROM AUTHOR]

Among the many “ocean worlds” of our solar system, Enceladus appears unique in its combination of astrobiologically relevant and exploration-worthy attributes: extensive liquid-water ocean with active hydrothermal activity, containing salts and organics expressed predictably into space. The Enceladus south polar plume allows direct access to telltale molecules, ions, isotopes, and potential cytofragments in space. Plume mass spectroscopy and sample return, in situ investigation of surface fallback deposits, direct vent exploration, and eventually oceanographic exploration can all be envisioned. However, building consensus to fund such ambitious exploration hinges on acquiring key new data. A roadmap is essential. It could start with cost-capped onramps such as flythrough analysis of the plume, following up on Cassini measurements with modern instruments; and sample return of plume material for analysis on Earth. A methodical mission sequence in which each step depends on emergent results from prior missions would push in situ oceanographic exploration into the second half of this century. Even for this scenario, prioritization by the next planetary Decadal Survey would be pivotal. [ABSTRACT FROM AUTHOR]

In this work we evaluate a new model on the possibility, could microscopic liquid water supported grain movement on Mars happen at the circumpolar region (in Richardson crater) today, combined with the analysis of new HiRISE ESP images. We confirmed earlier (PSP images based) findings on the morphology, sequential growth and two separate phased formation method of flow features emanate from Dark Dune Spots (1: gas-jet driven streaks toward different directions, 2: flow-like streaks downward). We also identified that the gas-jet ejected and back fallen grains surrounded by water ice produce local enrichment of H 2 O, forming local water ice layer. Several model scenarios were developed and evaluated to exploit the possibilities of liquid supported flow, including the increased thickness of interfacial liquid layer by salts and impurities, the collapse and movement of loose stratum of air-fallen dust–salt mixture with interbedded liquid layers, the mechanical force to kick-off the movement by hydration/dehydration cycles, and the migrating phase change plus the seeping of thin liquid film around interconnected grains. Selecting the most relevant elements among them, which are also compatible to our current knowledge of Mars, a comprehensive model was built that could be tested. This best model contains four interconnected and subsequent elements: 1. deposition of airfall dust in autumn and winter producing a loose surface layer, 2. spatial concentration of H 2 O ice by gas-jet activity during the CO 2 sublimation phase, 3. mechanical kick-off by daily expansion/contraction cycles to mix the components, 4. engulfed hygroscopic salts and dust grains to enlarge the ratio of liquid to support the flow. The emerged self-amplifying process could produce daily movement in theory. The scenario contains realistic elements; it is in agreement with the observations, and also being testable by laboratory modelling. The analyzed locations are important because of the joint occurrence of concentrated water ice, elevated temperature and moving flow-features; and it also provides insight into the possible current action of liquid water on Mars. [ABSTRACT FROM AUTHOR]

This work is intended to answer the question, whether on comet 67P/Churyumov–Gerasimenko pristine, not hardened material can be locally preserved close to the surface. Simulated is the thermally driven sintering of ice-dust grains underlying the dust mantle. Considered is the Ma׳at region located at the north side of the small lobe Head. It is shown that locally thermal conditions can allow preservation of a not thermally hardened ice-dust material. [ABSTRACT FROM AUTHOR]

Photometric observations of asteroid (596) Scheila were obtained during and after its 2010 outburst. The estimated radius of the body (spherical approximation of the asteroidal body) was 51.2±3.0 km and 50.6±3.0 km for different methods. The ejected dust mass from the asteroid ranged from 2.5 × 10 7 to 3.4 × 10 7 kg for different methods. An impact mechanism for triggering Scheila׳s activity is discussed. A few days before the impact, Scheila passed through the corridors of two potential cometary streams. [ABSTRACT FROM AUTHOR]

Polarimetric observations of comets have provided crucial insight into the composition and evolution of cometary dust particles. Herein, we present a brief overview of the polarization properties observed in comets, and some possible interpretations. We also discuss recent imaging polarimetry observations of C/2012 S1 (ISON) and 67P/Churyumov–Gerasimenko using the Hubble Space Telescope . The observations of 67P/Churyumov–Gerasimenko are of particular interest, as they were timed to be contemporary with the initial rendezvous of Rosetta and the subsequent landing of the probe Philae. We also outline some unanswered questions and future developments that will greatly enhance our ability to further leverage the power of polarimetry for cometary research. [ABSTRACT FROM AUTHOR]

It is important to monitor the extra-terrestrial dust flux in the Earth׳s environment and into the atmosphere. Meteoroids threaten the infrastructure in space as hypervelocity hits by micron-sized granules continuously degrade the solar panels and other satellite surfaces. Through their orbital elements meteoroids can be associated to the interplanetary dust cloud, comets, asteroids or the interstellar space. The ablation products of meteoroids participate in many physical and chemical processes at different layers in the atmosphere, many of them occurring in the polar regions. High-power large-aperture (HPLA) radars, such as the tristatic EISCAT UHF together with the EISCAT VHF, have been versatile instruments for studying many properties of the meteoroid population, even though they were not initially designed for this purpose. The future EISCAT_3D will comprise a phased-array transmitter and several phased-array receivers distributed in northern Scandinavia. These will work at 233 MHz centre frequency with power up to 10 MW and run advanced signal processing systems. The facility will in many aspects be superior to its predecessors as the first radar to combine volumetric-, aperture synthesis- and multistatic imaging as well as adaptive experiments. The technical design goals of the radar respond to the scientific requests from the user community. The VHF frequency and the volumetric imaging capacity will increase the collecting volume compared to the earlier UHF, the high transmitter power will increase the sensitivity of the radar, and the interferometry will improve the spatial resolution of the orbit estimates. The facility will be able to observe and define orbits to about 10% of the meteors from the established mass flux distribution that are large or fast enough to produce an ionization mantle around the impacting meteoroid within the collecting volume. The estimated annual mean of about 190 000 orbits per day with EISCAT_3D gives many orders of magnitude higher detected orbit rates than the earlier tristatic UHF radar. [ABSTRACT FROM AUTHOR]

A smart dust is a micro spacecraft, with a characteristic side length on the order of a few millimeters, whose surface is coated with electrochromic material. Its orbital dynamics is controlled by exploiting the differential force due to the solar radiation pressure, which is obtained by modulating the reflectivity coefficient of the electrochromic material within a range of admissible values. A significant thrust level can be reached due to the high values of area-to-mass ratio of such a spacecraft configuration. Assuming that the smart dust is designed to achieve a passive Sun-pointing attitude, the propulsive acceleration due to the solar radiation pressure lies along the Sun-spacecraft direction. The aim of this paper is to study the smart dust heliocentric dynamics in order to find a closed form, analytical solution of its trajectory when the reflectivity coefficient of the electrochromic material can assume two values only. The problem is addressed by introducing a suitable transformation that regularizes the spacecraft motion and translates the smart-dust dynamics into that of a linear harmonic oscillator with unitary frequency, whose forcing input is a boxcar function. The solution is found using the Laplace transform method, and afterwards the problem is generalized by accounting for the degradation of the electrochromic material due to its exposition to the solar radiation. Three spacecraft configurations, corresponding to low, medium and high performance smart dusts, are finally used to quantify the potentialities of these advanced devices in an interplanetary mission scenario. [ABSTRACT FROM AUTHOR]

This paper presents evidence of the first detection of interstellar dust in ice age polar ice. Neutron activation analysis (NAA) results are reported for 15 elements found in dust filtered from eight samples of Camp Century Greenland ice dating from 40 to 78 kyrs BP. High concentrations of Sn, Sb, Au, Ag, Ir, and Ni were found to be present in three out of these eight samples. One compositionally anomalous dust sample from an ice core depth of 1230.5 m (age ∼49 kyrs BP, near the beginning of D/O stadial No. 13) was found to contain tin with an average weight percent of 49% as determined by energy dispersive X-ray analysis (EDS). This sample was also found to contain high concentrations of Pb with an average weight abundance of 8.4% and matching the Sn:Pb ratio observed in interstellar spectra. Dust particles in this sample generally have a platy morphology and range from submicron size up to a size as large as 120 μm, a particle consisting almost entirely of SnO 2 and being the largest monomineralic extraterrestrial dust particle so far discovered. One porous aggregate tin-bearing particle was found to contain nanometer sized chondrules indicating an extraterrestrial origin. The extraterrestrial origin for the tin is also indicated by the presence of isotopic anomalies in the 114 Sn, 115 Sn and 117 Sn isotopes. Follow up isotopic measurements of this tin-rich dust need to be performed to improve confidence in the anomalies reported here. High abundances of the low melting point elements Ag, Au, and Sb are also present in this tin-rich sample along with elevated abundances of the siderophiles Ir, Ni, Fe, and Co, the latter being present in chondritic proportions and indicating that about 9% of the dust has a C1 chondrite component. Measurements indicate that about 97% of this dust is of extraterrestrial origin with a 3% residual being composed of terrestrial windblown dust. EDS analysis of another tin-rich Camp Century ice core dust sample dating to ∼130 kyrs BP was found to contain tin-rich particles with a similar platy morphology and to have Sn and Pb weight abundances averaging 39% and 7.5% respectively, again approximating the interstellar Sn:Pb ratio. The relative absence of cosmic microspheres and the unmelted appearance of the tin-rich particles in both of these samples suggests that these particles entered the Earth’s atmosphere at low velocity, implicating a gradual accumulation of dust from a dispersed state in the near Earth space environment. The unusual enhancement of Sn and Pb could be explained if these dust particles were originally present in the solar system’s interstellar environment in a superconducting native metal state and were preferentially concentrated through Meissner effect forces by the passage of cosmic ray driven hydromagnetic shocks which may also have transported them into the solar system. The 49 kyrs BP event is estimated to have lasted over 6 years and to have deposited dust onto the Earth at a rate 10 4 –10 5 times higher than present rates. This had a significant cooling effect on climate and resulted in a transient 33 fold increase in snow accumulation. Future discovery of these events in ice cores at other locations should void any lingering thoughts that this heavy metal enhancement may be due to sample contamination. [ABSTRACT FROM AUTHOR]

We report our systematic study on dust emission in massive star-forming regions indicative of large-scale cloud–cloud collisions, using the AKARI infrared (IR) all-sky survey data at wavelengths of 9, 18, 65, 90, 140, and 160 μ m . We focus on the Galactic bubbles catalogued by Spitzer, which are categorized into two types of morphology, closed and broken bubbles. A broken bubble has a possibility of being created by a cloud–cloud collision, judging from its morphological similarity to the structure theoretically predicted as a product of the collision. Therefore we search for systematic differences in IR properties between the two types. We performed aperture photometry for 111 Spitzer bubbles and created the spectral energy distribution (SED) of each bubble. We decomposed the SED into polycyclic aromatic hydrocarbon (PAH), warm and cold dust components by model fitting, and calculated their luminosities, L PAH , L warm and L cold respectively, by integrating each SED component as a function of the wavelength. We then investigated the total IR luminosity ( L TIR = L PAH + L warm + L cold ), the ratio of L PAH to L TIR and the ratio of L warm to L TIR as a function of the bubble radius. As a result, we find systematic differences between the closed and broken bubbles for the former two relations. We discuss the implications of the differences for the scenario of the large-scale cloud–cloud collisions. [ABSTRACT FROM AUTHOR]

The telltale mirror, a smooth inclined surface raised over 1 m above the deck of the Phoenix Mars Lander, was observed by the Surface Stereo Imager (SSI) several times per sol during the Phoenix Mars Lander mission. These observations were combined with a radiative transfer model to determine the thickness of dust on the wind telltale mirror as a function of time. 239 telltale sequences were analyzed and dustiness was determined on a diurnal and seasonal basis. The thickness of accumulated dust did not follow any particular diurnal or seasonal trend. The dust thickness on the mirror over the mission was 0.82±0.39 µm, which suggests a similar thickness to the modal scattering particle diameter. This suggests that inclining a surface beyond the angle of repose and polishing it to remove surface imperfections is an effective way to mitigate the accumulation of dust to less than a micron over a wide range of meteorological conditions and could be beneficial for surfaces which can tolerate some dust but not thick accumulations, such as solar panels. However, such a surface will not remain completely dust free through this action alone and mechanical or electrical clearing must be employed to remove adhered dust if a pristine surface is required. The single-scattering phase function of the dust on the mirror was consistent with the single-scattering phase function of martian aerosol dust at 450 nm, suggesting that this result is inconsistent with models of the atmosphere which require vertically or horizontally separated components or broad size distributions to explain the scattering behavior of these aerosols in the blue. The single-scattering behavior of the dust on the mirror is also consistent with Hapke modeling of spherical particles. The presence of a monolayer of particles would tend to support the spherical conclusion: such particles would be most strongly adhered electrostatically. [ABSTRACT FROM AUTHOR]

An ejecta curtain is produced as a result of impact cratering of celestial bodies that excavates and ejects their surface and underground material. Since ejecta particles are thought to reflect the interior materials and structures of celestial bodies, ejecta and ejecta curtains provide us with valuable information about the interior of the bodies. Following the Deep Impact mission, more and more in situ data on ejecta curtains are expected to become available in future space missions. To draw valuable information from such in situ measurements, a radiative-transfer model of the ejecta curtain plays an important role. This urges us to carefully assess the model parameters with experimental results as well as understand the contribution of each model parameter to the predicted intensities of the radiative calculations. In this work, we study the dependences of the projected intensity images of the ejecta on the scattering phase function and the geometry of an ejecta curtain produced by impact on an airless-body's surface, as a first step toward a correct interpretation of ejecta observations. Using the Monte-Carlo multiple scattering method, we have calculated the scattered intensities for three different orientations of the ejecta curtain. We have also computed the intensities for ejecta material using different phase functions. We find that the scattered intensities are highest for the isotropic phase function irrespective of the orientation of the ejecta cone for the scattering angles and geometry considered here. Observations from the other side could lead to higher intensities for forward scattering grains that are typical for asteroids. Therefore in situ observations of ejecta-curtains at different angles will enable us to use our model predictions to extract the phase functions as well as column densities of its component dust grains. [ABSTRACT FROM AUTHOR]

We performed near-infrared line mapping of the supernova remnant IC 443 with the IRSF 1.4-m telescope, using the narrow-band filters tuned for [Fe II] 1.257 μm, [Fe II] 1.644 μm, and Pa β . We detected the [Fe II] and Pa β emissions from a very wide area of the observed region ( 30 ′ × 35 ′ ). These line intensity maps reveal a global correlation between [Fe II] and Pa β . Kokusho et al. (2013) found that the [Fe II] emission is notably strong while dust emission is faint in inner regions of IC 443. These results indicate that the abundant Fe + is likely to be of interstellar origins through shock destruction of dust, rather than of ejecta origins. From the X-ray intensity map of the 6.7 keV Fe-K line obtained with Suzaku, we find that highly ionized He-like Fe ions exist in the inner regions of IC 443, toward which Fe + is detected. The presence of the He-like Fe ions and the faint dust emission indicates that Fe is likely to be interacting with X-ray plasma for a time long enough to be highly ionized. We discuss the implications of the detection of the lowly ionized Fe ions in such regions for the processing and composition of dust in the interstellar environment around IC 443. [ABSTRACT FROM AUTHOR]

Cosmic dust is a polydisperse mixture of irregular, often aggregated, particles. Previous attempts have tried to simulate polarimetric properties of this dust using aggregate dust models, but it has not been possible to consider particle sizes larger than a couple of microns due to limitations of computer memory and processing power. Attempts have also been made to replace aggregates by polydisperse regular particles (spheres, spheroids, cylinders), but those models could not consistently reproduce the observed photopolarimetric characteristics. In this study, we introduce to the astronomical community the software package developed by Dubovik et al. (2006) for modeling light scattering by a polydisperse mixture of randomly oriented smooth and rough spheroids of a variety of aspect ratios. The roughness of spheroids is defined by a normal distribution of the surface slopes, and its degree depends on the standard deviation of the distribution (which is zero for smooth surface and greater than zero for rough surface). The pre-calculated kernels in the software package allow for fast, accurate, and flexible modeling of different size and shape distributions. We present our results of a systematic investigation of polarization obtained with the rough and smooth spheroid models; we study differences in their phase angle dependence and how those differences change with the particle size distribution. We found that the difference between smooth and rough particles increases with increasing effective size parameter and affects mainly the value and position of the maximum polarization. Negative polarization was found to be typical only for silicate-like refractive indexes and only when the particles have size parameters within 2.5–25. As an example of an application of the rough spheroid model, we made computations for rough spheroids that have a size distribution and composition typical for cometary dust. We found that a mixture of porous rough spheroids made of absorbing material compositionally similar to comet Halley’s dust and solid silicate spheroids, dominated by particles of size parameter 5< x <20, can reproduce angular and spectral characteristics of the brightness and polarization observed for cometary dust. [ABSTRACT FROM AUTHOR]

Dust processing in the Carina nebula is investigated based on mid- to far-infrared spectroscopy with Infrared Space Observatory ( ISO ). Mapping observations over a central 40 ′ × 20 ′ area of the nebula with PHT-S, SWS, and LWS onboard ISO not only reveal spectroscopically that the mid-infrared unidentified infrared (UIR) bands at 6.2, 7.7, 8.6, and 11.3 μm are absent in the ionized region, but also indicate that the 11.3 μm may behave differently from the other three UIR bands near the edge of the ionized region, suggesting a variation either in the size distribution or in the ionization fraction of the band carriers. The correlation of [NII]122 μm and [SiII]35 μm line emissions observed with SWS and LWS is reinvestigated based on the recent atomic data as well as the latest cosmic abundance, suggesting that a large fraction ( > 70 %), if not all, of silicon returns to the gas phase in the Carina nebula, suggesting that silicates cannot survive under harsh conditions, such as massive star-forming regions. The present observations clearly show dust processing taking place in active regions in the Galaxy. [ABSTRACT FROM AUTHOR]

In these proceedings I briefly summarize our current understanding of the dusty torus of the AGN unified model: its structure, composition, and ideas about its origin and evolution. The paper is based on an invited review talk at the 7th Meeting on Cosmic Dust, which covered dust-related topics in areas from comets to debris disks and high-redshift galaxies. This is therefore intended to be an accessible, introductory overview of the torus with some emphasis on the solid-state spectral features observed. [ABSTRACT FROM AUTHOR]

A wealth of near infrared spectroscopic data for a large number of galactic objects was recorded with AKARI during its active lifetime. The hydrocarbon emission features around 3.3 – 3.5 m are modelled here as a series of 6 Voigt profiles arising due to hydrogen atoms found in different molecular structures within the emitting spectroscopic carriers. This model is compared and contrasted with a model consisting of 3 Gaussian profiles and found to produce a superior fit to AKARI data. Analysis of the 6 Voigt model shows that the 3.3 m aromatic hydrocarbon band is well described by two components at 3.28 m and 3.30 m . We confirm that the 3.28 μ m band is due to emission from aromatic molecules, and find a good correlation between the 3.28 μ m and 3.41 m bands, assigned to bay-hydrogen sites and linking methylene groups respectively. Results are discussed in terms of molecular processing and dust formation. [ABSTRACT FROM AUTHOR]

The spectral changes of hydrogenated amorphous carbon (HAC) could show variable distributions of solid carbon abundance in the interstellar medium (ISM). The variable optical properties of HAC analogs, produced by the laser ablation in a high vacuum, depends on the variation in its atomic and electronic structures. The fraction of hydrogen atoms in HAC increases proportionally with the laser’s power. The available solid carbon tied up in the interstellar HAC, being the carrier of the interstellar 3.4 μ m and 4.6 μ m −1 bands, is indicated by the strength of these bands. Comparing the strength of these bands with those of laboratory data indicates that the amount of carbon in HAC analogs is not inherently sufficient. The lack in the solid carbon (locked solid carbon) in these analogs can be analytically estimated to facilitate the simulation of cosmic carbon dust. The results show a reduction in the locked solid carbon when the fraction of hydrogen atoms in HAC analogs increases. When this fraction becomes approximately 0.52 relative to the total number of hydrogen and carbon atoms, there is no lack of carbon in HAC analogs. The interstellar distribution of variable solid carbon abundance is attributed to the modification of cosmic HAC, which occurs as a result of the variation in its hydrogen atom fraction and the UV processing taking place in the interstellar environments. This distribution reveals more solid carbon abundances reside in the dust phase and may assist in resolving the carbon crisis. [ABSTRACT FROM AUTHOR]

We present the impact rates of dust particles recorded by the Cosmic Dust Analyzer (CDA) aboard the Cassini spacecraft. The “dust counters” evaluate the quality of an impact and give rise to the apparent density of dust particles in space. The raw data is pre-selected and refined to a new structure that serves to a better investigation of densities, flows, and properties of interplanetary dust grains. Our data is corrected for the dead time of the instrument and corresponds to an assumed Kepler orbit (pointing of the sensitive area). The processed data are published on the website for the Magnetosphere and Plasma Science (MAPSview), where it can be correlated with other Cassini instruments. A sample is presented for the Titan flyby on DOY 250/2006. We find that the dust density peaks at two times, at least, in a void region between Titan and Rhea. Such features may point to extended clouds of small particles drifting slowly in space. These density clouds seem to be stable for as long as several months or few years before dispersing. [ABSTRACT FROM AUTHOR]

Repeated double cross validation (rdCV) has recently been suggested as a careful and conservative strategy for optimizing and evaluating empirical multivariate calibration models. This evaluation strategy is adapted in this work for k -nearest neighbor (KNN) classification. The basics of rdCV are described, including the search for an optimum k , and tests with Italian Olive Oil Data. KNN-rdCV is applied to classify 17 mineral groups, relevant for the composition of comet dust particles, characterized by the peak heights at 20 selected masses in time-of-flight secondary ion mass spectra (TOF-SIMS). Predictive abilities for 15 mineral classes are > 95%, for two classes 75 and 85%. [ABSTRACT FROM AUTHOR]

SSETO is the result of a phase-A study in context of the small satellite program of the University of Stuttgart that demonstrates the capability of a university institute to build a small satellite with a budget of 5 million Euro. The satellite will be capable of observing exoplanets in a Neptune–Earth scale and obtaining data of interstellar dust. Due to a system failure of NASA׳s Kepler mission, there is currently (October 2013) a lack of satellites searching for exoplanets. This paper details the design of subsystems and payload, as well as the required test tasks in accordance with the mission profile at a conceptional level. The costs for standard spacecraft testing and integration tasks are included, but not those of launch, ground support, operations and engineer working hours. [ABSTRACT FROM AUTHOR]

In preparation of the rendezvous of the European Space Agency Rosetta spacecraft with short period Jupiter Family comet 67P/Churyumov–Gerasimenko we undertook the selection and characterization of mineral grains to serve as analogs of dust from the comet. Specifically, these dust analogs are used to calibrate the performance of the onboard Grain Impact Analyser and Dust Accumulator (GIADA) instrument at the comet. Our selection of suitable natural analog minerals was guided by the finding of an asteroid-like mineralogy in Jupiter Family comet Wild 2. We selected (1) anhydrous silicate minerals [forsterite and fayalite (end-members of the olivine solid solution series), enstatite, melilite, alkali-feldspar and anorthite], (2) hydrated layer silicates (kaolinite, serpentine, and talc), (3) pyrrhotite, and (4) corundum. Four size fractions, viz . 500–250 µm, 250–100 µm, 100–50 µm and 50–20 µm, were prepared for each analog mineral. In addition, each selected analog mineral, from each size bin, was coated with carbon layer. Similarly another set of analog grains were coated with a layer of sodium hexafluorosilicate (Na 2 SiF 6 ) crystals representing comet water-ice, for what concerns their optical properties. Laboratory experiments to calibrate the GIADA performance using these analogs are currently underway. We report the availability of analogs that will enable the calibration of various instruments onboard Rosetta. [ABSTRACT FROM AUTHOR]

The Arrayed Large-Area Dust Detectors in INterplanetary space (ALADDIN) is an array of polyvinylidene fluoride (PVDF) based dust detectors aboard the solar power sail demonstrator named IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). The total sensor area of ALADDIN (0.54 m2) is the world?s largest among the past PVDF-based dust detectors. IKAROS was launched in May 2010 and then ALADDIN measured cosmic dust impacts for 16 months while orbiting around between 0.7 and 1.1 AU. The main scientific objective of ALADDIN is to reveal number density of =10-μm-sized dust in the zodiacal cloud with much higher time-space resolution than that achieved by any past in-situ measurements. The distribution of ≥10-μm-sized dust can be also observed mainly with the light scattering by optical instruments. This paper gives the scientific objectives, the instrumental description, and the results of microparticle impact calibration of ALADDIN conducted in ground laboratories. For the calibration tests we used Van de Graaf accelerators (VdG), two-stage light gas guns (LGG), and a nano-second pulsed Nd:YAG laser (nsPL). Through these experiments, we obtained depolarization charge signal caused by hypervelocity impacts or laser irradiation using the flight spare of 20-μm-thick PVDF sensor and the electronics box of ALADDIN. In the VdG experiment we accelerated iron, carbon, and silver microparticles at 1-30 km/s, while in the LGG experiment we performed to shoot 100·s-μm-sized particles of soda-lime glass and stainless steel at 3-7 km/s as single projectile. For interpolation to ≥10-μm size, we irradiated infrared laser at the energy of 15-20 mJ directly onto the PVDF sensor. From the signal analysis, we developed a calibration law for estimation of masses of impacted dust particles. The dynamic range of ALADDIN corresponds from 9×10-14 kg to 2×10-10 kg (4-56 μm in diameter at density of 2.0 g/cm3) at the expected impact velocity of 10 km/s at 1 AU on the IKAROS inbound orbit. It was found that ALADDIN has ability to measure spatial densities of interplanetary dust particles larger than 10 μm in size by setting the sensor threshold to an output voltage of 1 V. [ABSTRACT FROM AUTHOR]