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9,663 result(s) for "Cosmic dust"
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Impacts of Cosmic Dust on Planetary Atmospheres and Surfaces
Recent advances in interplanetary dust modelling provide much improved estimates of the fluxes of cosmic dust particles into planetary (and lunar) atmospheres throughout the solar system. Combining the dust particle size and velocity distributions with new chemical ablation models enables the injection rates of individual elements to be predicted as a function of location and time. This information is essential for understanding a variety of atmospheric impacts, including: the formation of layers of metal atoms and ions; meteoric smoke particles and ice cloud nucleation; perturbations to atmospheric gas-phase chemistry; and the effects of the surface deposition of micrometeorites and cosmic spherules. There is discussion of impacts on all the planets, as well as on Pluto, Triton and Titan.
Cometary Dust
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.
The Dawn of Dust Astronomy
We review the development of dust science from the first ground-based astronomical observations of dust in space to compositional analysis of individual dust particles and their source objects. A multitude of observational techniques is available for the scientific study of space dust: from meteors and interplanetary dust particles collected in the upper atmosphere to dust analyzed in situ or returned to Earth. In situ dust detectors have been developed from simple dust impact detectors determining the dust hazard in Earth orbit to dust telescopes capable of providing compositional analysis and accurate trajectory determination of individual dust particles in space. The concept of Dust Astronomy has been developed, recognizing that dust particles, like photons, carry information from remote sites in space and time. From knowledge of the dust particles’ birthplace and their bulk properties, we learn about the remote environment out of which the particles were formed. Dust Observatory missions like Cassini, Stardust, and Rosetta study Saturn’s satellites and rings and the dust environments of comet Wild 2 and comet Churyumov-Gerasimenko, respectively. Supplemented by simulations of dusty processes in the laboratory we are beginning to understand the dusty environments in space.
Interstellar Dust in the Solar System
Interstellar dust from the Local Interstellar Cloud was detected unambiguously for the first time in 1992 (Grün et al. in Nature 362:428–430, 1993 ). Since then, great progress has been made in observing local interstellar dust in the Solar System using a variety of methods that, all together, provide complementary views of the dust particles from our local galactic neighborhood. The complementary methods discussed in this paper are: (1) in situ observations with dust detectors, (2) sample return, (3) observations of dust in the infrared, and (4) detections using spacecraft antennae. We review the current state of the art of local interstellar dust research, with a special focus on the advances made in the last ∼10 years of interstellar dust research. We introduce this paper with an overview of the definitions of interstellar dust. We describe the dynamics of the dust particles moving through the heliosphere and report on the progress made in the modelling efforts especially in the last decade. We also review the currently available in situ measurements of interstellar dust flux, speed, direction and size distribution from various missions, in specific from Ulysses and Cassini, and their interpretation in context of the dust dynamics studies. Interstellar dust composition is also reviewed from Cassini in situ time of flight measurements and from the Stardust sample return mission that both took place in the last decade. Finally, also new dust measurements from spacecraft antennae are reviewed. The paper concludes with a discussion on currently still open questions, and an outlook for the future.
Stardust in meteorites
Primitive meteorites, interplanetary dust particles, and comets contain dust grains that formed around stars that lived their lives before the solar system formed. These remarkable objects have been intensively studied since their discovery a little over twenty years ago and they provide samples of other stars that can be studied in the laboratory in exquisite detail with modern analytical tools. The properties of stardust grains are used to constrain models of nucleosynthesis in red giant stars and supernovae, the dominant sources of dust grains that are recycled into the interstellar medium by stars.
The DNA of Bacteria of the World Ocean and the Earth in Cosmic Dust at the International Space Station
Cosmic dust samples from the surface of the illuminator of the International Space Station (ISS) were collected by a crew member during his spacewalk. The sampler with tampon in a vacuum container was delivered to the Earth. Washouts from the tampon’s material and the tampon itself were analyzed for the presence of bacterial DNA by the method of nested PCR with primers specific to DNA of the genus Mycobacteria, DNA of the strains of capsular bacteria Bacillus, and DNA encoding 16S ribosomal RNA. The results of amplification followed by sequencing and phylogenetic analysis indicated the presence of the bacteria of the genus Mycobacteria and the extreme bacterium of the genus Delftia in the samples of cosmic dust. It was shown that the DNA sequence of one of the bacteria of the genus Mycobacteria was genetically similar to that previously observed in superficial micro layer at the Barents and Kara seas’ coastal zones. The presence of the wild land and marine bacteria DNA on the ISS suggests their possible transfer from the stratosphere into the ionosphere with the ascending branch of the global electric circuit. Alternatively, the wild land and marine bacteria as well as the ISS bacteria may all have an ultimate space origin.
Dust Emission by Active Moons
In recent decades, volcanic and cryovolcanic activity on moons within the Solar System has been recognised as an important source of cosmic dust. Two moons, Jupiter’s satellite Io and Saturn’s satellite Enceladus, are known to be actively emitting dust into circumplanetary and interplanetary space. A third moon, Europa, shows tantalising hints of activity. Here we review current observations and theories concerning the generation, emission and evolution of cosmic dust arising from these objects.
Fluid-induced organic synthesis in the solar nebula recorded in extraterrestrial dust from meteorites
Significance Organic matter from the parent molecular cloud of our solar system can be located in primitive extraterrestrial samples like meteorites and cometary grains. This pristine matter contains among the most primitive organic molecules that were delivered to the early Earth 4.5 billion years ago. We have analyzed these organics by a high-resolution electron microscope that is exceptionally suited to study these beam-sensitive materials. Different carbon and nitrogen functional groups were identified on a submicron scale and can be attributed to early cometary and meteoritic organic reservoirs. Our results demonstrate for the first time to our knowledge that certain highly aromatic and nitrogen-containing ubiquitous organics were transformed from an oxygen-rich organic reservoir by parent body fluid synthesis in the early solar system. Isotopically anomalous carbonaceous grains in extraterrestrial samples represent the most pristine organics that were delivered to the early Earth. Here we report on gentle aberration-corrected scanning transmission electron microscopy investigations of eight ¹⁵N-rich or D-rich organic grains within two carbonaceous Renazzo-type (CR) chondrites and two interplanetary dust particles (IDPs) originating from comets. Organic matter in the IDP samples is less aromatic than that in the CR chondrites, and its functional group chemistry is mainly characterized by C–O bonding and aliphatic C. Organic grains in CR chondrites are associated with carbonates and elemental Ca, which originate either from aqueous fluids or possibly an indigenous organic source. One distinct grain from the CR chondrite NWA 852 exhibits a rim structure only visible in chemical maps. The outer part is nanoglobular in shape, highly aromatic, and enriched in anomalous nitrogen. Functional group chemistry of the inner part is similar to spectra from IDP organic grains and less aromatic with nitrogen below the detection limit. The boundary between these two areas is very sharp. The direct association of both IDP-like organic matter with dominant C–O bonding environments and nanoglobular organics with dominant aromatic and C–N functionality within one unique grain provides for the first time to our knowledge strong evidence for organic synthesis in the early solar system activated by an anomalous nitrogen-containing parent body fluid.
METEOR-L Device on the Lunar Orbital Vehicle Luna-26: Space Dust Detector
— The ionization-type cosmic dust detector METEOR-L is being developed for the lunar orbiter Luna-26 and is designed to study the distribution of meteoric bodies in space by mass and velocity, and for long-term monitoring of the dynamic evolution of the dust component in the lunar exosphere. Recent studies of dust clouds around the Moon show a close relationship between the constant and dynamic evolution of the components of the lunar exosphere, the geological history of the formation of the lunar regolith, the processes of formation and accumulation of volatiles in the lunar regolith with the constant impact of such components of the interplanetary medium as interplanetary dust of predominantly cometary origin and meteoroids from the belt asteroids. The cosmic dust detector is capable of registering meteoric particles 0.1–3 μm in size with a mass of 10 –14 –10 –9 g and speeds from 3 to 35 km s –1 . Tests and calibration at a particle accelerator have confirmed the declared functionality of the detector for detecting cosmic dust particles with parameters characteristic of the lunar exosphere.
Radical reactions on interstellar icy dust grains: Experimental investigations of elementary processes
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 H , H O, H CO, and CH OH 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.