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Paper: Dust in Interplanetary Space and in the Local Galactic Environment
Volume: 309, Astrophysics of Dust
Page: 245
Authors: Grun, E.; Dikarev, V.; Frisch, P.C.; Graps, A.; Kempf, S.; Kruger, H.; Landgraf, M.; Moragas-Klostermeyer, G.; Srama, R.
Abstract: The solar system is a natural laboratory, accessible by a variety of methods, for studying the astrophysics of dust. Astronomical measurements mostly at visible and infrared wavelengths, yield the large-scale distribution of dust and its average composition. Examining natural surfaces deployed to the space environment, and assessing those surfaces' micro-crater distributions, reveals the size distribution of dust. Meteor observations and their corresponding measurements provide orbital information of dust grains and their genetic interrelation to the larger bodies in our solar system: comets and asteroids. From analyses of meteorites and interplanetary dust particles collected in the stratosphere, we have a comprehensive understanding of the isotopic, elemental, and mineralogical composition of this primordial material. Finally, in situ dust analysis via dust detectors located in interplanetary space, the most versatile method, have been providing data to determine the dust particles' mass, speed, trajectory, and chemical composition.

An assortment of dust exhibiting a variety of dynamical processes has been identified in interplanetary space. In Jupiter's proximity, intense streams have been observed of nanometer-sized ash particles, which are emitted from the volcanoes of Jupiter's moon Io. These particles are accelerated by the powerful Jovian magnetic field to speeds of several 100 km/s, and are propelled further into interplanetary and interstellar space by the solar wind magnetic field. In interplanetary space, concentrations of collisional debris in the asteroid belt have been identified by infrared observations. The Poynting-Robertson effect drags these particles in towards the Earth and the Sun, where they sublimate. If the giant planets did not block their inward drift, a similar fate is expected for the dust assortment that is generated by collisions in the Kuiper belt. Another dust population is the mostly sub-micron-sized dust from comets, released while the comets traverse the inner parts of our solar system. These comet particles are shed from the comet's coma and consequently, quickly driven out of the solar system by radiation pressure forces. Larger particles form trails along the orbit of the parent comet, which result in a meteor storm as the Earth crosses the trail. Furthermore, the dust of comet trails can disperse via planetary perturbations into the background zodiacal cloud. Last, but not least, an important dust population identified by in situ dust instruments is the micron-sized interstellar grains flowing through the planetary system with the interstellar gas flow being part of the local interstellar cloud. This cloud is at the edge of the local bubble of hot tenuous gas which was excavated by supernova explosions in the near-by Scorpius-Centaurus and Orion Associations.

These dust populations are the target of future dust observatory missions in space. Such a dust observatory satellite carries a dust telescope, which is a combination of a dust trajectory sensor together with an analyzer for the particles' chemical composition. With accurate dust trajectory measurements, we can identify its place of origin: for example, comets, asteroids, or interstellar space. From the particles' bulk properties and their chemical composition, we can infer properties of the environments out of which the particles were formed, and in which they were subsequently altered.

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