Dust in the Solar System

Abstract

Dedicated to Heinrich Wanke on the occasion of his 60 th birthday Properties of cometary dust particles are better known since the space missions to Comet Halley. Their properties (densities, atomic composition) are compared with relevant observations from lunar microcraters and in-situ experiments. At 1 AU in the eliptic, 2/3 of the dust grains are normal density particles, presumably of asteroidal origin and irregularly shaped, while the remaining 1/3 are low density particles, presumably of cometary origin, but due to solar irradiation in a processed state (corresponding to "Brownlee"-particles). Beyond the asteroidal belt only black cometary dust grains are observed which have recently been released from comet nuclei orbiting on highly eccentric trajectories.

Dust Cloud near the Sun

“…We do not discuss here the relative abundances of grains in asteroidal and cometary populations, because this problem, despite a long discussion, has not been given a satisfactory solution even at 1 AU (Liou et al 1995). Ratios from 1 : 4 to 1 : 1 between the asteroidal and cometary dust (see, e.g., Fechtig 1989, Dermott et al 1992 could be used for crude estimates. The contribution of long-period comets is even more uncertain.…”

“…These two components may have different optical properties and, due to their different initial orbits, they may also have different distributions of orbital elements. The existence of two different dust populations in the ecliptic plane with different bulk densities and different relative velocities to the spacecraft has been revealed from the Helios in situ measurements and explained with a component of cometary dust and a component of asteroidal dust particles (Grün et al 1980, Fechtig 1989.…”

Plasma Accelerator Utilizing the Medium of Near-Earth Space for Orbital Transfer Vehicles

“…Drawing on astrophysical research [10][11][12][13][14][15][16][17][18][19][20][21][22][23], we briefly delve into the physical properties of matter in near-Earth space that are required, analyzing the efficiency of the proposed scheme. The primary constituents of interplanetary matter we focus on are the solar wind, high-energy charged particles, interplanetary dust, and neutral gas [19][20][21][22].…”

“…These limitations for plasma thrusters, however, may, in principle, be evaded when external power and matter sources are applied (see [8,9] and the references therein). Solar radiation could be an energy source for ionizing and propelling the operational matter collected from the interplanetary medium comprising cosmic dust and solar wind [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. However, the material captured from the space between planets falls short in quantity to produce the necessary thrust for a spacecraft.…”

Spatial Distribution and Orbital Properties of Zodiacal Dust

“…As according to Fechtig (1989) at least 2/3 of all ecliptic concentrated grains are of asteroid origin, the ecliptic component of the zodiacal cloud might have not only different orbital, but also different optical properties from those of the isotropic component. As cometary dust can be extremely dark (cf.…”