Face-Dependent Impact Probabilities Upon LDEF for Heliocentric Particle Orbits

Abstract

If the impact record upon LDEF is to be interpreted so as to determine the flux, orbits, sizes and compositions of natural meteoroids and dust, and space debris, then it is necessary to relate the microcraters and perforations recorded to the likely source orbit of the particle in each case. Here a single-particle approach is used to calculate the relative impact probabilities upon six orthogonal faces of LDEF for particles coming from heliocentric orbits confined to the ecliptic; the results are presented as functions of impact velocity and impact angle for each face. The flux from geocentric orbits to the Space-and Earth-pointing faces is much lower than to the other faces; experiments positioned on those faces are thus likely to be less contaminated by space debris. Particles from heliocentric orbits can impact both the Space and Earth faces, but the latter is less likely to be hit due to the shadowing effect of the planet. The cratering ratios for the East (or leading) face compared to the West (or trailing) and the Earth-directed faces are strongly dependent upon the velocities of the particles and can therefore indicate of the velocity distribution of meteoroids and interplanetary dust.