The LEO microparticle population: Computer studies of space debris drag depletion and of interplanetary capture processes

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The LEO microparticle population: Computer studies of space debris drag depletion and of interplanetary capture processes

Ratcliff, P.R. / Taylor, A.D. / McDonnell, J.A.M.

Abstract The effect of the Earth's atmosphere on micron-sized particles is quantified by showing that 1 μm particles in circular orbits below altitudes of approximately 500 km complete less than one orbit before being absorbed by the atmosphere, and that particles generated at low altitudes only survive for a significant time if they are in orbits of at least moderate eccentricity. Thus, micron-sized particles at low altitudes must generally be in eccentric orbits, rather than circular. In addition to acting as a very efficient sink for small particles in LEO, the atmosphere also enhances the flux of natural micrometeorites by three processes; atmospheric focusing, aerocapture, and aerofragmentation capture. The first two of these processes in combination provide an enhancement by a factor of ∼1.7 in addition to the calculated weighted mean gravitational focusing of 2.9. However, this still leaves natural material accounting for only ∼ 5% of the 1 μm particle population in the LEO environment.