The importance of the annual meteoroid streams to spacecraft and their detectors

In modelling dust fluxes to spacecraft surfaces and detectors, it is often assumed for simplicity that the influx is isotropic. The most popular working model used is that of Grun et al. (1985) which gives annual mean fluxes to a spinning flat plate detector at 1 A.U. However, particular spacecraft orientations can highlight anisotropies in the natural meteoroid environment. This paper considers one source of anisotropy by isolating the contribution to the annual mean flux from the major annual meteoroid streams. Flux (mass) distributions are derived for 50 annual streams, and it is found that the streams contribute to similar to 10% of the annual mean flux as seen by typical Low Earth Orbit (LEG) foil detectors at the (potentially hazardous) f(max) = 1 mm size regime (i.e. impacts that can penetrate 1 mm aluminium). Strong temporal variations are also seen, relevant to short-exposure missions.