Variation in the number of meteoroid impacts on the Moon with lunar phase

Data from the ALSEP 12 and 14 seismometers of the Apollo Passive Seismic Experiment Network are used to determine the statistics of the mass distribution of meteoroids and their direction of approach in near earth space. The cumulative number of meteoroid impacts detected is analyzed as a function of phase of the moon, taking into account the sensitivity of the seismometer and the seismic wave propagation characteristics of the moon. We conclude that, in the mass range studied (>5 kg), (a) most meteoroid orbits lie near the plane of the ecliptic, (b) the orbits have aphelia between 2 and 5 a.u., and (c) the mass distribution statistics are described by the relation log₁₀ n = B + G log₁₀ m, where n = number of meteoroids of mass m grams or greater, B ∼ 0.9 and G = −1.5.