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

Data obtained with the Apollo 12 and 14 long-period seismometers in the period between December 1969 and January 1973 are used to determine the direction of approach and mass-distribution statistics of meteoroids in near-earth space. The total number of detected meteoroid impacts in this period is analyzed as a function of lunar phase with allowance for seismometer sensitivity and characteristics of lunar seismic-wave propagation. A logarithmic relation is derived which describes the mass-distribution statistics. It is concluded that most orbits for meteoroids with a mass in excess of 5 kg lie near the plane of the ecliptic with aphelia between 2 and 5 AU.