The Relative Abundance of Recently-launched Meteorites from the Moon

Introduction: It has been known for over 20 years that certain meteorites originated on the moon and Mars. The launch and delivery of these stones is understood qualitatively as a consequence of impact events on those bodies. One of the puzzling features of the sample population is the relative abundance of lunar vs. Martian meteorites. One would think that lunar meteorites should be much more common than Martian meteorites. The moon has a much lower escape velocity, meaning many more fragments are launched from a given impact event. Smaller events can launch enough fragments to expect to find one on the Earth; hence, lunar meteorite-liberating events must be much more common than Martian meteorite-launching events. Moreover, the delivery efficiency from the moon to the Earth is higher by a factor of 10 [1]. Finally, the delivery time is shorter, meaning that the liberated lunar material from a given impact arrives at a much faster rate than comparable Martian material [1]. However, the total number of meteorites from the moon and Mars are comparable [2, 3]. The number of source craters represented by these samples appears to be of the same order of magnitude as well. For the reasons cited above, this has been difficult to understand. What I show in this work is that these arguments have missed a significant point and the observed relative abundances of lunar and Martian meteorites are just what one would expect if they are launched in relative small, frequent, impact events.