12054 and 76215 - New measurements of interplanetary dust and solar flare fluxes

The mass distribution and flux of micrometeoroids, variations in solar activity, solar-wind erosion and solar-flare track production are discussed on the basis of lunar sample analyses. A bimodal size frequency distribution of micrometeorites is found; the ratio of the density of craters larger than 0.1 micron to the density of those larger than 500 microns is 50 to 100 million. Solar cosmic-ray track ages determined for the lunar samples through use of the model of Blanford et al. (1975) indicate no variation in solar activity over a period of 2 million years. Solar wind erosion is set at no more than 0.03 A per year.