The Harvard Radio Meteor Project Meteor Velocity Distribution Reappraised

The relative distribution of atmospheric encounter speeds at constant mass for observations made as part of the Harvard Radio Meteor Project synodic year observations has been recalculated using a cumulative mass index, alpha = 1.1 +/- 0.1, and the mass velocity relation from F. Verniani (1973, J. Geophys. Res. 78, 8429-8462), gamma = 4.23 +/- 0.07. A discrepency in the bias-corrected values reported by Z. Sekanina and R. B. Southworth (1975, NASA Contractor Report CR 2316, Smithsonian Institution, Cambridge, MA) is identified as a possible typographical error with the relative numbers of high speed meteors increased by 10(2) times over that of the previous analysis. The reappraised distribution is in good agreement with that reported by J. E. Erickson (1968, J. Geophys. Res. 73, 3721-3762) but is based on data with considerably improved statistical reliability and samples a mass range more directly applicable to spacecraft impact studies. The mean impact speed weighted to equivalent crater diameter using a mass-velocity relation, mv(2), is 23.6 km sec(-1). This value moves the S. G. Love and D. E. Brownlee (1993, Science 262, 550-553) mass influx peak to 8 x 10(-6) g (175-mu m-diameter particles), half the previous mass, and brings their cumulative flux curve into much closer agreement with Grun et al. (1985, Icarus 62, 244-272).