Earth Encounter Velocities For Interplanetary Meteoroids

The speed distribution of meteoroids encountering the Earth is shown to be similar for all meteoroid masses in the range 1 g to 10(-12)g. The speed distribution of interplanetary meteoroids encountering the Earth has usually been inferred from meteor observations. This paper reviews commonly quoted distributions and introduces more recent estimates. The influence quoted measurement uncertainties have on the distribution of Earth encounter velocities presented by Sekanina and Southworth (1975) and Erickson (1968) is presented. The Divine (1993) model of interplanetary meteoroids fits a set of orbital distributions to a wide range of spacecraft and ground based dust detector observations. By 'flying' the Earth through this model the distribution of geocentric encounter velocities has been obtained for typical particle masses, 10(-9) and 10(-12) g while those at 10(-4) and 10(-5) g are shown to be in error.