An Automated Meteoroid Orbit Survey to Measure the Fragmentation History of (Mostly) Dormant Comets in the Near Earth Orbit Population

Grant #: NNX08AO64G
Senior Scientist: Peter Jenniskens

The primary goal of this study is to test the hypothesis that the disintegration of mostly dormant comets is the dominant contribution of dust to the zodiacal cloud. The new insight came from our recent discovery that most major meteor showers have associated weakly active or dormant comets. Few (mostly Halley-type showers) have active parent comets. The established cases point to a formation age in the past 2,000 years from periodic disruptions, rather than from the gradual loss of water vapor. Only eight cases have been established so far. Some 40 associations have been tentatively identified, but their proposed meteoroid streams are not sufficiently well defined.

The main obstacle for translating the observed frequency and dispersion of meteoroid streams at Earth into the frequency and nature of disruptions among (mostly) dormant and weakly active comets is that the streams are not well known. To remedy this, this study is a 3-year meteoroid orbit survey of meteoroids so large (> 0.01 gram) that they dominate the background of grains that had prior collisions with other grains in the solar system and lost their stream association.