Cosmic Dust in Planetary Atmospheres

In this seminar I will describe the results of a large study designed to determine the input rate of cosmic dust to the terrestrial atmosphere, using a self-consistent treatment of cosmic dust from the outer solar system to the Earth’s surface. An astronomical model which tracks the evolution of dust from various sources into the inner solar system was combined with a chemical ablation model to determine the rate of injection of metallic vapours into the atmosphere. Constraining these coupled models with observations of IR emission from the Zodiacal Cloud, lidar measurements of the vertical fluxes of Na and Fe in the terrestrial mesosphere, and the rate of accretion of cosmic spherules at the South Pole, indicates that about 30 tonnes of dust enters the Earth’s atmosphere each day. Having fitted the astronomical model to the terrestrial input, the same model can be used to predict the dust inputs into the atmospheres of Venus and Mars.