Steve KortenkampNASA Planetary Geology and GeophysicsInvestigation of a new resonant mechanism for accretion of interplanetary dust from EarthWe propose to investigate an unusual resonant mechanism for accretion of interplanetary dust particles (IDPs) by Earth to see if it is an important factor in the capturing the estimated 30,000 metric tons of IDPs that Earth accretes each year. In our proposed research we will carry out two distinct tasks: 

Task 1) Studying the current accretion of IDPs: We will use the current orbital elements of the planets and known asteroidal and cometary parent bodies of IDPs. This modeling will include several elements; i) a broad range of IDP diameters, ii) a broad range of IDP orbital eccentricity and inclination, iii) IDPs originating from specific parent body populations (asteroid & cometary), and iv) observational consequences of quasi-satellite dust (where to look for the infrared-emission from Earth's quasi-satellite dust cloud). 

Task 2) Long-term variations in the IDP accretion rate: We will study this new resonant IDP accretion mechanism over the past million years to determine if it matches the dust accretion history preserved in Earth's geologic record. Elements of this modeling include: i) determining the dependence on the planet's orbital eccentricity and inclination, ii) trapping efficiency at specific times in Earth's past, and iii) comparison with the published geologic record of IDP accretion. 

To accomplish our proposed tasks we will conduct a large number of computer simulations of the orbital evolution of IDPs under the influence of gravitational perturbations from all the planets as well as radiation pressure, Poynting-Robertson light drag and solar wind drag. We will use N-body numerical integration codes already in use by us for similar purposes. 

The outcome of our work will help scientists to better understand the origins of accreted IDPs that are collected from the stratosphere by NASA research aircraft and available for laboratory study. Analysis of these IDPs provides important chemical and isotopic information about the geology of their asteroidal and cometary parent bodies. A better understanding of how these dust particles come to be accreted by Earth will help constrain our interpretation of this geologic information. Additionally, our proposed research addresses the greater strategic objectives of NASA in that by studying IDPs we seek to understand the origin of the small solar system bodies from which they come (asteroids and comets) and the record of the very early solar system that is preserved within these bodies.