Abstract
On entering the Earth's atmosphere, micrometeoroids partially or completely ablate, leaving behind layers of metallic atoms and ions. The relative concentration of the various metal layers is not well explained by current models of ablation. Furthermore, estimates of the total flux of cosmic dust and meteoroids entering the Earth's atmosphere vary over two orders of magnitude. To better constrain these estimates and to better model the metal layers in the mesosphere, an experimental Meteoric Ablation Simulator (MASI) has been developed. Interplanetary Dust Particle (IDP) analogs are subjected to temperature profiles simulating realistic entry heating, to ascertain the differential ablation of relevant metal species. MASI is the first ablation experiment capable of simulating detailed mass, velocity, and entry angle-specific temperature profiles whilst simultaneously tracking the resulting gas-phase ablation products in a time resolved manner. This enables the determination of elemental atmospheric entry yields which consider the mass and size distribution of IDPs. The instrument has also enabled the first direct measurements of differential ablation in a laboratory setting.
Highlights
The total flux of interplanetary dust particles (IDPs36) entering the Earth’s atmosphere has been measured by a variety of methods both within and outside the atmosphere, with estimates ranging between 5 and 240 t d−1.1 A major reason for this large uncertainty lies in the different assumptions required to interpret each type of measurement, which need to be corrected for different biases and involve a number of untested assumptions
Interplanetary Dust Particle (IDP) analogs are subjected to temperature profiles simulating realistic entry heating, to ascertain the differential ablation of relevant metal species
Observations of infrared emission from the zodiacal cloud, measured by the Infrared Astronomical Satellite (IRAS), indicate that the majority (>80%) of the IR emission is produced by particles originating from Jupiter family comets
Summary
The total flux of interplanetary dust particles (IDPs36) entering the Earth’s atmosphere has been measured by a variety of methods both within and outside the atmosphere, with estimates ranging between 5 and 240 t d−1 (metric tonnes per day). A major reason for this large uncertainty lies in the different assumptions required to interpret each type of measurement, which need to be corrected for different biases and involve a number of untested assumptions. A major reason for this large uncertainty lies in the different assumptions required to interpret each type of measurement, which need to be corrected for different biases and involve a number of untested assumptions. Current efforts are being directed to reduce these uncertainties.. The major sources of IDPs are the asteroid belt, Jupiter family comets, Halley-type comets, and Oort cloud comets. In the Zodiacal Cloud Model (ZCM) developed by Nesvorny et al., sub-millimeter particles from these sources are launched and tracked as their orbits evolve under the influence of solar radiation pressure, Poynting-Robertson drag, and planetary perturbations. Observations of infrared emission from the zodiacal cloud, measured by the Infrared Astronomical Satellite (IRAS), indicate that the majority (>80%) of the IR emission is produced by particles originating from Jupiter family comets.
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