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| Paper: |
Meteoroids: an Item in the Inventory |
| Volume: |
107, Completing the Inventory of the Solar System |
| Page: |
75 |
| Authors: |
Ceplecha, Z. |
| Abstract: |
Very precise observational data on atmospheric trajectories of meteoroids are nowadays available for mass range from $10^{-9}$~kg to $10^4$~kg, i.e. for sizes from 0.1~mm to 3~m. Theoretical models (single-body with gross fragmentation) can explain photographic observations of meteoroids with a high precision. These meteoroids fragment under very low dynamic pressures, much lower than is the strength of their meteorites. Photographic data on the Lost City fireball and the videorecorded Peekskill fireball, both accompanied by meteorite falls, are used as an example. Recently new concepts of atmospheric fragmentation by explosion of interplanetary bodies of 10~m sizes and larger at extremely low heights under dynamic pressures of hundreds of Mdyn/cm$^2$ were published by several authors. Ablation with final stage of hot vapor from ablated material is typical for photographic meteoroids: we see the meteor because its radiation originates mostly from low excited metallic atoms. Contrary to this, theoretical models of very large bodies assume ablation mostly in the form of explosive fragmentation. Such models could bring bodies to lower heights, i.e. to higher dynamic pressures, than it were for early low pressure fragmentation (as observed for meteoroids up to meter sizes). If large bodies would behave different way from the smaller meteoroids, then we should see the change of body dynamics and radiation at some intermediate size. The 10-m-size bodies form the most important component of the Earth's influx of interplanetary bodies during time spans of years and observations of their atmospheric trajectories are extremely needed. |
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