The Mesopause as a physical penetration boundary

Abstract In this work we have analyzed the entry behavior of all known types of meteoroids using a single-body end height model in order to test their entry penetration into the earth's middle and upper atmosphere. We have utilized a new physically based model that incorporates a number of new features including a total power budget during entry as well as the very important processes of ablation and deceleration. More specifically, we have examined the meteoroid sizes and masses that are capable of terminating their visible flight at the Mesopause. In order to accomplish these calculations, we have assigned specific shape, shape change, angle of entry, radius, velocity, the kinetic energy removal D parameter of ReVelle, bulk density (or equivalently formulated in terms of uniform volume-weighted porosity), etc. We have further tested the reliability and done a test calibration of the model predictions utilizing an extreme entry case (for a Leonid bolide that penetrated to the Mesopause on November 15, 2001 and that was detected by photometry as well as by using infrasound). Finally, after assuming specific velocity limits for each group with the specific size limits being predicted by the model, we have also compared our predicted mass influx results (number per year on Earth versus initial mass) against recent Large Aperture Radar data obtained at the Arecibo Observatory by Janches (personal communication, 2003). Generally, quite small meteors are “stopped” at the Mesopause, but for the weakest materials, bodies as massive as ∼0.14 kg can be stopped above the Mesopause, especially at shallower entry angles. Generally reasonable agreement was found, but there are still a number of uncertainties as well. Eventually, this analysis should be redone using our advanced meteor modeling techniques including our triggered progressive fragmentation model, etc. [ReVelle, 2001a. Theoretical Leonid entry modeling, In: Warmbein, B., (Ed.), Proceedings of the Meteoroids 2001 Conference, Kiruna, Sweden, ESA (European Space Agency) SP-495. ESTEC, Noorwijk, The Netherlands, pp. 149–154; ReVelle, 2001b. Bolide dynamics and luminosity modeling: comparisons between uniform bulk density and porous meteoroid models. In: Warmbein, B. (Ed.), Proceedings of the Meteoroids 2001 Conference, Kiruna, Sweden, ESA (European Space Agency) SP-495. ESTEC, Noorwijk, The Netherlands, pp. 513–518; ReVelle, 2001c. Bolide fragmentation processes: single-body modeling versus the catastrophic fragmentation limit. In: Warmbein, B. (Ed.), Proceedings of the Meteoroids 2001 Conference, Kiruna, Sweden, ESA (European Space Agency) SP-495. ESTEC, Noorwijk, The Netherlands, pp. 491–496; ReVelle, 2001d. Bolide global infrasonic monitoring of large bolides. In: Warmbein, B. (Ed.), Proceedings of the Meteoroids 2001 Conference, Kiruna, Sweden, ESA (European Space Agency) SP-495. ESTEC, Noorwijk, The Netherlands, pp. 483–490; ReVelle, 2002a. Fireball dynamics, energetics, ablation, luminosity and fragmentation modeling. In: Warmbein, B. (Ed.), Proceedings of the ACM (asteroids, Comets and meteors) Conference, Berlin, Germany, ESA (European Space Agency) SP-500. ESTEC, Noorwijk, The Netherlands, pp. 127–136; ReVelle, 2002b. Porosity: a natural alternative explanation of bolide types, their atmospheric behavior and the implications. In: Warmbein, B. (Ed.), Proceedings of the ACM (asteroids, Comets and meteors) Conference, Berlin, Germany, ESA (European Space Agency) SP-500. ESTEC, Noorwijk, The Netherlands, pp. 233–236].