Fragmentation model and strewn field estimation for meteoroids entry
release_qezpp3olqvfltjwo5lwb6beasu
by
Simone Limonta, Mirko Trisolini, Stefan Frey, Camilla Colombo
2021
Abstract
Everyday thousands of meteoroids enter the Earth's atmosphere. The vast
majority burn up harmlessly during the descent, but the larger objects survive,
occasionally experiencing intense fragmentation events, and reach the ground.
These events can pose a threat for a village or a small city; therefore, models
of asteroid fragmentation, along with accurate post-breakup trajectory and
strewn field estimation, are needed to enable a reliable risk assessment. In
this work, a methodology to describe meteoroids entry, fragmentation, descent,
and strewn field is presented by means of a continuum approach. At breakup, a
modified version of the NASA Standard Breakup Model is used to generate the
distribution of the fragments in terms of their area-to-mass ratio and ejection
velocity. This distribution, combined with the meteoroid state, is directly
propagated using the continuity equation coupled with the non-linear entry
dynamics. At each time step, the probability density evolution of the fragments
is reconstructed using GMM interpolation. Using this information is then
possible to estimate the meteoroid's ground impact probability. This approach
departs from the current state-of-the-art models: it has the flexibility to
include large fragmentation events while maintaining a continuum formulation
for a better physical representation of the phenomenon. The methodology is also
characterised by a modular structure, so that updated asteroids fragmentation
models can be readily integrated into the framework, allowing a continuously
improving prediction of re-entry and fragmentation events. The propagation of
the fragments' density and its reconstruction, currently considering only one
fragmentation point, is first compared against Monte Carlo simulations, and
then against real observations. Both deceleration due to atmospheric drag and
ablation due to aerothermodynamics effects have been considered.
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