Lecturer: Maria Gritsevich Date: 2023-12-14 10:00 Place: Aniara
Meteor phenomena: from atmospheric entry processes to impact craters
Maria Gritsevich
University of Helsinki
The seminar is also online. See emails for connection details.
Abstract.
A crucial step in predicting the impact threat posed by space objects to Earth involves understanding and modeling the processes accompanying the object's entry into the atmosphere. This knowledge facilitates the characterization, simulation, and classification of potential impact consequences. For observed meteor events, the reconstructed atmospheric trajectory plays a key role in deriving the pre-impact meteoroid orbit in the Solar System. Simultaneously, it is essential for dark flight simulations, aiding in the identification of surviving meteorite fragments on the ground.
Using dimensionless expressions involving pre-atmospheric meteoroid parameters, we have developed a physically based parametrization to describe changes in mass, height, velocity, and luminosity of the object along its atmospheric path. This model proves effective in estimating crucial unknown values, including the shape change coefficient, ablation rate, and surviving meteorite mass. Additionally, it can be used to predict the terminal height of the luminous part of the trajectory, thereby determining the duration of the fireball.
Beyond detailing the model, we demonstrate its application using a wide range of observational data, spanning from radar detections to meteorite-producing events occurring annually (such as Ådalen, Košice, and Neuschwanstein) and larger scale impacts (such as Chelyabinsk, Sikhote-Alin, and Tunguska event). This approach has already enabled the successful recovery of the Annama and Ozerki meteorites through the analysis of the fireball observations.
Created 2023-12-06 17:57:05 by Mats Holmström Last changed 2023-12-06 17:57:05 by Mats Holmström
