Wed 29th November @ noon, Rm 502C.102
Abstract:
One of the important steps in the prediction of an impact threat to Earth raised by potentially hazardous asteroids is the understanding and modeling of the processes accompanying the object’s entry into the terrestrial atmosphere. Such knowledge enables characterization, simulation and classification of possible impact consequences. For observed meteor events the reconstructed atmospheric trajectory is the key to deriving the pre-impact meteoroid’s orbit in the Solar System on one hand, while on the other hand, it is also required for dark flight simulations which enables us to locate surviving meteorite fragments on the ground. Using dimensionless expressions, which involve the pre-atmospheric meteoroid parameters, we have built physically based parametrisation to describe the changes in mass, height, velocity and luminosity of the object along its atmospheric path. The developed model is suitable to estimate a number of crucial unknown values including the shape change coefficient, ablation rate, and surviving meteorite mass. It is also applicable in the prediction of the terminal height of the luminous portion of flight and therefore, the duration of the fireball. Besides the model description, we demonstrate its application using the wide range of observational data from meteorite-producing fireballs appearing annually (such as e.g. the Annama, Košice, Neuschwanstein and Osceola fireballs) to larger scale impacts (such as the Chelyabinsk, Sikhote-Alin and Tunguska event). In particular, this approach enabled us to successfully recover the Annama meteorite based on the analysis of the fireball observed by the Finnish Fireball Network on 19 April 2014.
Short bio:
Maria Gritsevich is a Senior Scientist at the Department of Physics, University of Helsinki (UH), currently working for the ERC Advanced project SAEMPL (Scattering and absorption of electromagnetic waves in particulate media). She has also worked as a research fellow at the European Space Agency, and as a Specialist Research Scientist at the Finnish Geospatial Research Institute. She received the International Academic Publishing Company “Nauka/Interperiodica” and the Pleiades Publishing Inc. best journal publication in Physics and Mathematics award in 2009 and was awarded the Gold Medal for young scientists from the Russian Academy of Sciences in 2010.
