Atmospheric Energy Deposition Modeling and Inference for Varied Meteoroid StructuresOPEN ACCESS

29/06/2018 12:22 · by karmaka · in Chelyabinsk / Челябинск, meteor/meteoroid/bolide, Tagish Lake, witnessed fall

Lorien F. Wheeler, Donovan L. Mathias, Edward Stokan, Peter G. Brown

Icarus
Available online 28 June 2018

LINK (OPEN ACCESS)
PDF (OPEN ACCESS)

“Highlights

• The fragment-cloud model is extended to represent atmospheric breakup of meteoroids with varied structures.
• The model provides excellent matches to energy deposition estimates for observed meteors.
• Matches for the Chelyabinsk, Benešov, Košice, and Tagish Lake meteors are presented.
• Results enable inference about pre-entry asteroid structures, breakup behavior, and potential model refinements.”

“Asteroids populations are highly diverse, ranging from coherent monoliths to loosely bound rubble piles, with a broad range of material and compositional properties. These different structures and properties could significantly affect how an asteroid breaks up and deposits energy in the atmosphere, and how much ground damage may occur from resulting blast waves. We have previously developed a fragment-cloud model (FCM) for assessing the atmospheric breakup and energy deposition of asteroids striking Earth. The approach represents ranges of breakup characteristics by combining progressive fragmentation with releases of variable fractions of debris and larger discrete fragments. In this work, we have extended the FCM to also represent asteroids with varied initial structures, such as rubble piles or fractured bodies. We have used the extended FCM to model the Chelyabinsk, Benešov, Košice, and Tagish Lake meteors, and have obtained excellent matches to energy deposition profiles derived from their light curves. These matches provide validation for the FCM approach, help guide further model refinements, and enable inferences about pre-entry structure and breakup behavior. Results highlight differences in the amount of small debris vs. discrete fragments in matching the various flare characteristics of each meteor. The Chelyabinsk flares were best represented using relatively high debris fractions, while Košice and Benešov cases were more notably driven by their discrete fragmentation characteristics, perhaps indicating more cohesive initial structures. Tagish Lake exhibited a combination of these characteristics, with lower-debris fragmentation at high altitudes followed by sudden disintegration into small debris in the lower flares. Results from all cases also suggest that lower ablation coefficients and debris spread rates may be more appropriate for the way in which debris clouds are represented in FCM, offering an avenue for future model refinement.”