Determination of strewn fields for meteorite falls

Abstract

When an object enters the atmosphere it may be detected as a meteor. A bright meteor, called a fireball, may be a sign of a meteorite fall. Instrumentally observed meteorite falls provide unique opportunities to recover and analyse unweathered planetary samples supplemented with the knowledge on the Solar System orbit they had. To recover a meteorite from a fireball event, it is essential that recovery teams can be directed to a well-defined search area. Until recently, simulations showing the realistic mapping of a strewn field was difficult, in particular due to the large number of unknowns not directly retrieved from the fireball observations. These unknowns include the number of fragments and their aerodynamic properties, for which the masses of the fragments need to be assumed in a traditional approach. Here we describe a new Monte Carlo model, which has already successfully assisted in several meteorite recoveries. The model is the first of its kind as it provides an adequate representation of the processes occurring during the luminous trajectory coupled together with the dark flight. In particular, the model comprises a novel approach to fragmentation modelling that leads to a realistic fragment mass distribution on the ground. We present strewn field simulations for the well-documented Košice and Neuschwanstein meteorite falls, which demonstrate good matches to the observations. We foresee that our model can be used to revise the flux of extra-terrestrial matter onto the Earth, as it provides a possibility of estimating the terminal mass of meteorite fragments reaching the ground.

Bolide fragment detection in Doppler weather radar data using artificial intelligence/machine learning

“…(2004) and Moilanen et al. (2021). Both have potential benefits that tie back to the original problem statement and motivation behind this research.…”

“…2015; Moilanen et al. 2021). The period between the meteor terminus and impact with the ground is known as “dark flight” (Fries and Fries 2010c; Moilanen et al.…”

“…The period between the meteor terminus and impact with the ground is known as “dark flight” (Fries and Fries 2010c; Moilanen et al. 2021). NEXRAD radars typically interrogate a volume with a maximum altitude of ˜16 km, so direct detection of the luminous meteor by a weather radar is not expected although it is possible (Laird et al.…”

Dark-flight Estimates of Meteorite Fall Positions: Issues and a Case Study Using the Murrili Meteorite Fall

“…They describe their method in some detail and begin by fitting the later part of the observed bright flight, calculating forward and requiring any fragments to have an appropriate shape/density/mass to fit subsequent bright-flight observations. Most recently, Moilanen et al (2021) have published details of their modeling approach to dark flight, which incorporates both bright-flight and dark-flight calculations with modeling of fragmentation events, in order to derive a strewn field estimate to aid in search and recovery. For the Desert Fireball Network (DFN) recovery of Bunburra Rockhole (Spurný et al 2012), the paper summarizes the DFN approach as applied at the time; here we briefly describe the current DFN approach in more detail.…”

On the Mass Distribution of Fragments of an Asteroid Disrupted in the Earth’s Atmosphere

“…e mass distribution of recovered fragments after Košice meteorite fall was approximated in [69] using various complex statistical models having several adjusted free parameters; the most appropriate of them were bimodal Weibull, bimodal Grady, and bimodal lognormal distributions. e bimodal lognormal distribution and the more generic exponential distribution were used to model the meteoroid fragmentation in Monte Carlo simulations [70] to predict the strewn field of fallen meteorites, in particular for Košice. e exponential, bimodal exponential, q-exponential, and q-stretched exponential distributions were used in [71] to fit the Košice, Sutter's Mill, and Whitecourt meteorite mass distributions.…”