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What do Meteorite Falls Tell Us about the Strength of Asteroid Boulders?

Author: 
Michael Demasi
Topic: 
Asteroid Population Characterization
Delivered As: 
Poster
Abstract Text: 

One of the questions raised by the proposed Asteroid Retrieval Mission (ARM) is “what is the strength of a boulder on an asteroid’s surface?” One possible source of data is the meteorite collection. Since highly fractured boulders should breakup in the atmosphere and arrive as meteorite showers, the abundance of showers vs. boulders can provide insight into boulder strength. About 85-95% of a meteoroid’s mass is lost during atmospheric entry, so we have defined a meteoritic “boulder” as having a final delivered mass of 10 kg. Using the Catalogue of Meteorites published in 2000 and the Meteoritical Bulletins published from July 2004 through April 2012 [1,2,3], we compiled a list of all observed meteorite falls with a total recovered mass greater than or equal to 10 kg. We found a total of 279 meteorites that meet these criteria, ranging in total recovered mass from 10 kg to 27,000 kg, over a sample size of 270 meteorites (nine falls were incompletely reported in the cited literature), and ranging in largest individual mass in the fall from 0.5 kg to 20 000 kg, over a sample size of 254 meteorites (in 25 cases the largest masses were not reported). The mean and standard deviation for the total masses of the falls was 266.37 ± 2057.89 kg while that for the largest individual mass in each fall was 135.60 ± 1260.20 kg. The frequency representation of the both the total mass and largest mass populations resembled a power law distribution with the smallest objects being by far the most common.
In determining which multi-stone falls were to be classified as boulders and which were to be classified as showers, a demarcation line of 10 stones as the maximum number for “boulder” compared to “shower” was employed. The ratio of boulders to showers reported was found to be around 3.53:1, with 200 boulders and 73 showers reported. The overall percentage of observed single-stone falls was found to be around 42.5%, based on a sample size of 275 meteorites.

References:
1. Grady, M. M, and A. L Graham. Catalogue Of Meteorites: with special reference to those represented in the collection of the Natural History Museum, London. Cambridge: Cambridge University Press, 2000. Print.
2. Russell, Sara S., Luigi Folco, Monica M. Grady, Michael E. Zolensky, Rhian Jones, Kevin Righter, Jutta Zipfel, and Jeffrey N. Grossman. "The Meteoritical Bulletin, No. 88, 2004 July". Meteoritics & Planetary Science 39, Nr 8 (2004): Supplement, A215–A272. Print.
3. Russell, Sara S., Michael E. Zolensky, Michael E. Zolensky, Luigi Folco, Rhian Jones, Harold C. Connolly, Jr, Monica M. Grady, and Jeffrey N. Grossman. "The Meteoritical Bulletin, No. 89, 2005 September". Meteoritics & Planetary Science 40, Nr 9 (2005): Supplement, A201–A263. Print.

Co-Authors: 
Andy G. Tindle, Simon P. Kelley and Judith M. Pillinger
SSERVI Identifier: 
NESF2016-038

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Recognizing that science and human exploration are mutually enabling, NASA created the Solar System Exploration Research Virtual Institute (SSERVI) to address basic and applied scientific questions fundamental to understanding the Moon, Near Earth Asteroids, the Martian moons Phobos and Deimos, and the near space environments of these target bodies. As a virtual institute, SSERVI funds investigators at a broad range of domestic institutions, bringing them together along with international partners via virtual technology to enable new scientific efforts."