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*To*: dinosaur@lepomis.psych.upenn.edu*Subject*: Bolides and crater diameters*From*: pjanke@maroon.tc.umn.edu*Date*: Fri, 12 Aug 1994 18:32:59 -0500 (CDT)

Eugene Shoemaker describes a formula for calculating the relationships between a bolide's kinetic energy and what the associated crater diameter would be if it should hit mother Earth. The calculations are slightly involved so I will only summarize how his model works. Get the article if you want to try this at home ;-) D = C Kn W where D=crater diameter in km C=collapse factor(1 for craters <=3km and 1.3 for those >=4km Kn=(0.074 km kilotons)^-1/3.4 W = the kinetic energy of the incoming body... The constant (Kn) was derived using empirical data from the Jangle U nuclear test site in Yucca Flat, Nevada. I did a few simulations using this formula. The first three cases assume a bolide with a density of 3grams/cc hits Earth. CASE 1 bolide diameter = 10km bolide velocity = 20km/sec resultant crater= 136km diameter CASE 2 Same bolide at twice the velocity(40 km/sec) resultant crater= 205km diameter Note: You can see why 10km is a convenient estimate for the size of the bolide that resulted in the Chicxulub(180km) structure. CASE 3 What if fragment "G" of SL9 which recently hit Jupiter were to hit the Earth instead? resultant crater= 60km diameter CASE 4 "Reverse engineer" the Barringer Crater(Meteor Crater, AZ). Since we have evidence for an iron/nickel body, let's assume the density to be 10g/cc. The original bolide would then have a diameter of 40meters. -Paul --- References: Asteroid and Comet Bombardment of the Earth, Eugene M. Shoemaker, Ann. Rev. Earth Planet Sci., 1983,41.

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