Park Forest: A Suburban Strewn Field and the Mass Budget of a Fragmenting Stone

This paper computes a complete entry budget for the Park Forest fall, working only from published values and stated assumptions. The nominal body has a diameter of 0.7 metres at a bulk density of 3.40e+03 kilograms per cubic metre, giving an incoming mass of 0.611 tonnes. At the published entry speed of 19.5 kilometres per second its kinetic energy is 0.0277 kilotonnes of TNT equivalent. At the characteristic altitude of 25 kilometres the exponential atmosphere has a density of 0.038 kilograms per cubic metre, the ram pressure on the body is 14.5 megapascals, the stagnation heating flux is 1.41e+05 megawatts per square metre, and the aerodynamic deceleration is 929 times terrestrial gravity. The ram pressure first reaches representative material strengths at computed altitudes of 60.8, 44.2 and 32.6 kilometres for the weakest, intermediate and strongest cases examined. The recovered material, the recovered stones collected across the fall area, amounts to 18 kilograms, which is 2.95 percent of the computed incoming mass. The largest recovered piece, at 2.5 kilograms, has a characteristic diameter of 11.2 centimetres, a terminal velocity of 93 metres per second, a fall time of 129 seconds from the end of the luminous path at 12 kilometres, and a wind drift of 1.29e+03 metres under a representative wind. Over the mapped strewn area of 20 square kilometres, the recovered mass corresponds to 0.9 kilograms per square kilometre. The fragment census gives a mean collected mass of 0.09 kilograms per fragment. The largest stone, at 2.5 kilograms, carries 13.9 percent of the recovered total. All values are computed by the deposited program from the stated inputs; scenario calculations accompany every headline figure so that the sensitivity of each conclusion to its inputs is visible in the same record.