Sikhote-Alin: Iron Survival and the Mass Density of a Strewn Field

This paper computes a complete entry budget for the Sikhote-Alin fall, working only from published values and stated assumptions. The nominal body has a diameter of 2.58 metres at a bulk density of 7.80e+03 kilograms per cubic metre, giving an incoming mass of 70 tonnes. At the published entry speed of 14.5 kilometres per second its kinetic energy is 1.76 kilotonnes of TNT equivalent. At the characteristic altitude of 5.6 kilometres the exponential atmosphere has a density of 0.563 kilograms per cubic metre, the ram pressure on the body is 118 megapascals, the stagnation heating flux is 8.58e+05 megawatts per square metre, and the aerodynamic deceleration is 900 times terrestrial gravity. The ram pressure first reaches representative material strengths at computed altitudes of 56.5, 40 and 28.4 kilometres for the weakest, intermediate and strongest cases examined. The recovered material, the collected iron mass held in collections, amounts to 2.30e+04 kilograms, which is 32.9 percent of the computed incoming mass. The largest recovered piece, at 1.74e+03 kilograms, has a characteristic diameter of 99.3 centimetres, a terminal velocity of 277 metres per second, a fall time of 20.2 seconds from the end of the luminous path at 5.6 kilometres, and a wind drift of 202 metres under a representative wind. Over the mapped strewn area of 12.5 square kilometres, the recovered mass corresponds to 1.84e+03 kilograms per square kilometre. The fragment census gives a mean collected mass of 65.7 kilograms per fragment. The largest stone, at 1.74e+03 kilograms, carries 7.59 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.