Hoba Iron Merteorite / no crater or impact rocks !! The Hoba meteorite is thought to have fallen more recently than 80,000 years ago. It is inferred that the Earths atmosphere slowed the object to the point that it fell to the surface at terminal velocity, thereby remaining intact and causing little excavation. Assuming a drag coefficient of about 1.3, the meteor would have been slowed to a mere 716 miles per hour (320 metres per second (1,000 ft/s) )(contrast this with typical orbital speeds of several km/s). The meteorite is unusual in that it is flat on both major surfaces, possibly causing it to have skipped across the top of the atmosphere in the way a flat stone skips on water. The Hoba meteorite left no preserved crater and its discovery was a chance event. The owner of the land, Jacobus Hermanus Brits, encountered the object while ploughing one of his fields with an ox. During this task, he heard a loud metallic scratching sound and the plough came to an abrupt halt. The obstruction was excavated, identified as a meteorite and described by Mr. Brits, whose report was published in 1920 and can be viewed at the Grootfontein Museum in Namibia. Hoba is a tabloid body of metal, measuring 2.7×2.7×0.9 metres (8.9×8.9×3.0 ft). In 1920 its mass was estimated at 66 tons. Erosion, scientific sampling and vandalism have reduced its bulk over the years. The remaining mass is currently estimated at just over 60 tons. The meteorite is composed of about 84% iron and 16% nickel, with traces of cobalt. It is classified as an ataxite iron meteorite belonging to the nickel-rich chemical class IVB. A crust of iron hydroxides is locally present on the surface, owing to weathering.
Posted on: Fri, 21 Nov 2014 23:27:03 +0000
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