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www.niger-meteorite-recon.de
Niger 2002 - illustrated report
go to page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | Team | Area Map
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With a diameter of 300 kilometres asteroid Gaspra belongs to the larger representatives of his kind. Today scientists assume that these planetoids are already differentiated in a metallic core and a mantle composed of silicate material.
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As we move away from the river deposits we change course the following day and continue in south-westerly direction. Its not until early midday that a shallow plateau comes into view that bears no sign of rocky debris on its surface. Tension rises as our Landcruisers cautiously navigate uphill through winding gullies in the escarpment. Up on top of the plateau a bright gravel surface awaits us on which meteorites, should they be here, could easily be recognized. At walking speed we follow a zigzag course calculated by our GPS to cover the terrain to a maximum extent. Three binoculars in each of the two cars scan the ground with determined concentration.
Shortly before we have to suspend the search due to the brutal midday heat we finally succeed. The second jeep gives a signal. Souleymane, the interpreter, has spotted a dark rock. A test with the magnet detected an appreciable amount of iron, which is a good sign, since even the stone meteorites contain a detectable fraction of fine grained nickel-iron. As I come up the team stands reverently silent in front of a fist sized chestnut-colored stone, which rests embedded in the bright gravel surface. They are waiting to hear the judgment of the "Mudir".
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Type 6 chondrite as found
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My initial impression fulfils their expectations. No doubt, it came from outer space. The dark layer of oxide indicates that this specimen already spent a considerable amount of time in the desert. The pitch black melted crust a meteorite shows after its fiery passage through the atmosphere has long since weathered away. This piece of rock might have been here as long as 5,000 years. But the visitor from the asteroid belt still bears the scars of a fiery encounter with our planet. Almond-shaped depressions called regmaglypts are formed by the atmospheric-induced turbulence in the melting mantle during its penetration of the upper atmosphere. Reagmaglypts clearly document the speed of cosmic matter with velocities up to 156,500 mph in the early entry stage.
Collisions of these celestial bodies can release gigantic clouds of debris that might overcome the gravity of their parent body and start to cruise in different orbits. From time to time they get attracted by the mass centers of other planets in the solar system.
Especially large planets with thin atmospheres are under frequent bombardment of these asteroid fragments.
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A neolithic grind stone called a saddle quern. Together with a convex or barrel shaped rubbing stone the quern was used to grind corn, to crush roots, or to extract color pigments for example from red chalk. Quite frequently one finds these tools intentionally broken and destroyed. The cause is not quite clear but scientists presume that some cult rituals may explain this phenomenon.
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Earth is a target as well. Day after day thousands of meteoroids rain down on our world. Most of them are tiny specks of rocks that disintegrate completely early during their entry. But about five to ten times a year larger specimens are witnessed to fall and fragments are recovered. Those who have had the fortune to experience such a rare sight report spectacular sound and visual phenomena.
Forked lightning out of the blue, whizzing sound as if hot metal had come in contact with water, smoke-trails, thunder and sonic booms are common sights experienced by someone who has a close encounter with a meteorite. Some have reported feeling the pressure wave of sonic booms during these encounters.
www.niger-meteorite-recon.de
Niger 2002 - illustrated report
go to pagee: 1 | 2 | 3 | 4 | 5 | 6 | 7 | Team | Area Map
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