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 Credit: NASA/JPL-Caltech |
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Aug 25, 2004 Overlapping, central peaks, clean excavation, melting, and "pinched up" rims are all signs of electrical discharge machining for these crater chains. The chances of having an impacting body break up to form a neatly graded and spaced line of objects that might provide this series of overlapping craters is practically zero. Instead, crater chains are a common result of electric arcs passing over a cathode surface. With slight variations in the current or the surface, the arc may stop jumping from one crater to the next and cut a trench instead. In this example on Jupiter's moon, Ganymede, the craters overlap so closely that the distinction between "crater chain" and "straight rille" blurs. There are sections of this crater chain that could pass for a rille. When examined closely, the smaller rilles in the image have scalloped sections that could pass for overlapping craters. Notice that the sizes of the craters are similar, with an increase toward the middle. From an Electric Universe point of view, this size gradation is a reflection of the initial increase in current as an arc becomes established, followed by a decrease as the arc quenches. In lightning strikes with multiple strokes, the middle strokes are usually the strongest. Notice also that many of the craters retain their central peaks. The arc that carves a crater is a Birkeland current consisting of a pair of filaments that rotate around the current's axis. If the crater is large enough, the two filaments will not meet in the center, leaving a central spire intact.
Because the arc lifts material from the surface,
the excavation is left relatively clean. Only a small portion of the
detritus falls back around and in the crater or rille. The "collapsed
lava tube" explanation of rilles fails on this account: The remains of
the tube's roof are not inside the rille. "Missing" debris is one
defining characteristic that distinguishes electrical erosion from
mechanical processes: The debris is not really "missing", itıs just not
where other processes typically leave it Melting is another defining characteristic of electrical erosion. Although extensive melting is ascribed to impacts, impacts in fact produce little melting. The particles of rubble may be immersed in hot gases from the impact, but the heat dissipates too quickly for conduction to carry much of it into the particles. Electrical erosion, on the contrary, generates heat inside the eroded particles, in the manner of a heating element on an electric stove. A general expectation of the Electric Universe is that the floors of craters and rilles will show extensive glassification. Unfortunately, it can only be confirmed by on-site observations. A final observation is that many craters appear to have their rims "pinched up," rather than "rolled over" or splattered as would be expected from debris thrown out by an impact. Many rilles, too, have "pinched up" dikes along their edges. This emphasizes the indication from missing debris that the erosional forces were directed upward. |
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Copyright 2004: thunderbolts.info |
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