Questions about Cratering in the Solar System

Your post raises several questions. First you introduce the matter of Tunguska and require further information about this.

Let me preface my remarks by noting three points. First, that every planet has an ionosphere or plasma-sphere/magnetosphere enveloping it. Jupiter's, for instance, ranges from 3-7 million miles across. These ionospheres then stretch out behind each planet, away from the sun, like a giant wind sock. Jupiter’s reaches beyond Saturn. In the inner Solar System, satellites and probes have detected “stringy things” from Venus’ plasmasphere reaching as far as Earth’s orbit. Second, the solar wind, a stream of positive particles (mainly protons) from the sun, accelerate away from the sun and keep going faster the farther out in the solar system they are. This indicates that the solar system has a potential gradient being progressively more negative the farther out you go. So all the plasmaspheres are at an increasingly negative electric potential going away from the Sun. Third, when there is a planetary alignment, such as Sun-Jupiter-Saturn, then Jupiter’s plasma-sphere interacts with Saturn’s more negative plasmasphere, perhaps with an interplanetary lightning discharge. Today, these plasmaspheres are in dark current mode and so are invisible to our naked eye, but seen by instruments (IR and radio). But in the early days of our solar system currents were higher and voltages greater. Thus Jupiter’s visibly glowing plasmasphere was the largest object in the Solar System in the night sky – larger than the Sun by day but not nearly as bright. And so Jupiter was called the ‘King of the Gods’. When it lined up with Saturn, in the early days, the interplanetary lightning discharge between them would have been very visible. Similarly for other planets, which may be the origin of the idea of the Thunderbolts of the Gods, and the old fear that terrible things will happen when the planets align.

With that introduction let me get back on track about Tunguska. On about June 30th 1908, there was an unusual alignment of the Sun, Mercury, a comet (Encke, I think), Venus, and Earth. The key eyewitness said that they saw a blue-white streak coming in the sky for about 7 minutes before the explosion. A meteorite does not take that long to go through our atmosphere, and no meteoritic debris of any significance has been found associated with Tunguska. However, if it was an interplanetary lightning bolt similar to that experienced in the much earlier days of our Solar System, the 7 minute travel time would make sense. So, too would a lot of other features of the event. So, at the moment, my money is on an interplanetary lightning bolt as the cause of the Tunguska event.
You go on to talk about “electrically induced shock waves” associated with bolides or asteroid fragments coming through our atmosphere. There is an element of truth in this as meteorites and asteroids come from the asteroid belt. Other objects may come from the Kuiper belt. In both cases, these regions of the Solar System are at a more negative potential than the Earth’s environment. Therefore, as they come in to our atmosphere, some electrical discharge might occur, depending on the size of the object: larger bodies might be expected to have a greater charge. So relatively small bodies would probably have a lesser discharge. In these cases, the effects would not be described as “explosive”. However, in the case of very large objects, the story might be different. To put this in perspective, the Tunguska event released something like the energy equivalent of 500 kilotons of TNT. The Hiroshima bomb was only 15-20 kilotons of TNT. This Tunguska event, 25 times stronger than the first nuclear blast, is probably the full size of a blast of an interplanetary lightning bolt – it is top of the range in its class! All other astronomically induced electrical interactions with individual items of asteroidal or meteoritic debris would be significantly less. A whole swarm of such debris might be a different story, however. Such events occurred at the close of each geological Eras (which correspond with key Biblical events according to the research I have been involved with).

You then write that

“Others have even suggested that the physical impact of a bolide with the ground exceeding 10m/s would result in the necessary temperature-pressures required to initiate a thermonuclear detonation of the bolide, or even that explosive charge differential has somehow initiated nuclear fusion in the materials of the bolide.”

These claims do not bear close examination. While some impact events on earth have been so powerful that their energy release has been many times greater than a Hiroshima bomb, the explosion itself was definitely non-nuclear in origin. Even the interplanetary lightning bolt of Tunguska was not from nuclear fission or fusion. Indeed, the huge impacts which closed the geological Eras were not nuclear in origin, nor did they ignite a thermonuclear response. If they had, the relevant chemical elements would still be in evidence, but there are none. To think otherwise is misleading speculation without any evidence.

The final paragraph is a quote which reveals some lack of understanding of what is going on with the impact of asteroidal or meteoric debris, no matter what size. Let me walk you through such an event and clear up some misconceptions as we go.
Bolides, meteorites, asteroids or whatever, can impact the earth at speeds of up to 45 miles per second. The object can approach the ground from any angle. The statement was made that implied that any angle other than vertical produced elongated craters. This is false as will be shown in a moment. Elongated craters can only from low velocity impacts at shallow angles. To understand why, look at the data we have from impact experiments and actual impact events where nickel-iron fragments rich in iridium – only found in asteroids in those isotopes and concentrations -  have permeated the whole structure and surroundings. This is obviously not just a lightning-type discharge but an impact of some cosmic body.

As the body hits the ground at an angle its high speed causes it to bore its way into the ground.  The object is moving so fast that the ground does not have time to get out of its way. The fastest the ground could possibly move to do that is the speed of sound in rock, and the maximum for that is given by the P waves in earthquakes as 5 miles per second. The object is usually traveling at speeds from 7 miles per second (minimum) to 45 miles per second (maximum). As a result, the impacting object bores a hole and pushes ahead of it an increasingly large plug of matter whose temperature and pressure increase as the impact energy is absorbed. The temperature of this plug of matter is over 1200 degrees Celsius (2200 degrees F) and the pressures ranging above 100,000 atmospheres (10 Giga Pascals - GPa). At the point where the impact energy is absorbed and the forward motion of the impactor is stopped, the plug of matter is at a temperature over 1700 C (3100 F) and pressure over 500,000 atmospheres (50 GPa). Since these conditions are in excess of the melting point of silicon dioxide, a major component of rock, it may be assumed that some of the plug of matter has vaporized. At that point a massive, non-nuclear, explosion occurs. While the trajectory of the impactor is at an angle to the ground, this has no effect on the resulting explosion. The resulting crater is radially symmetrical (circular) about the explosion point.

We know these facts from the experimental results of high energy impacts. Furthermore, these results coincide with what we find associated with actual impact craters from asteroids where there is a high concentration of nickel-iron and iridium. The high temperatures and pressures convert silicate rocks into unique forms of shocked quartz, namely coesite (formed at pressures above 2.5 GPa and temperatures above 700 degrees C) and stishovite (formed above 10 GPa pressure and above 1200 degrees C). There are other details which confirm this scenario. While high temperatures may be attainable by electric discharge and its machining, the extreme pressures are not attained by that process as evidenced by the Tunguska event where no coesite or stishovite was produced.

For a detailed comparison between craters formed by Electric Discharge Machining (EDM) and impact and a simple experiment which may be done, please read my article on Crater Origins.

On that URL you will also find a list of the characteristics which distinguish EDM craters from the impact variety. This work was initially praised by the Electric Universe principals in one of their discussion forums. Later they took the view that all craters had to be from EDM in their presentations, despite the experimental evidence. This is disappointing and misleading and has given rise to the sort of discussion you have been involved with.