I first tried to have this paper published within the Electronic Journal of the Astronomical Society of the Atlantic. After review by one scholar, publication was refused. I thought there still may be some merit within the paper, thus this posting. The paper, the reviewer's comments and my replies follow in the hope that other comment will be generated both before and after the Jupiter/Shoemaker-Levy encounter. A Radical Path for Shoemaker-Levy In the popular press as well as peered journals, scientists have shown great interest in the coming collision between the twelve fragments of the comet Shoemaker-Levy and the planet Jupiter. The predicted date for the encounter is within July of this year. The anticipated scenario is illustrated as similar to a rock striking an ocean. With the velocity calculated at 60 km per second, the impact is thought to be as energetic as several atomic bombs. Unfortunately for earth bound observers, this spectacular solar system event is to occur on the far side of Jupiter and will not be directly observed. With Jupiter's rapid rotation, 9.841 hours at its equator, the after-effects of the event should be seen here in a relatively short time. What does not seem to have been considered in the comet-planet encounter are possible electromagnetic effects. This paper suggests that these effects may deflect the comet around Jupiter. The basis of this suggest is found within the work of Hannes Alfven. Alfven, writing with another Nobel laureate, Gustav Arrhenius, made an attempt to explain the explain the origin of the solar system by incorporating electro- magnetic forces. (footnote 1) There were two principles involved in the two scientist's text: 1. A critical ionization velocity. Simply stated when an object reaches a certain velocity it will ionize. The ionization depends upon two variables, the velocity itself and the chemical make-up of the object. This chemical make-up was charted by the two men as ranging from about 4 km per second for potassium and about 50 km per second for hydrogen. 2. Magnetic braking. When a object reaches a critical ionization velocity and ionizes, if falling towards a magnetized body, there will be a strong interaction between the two bodies. This interaction will be a discharge from the magnetized body to the approaching ionized body. The interaction will cause the body to deflect and tend to revolve around the magnetized body. This concept is not merely a theoretical or laboratory speculation. (The observation of the interaction between Jupiter and its satellite Io demonstrates the principle. One author, Belcher, calculates that two billion kilowatts of power are generated by this encounter. Belcher also notes in his conclusion that the electromagnetic effect between Jupiter and Io tends to slow Jupiter and increase the orbit of Io (footnote 2)) The context of these two principles was within an explanation by the two Nobelists of the Origin of the Solar System. This explanation, accepted by few now, has considerable merit as it is the only origin of the solar system theory which can explain the transfer of angular momentum from the sun to the planets. Another author, James McCanney, who sees a star like nature of Saturn and Jupiter, writing in the journal Kronos said: " .....two charging processes, both resulting in a net negative charge on a body moving in a hot plasma (either planetary radiation belts or the solar wind). The first has been detected and is induced as the body enters regions of varying electrical potential within the plasma. A small space craft can quickly change to a potential of 10,000 volts, so if size is assumed to be important, then a small asteroidal body could quickly change to a substantial voltage. This was observed when Pioneer-Saturn passed under the small asteroidal moon 1979-S2 and experienced a "great mass" with large magnetic field. The great mass sensed by telemetry was the result of the induced electric dipole force on the space craft...... The second charging mechanism occurs during the discharge of the Sun's (or Saturn's) capacitor formed by an excess current of protons in its solar wind. The capacitor forms between the negatively charged center star and the positively ionized nebular cloud which surrounds the star in the form of a donut. The discharge of this capacitor is triggered by the intrusion of an already charged asteroidal body (charged initially by the first process). Current flows in a line between the star and surrounding neutralizing ion cloud via the comet nucleus. Electrons flow outward from the negatively charged star (sometimes visible as the sunward spike) while positive ions flow inward form the nebular ion cloud (forming the comet tail). Due to the higher mobility of electrons, they arrive in greater numbers at the asteroidal comet nucleus which create the comet shape." [footnotes omitted] (footnote 3) McCanney, while not specially citing Alfven or Arrehenis, seems to compliment the principles which those scientists used to develop their origin of the solar system theory. These principles are rarely incorporated in other papers. One notable exception was a paper by Chang, Rahman, and White of the University of California, Riverside. These scientists conducted an experiment in which ice was shot out a laboratory gun. When the ice reached the critical ionization velocity (about 12 km per second) it did ionize and the scientists were able to photograph the event. (footnote 3) With a calculated velocity of 60 km per second it would seem that Shoemaker-Levy will reach a critical ionization velocity when it approaches Jupiter. A cautionary note from the writing of Arrehenius and Alfven is that those authors speak of relative velocity. It is beyond this paper's scope to calculate the actual relative velocity between SL-9 and Jupiter, but it appear to be have sufficient velocity to effect the Critical Ionization Velocity if the comets composition is mainly water. Chang et at calculated the CIV of water at 10 cm X 10 to the fifth power per second. If then SL-9 achieves a critical velocity when approaching Jupiter it should rapidly ionize and thus be electrically out-of-balance with Jupiter. There should then be a discharge from Jupiter, acting as a capacitor, to the comet. This discharge should cause the comet to circle rather collide with planet. This discharge which may be a specific demonstration of the transfer of angular momentum from a central magnetized body to an approaching object and would be similar to what Belcher observes between Jupiter and Io. Looking at an illustration within Louis Franks' The Big Splash, one can see that author indicating breakup of small comets approaching earth at a point 800 miles above earth by "tidal or electrostatic forces". Similarly, a recent article "Atmospheric-Scientists Puzzle Over High-Altitude Flashes" by Richard Kerr in Science, vol 264, 27 May 1994, may have an explanation within the framework of the CIV and magnetic braking theories. Another occurrence may be the so-called sun grazing comets. Here these objects "collide" with the sun and seem to skirt around it. See the Moon & Planets, 3rd Ed William K. Hartmen, figure 8-16 p 235 for photographs of a sungrazing comet). Hartmen also comments on page 233 that "...However, not all comet disruptions are due to solar heating in sun-grazers. Strangely, Comet Wirtanen (1957 VI) broke into two pieces near the orbit of Jupiter for no apparent reason." The reason could have been a strong electromagnetic interaction between Comet Wirtanen and Jupiter. Interestingly enough Alfven and Arrhenius would seem to deny this possibility. Paragraph 5.4 "LIMIT BETWEEN ELECTROMAGNETICALLY AND GRAVITATIONALLY CONTROLLED MOTION" within their Evolution of the Solar system yields an equation for a limitation on the radius of grains which would be effected by a plasma. This equation is the square root of the quantity found by multiplying 3 times the electrostatic potential (in esu) times the magnetic field (in G) times the Kepler period (in seconds) divided by the quantity of 8 pi squared times the speed of light times the density of the object (in g/cm cubed). This equation gives a limitation on the radius of the grain of 0.3 X 10 to the minus 5th power cm. In arriving at this conclusion, the two scientists use a an electrostatic potential of .001 esu and a magnetic field with a strength of .00003 Gauss. It is submitted that both variables should be several orders of magnitude higher when Shoemaker-Levy approaches Jupiter and thus the limitation imposed by the above equation may not effect the motion of the comet approaching the magnetic field of Jupiter. I note that McCanney claims that the discharge between Jupiter and Io is 5 million amps., so a discharge between Jupiter and Shoemaker-Levy probably cannot be ignored. If the comet does reach 60 km per second it may reach the critical ionization velocity relative to Jupiter and as a charged object it should interact with Jupiter in a way to deflect it from penetrating the atmosphere of Jupiter or breaking up before it reaches the Jovian planet. It is also speculated that the same process may have already caused Shoemaker-Levy to be as fragmented as observed. The common thought that tidal interaction or approach within a Roche limit caused the past break up would appear to be difficult to model, while a force acting at 90 degrees to the comet's direction would more readily yield a string of pearls break up as previously observed. Joe Canepa Footnote 1 Arrhenius and Alfven, Evolution of the Solar System, NASA SP-345 1976 Footnote 2 John W. Belcher, The Jupiter-Io Connection: An Alfven Engine in Space, Science, Oct 87, 169-175 Footnote 3 Tsuey-Fan Chang, H.U. Rahman, and R.S. White, Laboratory Simulation of Cometary Neutral Gas Ionization, Journal of Geophysical Research, Vol. 94 pp 5533-5538 Footnote 3 J. McCanney's two first two papers, in Kronos IX:1 Fall 1983, Kronos IX:3 Summer 1984 titled The Nature and Origin of Comets and the Evolution of Celestial Bodies Part I and Part II. These papers further discuss Jupiter as a capacitor. Reviewer's Reply Subj: Review of Joe Canepa's paper I have gone through Joe Canepa's outline "A Radical Path for Shoemaker-Levy" and the references he kindly supplied. While the premise that the fragments of Comet Shoemaker-Levy 9 (SL-9) will become charged and be deflected away from Jupiter is interesting there is nothing in the article to quantitatively prove this premise and the references are either questionable or do not fully support his position. First we will address the concept of Critical Ionization Velocity (CIV). While I had not heard of this phenomenon before reading this paper, a friend of mine was familiar with it and was involved in a Space Shuttle experiment on CIV a few years ago. According to the information she supplied (as well two of Mr. Canepa's references) CIV is only an important charging process for GASES not solids. The referenced paper by Chang, Rahman, and White (JGR Vol 94 pp 5533-5538) does not support Mr. Canepa's statement "When the ice reached critical ionization velocity... it did ionize and the scientists were able to photograph the event". In the abstract of the this paper it clearly states that CIV is "a triggering mechanism for the ionization of neutral gas by the plasma flow". There is nothing in this paper about any observed ionization or anomalous charging of the solid ice pellet used in their experiments. Even in the referenced work of Alfven and Arrhenius (NASA SP-345 1976) it clearly states in paragraph 21.8 that "the prescence of neutral gas, however, is a necessity for this effect (i.e. CIV) to occur". All the discussion in the portions this reference that I have received seems to deal with CIV in connection with gas clouds or small dust grains, not large objects like the nucleus of a comet. While I readily admit to my ignorance on the subject of CIV, the reading I have done indicates that it is limited to affecting gases and not large solid bodies. In addition, since the gases given off by a comet are only very weakly coupled to its nucleus, what happens to the gases after they are expelled by the nucleus will not affect the motion of the solid nucleus. Assuming for the moment that CIV DOES affect solids but at a slower rate (possibly because of the lower effective area-to-mass ratio of solids compared to gases), I would want to see some sort of calculation showing that a piece of ice the size of a comet nucleus can build up a large charge in the couple of days that SL-9 will exceed the CIV for ice. Without this key piece, there is no paper. Assuming for the moment that the nucleus does get charged, there is the issue of how its trajectory will be affected by the Jovian magnetic field. Mr. Canepa gives only hand waving arguments and cites generalized references to "prove" that the fragments of SL-9 will miss Jupiter because of being charged. One of the authors he cites for proof, James McCanney, lends absolutely no creedance to Mr. Canepa's arguments. McCanney, at best, plays it fast and loose with his facts and physics. Just scanning through the McCanney reference I was supplied, I found a dozen and a half errors, misexplanations, and outright fabrications of various issues in planetary sciences. And his explanation of how charged bodies interact with planetary electric and magnetic fields defies understanding by anyone with more than a sophmore college level education in the physics of electricity and magnetism. It just sounds like a lot of mumbo jumbo with no basis in any physics that I am aware of. I have also heard more about the journal in which McCanney's work originally appeared, KORONOS. I will spare the details but this "journal" is an unrefereed publication with a known history of publishing "fringe" science. It is hardly considered to be a reputable or trusted publication. If Mr. Canepa wants his work to be taken seriously, I strongly suggest that he use a different reference. Still, despite this I do agree that a charged body traveling through a magnetic field will have its path perturbed. That perturbing force, or Lorentz force, is given by: F = q v B sin(v,B) where F is the force, q is the body's charge, v is the velocity of the body, B is the magnetic field strength, and sin(v,B) is the sine of the angle between the velocity and magnetic field vectors. The force would be directed perpendicular to both the velocity and magnetic field vectors according to the right hand rule. With this in mind we can perform a little thought experiment. Imagine a positively charged body (as Mr. Canepa claims a comet fragment would be) is moving in a prograde path parallel to the equator of a planet that possesses a simple dipole field with magnetic north pointing up like Earth. Using the right hand rule (i.e. the thumb of the right hand pointing down representing the magnetic field direction as it goes from the north magnetic pole to the south, the index finger extended out to be parallel with the ground representing the velocity vector, and the middle finger extended to the right representing the direction of the force) we can easily see that a positively charged body would be defelected AWAY from the planet which would be off to the left. Unfortunately, Jupiter's magnetic field is oriented in the opposite direction to that of the Earth. In other words, Jupiter's magnetic south pole is located near its geographical north pole. Again using the right hand rule but with the thumb pointing up to indicate the flipped magnetic field, we see that the charged body is now deflected TOWARDS Jupiter. Only after the positively charged body's orbit was perturbed from being prograde to retrograde would the object start to be deflected away from Jupiter. Given the speed of SL-9 and the strength of Jupiter's gravitational field, that would require a very hefty charge-to-mass ratio. While it is true that SL-9 will not be traveling parallel to the equator but at a 75 degree angle, this only serves to lessen the strength of the Lorentz force by about 74% requiring the object to have almost four times the charge-to-mass ratio to obtain the same amount of deflection. There is also the issue of what would happen if there was too much charge (assuming for the moment that the fragments' charging process is very efficient and that the fragments do not disrupt from electric repulsion). If the body gets too much charge, it will start to spiral along the magnetic field lines like the other charged particles near Jupiter. Eventually the fragments would hit Jupiter's atmosphere near one of the magnetic poles and be destroyed anyway. Personally I doubt we would have to worry about this scenerio. If any charging process was that efficient, the icy moons of the outer planets would have at least some measurable charged built up that would affect their motions. To my knowledge there have been no observations of outer planet satellite motions that support this. If Mr. Canepa wants to make a case that fragments of SL-9 will miss Jupiter if they become charged, I would want to see some calculations to quantify at what charge-to-mass ratio the minimum required deflection could occur given the path of SL-9 through the Jovian magnetosphere. Once this minimum charge-to-mass ratio is calculated, it should be checked against the previous calculations of the amount of charge the fragments of SL-9 would expect to get from CIV or some other process. If the fragments have more than the needed charge, then Mr. Canepa will have a reasonable case to make. Drew LePage Reply Both these objections have some validity. First, Alfven & Arrhenius were discussing the conditions which they thought occurred prior to the formation of the solar system. With one exception, these conditions apparently did not include either solids or liquids. Alfven, did state in his 1978 thesis Origin of the Solar System that ".. there is no known mechanism for the transfer of momentum to a solid body,.." He therefore proposed that the transfer of angular momentum occurred from the central magnetized rotating body to a dusty plasma and the dusty plasma eventually evolved into the systems of planets and satellites that we see today. The exception to the concepts that Alfven and Arrhenius without question solids. The limitation which A & A impose is upon the radius of the particle and has nothing to do with whether the particle is solid liquid or neutral gas. A & A place a limit on the size of a particle which can be controlled electromagnetically rather than gravitationally. In proof that he and Arrhenius used they ended there paragraph with: "In our numerical examples, we have assumed the electrostatic potential to be a few volts. This is a value for a charged solid body in a laboratory plasma. ....It is known that spacecrafts often acquire a potential of some thousand volts due to the charge received by high energy particles......" In short A & A's proof is not an absolute and is dependant upon variables such as the voltage acquired by the body approaching the central body and the strength of the magnetic flied of the central body. The magnetic field of Jupiter has been measured as 4.2 Gauss (in contract to A & A's 3 X 10 [minus 5th power]). It is submitted that this value may also be a variable. The amount of charge which SL-9 fragments acquire will certainly exceed the A & A 10 [minus 2 power] and do so by several orders of magnitude. The application of the electronically induced motions to solids, as opposed to neutral gases, would seem to be dependent upon the chemical make up of the solid. The Chang et al experiment was made to simulate what these scientists thought were the make-up of a comet nucleus. The experiment was conducted by placing an ice ball of 1.5 cm diameter in a vacuum chamber and subjecting the ice to plasma shoot from a plasma gun. The scientist could vary both the velocity of the plasma and the magnetic field via a coil around the vacuum chamber. Application of the plasma stream to the water ice ball did produce the desired CIV. To argue therefore that CIV applies only to gases has a quality of argue for debating points as opposed to trying to learn something. The Chang experiment started with an ice ball and produced the CIV. The stage in the experiment where the water ice ball became water vapor does nothing to negate the fact that a water ice ball subject to sufficient plasma velocity and magnetic field strength will show a rapid increase in ionization. The CIV effect is no longer a subject of doubt as a result of the experiment. The predicted CIV of approximately 12 km per second was demonstrated. The next step in the A & A reasoning, magnetic braking is what my paper is trying to address. The transfer of angular momentum to a solid body which Alfven did not see in 1978, was shown in the interaction between Io and Jupiter and discussed within the Belcher Science paper. I note that Drew Lepage does not even mention the Belcher paper, but according to Belcher Io is being subject to an electromagnetic force in terms of millions of watts and that force is moving Io away from Jupiter, albeit in Belcher's hundreds of kilometers over a billion years. Why this is apparently not happening to other satellites subject to the central bodies magnetic field is another good point and should be further explored by others. McCanney claims that Dione is similarly effected by Saturn. To analyize each satellite and each magnetic field Drew Lepage's comment as the direction of the Lorenz force is an excellent point. If SL-9 does deflect towards Jupiter, Lepage's suggestion is one explanation. The question is whether electromagnetic forces will alter the course of SL-9 and this question should be answered by observation within a matter of days. It is interesting that despite indications by the self-described conservative scientist, Louis Frank, that objects approaching Earth are observed to break-up by "tidal or electrostatic forces", that no one seems to want to apply the electrostatic approach to SL-9. The reason for this omission in the literature may be two fold. First here on Earth, matter for the most part is in the neutral state. In space, however, the opposite is true: Matter is overwhelmingly in the plasma state. Secondly, plasma physics seems to be a field which is so complex that only plasma physicist can effectively communicate with other plasma physicists, leaving most other scientists and scholars unaware of basic plasma principles. This is demonstrated by the scholarly Drew Lepage never even hearing of the term Critical Ionization Velocity and by items such as within a note in the August issue of Sky & Telescope page 13 where it was said that astronomers were "baffled" what an observation of Supernova 1987A. It is submitted that if the astronomers considered that the observed matter in the post supernova scenario was subject in the plasma state and subject to electromagnetic forces they may not have been as baffled. In asking Drew Lepage's permission to post his comments, Drew ventured further: "I would just like to emphasize that the one glaring omission from your paper is the lack of any quantitative analysis. First you have to calculate how much charge the comet fragments will build up and present them in such a way that others can follow your reasoning and verify the results. Secondly, you have to calculate how much deflection will take place for a given build up of charge again in such a way that others can follow your reasoning and verify the results. You just can't make the statement "the fragments will become charged and therefore will be deflected". Depending on what the charge-to-mass ratio (Q/M) of the fragments are, you could have any of the following situations: 1) Zero to low Q/M: The fragments are not deflected at all or are only slightly deflected but still collide with Jupiter 2) Low to moderate Q/M: The fragments are deflected but still hit Jupiter, just further away from the limb and out of view from us on Earth 3) Moderate to high Q/M: The fragments are completely deflected away from Jupiter and out into a "safe" retrograde orbit. 4) High to very high Q/M: The fragments become trapped along Jupiter's magnetic field lines and oscillate between the magnetic poles eventually colliding with Jupiter. You have to be able to quantitatively demonstrate which of the four scenarios will take place and NONE of your references give this sort of information. Without a quantitative, verifiable calculation,there is no science and your premise is nothing more than a untestable belief. I wish you the best of luck with this. Thanks for the opportunity to review your paper. It was a good exercise in physics." Drew LePage Further Reply Drew Lepage is correct in that the paper fails to quantify. There is little quantification I can do from "an armchair" in Kitty Hawk. The purpose of the paper is to stimulate others into inquiries as to electromagnetic effects and solar system events. If Lepage's (1) occurs, then there would seem to be little point in pursuing the question further. If the encounter produces (2), (3) or (4) then looking further may yield rich results. The difference between Alfven's beginning of the solar system model parameters and those proposed by a Jupiter encounter may vary by 13 orders of magnitude. The square root of 13-14 orders of magnitude is 7.0 - 6.5. This would lift the limiting radius from the Alfven Arrhenius 0.3 * 10 (-5 power) cm to only 10 (1.5 - 2) cm. The problem with this simplistic calculation is that the composition and size of the comet fragments are not certain, so the ability to hold a charge is not easily ascertained. One must also consider the nature of the comet itself with its tail of particles stretching millions of kilometers. Since these particles do occasionally ionize, one wonders what effect the magnetic field of Jupiter and whether this effect the charging process of the fragments of the nucleus. The Jupiter atmosphere with its huge storms, lightening which is thought to be many orders of magnitude greater than that we observe on earth, and 10 hour rotation, the Jupiter atmosphere must contain much matter in the plasma form. If approached by a comet containing much charged matter, will the Jupiter magnetic field be a consistent 4.2 Gauss and what will the probable current flow? The last sentence within the Belcher paper on the Jupiter/Io interaction was: "The insights provided in quantitative measurements in complicated systems such as this help us understand better the physics of other large-scale plasma systems found in nature, the vast majority of which are not subject accessible to direct investigations." It is submitted that the interaction between a Jovian planet and a comet is perhaps more complicated that of a planet and its satellite. The study of this interaction can only add to our scientific knowledge, thus the rationale for this posting. Joe Canepa