The Electric Comet theory

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solrey said:
Hmmmmm, could I just maybe know what I'm talking about here? :cool:
seattlecentral.edu/faculty/mvillarba/CHEM139/Chapter08.pdf
pg. 9

In the case of the comet, we're dealing with a gaseous solution instead of an aqueous one, but the chemistry remains the same as it's only H+ and OH- (from the mineral base) that are involved in the reaction.
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As I understand chemical reactions, the energetics have to work out too.

For example, fire a stream of relativistic protons into a cloud containing lots of OH radicals, and you don't get any water!

Further, densities matter (pardon the pun); the proton-OH radical reaction rate in a low density gas (or plasma) will likely be extremely low (unless there are special circumstances), and IIRC the density in a comet's coma would make it a very good terrestrial vacuum.

The next reaction in the chain is the electro-chemical reaction between the mineral salts and H2O




That's one key reaction chain. I see several others that could apply to comets as well, in the above pdf., primarily the H2O produced by a Hydrogen - Oxygen reaction either thermally induced (burning in the heat of the discharge on the surface) or catalytically (analogous to the catalytic reaction in a hydrogen fuel cell).
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See above.

I suspect data on reaction rates vs density would be relatively easy to find.

There's also temperature to consider.

I have confirmed the proposed composition of a semi-conducting rock via comparison with the material analyzed in the stardust mission and all of the necessary materials are present.

I have analyzed and presented citations confirming the chemical/electro-chemical reaction chains.
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But not - yet - shown what sort of rates these would proceed at, given the specific environments of comet comas.

Right?

I have reviewed the measured EM environment ( of one comet at least ) and compared it to laboratory research involving multiple double layers, ion-drag effects, as well as radius and thickness of the DL sheaths.
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You reminded me; your posts with materials on this are waiting for me to read and understand ...

I'll hopefully get around to doing the math as applies to comets, but I'm afraid that insufficient data is available for some critical variables so I'm going to have to make some educated guesses, I suppose.
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Yep ... but you should be able to constrain things quite nicely, by bounded estimates (e.g. highly unlikely to be greater than x, equally unlikely to be less than y).

But hey, it's just an "idea"...right? :rolleyes:
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Yes; it advances from that status once you've done back-of-the-envelope calculations, and can show consistency and quantitative plausibility (within a factor of 100 should suffice).
 
realitycheck,
Most of the articles on the EC/EU related sites are written for laypeople, to be understood by a variety of knowledge levels, same as most science interest sites, or print mags, cater towards a general audience.
There is a section in the forum as a repository for scientific papers for those who wish to dig deeper into more details.
Many of us are waaayyy beyond the comprehension level required for the general articles, some are not.
Personally, I'm also pretty good at applying theory to function.
Sometimes I screw up the terminology, or muddle through some of the details, I admittedly am missing the particular "pedigrees", and I welcome constructive criticism and feedback and try to respond with appreciation.
:o
 
An old question, solrey, which goes to consistency: why are comets different?

For example: why don't all those (electro-)chemical reactions happen on the Moon? or Eros? or the MESSENGER spaceprobe?
 
solrey said:
realitycheck, have you reviewed my comments regarding Main Belt Comets and localized perturbations to their EM/chemical environment initiating a cometary phase or display? Or remember that I've been saying that all densities are valid within the EC?

Just for the sake of discussion, to consider a comet of ~ 0.6 g/cm3, of similar material as revealed in Stardust, fits easily within EC, as a factor of porosity.
It's that simple. ;)

It's not worth dwelling on, really.

Tomaytow, tomahhtow...whaddya do?
:)
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The EC authors have stated that comets are asteroids. This makes density an issue because comets do not have the density of asteroids.

All you have to do is cite where this part of the EC idea has been retracted. It's that simple. ;)

The fact that this is part of the EC "model" makes it worth dwelling on. :)

If you want to change the EC idea from "comets are asteriods" to "comets are dustballs" then you should get the web site updated. After that you will have to show that dustballs can have the porosity that comet densities require. My impression is that in the scientific model it is dust combined with a bit of ice that allows the porosity of comets to be so high.
 
solrey said:
realitycheck,
Most of the articles on the EC/EU related sites are written for laypeople, to be understood by a variety of knowledge levels, same as most science interest sites, or print mags, cater towards a general audience.
There is a section in the forum as a repository for scientific papers for those who wish to dig deeper into more details.
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Can you give a link to the section in the forum used as a repository for scientific papers?
Maybe a list of the scientific papers published on the EC idea?

My guess is that the scientific papers are similiar to the ones you have been citing, i.e. papers with no menton at all of the EC idea.
This means that you have to show how these papers apply to the EC idea. That is impossible without an actual EC model other then "electricity did it".
 
solrey, I've started going through the material I hadn't read before, and the question I keep asking is "how is this relevant to comets?"

To take just one example, at random: you quote from a document on the types of discharges, in which glow discharges are characterised as occurring in low density plasmas (pressure of ~1 mbar, IIRC) ... but the density of the solar wind is way, way, way lower, and the density at the surface of Mercury, the Moon, ... essentially the same.

So if you are interesting in claiming that there are glow discharges on comets (whether of the magnetron variety or not), surely you need to show that the parameter space in which glow discharges have been observed overlaps with that of comets, don't you? And, as far as I can see, so far you haven't.

Also, the MESSENGER diagram refers to a magnetosphere, which plasma structure the Earth, Jupiter, ... also possesses, by virtue of their intrinsic magnetic fields. But in one post you stated, apparently quite clearly, that comets do not have intrinsic magnetic fields! If so, why do you expect the same plasma processes to occur in comets' comas?

I stress that this is just a random sample of questions, from a fairly cursory read of the material you have presented; however, I think it gives you an idea of the sorts of things you would need to address in order to move on from idea (well, some anyway; there is other stuff too).
 
solrey said:
Tusenfem, It's my understanding that the DL sheaths are perpendicular to the direction of particle flow. Introducing a magnetic field affects the direction of particle flow, thus the orientation of the sheaths. In the case of the comet, the particle flow is perpendicular to the surface therefore the sheaths will be perpendicular to this flow, thus parallel to the surface.
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It all depends on what kind of DL you are looking at (just using an ideal situation for simplicity). At the boundary of two different plasmas the "two charge layers" are parallel to the boundary. In a current carrying DL the "two charge layers" are perpendicular to the current direction.

I have no idea what you mean with "perpendicular to the particle flow." Just a particle flow (even when charged) will not generate a DL.

The solar wind draping around the comet will have plasma flow along it, and thus "parallel to the surface of the comet" Here is a figure showing the draped field (at venus). So, how do you put a DL in that picture? Also, the paper by Laakso says that The electric field component measured by the double probe antenna is almost parallel to y and is larger than the vxB electric field. Such strong fields cannot be supported near a comet and the reason such a large field is measure is because of photo emission, dust impact. The variations in the DC field that are measured correlate well with the measured ion fluxes.

So, we can see that the electric field is "in the flow direction" however this is most likely just the co-moving electric field of the solar wind. This layer where there is this electric field also has a current layer (which one would expect, in order to slow down the field as it drapes around the comet). The total potential drop that is estimated it large over the region but the region itself is also very large. However, this is a radial distance, which means perpendicular to the magnetic field. A double layer thus does not come into the picture as the 10000 km size of the layer is way to large for a DL (10 to 25 times the Debye length, see Alfvén). And there is the problem that it is unclear how this DL should be created, perpendicular to the magnetic field.

Ah, questions questions.
 
solrey said:
Note the qualifier, would, which I used intentionally. Not IS.
Regardless, the answer is that a DC electric field has been measured, as related below, but I don't have numbers on the exact strength of that field.
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You could always have asked for a copy of the paper.
The total potential drop over that layer was 50 kV according to Laakso.
Hardly your expected "orders of magnitude higher than 109 V."
 
Yep, relating the orientation of the DL to the direction of particle flow was not a good description. DL's around an electrode will generally be parallel to the surface, though.

Tusenfem, would you be so kind as to provide a link to that paper on the electric field?

Have you reviewed the papers I cited regarding Debye length, specifically this one?
Relationship Between the DC Bias and Debye Length in a Complex Plasma.
arxiv.org/pdf/astro-ph/0701063
 
Mercury like a comet? This is not just my opinion.

Mercury has a comet-like gas tail.

What about the atmosphere?

MESSENGER Scientists "Astonished" to Find Water in Mercury's Thin Atmosphere

Well, not really water. Water related ions, like OH-.

The surprising result is the detection of water-related ions like O+, OH-, and H2O+. Credit: NASA / JHUAPL / U. Michigan
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How could there be water on Mercury? Zurburchen listed three possibilities, which are not mutually exclusive. Firstly, it has long been theorized (but not yet proved) from Earth-based radar observations that there may be reservoirs of water ice in small areas of Mercury's poles where local topography creates permanently shadowed spots in crater walls that might trap water over the age of the solar system. Second, the water could come from comets. Third, the process of chemical sputtering could create water where none existed before from the ingredients of solar wind and Mercury rock, as Zurburchen explains.

"The solar wind is highly ionized. Those are radicals -- they want to make connections with everything that they can. Imagine a solar wind hydrogen showing up and hitting the surface. It weathers whatever the mineral is, and steals an oxygen. If you do that, you get something like OH-, for example." OH-, also known as a hydroxyl group, would produce a peak at atomic mass 17 on the FIPS spectrum. "You can do it in reverse -- an oxygen from the solar wind can steal a hydrogen. The process is called chemical sputtering."
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I think I've mentioned chemical sputtering as a way to produce OH-. Sodium is abundant, and the water related ions were surprisingly abundant, given the data on "magnetic tornado's", a.k.a. "flux transfer events", or a "discharge vortex" implies a Townsend dark discharge which could be another process for producing OH- as I've previously described. Was this overlooked, or was this discounted, or even feasible?


In an acid-base neutralization reaction,
– H+ from acid reacts with the OH– from base → water, H2O
– The cation (M+) from base combines with anion from acid (X–) → the salt

HX(aq) + BOH(aq) → H2O(l) + BX(aq)
acid base water salt
Note: -An acid will always react with a base to produce water and a salt.
– It does not matter if the salt produced is soluble or insoluble since water always forming means a reaction always occurs.

The next reaction that would occur is when that water then reacts with free electrons, liberated from the surface, within the electric field of the discharge current. Mineral salts in the dust and flakes etched from the surface are probably involved in this reaction. The cathode reaction is:
2H2O + 2e- -> 2OH- + H2
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The reaction chain would result in a certain ratio of leftover sodium, likely a factor of the strength of the discharge.

In September 1985, the International Cometary Explorer (ICE) Spacecraft passed through the plasma tail of Comet Giacobini–Zinner at a distance of 7800 km downstream from the nucleus. The relative velocity between comet and spacecraft was 21 km/s, and instruments aboard the spacecraft made magnetic field, energetic particle, and ion composition measurements. The composition measurements showed the presence of water group and CO+ions, as well as an appreciable, but localized flux of ions havingM/Q= 24 ± 1 adjacent to the edges of the plasma tail. These ions were tentatively identified by M. A. Coplanet al.(1987,J. Geophys. Res.92, 39–46) as either C+2or Na+. Motivated by recent observations of neutral sodium in the tail of Comet Hale–Bopp (G. Cremoneseet al., 1997,Astrophys. J. Lett.490, L199), the Giacobini–Zinner composition data have been reexamined, particularly with regard to the spatial distribution of theM/Q= 24 ± 1 ions, now identified as Na+. This conclusion along with other observations of neutral sodium in comets clearly show that there are a variety of sources of sodium in comets.
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:o
 
solrey said:
Mercury like a comet? This is not just my opinion.

Mercury has a comet-like gas tail.
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At that level, the Moon has one too (IIRC), as does Io (sorta), ... but 'a comet-like gas tail' does not a comet make.

From that article - which is not a paper, so one needs to take what it says with the appropriate caution - it seems the 'like' is limited to a shape and a linear dimension ... certainly the composition is different, etc.

Surely this can have relevance only if you can show - quantitatively (at the back-of-envelope level) - that your proposed 'generate gas tails' processes produce results which match the data (in this case, comets and Mercury)?

What about the atmosphere?

MESSENGER Scientists "Astonished" to Find Water in Mercury's Thin Atmosphere

Well, not really water. Water related ions, like OH-.





I think I've mentioned chemical sputtering as a way to produce OH-. Sodium is abundant, and the water related ions were surprisingly abundant, given the data on "magnetic tornado's", a.k.a. "flux transfer events", or a "discharge vortex" implies a Townsend dark discharge which could be another process for producing OH- as I've previously described. Was this overlooked, or was this discounted, or even feasible?
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Who knows?

One thing that is known is that Mercury has an intrinsic dipole magnetic field, of strength x, and comets don't.

Unless and until you start crunching some numbers, it's all just disconnected ideas buzzing around, isn't it?

Oh, and once again, a popsci article is not a paper (who knows; perhaps most of what's here would never appear in a peer-reviewed paper, if only because it's too speculative?)

The reaction chain would result in a certain ratio of leftover sodium, likely a factor of the strength of the discharge.




:o
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Same comments as above ... time to roll up your sleeves and start making some serious estimates?

Oh, and what is the source of the last two quotes? It's always a good idea to provide details of your sources ...
 
From Science News, August 1985

The relative abundance of sodium in Mercury's atmosphere invites comparison with Jupiter's satellite Io, which also has a lot of sodium. In Io's case sodium appears to be sputtered off the satellite's surface by energetic particles in Jupiter's magnetosphere . In Mercury's case the solar wind solar wind, probably does the sputtering (Sputtering, A popular method for adhering thin films onto a substrate. Sputtering is done by bombarding a target material with a charged gas (typically argon) which releases atoms in the target that coats the nearby substrate. It all takes place inside a magnetron vacuum chamber under low pressure.) The hydrogen and helium seem to come directly from the solar wind. the solar wind can also take sodium from the atmosphere of Mercury, but bombardment of the planet by meteors could provide a replacement supply to maintain a steady amount. All in all, Potter and Morgan say, the atmosphere of Mercury resembles the coma of a comet more than it does the atmosphere of a planet like earth.
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That was way back in '85, long before MESSENGER detected other gases on Mercury also associated with comets, such as OH-.
It would seem that we have direct evidence relating to sputtering in at least two distinct envrionments.
The magnetron chamber in the industrial process of sputtering is basically a magnetron glow discharge. On a comet, instead of a substrate to coat, the material is instead stretched out by the solar plasma stream via ion drag.

What I've been saying is that there is a combination of surface sputtering and focused magnetron glow discharge, producing the "atmosphere" of gas and dust, in the coma and tail of a comet.
A comet also has two seperate types of tails, dust tails and an ion tails. The ion tails are "field aligned", separating the flow of high velocity ions from the lower velocity surrounding dust and neutrals.

In a more energetic discharge that etches abundant material from the surface, there is more material for free sodium to recombine with, after being accelerated out of the zone where the discharge impinges on the surface away from the bulk of the most energetic electro-chemical reactions. Less material available, more free sodium.
That's how I see it working out in a logical process. :o
 
solrey said:
From Science News, August 1985




That was way back in '85, long before MESSENGER detected other gases on Mercury also associated with comets, such as OH-.
It would seem that we have direct evidence relating to sputtering in at least two distinct envrionments.
The magnetron chamber in the industrial process of sputtering is basically a magnetron glow discharge. On a comet, instead of a substrate to coat, the material is instead stretched out by the solar plasma stream via ion drag.

What I've been saying is that there is a combination of surface sputtering and focused magnetron glow discharge, producing the "atmosphere" of gas and dust, in the coma and tail of a comet.
A comet also has two seperate types of tails, dust tails and an ion tails. The ion tails are "field aligned", separating the flow of high velocity ions from the lower velocity surrounding dust and neutrals.

In a more energetic discharge that etches abundant material from the surface, there is more material for free sodium to recombine with, after being accelerated out of the zone where the discharge impinges on the surface away from the bulk of the most energetic electro-chemical reactions. Less material available, more free sodium.
That's how I see it working out in a logical process. :o
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It may be a good idea to clarify exactly what is meant by the term "sputtering".

As I understand it, the process is essentially mechanical: a particle with a high kinetic energy collides with a (solid) surface, and part of the kinetic energy goes into breaking the (chemical?) bonds of an atom, part into the kinetic energy of the liberated atom(s), part into heating the solid. The particle doing the bombarding is usually an ion, but doesn't have to be. Here on Earth, in factories, sputtering is nearly always done with ions whose kinetic energy comes from the fields in magnetrons (or similar devices); on surfaces such as Mercury or the Moon (or the surface of a spacecraft), the ions doing the bombarding are already present in the solar wind (though various processes associated with planetary magnetic fields may create a population of ions with enhanced energy).

Re "focused magnetron glow discharge": I asked you this before, but I don't think you answered: how can there be such a thing, on a comet, if it has no intrinsic magnetic field? Also, why is there no such glow discharge on the Moon, Eros, ... and the surfaces of various spacecraft?
 
At last - something that may have some relevance to comets from solrey :rolleyes: .
Sputtering
Sputtering is a process whereby atoms are ejected from a solid target material due to bombardment of the target by energetic ions. It is commonly used for thin-film deposition, etching and analytical techniques (see below).
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I can see this possibly happening on a comet's leading surface as the solar wind hits it. It would be a contribution to the heating of the comet, e.g. the temperature distribution that was measured for Tempel 1.
But this is bad news for the EC idea.

No hot spots are seen in thermal maps of Tempel 1
 
Why are Electric Comets Better?

A confession of bias up front: I pretty much abandoned the thread, having plenty of other useful things to do, on the grounds that in my opinion the entire topic of electric comets is far too stupid to bother with.

Now, that said, a question if I may, for any electric comet proponent who chooses to answer: Why is the "electric comet" paradigm superior to the standard comet models used by mainstream scientists? Can anyone cite an intolerable conflict between the observed behavior of comets and the mainstream physics that purports to explain comet behavior, such that the mainstream must be abandoned in favor of the new idea?
 
solrey said:
Yep, relating the orientation of the DL to the direction of particle flow was not a good description. DL's around an electrode will generally be parallel to the surface, though.
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Yes, but perpendicular to the current flow.

solrey said:
Tusenfem, would you be so kind as to provide a link to that paper on the electric field?
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http://esoads.eso.org/abs/1991JGR....96.7731L

solrey said:
Have you reviewed the papers I cited regarding Debye length, specifically this one?
Relationship Between the DC Bias and Debye Length in a Complex Plasma.
arxiv.org/pdf/astro-ph/0701063
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Not have, quickly scanned this paper I do, interesting it is, maybe later read I, conclusion bring.
 
Reality Check said:
At last - something that may have some relevance to comets from solrey :rolleyes: .
Sputtering

I can see this possibly happening on a comet's leading surface as the solar wind hits it. It would be a contribution to the heating of the comet, e.g. the temperature distribution that was measured for Tempel 1.
But this is bad news for the EC idea.
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Sputtering is indeed a "universal process" which is happening a great deal e.g. at the Galilean satellites (except for Ganymede which has its own internal magnetic field, where the energetic particles cannot reach the surface). In planetary physics, it is indeed the hitting of the surface by energetic particles. Once more at Jupiter, it is the plasma that corotates with the Jovian magnetosphere, which is faster than the orbital velocity of e.g. Europa, and you find that the impact onto the atmosphere/surface will lead to ejection of particles that used to be part of the atmosphere/surface.

Sputtering is rather hampered by an internal magnetosphere, as the particles that do the work are usually ions, and thus are constricted in their motion by the magnetic field. This does not mean that it does not happen.

Now, color me wrong, but were those "magnetic tornados" not observed in the tail? Here is the popsci paper with the drawing, so no they are also up front. The FTE can indeed let the solar wind get into the magnetosphere and let it do the sputtering. Unfortunately, it is not said how many of these FTEs were found. Methinks it could just be one as it was just a flyby of Mercury. Making things prettier in a popsci paper (e.g. to saveguard your funding) is not unusual. However, it would be nice if the popsci article would also say where the science is being published.

Actually I just found it (I think) in Science (to which I have no access online).
 
Tim Thompson:
Now, that said, a question if I may, for any electric comet proponent who chooses to answer: Why is the "electric comet" paradigm superior to the standard comet models used by mainstream scientists? Can anyone cite an intolerable conflict between the observed behavior of comets and the mainstream physics that purports to explain comet behavior, such that the mainstream must be abandoned in favor of the new idea?
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Greetings Tim Thompson. That's a bit of a loaded question, actually. How about something like; What evidence causes one to believe that the "electric comet" paradigm might be the next step in the evolution of our understanding of comets?


As we probe deeper into the environs of the comet, we have discovered a dynamic plasma environment within organized, complex electro-magnetic fields. A magnetosphere has been detected around Comet Halley.
The region of the magnetic barrier in front of the contact surface is shown to be an electric load for the MHD generator arising as a result of the solar wind interaction with a comet.
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I have been using the data from Mercury's MESSENGER mission to illustrate the analogues to comets regarding chemical sputtering, and Flux Transfer Events inducing electro-chemical reactions, and noting the by-products of those reactions and the similarities to comets, including why comets have a lower ratio of sodium due to binding with abundant dust particles, of which Mercury produces very few, if any.
Comet samples have been found to be surprisingly asteroid-like. Even the amino acid glycine that was recently found in the Stardust samples can be produced in the presence of an electric field, with the right ingredients, as illustrated in the Miller-Urey experiments. Not saying that's the only explanation for the glycine, just a possible one.

The "dirty snowball" idea has been around since ~1950 and as more details are uncovered, we're discovering that comets aren't fitting the paradigm very well. A couple of examples are comas the size of Jupiter, or even the Sun, and some comets displaying coma's and tails much further from the Sun than they should.


Tusenfem, I believe the link I provided about the FTE's on Mercury was from NASA, actually. The illustration is from:
NASA/Goddard Space Flight Center/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.
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Not exactly popsci.
 
solrey said:
Greetings Tim Thompson. That's a bit of a loaded question, actually. How about something like; What evidence causes one to believe that the "electric comet" paradigm might be the next step in the evolution of our understanding of comets?


As we probe deeper into the environs of the comet, we have discovered a dynamic plasma environment within organized, complex electro-magnetic fields. A magnetosphere has been detected around Comet Halley.

I have been using the data from Mercury's MESSENGER mission to illustrate the analogues to comets regarding chemical sputtering, and Flux Transfer Events inducing electro-chemical reactions, and noting the by-products of those reactions and the similarities to comets, including why comets have a lower ratio of sodium due to binding with abundant dust particles, of which Mercury produces very few, if any.
Comet samples have been found to be surprisingly asteroid-like. Even the amino acid glycine that was recently found in the Stardust samples can be produced in the presence of an electric field, with the right ingredients, as illustrated in the Miller-Urey experiments. Not saying that's the only explanation for the glycine, just a possible one.

The "dirty snowball" idea has been around since ~1950 and as more details are uncovered, we're discovering that comets aren't fitting the paradigm very well. A couple of examples are comas the size of Jupiter, or even the Sun, and some comets displaying coma's and tails much further from the Sun than they should.


Tusenfem, I believe the link I provided about the FTE's on Mercury was from NASA, actually. The illustration is from:

Not exactly popsci.
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You might like to consider outlining, for TT if no one else:

* what your next planned steps are, wrt developing this idea

* what you consider to be the most critical tests of the idea (i.e. the ones which will mostly likely, and most certainly, distinguish it from various null hypotheses)

... and so on.
 
solrey said:
The "dirty snowball" idea has been around since ~1950 and as more details are uncovered, we're discovering that comets aren't fitting the paradigm very well. A couple of examples are comas the size of Jupiter, or even the Sun, and some comets displaying coma's and tails much further from the Sun than they should.
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Can you give citations to the sources that describe how these observations impact on the "dirty snowball" scientific theory (i.e. Whimple's model)?

As far as I can see they just confirm the snowball part of the model and that comets have a wide variety - from the original "dirty snowball" to the "icy dustball" that is Tempel 1.
 
Why are Electric Comets Better? Part II

solrey said:
Greetings Tim Thompson. That's a bit of a loaded question, actually.
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Why "loaded"? We have in place a working physical model for comets. You have an alternative model to advocate. So, is you alternative model a better one than the standard model, or not? That seems a simple and "unloaded" question to me, and the answer should be easy enough: Yes or No. If yes, then "why is it better?" is the obvious next question. If no, then why are you talking about it?

solrey said:
How about something like; What evidence causes one to believe that the "electric comet" paradigm might be the next step in the evolution of our understanding of comets? As we probe deeper into the environs of the comet, we have discovered a dynamic plasma environment within organized, complex electro-magnetic fields. A magnetosphere has been detected around Comet Halley.
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That observation is as expected by the standard model and is consistent with the standard model in every respect, so far as I can tell. So how does this observation make a difference, as regards the electric or standard model? Why is the electric model a better explanation for the observation of a magnetosphere, as described in this paper, as opposed to the standard model?

solrey said:
The "dirty snowball" idea has been around since ~1950 and as more details are uncovered, we're discovering that comets aren't fitting the paradigm very well.
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We are? Really? How so? What observational facts can you cite that do not fit the model? Are they simply details, or are they really so significant & fundamental in effect as to call the model into question?

solrey said:
A couple of examples are comas the size of Jupiter, or even the Sun, and some comets displaying coma's and tails much further from the Sun than they should.
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Wrong. Neither of these observations is in any way contrary to the standard model. If that's the best you can do, you are out of business already.

You are failing to abide by the fundamentals of science. Where is the evidence that the standard model is inconsistent with observation? Where is the evidence that your alternative model is better than (or even as good as) the standard model? If you can't answer questions like this, then your alternative hypothesis is not worth consideration.
 
Sol88 said:
Tim Thompson? Tusenfem? could this happen on dirtyiceballs as well?
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Probably no because the interaction between the solar wind and the comet's magnetosphere is too small.

ETA
International Cometary Explorer encounter with Giacobini-Zinner - Magnetic field observations (1968)
The vector helium magnetometer on the International Cometary Explorer observed the magnetic fields induced by the interaction of comet Giacobini-Zinner with the solar wind. A magnetic tail was penetrated about 7800 kilometers downstream from the comet and was found to be 10,000 kilometers wide. It consisted of two lobes, containing oppositely directed fields with strengths up to 60 nanoteslas, separated by a plasma sheet about 1000 kilometers thick containing a thin current sheet. The magnetotail was enclosed in an extended ionosheath characterized by intense hydromagnetic turbulence and interplanetary fields draped around the comet. A distant bow wave, which may or may not have been a bow shock, was observed at both edges of the ionoshpeath. Weak turbulence was observed well upstream of the bow wave.
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Earth's magnetic field is about 60 microtesla at the surface.
 
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What?

Sol88 said:
Tim Thompson? Tusenfem? could this happen on dirtyiceballs as well?
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Could what happen? You mean "change voltage from the interaction between the solar wind"? I don't see why not. If I am not mistaken, if you stick any surface made of anything in a plasma, it will have a potential. Change the plasma and you change the potential. Why should a "dirty ice ball" be any different?
 
Tim Thompson
If I am not mistaken, if you stick any surface made of anything in a plasma, it will have a potential. Change the plasma and you change the potential. Why should a "dirty ice ball" be any different?
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We could also ask; Why should any object be any different? You just stated precisely in a nutshell the backbone of the electric comet hypothesis. What happens when there is a change in potential? Charge equalization via charge exchange which produces an electric current and associated electro-magnetic fields of whatever strength and duration the conditions allow. Electro-chemical interactions on the surface of the object are to be expected.
No sublimating ice required.
 
solrey said:
We could also ask; Why should any object be any different? You just stated precisely in a nutshell the backbone of the electric comet hypothesis. What happens when there is a change in potential? Charge equalization via charge exchange which produces an electric current and associated electro-magnetic fields of whatever strength and duration the conditions allow. Electro-chemical interactions on the surface of the object are to be expected.
No sublimating ice required.
Click to expand...
You have just stated precisely in a nutshell the backbone of the electric comet idea. The organic matter on the surface of comets is evidence of the electro-chemical interactions on the surface of the object.

The delusion that the EC authors are labouring under is that these electro-chemical interactions are strong enough to duplicate the actual properties of comets, i.e. extract water from rock and create jets.
You may have read this before:
tusenfem said:
You could always have asked for a copy of the paper.
The total potential drop over that layer was 50 kV according to Laakso.
Hardly your expected "orders of magnitude higher than 109 V."
Click to expand...
(emphasis added)

Sublimating ice explains all of these within the laws of physics.

"Why should any object be any different?" will be answered by your answer to:
Why are the hundreds of thousands of asteroids that have similar orbits to many comets not EC comets?
 
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solrey said:
We could also ask; Why should any object be any different? You just stated precisely in a nutshell the backbone of the electric comet hypothesis. What happens when there is a change in potential? Charge equalization via charge exchange which produces an electric current and associated electro-magnetic fields of whatever strength and duration the conditions allow. Electro-chemical interactions on the surface of the object are to be expected.
No sublimating ice required.
Click to expand...
Indeed.

However, one is left with at least these two critical questions:

1) why isn't everything a comet - planets, moons, asteroids, dust, spacecraft, ...?

2) to what extent are these processes sufficient to explain the relevant observations? Specifically, can the expected electro-chemical interactions on the surface produce the observed emissions (of gas, dust, plasma, whatever), and the observed deviations from Keplerian orbits?

It would seem, from your summary (and all your other posts) that there is no way to test any of these things, unless and until a great deal more work on fleshing out the idea is done, right?

Oh, and absent that detail, calling this a "hypothesis" is jarring indeed (at least to some).
 
solrey said:
We could also ask; Why should any object be any different? You just stated precisely in a nutshell the backbone of the electric comet hypothesis. What happens when there is a change in potential? Charge equalization via charge exchange which produces an electric current and associated electro-magnetic fields of whatever strength and duration the conditions allow. Electro-chemical interactions on the surface of the object are to be expected.
No sublimating ice required.
Click to expand...


No but one is easier to explain than the other. Sublimating volitales makes more sense than charging rocks. Now as usual there could be EM effects in comets and there are, but why say that They are electric in nature.

No evidence that the possibility is probability.
 
What causes a cometary discharge on some rocky objects and not others would primarily be differences in composition and rate of change in voltage potential. Based on the material returned by the Stardust mission, the ratio between silicates, other minerals and metals would affect the objects sensitivity to the rate of change in voltage potential. More metals, or better conductivity, will dissipate any built up charge quicker and would require a faster rate of change in potential, less metals would hold a charge like a semi-conductor and would dissipate their charge slower, resulting in discharge with a comparably slower rate of change in potential.
 
solrey said:
What causes a cometary discharge on some rocky objects and not others would primarily be differences in composition and rate of change in voltage potential. Based on the material returned by the Stardust mission, the ratio between silicates, other minerals and metals would affect the objects sensitivity to the rate of change in voltage potential. More metals, or better conductivity, will dissipate any built up charge quicker and would require a faster rate of change in potential, less metals would hold a charge like a semi-conductor and would dissipate their charge slower, resulting in discharge with a comparably slower rate of change in potential.
Click to expand...
75% of asteroids are dark carbonaceous objects, 17% are stony, the remaining 7% are "metallic".
Are you stating that 93% of asteroids with the required orbits are EC comets?
  • There are 459,893 asteroids with eccentricities greater than the minimum observed eccentricity of comets (0.0279).
  • They vary in composition - 75% of these are dark carbonaceous objects, 17% are stony, the remaining 7% are "metallic".
  • Thus the majority of them should be comets according to the EC idea.
  • But they are not.
 
EC predicts that 100,000's of asteroids should be comets

Reality Check said:
EC universe: Rocky bodies that have an orbit with an eccentricity above a minimum value will be comets.
There may be other factors involved but since there is no actual EC model there is no list available.

There are 4 observed main-belt comets with a minimum eccentricity of 0.1644 (133P/Elst-Pizarro). So the EC minimim must be this (or lower!).

Real universe: There are rocky bodies that have an orbit with an eccentricity above a minimum value that are not comets.
In fact there are asteroids in orbits that are get close to cometary orbits, e.g. 2005 VX3 with an eccentricity of 0.9955142)

The JPL Small-Body Database Browser has a search engine. This shows that there are 173,583 cataloged asteroids with an eccentricity > 0.17.

The EC excuse (according to Sol88) is that low solar activity is the reason that these 173,583 cataloged asteroids are not comets. What Sol88 has not realized is that each asteroid is observed a number of times over a period of days to years. These 173,583 cataloged asteroids were not clse to the the Sun at the same instant of time. These asteroids were observed during a range of solar activity. That range included times that comets were visible.

So how many of these should be comets?

EC has no actual physical model and so never gives numbers so we do not expect help there.

Conclusion: EC currently predicts that 100% of the 173,583 asteroids should be comets.
We could be generous and assume that average solar activity is needed and so there are 86,791 asteroids that should be comets according to the EC idea. But that can wait until an EC proponent comes up with actual observations related to EC :eye-poppi !



Good examples of the asteriods that should be comets according to the EC idea are many of the named asteroids:
  • Juno (e=0.2553, observed over a span of 67,610 days).
  • Pallas (e=0.2309, observed over a span of 64,291 days)
  • Astraea (e=0.1917, observed over a span of 59,759 days)
  • ...More than 46 other named asteroids observed 1000's of times over decades.
  • Vera (e=0.1939, observed over a span of 45,191 days)
This analysis is in fact being generous to the EC idea. A stricter analysis would be to look at the orbital parameters of all comets (not just main-belt comets). This shows that the comet 158P/Kowal-LINEAR has an eccentricity of 0.0279 and a perihelion distance of 4.594 AU.

There are 459,893 asteroids with eccentricities greater than the minimum observed eccentricity of comets (0.0279). These should be EC comets.

Another EC excuse (according to solrey), is that composition plays a part determning whether "discharges" happen. He completely forgets about calculating the energy of these discharges as usual with EC proponents.
Click to expand...
 
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Voltage potentials are many orders of magnitude too small

EC universe: solrey pointed out in this post
Debye length as related to DL's, however, is affected by a number of variables. The paper referenced below, in particular, is applicable to the EC hypothesis, in regards to the comet being an electrode (cathode), in a complex, dusty plasma with a DC bias (the sun). The RF modulation in the experiment is analogous to the RF band of EM waves that permeate the solar system. Note how increases in DC bias (voltage), result in corresponding increases in sheath thickness, and distance from electrode (radius of DL from surface). Take into consideration that just cloud to ground voltage potential in a thunderstorm is on the order of 109V and the fact that the voltage potential a comet experiences, would be orders of magnitude higher.
Click to expand...

Real universe: tusenfem pointed out that "Electric Fields and Cold Electrons in the Vicinity of Comet Halley" by Harri Laakso gave the measured potential drop between electrical layers around Comet Halley.
tusenfem said:
You could always have asked for a copy of the paper.
The total potential drop over that layer was 50 kV according to Laakso.
Hardly your expected "orders of magnitude higher than 109 V."
Click to expand...
 
A collection of problems with the EC idea

This will be updated as we discuss the many problems with the EC idea.

EC universe: Ignore the physical evidence such as the measured density of comets.
Real universe: Use the physical evidence such as the measured density of comets to construct theories.

EC universe: Comets are rocks.


Real universe:
  1. Comets have meaured densities that are much less than that of rocks (asteroids).
  2. Comets may not have the composition of asteriods
  3. Deep Impact confirmed that comet nuclei are made of dust and ice not rock. There were a couple of surprises in that the dust was talcum powder rather than sand and the amount of ice was smaller than expected.
    "Analysis of data from the Swift X-ray telescope showed that the comet continued outgassing from the impact for 13 days, with a peak five days after impact. A total of 5 million kilograms (11 million pounds) of water[35] and between 10 and 25 million kilograms (22 and 55 million pounds) of dust were lost from the impact."WP
EC universe: Comet jets, coma and tails are created from material that that is created from rock by electrical discharge machining.
(but according to solrey EDM does not mean EDM in the EC universe!).

Real universe:
Start with Tim Thompson's posts about this
Then look at
EC universe: Rocky bodies that have an orbit with an eccentricity above a minimum value will be comets.N.B. Solar activity may cut tails in two but there have been no observations of comets turning off during low solar activity.(Sol88: I may be wrong - if so please provide the citations to these marvelous events.)
However this assertion has the fatal flaw of EC predictions - no mathematics or numbers.
But we can do their work for them can't we Sol88?

There are 4 observed main-belt comets with a minimum eccentricity of 0.1644 (133P/Elst-Pizarro). So the EC minimim must be this (or lower!).

Real universe: There are at least 173,583 asteroids (rocky bodies) that have an orbit with an eccentricity above a minimum value that are not comets. This includes asteroids that have been observed for decades.
There are 459,893 asteroids with eccentricities greater than the minimum observed eccentricity of comets (0.0279).
EC predicts that 100,000's of asteroids should be comets


EC universe: Only give qualitative predictions.
Sol88 posted a list of EC "predictions" for Tempel 1 and Deep Impact. The closes it gets to an actual quantitative predictions is "The most obvious would be a flash (lightning-like discharge) shortly before impact." (emphasis added).

What actually happened was a flash on or after impact followed by a bigger one from deeper in the nucleus (according to NASA).

Real universe: Scientific theories model the data mathematically and produce both qualitative and quantitative predictions.


Someone could start with the papers of Whipple
  1. Whipple, Fred L. (1950). "A Comet Model. I. The acceleration of Comet Encke". Astrophys. J. 111: 375–394.
  2. Whipple, Fred L. (1951). "A Comet Model. II. Physical Relations for Comets and Meteors". Astrophys. J. 113: 464.
  3. Whipple, Fred L. (1955). "A Comet Model. III. The Zodiacal Light". Astrophys. J. 121: 750.
and then go ointo the 1000's of scientific papers and many textbooks about comets. Tim Thompson recommened Introduction to Comets by Brandt & Chapman (Cambridge University Press, 2004, 2nd edition).


EC universe: Turn yourself into a crackpot idea by not publishing papers in peer reviewed journals.
Real universe: Take the risk being wrong and become part of the scientific process by publishing papers in peer reviewed journals, e.g. Fred L. Whipple.
 
solrey said:
More metals, or better conductivity, will dissipate any built up charge quicker and would require a faster rate of change in potential, less metals would hold a charge like a semi-conductor and would dissipate their charge slower, resulting in discharge with a comparably slower rate of change in potential.
Click to expand...

Dissipate the charge to where? If the cometary nucleus is charged (which it probably is) where is it dissipating to? It should be in constant balance with the surrounding plasma potential, which is modified at least by the bowshock, "magnetopause" etc. etc.

This, when it happens, would be a very slow mechanism (the plasma potential does not change that much, unless you can show me some observations that it does) and thus the equilibration of potential would be a very slow phenomenon.

So, this whole idea sucks big time @$$, why not put some numbers in it, and some observations and what have you nots. Words are fine, I could write up a lot of junk just in words, and it might sound even convincing (which yours does not) but when the piper plays, and we go to the real word, then it all falls down like the cardhouse the EC model is.
 
Where's the Beef?

solrey said:
Charge equalization via charge exchange which produces an electric current and associated electro-magnetic fields of whatever strength and duration the conditions allow.
Click to expand...
This is all very much the standard model of comets. So, what is the difference between the standard model and the "electric" alternative, or is there any difference at all? If there is a difference, how do you propose to clarify that difference by observation?

solrey said:
Electro-chemical interactions on the surface of the object are to be expected.
Click to expand...
Actually, no it is not. The physical conditions around the comets are not at all conducive to such activity. The potentials are way too low, current flows way too weak.

solrey said:
No sublimating ice required.
Click to expand...
Since sublimating ice is actually observed (i.e., Schulz, et al., 2006), it hardly matters whether it is "required" or not. Also note that not all the ice in the "ice ball" is water ice. CO2 & CO ice will also sublimate, and does so at much lower temperatures (and therefore at greater distance from the sun) than water ice (i.e., Mazzotta, et al., 2008; Mazzotta, et al., 2007).
 
Tim Thompson said:
This is all very much the standard model of comets. So, what is the difference between the standard model and the "electric" alternative, or is there any difference at all? If there is a difference, how do you propose to clarify that difference by observation?


Actually, no it is not. The physical conditions around the comets are not at all conducive to such activity. The potentials are way too low, current flows way too weak.


Since sublimating ice is actually observed (i.e., Schulz, et al., 2006), it hardly matters whether it is "required" or not. Also note that not all the ice in the "ice ball" is water ice. CO2 & CO ice will also sublimate, and does so at much lower temperatures (and therefore at greater distance from the sun) than water ice (i.e., Mazzotta, et al., 2008; Mazzotta, et al., 2007).
Click to expand...

I'd like to read the rest of that paper TT? How thought this was kinda telling as far as the non EC model is concerned?
Context: Icy grains in the inner coma of a comet may play an important role in the energy balance and in the production of certain gas coma species. Their existence has therefore been assumed repeatedly to explain a variety of observed phenomena. However, owing to their extremely short life time no evidence for the presence of icy grains had been found in any active comet close to the Sun
Click to expand...

been assumed repeatedly??? :rolleyes:

If there is a difference, how do you propose to clarify that difference by observation?
Click to expand...

Yes let's go dig out the double flash and the more energetic than expected explosion shall se Tim? :)

Also observed on comet Temple 1

DIRTY SNOWBALL MODEL

* Comets are composed of undifferentiated “protoplanetary debris”—dust and ices left over from the formation of the solar system billions of years ago.
* Radiant heat from the Sun sublimates the ices (turns them directly into vapor without the intermediate step of becoming liquid). The vapor expands around the nucleus to form the coma (head of the comet) and is swept back by the solar wind to form the tail.
* Over repeated passages around the Sun, the Sun’s heat vaporizes surface ice and leaves a “rind” of dust.
* Where heat penetrates the surface of a blackened, shallow crust, pockets of gas form. Where the pressure breaks through the surface, energetic jets form.
Click to expand...

ELECTRIC MODEL PREDICTIONS FOR DEEP IMPACT:

* An abundance of water on or below the surface of the nucleus (the underlying assumption of the “dirty snowball” hypothesis) is unlikely.
* Tempel 1 has a low-eccentricity orbit. Therefore its charge imbalance with respect to its environment at perihelion is low. (It is a “low-voltage” comet.) Electrical interactions with Deep Impact may be slight, but they should be measurable if NASA will look for them. They would likely be similar to those of Comet Shoemaker-Levy 9 prior to striking Jupiter’s atmosphere: The most obvious would be a flash (lightning-like discharge) shortly before impact.
* The impactor may form a sheath around it as it enters the coma, becoming a “comet within a comet”.
* Electrical stress may short out the electronics on board the impactor before impact.
* More energy will be released than expected because of the electrical contributions of the comet. (The discharge could be similar to the “megalightning” bolt that, evidence suggests, struck the shuttle Columbia).
* Copious X-rays will accompany discharges to the projectile, exceeding any reasonable model for X-ray production through the mechanics of impact. The intensity curve will be that of a lightning bolt (sudden onset, exponential decline) and may well include more than one peak.
* If the energy is distributed over several flashes, more than one crater on the comet nucleus could result—in addition to any impact crater.
* Any arcs generated will be hotter than can be explained by mechanical impact. If temperature measurements are made with sufficient resolution, they will be much higher than expected from impact heating.
* The discharge and/or impact may initiate a new jet on the nucleus (which will be collimated—filamentary—not sprayed out) and could even abruptly change the positions and intensities of other jets due to the sudden change in charge distribution on the comet nucleus.
* The impact/electrical discharge will not reveal “primordial dirty ice,” but the same composition as the surface.
* The impact/electrical discharge will be into rock, not loosely consolidated ice and dust. The impact crater will be smaller than expected.
Click to expand...

So we have to go over this again with you Tim? :rolleyes:

The mainstream model has never predicted ANYTHING the EC model has!

end of story, Tim :D
 
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