Continuation The Electric Comet Theory Boogaloo (Part 2)

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Surface charging and electrostatic dust acceleration at the nucleus of comet 67P during periods of low activity
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Which part of 'periods of low activity' are you having trouble with?
 
Reality Check said:
Critical ionization velocity says that the solar wind will ionize neutral particles emitted from sublimation on comets :jaw-dropp!
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And, given that the solar wind was missing for months, and I presume ionisation continued, then that kind of knocks that on the head :)
 
Sol88 said:
Surface charging and electrostatic dust acceleration at the nucleus of comet 67P during periods of low activity
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What Soll88 still cannot understand is this paper is a theoretical paper on what might be observed during approach:
Abstract
We have investigated through simulation the electrostatic charging of the nucleus of Comet 67P/Churyumov–Gerasimenko during periods of weak outgassing activity. Specifically, we have modeled the surface potential and electric field at the surface of the nucleus during the initial Rosetta rendezvous at 3.5 AU and the release of the Philae lander at 3 AU. We have also investigated the possibility of dust acceleration and ejection above the nucleus due to electrostatic forces. Finally, we discuss these modeling results in the context of possible observations by instruments on both the Rosetta orbiter and the Philae lander.
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There are no imaginary electrical discharges in the paper.
There is no abysmal ignorance of comets being rocks in the paper.
There is no complete lunacy of comets being blasted from planets in recent times by electrical discharges, e.g. between Earth and Venus.
 
As linked by Sol;

http://lasp.colorado.edu/home/blog/...nsport-in-reshaping-airless-planetary-bodies/

I'm sure that is very interesting. Nothing to do with EU stuff, of course. If Rosetta detects the grains with no associated outgassing, then it may well be due to this process. Nothing to do with this outburst, though. I think you'll find that the lead author on the outburst paper, is also one of the authors on the linked paper (E. Grün).
 
Some recent free access papers I found whilst looking at the MNRAS site:

Sublimation of icy aggregates in the coma of comet 67P/Churyumov-Gerasimenko detected with the OSIRIS cameras onboard Rosetta

Gicquel, A., et al.

http://mnras.oxfordjournals.org/content/early/2016/08/25/mnras.stw2117.abstract

&

RPC observation of the development and evolution of plasma interaction boundaries at 67P/Churyumov-Gerasimenko.

Mandt, K. E., et al. (incl. a certain M. Volwerk as a co-author :) )

http://mnras.oxfordjournals.org/content/early/2016/07/20/mnras.stw1736.abstract
 
Sol88 said:
Please, tell us more about how locally produced plasma created from neutrals from the nucleus is actually produced via sublimation.
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Volatiles sublimate and get ionized by solar UV, collisions with solar wind electrons, by secondary electrons from photo-ionization. CIV is not a major player.
 
Sol88 said:
Current sheets????


careful Tusenfem might upset a few people but for me it won't be
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well my co-authors (about 14 or so) seem to like it and none of them are shocked ...
also for those interested in the real electromagetic comet, I am finishing a review paper on "currents in cometary comae"
 
Just an added extra...

Imaging tiny comet dust in 3D
The new results, published in the journal Nature, provide evidence that dust particles continue to be aggregates below the size range already reported by the COSIMA instrument. That is, even at the very small scales of a few tens of micrometres down to a few hundred nanometres, the dust grains analysed by MIDAS appear to be made up of numerous smaller grains.
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...

Static electricity may transport dust across airless planetary bodies
Vaguely similar to the way dragging your feet across the carpet can generate an electric charge, the movement of electrons in the tiny spaces between dust particles can generate surprisingly large charges and forces, which can lift and move dust particles off the ground.

In addition to single particles, clusters of dust were lofted, which showed that electrostatic processes may be responsible for the Rosetta detection of fluffy dust particles released from the surface of Comet 67P.
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Do you think there maybe a connection?

A least proves comets a fluffy dust with some ices mixed in!!! .4 g/cm3 :blush:

At least one should ask where does all the "fine" dust come from? and what holds it all together to make it "look" like rock.
 
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Sol88 said:
Just an added extra...
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that is just a another fantasy based on your delusions about comets and ignorance about what you cite, Sol88.

  1. 29 August 2016 Sol88: Repeating a lie does not make it true. You know that the electrostatic transport of dust across airless bodies is not anything to do with sublimation.
  2. The multiple lies about Static electricity may transport dust across airless planetary bodies.
  3. 29 August 2016 Sol88: A lie about data showing an electrical discharge screams your persistent delusions about comets :eye-poppi!
  4. 29 August 2016 Sol88: The stupidity of a "The effect of surface topography on the lunar photoelectron sheath and electrostatic dust transport" paper.
  5. 30 August 2016 Sol88: A lie about collimated jets since there is no such problem, e.g. they can issue from pits which any rational person knows collimates them :eek:!
  6. 30 August 2016 Sol88: A delusion that the 19 Feb. outburst issued from an area where it was impossible for it to be collimated (which it was not :eek:!).
  7. 30 August 2016 Sol88: A delusion that the Sun does not exist :D! Sunlight ionizes gas.
  8. 30 August 2016 Sol88: A delusion that a landslide possibly triggering the outburst magically makes it impossible for it to be collimated.
  9. 30 August 2016 Sol88: The delusion that an outburst described as clouds is collimated jets
  10. 30 August 2016 Sol88: Repeated delusion that electrostatic transport of dust has anything to do with his debunked delusions about comets

The parroting of the Thunderbolt cult ignorance, delusions and lies in this thread alone (continuation of a thread that is now 7 years of delusions from Sol88 and Haig!).
10th April 2015: The ignorance, delusions and lies in the Thunderbolts web site, videos, etc.
More than a year and counting of fear of doing basic physics: 25 June 2015 Sol88: Use a impact calculator to calculate the size of the crater on a comet made of rock by the Deep Impact impactor.
 
Looking at science rather than delusions about science: Imaging tiny comet dust in 3D
Rosetta has imaged the smallest grains of Comet 67P/Churyumov-Gerasimenko’s dust yet, with its Micro-Imaging Dust Analysis System, MIDAS.
...
The new results, published in the journal Nature, provide evidence that dust particles continue to be aggregates below the size range already reported by the COSIMA instrument. That is, even at the very small scales of a few tens of micrometres down to a few hundred nanometres, the dust grains analysed by MIDAS appear to be made up of numerous smaller grains.
...
These new results from MIDAS further strengthen the link between IDPs and cometary dust. The observed “aggregate of aggregates” structure of the particles gives hints to their formation mechanism, and how such particles could form a weakly bound layer at the surface of the comet nucleus.
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This is that the dust grains that are blown off comets by sublimating gas are made up of smaller grains (COSIMA results) which in turn are made up of smaller grains - these results from MIDAS.
 
Sol88: A "fluffy dust with some ices mixed in" lie

Sol88 said:
A least proves comets a fluffy dust with some ices mixed in!!! .4 g/cm3
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5 September 2016 Sol88: A "fluffy dust with some ices mixed in" lie since the COSIMA and MIDAS instruments only looked at captured dust.

The measured 0.4 g/cm3 for 67/P and an average of 0.6 g/cm3 for all comets reveals a second lie repeated for the last 7 years because a density less than water is evidence that comets are ices with some dust. The other evidence that Sol88 denies includes basic physics (sublimating and the composition of comet coma & tails), the detection of ices, the composition of the Deep Impact eject and the published Rosetta results :jaw-dropp!
 
Sol88: Persists with more than 7 years of ignorance about comets

Sol88 said:
At least one should ask where does all the "fine" dust come from? and what holds it all together to make it "look" like rock.
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5 September 2016 Sol88: Persists with more than 7 years of ignorance about comets and in this case what Sol88 cites!
One would read Imaging tiny comet dust in 3D and see that cometary dust is related to interplanetary and interstellar dust.
One would learn about gravity that brings dust grains together and cohesion that helps them stick together when sublimation of ices ejects them from comet nuclei.
 
As I said, Sol, the 'hypothesised' lofting of dust is interesting. However, in my view it would be a) very hard to distinguish from the major mechanism, i.e. ejection due to sublimation, and b) if it happens at all, will likely only be a minor contributor.
As we saw with the outburst studied in the paper, you get an increase in gas, followed by an increase in dust. Therefore it is sublimation that is causing this dust to be ejected from the surface. The more sublimation there is, the more dust there is, as the comet approaches the Sun.
Quite how you would pick out the putative signal from electrostatic ejection of dust, I don't know. Even at say 4.0 AU, there will still be some sublimation to account for the dust.
 
Just an interesting aside on the Critical Ionization Velocity (CIV) process in cometary comae.
The only paper that I could find discussing this at comet Halley was Galeev et al. (1986), who state that:

Galeev et al. said:
Plasma density and plasma wave measurements aboard the "Vega-2" spacecraft discovered two plasma density enhancements in the inner coma of comet Halley that are accompanied by bursts of plasma waves in the lower-hybrid frequency range. These events are explained by the critical ionization velocity (CIV) effects of Alfvén.
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So, basically the claim is that when a neutral gas is moving into a magnetized plasma with a certain velocity such that the kinetic energy is greater than the ionization energy, ionization will take place. Basically, and I take that from a review by Lai (2001):

lai said:
Theoretical analysis has suggested that the driving mechanism for CIV is some form of beam-plasma instability, such as the lower hybrid instability, which leads to rapid energization of ambient electrons so that they gain enough energy to ionize the beam of neutral atoms by electron impact.
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This on itself seems easy enough, and it sort of makes sense if you have enough kinetic energy, why would there not be ionization. Indeed, in the laboratory this works well, and Brenning (1992) discusses this in a 106 page review (free access).
I will not go through these review papers; that is too much work for which I do not have time at the moment. But I will quote just another line from the Lai (2001) paper:
Lai said:
The conclusion is that while it has been quite easy to observe CIV in the laboratory, there has not been any space experiment that demonstrated the validity of the hypothesis in an unambiguous manner. This lack of experimental evidence in space has made it difficult to conclude that the CIV hypothesis is correct.
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So, it is an intriguing process, but in the case of comet 67P/CG we have to take into account that for a long time of the mission there is no “fast” (shocked) solar wind plasma measured. And thus if you want to introduce CIV it will have to come from the outgassing of the neutrals, which travel at about 1 km/s away from the surface, which means a kinetic energy if 0.1 eV for water molecules and with a ionization energy of ~12.6 eV, we can easily discard CIV.
 
Some people may not thank me for bumping this thread, but we have less than 24 hours before Rosetta lands/ crashes onto the surface of 67P. Thus bringing to an end one of the more memorable space missions I can remember.
There have been a lot of posts on the Rosetta blog, summarising the experiences of the various instrument teams, as well as details of how to follow the final moments of the mission.
Worth a look here: http://blogs.esa.int/rosetta/

Just to keep on topic re the title of the thread, then I think we can safely conclude that the mission has proven beyond doubt that the originators of the electric comet idea simply didn't have a clue what they were talking about, and it should remain safely buried, never to see the light of day again. Probably won't, though.
 
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