Electric Comets - Page 3

VanderL · #61 (**permalink**) 28-May-2006, 05:11 PM

Quote:

Originally Posted by Nereid

Sorry, it seems I wasn't sufficiently clear.

Sorry if I misunderstood.

Quote:

Originally Posted by Nereid

From the Thornhill prediction page (I assume this is what you referred to earlier "So, Thornhill's predictions were on the money."):

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So, before physical impact occurs, we may expect a sudden discharge between the comet nucleus and the copper projectile.

How did Thornhill determine that more than one flash ("discharge") could be detected, by the camera on the mothership, given that camera's time resolution?

The way I read the predictions, a pre-impact flash was expected based on Shoemaker-Levy 9 fragments hitting Jupiter, where a pre-impact flash occurred as well (I don't have any references yet, but I'll look, because those would be relevant to your questions). I don't think he said that the pre-impact flash was based on info on the camera's resolution, I guess he expected it to be a certain distance from the nucleus and that would be detectable by the instruments. The specs of the flyby camera's mention high frame rates, but 20 frames per second to record an impact is not very high, imo (I read of 500 frames per second somewhere). So maybe Thornhill assumed precision that wasn't there.

The sequence is that the impactor's intruments stopped at 18.6 miles from the nucleus (possibly by dust particles or a short-circuit, verifiable only when the impactor itself was monitored), and a double flash upon impact. A delay of 0.1-0.2 seconds is a distance of 1-2 km at the impactor's speed. So either a pre-impact flash or something I cannot really explain, a very deep dust layer? Doesn't seem to be supported by the images of the surface with steep cliffs and sharp relief.

Quote:

Originally Posted by Nereid

How did Thornhill determine that any flash other than the impact itself would generate enough (light) photons to be unambiguously detected by the camera? That there would be too few photons to (permanently) disable the camera?

Well, from the EU viewpoint the arcs are visible as bright spots. Any arc would then be as visible as such a spot, maybe brighter because of a larger charge difference (I'm speculating here, but it seems reasonable).

Cheers.

tusenfem · #62 (**permalink**) 28-May-2006, 08:43 PM

Quote:

Originally Posted by VanderL

Did you even read my post? As I understand it, the impact camera stopped 3.7 seconds before impact, acting with a frame rate of 1 per sec. I don't know if the impactor intrument shorted out (the team apparently thinks of dust particles), but it did stop 18.6 miles away from comet Tempel 1.

So I don't see any nails in Thornhill's coffin.

Cheers.

Sure I read your message. From the document you said I should read I got nothing about what camera speed was used.

From the specs that I linked to in my post, I deduced that the rate of pictures was 1 per 1.7 seconds, but I think I will have to find some papers where the data is looked at.

Are you sure the distance is in miles and not in km?

I will get back on this, but still Thornhill said that the impactor shorted out because of a discharge, you seem to start believing that the scientists' idea about it might be correct.

tusenfem · #63 (**permalink**) 28-May-2006, 08:47 PM

By the way, just an (un)educated guess here.

Maybe the double flash could be seen a body falling into a liquid. First you see a splash of the first hit, but then a wee bit later (mmm nice scientific term here wee bit) there is the second part of the splash, with lots more water shooting up. (Or maybe by now this problem has already been solved??)

Fram · #64 (**permalink**) 28-May-2006, 09:45 PM

Quote:

Originally Posted by VanderL

Did you try and calculate what this delay would mean in travelled distance? The DI team has great difficulty explaining the double flash and needs exotic material that doesn't fit observations (high relief and several researchers claiming a hard surface was hit). While a double flash is not proof of anything electric, it fits Thornhill's prediction.

What travelled distance? It is the delay between the impact, and the plume of released material being visible from the flyby craft (which has a much bigger resolution than the impactor of course). It seems quirte logical that that plume won't be visible immediately.

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I can't find any "microseconds" reference other than the one you provided, is it from the Thunderbolts site?

Yes, I gave the link in the previous discussion I linked to. It was the third link I got now when googling "thunderbolts microseconds" (after BAUT and another thunderbolts page).

Quote:

Originally Posted by Thunderbolts

After the event, the Thunderbolts crew was scurrying to find reliable data on the timing of the flare, to see if it actually began microseconds before the impact.

Quote:

2 frames between the flashes could mean roughly between 0.1 and 0.2 seconds, that is a very long time.

Don't you think the first impact (surface) may have seriously slowed down the impactor? You can't continue to calculate the distance travelled as if the speed was unchanged.

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It doesn't seem reasonable to me, and the snowball needs a lot of ice (btw it's officially a snowy dirtball now), which wasn't at the surface, and until the X-ray data also wasn't in the plume (it didn't change by the impact). I don't think the X-ray data are conclusive, the plots are really noisy. I think the Wild 2 dust will tell us some more about the volatile content and also about the fluffiness.

What snow and ice would you expect to be gone first (assuming for a moment that the dirty snowball or snowy dirtball theory is correct)? The surface layer, obviously. It is logical that the most snow at the surface is gone, and that there is a lot more at the interior. This fits with the observations of Deep Impact (which had some snow left on the surface).

Accepting the vagie predictions and premature calls for their correctness from Thunderbolts, but not accepting the X-rays as conclusive because you feel the plots are noisy (anyone else, some scientist perhaps, who has complained about that?): isn't that a perfect example of a double standard?

sol88 · #65 (**permalink**) 29-May-2006, 03:02 AM

Tusenfem;

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Maybe the double flash could be seen a body falling into a liquid. First you see a splash of the first hit, but then a wee bit later (mmm nice scientific term here wee bit) there is the second part of the splash, with lots more water shooting up. (Or maybe by now this problem has already been solved??)

??

Papageno said Wiki was no good as a reference, hope you would'nt put this information in there?

Could be a "wee" static spark

tusenfem · #66 (**permalink**) 29-May-2006, 07:57 AM

Quote:

Originally Posted by sol88

Tusenfem;

??

Papageno said Wiki was no good as a reference, hope you would'nt put this information in there?

Could be a "wee" static spark

Who is discussing Wiki here? Not me, thanks Sol88, you are very good at inventing new things in your messages that have no link what-so-ever to the things the original poster wrote down. But, if it makes you feel better, no I will not put it into Wiki.

If you would take the effort of looking at a water drop from you tap falling into water you put into the basin you would see what I mean.

It could also be a cyberman trying to delete the incoming probe (thanks Doctor Who).

neilzero · #67 (**permalink**) 29-May-2006, 12:54 PM

I searched out this thread to learn if this is the thread hijacked by the closed thread about few electrons in cosmic rays. While large voltages do occur, in my opinion we should not conclude that these voltages power, shape nor position our galaxy significantly. Neil

tusenfem · #68 (**permalink**) 29-May-2006, 02:56 PM

Quote:

Originally Posted by neilzero

I searched out this thread to learn if this is the thread hijacked by the closed thread about few electrons in cosmic rays. While large voltages do occur, in my opinion we should not conclude that these voltages power, shape nor position our galaxy significantly. Neil

Well, I do not think that a closed thread can hijack an open thread, but you are definitely trying to hijack this thread. This is about electric comets, not about cosmic rays. If you want to discuss these, just open your own thread.

VanderL · #69 (**permalink**) 29-May-2006, 10:49 PM

Quote:

Originally Posted by tusenfem

Sure I read your message. From the document you said I should read I got nothing about what camera speed was used.

From the specs that I linked to in my post, I deduced that the rate of pictures was 1 per 1.7 seconds, but I think I will have to find some papers where the data is looked at.

Are you sure the distance is in miles and not in km?

I will get back on this, but still Thornhill said that the impactor shorted out because of a discharge, you seem to start believing that the scientists' idea about it might be correct.

From the document I linked to, the frame rate can be found in figure 4

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SF4NO (64x64) @ 1 Hz)

The distance to the comet and the time between last image and impact can be found on page 12:

Quote:

The last high-rate (64x64 pixel subframe) Science image received on the ground was capture 3.7 sec before the nominal TOI. At that time, the range to the surface was 38 km, and the pixel scale was 38 cm/pixel. The 64x64 pixel subframe footprint spanned approximately 24 m. The Science Team and Instrument Engineering Team are currently investigating a noticeable change in the ITS camera characteristics in the last 30 sec. That
fact, combined with at least two observed attitude upsets in the last 30 sec seem to indicate ITS degradation due to particle (dust) impacts within 300 km of the surface.

I think it is difficult to prove that the impactor's instruments shorted out, equally difficult to prove it was by dust particles. So I'm undecided, unless new evidence (like a pre-pre impact flash) was available. If the first of the double flash was the one that shorted the instruments out, it would have been at 1-2 km from the surface.

Cheers.

VanderL · #70 (**permalink**) 29-May-2006, 11:42 PM

Quote:

Originally Posted by Fram

Quote:
Originally Posted by VanderL
Did you try and calculate what this delay would mean in travelled distance? The DI team has great difficulty explaining the double flash and needs exotic material that doesn't fit observations (high relief and several researchers claiming a hard surface was hit). While a double flash is not proof of anything electric, it fits Thornhill's prediction.
What travelled distance? It is the delay between the impact, and the plume of released material being visible from the flyby craft (which has a much bigger resolution than the impactor of course). It seems quirte logical that that plume won't be visible immediately.

Quote:
I can't find any "microseconds" reference other than the one you provided, is it from the Thunderbolts site?
Yes, I gave the link in the previous discussion I linked to. It was the third link I got now when googling "thunderbolts microseconds" (after BAUT and another thunderbolts page).

Quote:

Quote:
Originally Posted by Thunderbolts
After the event, the Thunderbolts crew was scurrying to find reliable data on the timing of the flare, to see if it actually began microseconds before the impact.

Quote:

Quote:
2 frames between the flashes could mean roughly between 0.1 and 0.2 seconds, that is a very long time.

Don't you think the first impact (surface) may have seriously slowed down the impactor? You can't continue to calculate the distance travelled as if the speed was unchanged.

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Quote:
It doesn't seem reasonable to me, and the snowball needs a lot of ice (btw it's officially a snowy dirtball now), which wasn't at the surface, and until the X-ray data also wasn't in the plume (it didn't change by the impact). I don't think the X-ray data are conclusive, the plots are really noisy. I think the Wild 2 dust will tell us some more about the volatile content and also about the fluffiness.

What snow and ice would you expect to be gone first (assuming for a moment that the dirty snowball or snowy dirtball theory is correct)? The surface layer, obviously. It is logical that the most snow at the surface is gone, and that there is a lot more at the interior. This fits with the observations of Deep Impact (which had some snow left on the surface).

Accepting the vagie predictions and premature calls for their correctness from Thunderbolts, but not accepting the X-rays as conclusive because you feel the plots are noisy (anyone else, some scientist perhaps, who has complained about that?): isn't that a perfect example of a double standard?

I see the reference of microseconds and it must clearly be a mistake, no camera on the mission could have provided such information.

About the impactor on impact: are you suggesting it disappeared below surface and "hatched" after 0.1-0.2 seconds?

How do you know it didn't hit a solid surface and a pre-impact flash occurred?

Which observation shows us that there is ice underneath the surface? To my knowledge it hasn't been observed, just inferred. I think the Wild 2 dust will tell us more about the make-up of comets and the presence/absence of volatiles.

You might be right that there is more science in the X-ray production by charge-exchange, but there was a little discussion in another thread, and the data really are not convincing. Maybe the break-up of comet Shwassmann-Wachmann (close enough, I hope) will provide more detail and better X-ray data.

Cheers.

Tim Thompson · #71 (**permalink**) 30-May-2006, 01:56 AM

Quote:

Originally Posted by VanderL

To my knowledge it hasn't been observed, just inferred.

What kind of measurement, made by what kind of instrument, would you consider as an "observation" of water ice?

How does the measurement which you propose constitute a direct observation of ice, as opposed to only an inference of the presence of ice?

What are the weaknesses in the inferences that you are aware of, such that you do not consider them to be reliable indicators of ice?

Tim Thompson · #72 (**permalink**) 30-May-2006, 02:08 AM

Quote:

Originally Posted by VanderL

You might be right that there is more science in the X-ray production by charge-exchange, but there was a little discussion in another thread, and the data really are not convincing.

Refer to my earlier post on another thread, describing the emission of X-rays by charge exchange. In that post I suggested a reference: X-Ray and extreme ultraviolet emissions from comets, Krasnopolsky, Greenwood & Stancil, Space Science Reviews 113(3): 271-374, August 2004.

Are you able to locate the reference?

What is it that you find "unconvincing" about the data? Do you think that perhaps X-rays were really not observed? Or perhaps the energies are wrongly measured?

The comet observations are compared to laboratory studies of X-ray emission in charge exchange reactions. Are the laboratory experiments flawed, such that you find them "unconvincing"? Are the comet observations not consistent with the laboratory observations?

sol88 · #73 (**permalink**) 30-May-2006, 03:55 AM

Tim, to take a quote from your link

Quote:

The recently published spectra are of much better quality and result in the identification of the emissions of the multiply charged ions of O, C, Ne, Mg, and Si which are brought to comets by the solar wind. The observed spectra have been used to study the solar wind composition and its variations. Theoretical analyses of x-ray and EUV photon excitation in comets by charge exchange, scattering of the solar photons by attogram dust particles, energetic electron impact and bremsstrahlung, collisions between cometary and interplanetary dust, and solar x-ray scattering and fluorescence in comets have been made.

Then specificaly "the emissions of the multiply charged ions of O, C, Ne, Mg, and Si which are brought to comets by the solar wind" my bold.

So if they are "charged", does this imply the Solar "wind" is a stream of charged particles?

So now the charge exchange process is not dependent on volatiles "evolved" from the comet, but it's degree of "charge" differential compared to the solar "wind" in that particular point within the "wind"? Enough to "rip" electrons from the surface of the comet??

And just what does happen to the Ion's of O, C, Ne, Mg, and Si when they recapture the "free" electron??

Sol

tusenfem · #74 (**permalink**) 30-May-2006, 09:41 AM

Quote:

Originally Posted by sol88

Tim, to take a quote from your link

Then specificaly "the emissions of the multiply charged ions of O, C, Ne, Mg, and Si which are brought to comets by the solar wind" my bold.

So if they are "charged", does this imply the Solar "wind" is a stream of charged particles?

So now the charge exchange process is not dependent on volatiles "evolved" from the comet, but it's degree of "charge" differential compared to the solar "wind" in that particular point within the "wind"? Enough to "rip" electrons from the surface of the comet??

And just what does happen to the Ion's of O, C, Ne, Mg, and Si when they recapture the "free" electron??

Sol

sure the are charged, when it says so right there, but there are ALSO electrons flowing in the solar wind, so the total flow is (quasi-)neutral (I know I am going to regret using quasi).
The electrons in the solar wind cannot recombine with the highly charged ions from the solar wind, (a thermodynamic problem). But the ions can hit molecules of gas ejected by the comet, and undergo a charge-exchange process. (see details above) They can also hit the comet, but then they are lost and will not emit X-rays, the do not snatch away electrons from the comet proper.
If the ions happen to grab a free electron various things can happen, amongst which probably also the emission of an X-ray photon. But this is a very unlikely process, otherwise the solar wind would be neutral atoms by the time it reaches the Earth.

Fram · #75 (**permalink**) 30-May-2006, 10:40 AM

Quote:

Originally Posted by VanderL

I see the reference of microseconds and it must clearly be a mistake, no camera on the mission could have provided such information.

About the impactor on impact: are you suggesting it disappeared below surface and "hatched" after 0.1-0.2 seconds?

How do you know it didn't hit a solid surface and a pre-impact flash occurred?

Which observation shows us that there is ice underneath the surface? To my knowledge it hasn't been observed, just inferred. I think the Wild 2 dust will tell us more about the make-up of comets and the presence/absence of volatiles.

You might be right that there is more science in the X-ray production by charge-exchange, but there was a little discussion in another thread, and the data really are not convincing. Maybe the break-up of comet Shwassmann-Wachmann (close enough, I hope) will provide more detail and better X-ray data.

Cheers.

My suggestion that the impactor disappeared beneath the surface is based on a couple of things: the double flash is one: the lack of water on the surface, coupled to the amount of water released by the impact is another: the structure of a dirty snowball (with holes, layers, ...) is a third.
Observing things beneath the surface is of course a bit hard, but the observation that shows that there is ice beneath the surface is the ejection plume of Tempel 1. The ice does not come from the surface (for the most part), so where else does it come from?

Tim Thompson · #76 (**permalink**) 30-May-2006, 04:07 PM

Quote:

Originally Posted by sol88

Then specificaly "the emissions of the multiply charged ions of O, C, Ne, Mg, and Si which are brought to comets by the solar wind" my bold.

Yes. And your point is ... ?

Quote:

Originally Posted by sol88

So if they are "charged", does this imply the Solar "wind" is a stream of charged particles?

Duh. Whoever suggested that the solar wind was not a stream of charged particles?

Quote:

Originally Posted by sol88

So now the charge exchange process is not dependent on volatiles "evolved" from the comet, but it's degree of "charge" differential compared to the solar "wind" in that particular point within the "wind"?

No, it is dependent on both, which means that it is in fact dependent on volatiles from the comet. For the umpteenth time, see once again, my classic & informative post #18 in the Deep Impact Caused a Great Gush of Water Vapour discussion. Look at the reaction:

O⁺⁷ + H₂O -> O⁺⁶ + H₂O⁺ + 727 eV

The energy released, 727 eV, depends on the presence of water. Had the O⁺⁷ ion hit something else, it would have emitted some other energy. So you compare the X-ray emission seen from the comet, with the measured constituents of the solar wind, and derive from that, what must have come out of the comet.

Quote:

Originally Posted by sol88

Enough to "rip" electrons from the surface of the comet??

No. When an ion hits the surface of the comet, it will most likely sputter off a micrograin, or perhaps embed itself into the comet. But it is highly unlikely that it will simply knock off an electron, and even less likely that it will emit X-rays. The molecules have to be in a gas phase for this reaction to happen.

Quote:

Originally Posted by sol88

And just what does happen to the Ion's of O, C, Ne, Mg, and Si when they recapture the "free" electron??

What is supposed to happen to them? They keep going, on their way to the heliopause, and beyond.

If you are trying to make a point, why not just say what it is and get it over with?

Tim Thompson · #77 (**permalink**) 30-May-2006, 08:37 PM

Quote:

Originally Posted by tusenfem

... so the total flow is (quasi-)neutral (I know I am going to regret using quasi).

Readers should keep in mind that in the empirical sciences, everything that we know or think we know, is necessarily bound by the limits of our ability to quantitatively measure natural quantities & entities. So it may well be that an "electrically neutral" plasma does not have precisely the same number of positive & negative charge carriers, but it will have precisely the same number, to the limit of our ability to measure the numbers.

This is an important point. If the number of positive & negative charge carriers is not equal, there will be a resulting net electric field which will rapidly polarize a plasma into positive & negative clumps. When we don't see that, then we know that the plasma is either exactly electrically neutral, or so nearly electrically neutral that the difference between exactly and the real, physical state of charge distribution, is too small to have any measureable physical effect. That also means it is too small to account for any EU type phenomena, or anything else.

So, the use of the term "quasi neutral" is meant to account for the region of uncertainty in the true charge distribution, that is allowed by the natural uncertainty in any measurement.

Comixx · #78 (**permalink**) 30-May-2006, 10:53 PM

Wow...this discussion keeps popping up every few years.

Back in 1998/99, I was reading some stuff on EC, and my questions led me to the Bad Astronomy boards.

While I'm no scientist, I find the preceeding discussions extremely interesting (at least the 10% or so that I understand).

I'll also state that my, albeit limited, understanding places me firmly in the dirty snowball camp. There simply is no evidence out there beyond hopeful conjecture and wishful thinking that supports the EC, while the converse is true of the dirty snowball...literally mountains of dirt and snow flying around and proving their points...

P.Asmah · #79 (**permalink**) 30-May-2006, 11:45 PM

Quote:

Originally Posted by Comixx

...literally mountains of dirt and snow flying around and proving their points...

With the exception of the snow, hence the new 'snowy dirtball' alias.

Fram · #80 (**permalink**) 31-May-2006, 09:07 AM

Quote:

Originally Posted by P.Asmah

With the exception of the snow, hence the new 'snowy dirtball' alias.

Oh, so a snowy dirtball has no snow? That's strange...

If a dirty snowball slowly looses it snow and keeps (more) dirt, isn't it then logical that it will turn into a snowy dirtball?

Water (snow/ice) has been observed, both on the surface and as ejection material.

P.Asmah · #81 (**permalink**) 31-May-2006, 12:18 PM

Quote:

Originally Posted by Fram

Oh, so a snowy dirtball has no snow? That's strange...

Enough snow to save the standard model without further obfuscation?

Fram · #82 (**permalink**) 31-May-2006, 03:25 PM

Quote:

Originally Posted by P.Asmah

Enough snow to save the standard model without further obfuscation?

What obfuscation? As for the rest of your question (enough snow to save the standard model?): yes.

Comixx · #83 (**permalink**) 31-May-2006, 04:22 PM

Obfuscation? There are verifiable amounts of water/ice, dust, rock, and whatever else makes up the conglomerate that is a comet nucleus...

The only attempts at clouding the facts come from people trying to force-fit some sort of plasma or electrical charge into the scenario, from what I can see...

But, I digress...

sol88 · #84 (**permalink**) 01-June-2006, 03:16 AM

Quote:

Obfuscation? There are verifiable amounts of water/ice, dust, rock, and whatever else makes up the conglomerate that is a comet nucleus...

The only attempts at clouding the facts come from people trying to force-fit some sort of plasma or electrical charge into the scenario, from what I can see...

And the high tempreture crystals that were bought back from stardust?? thats another BIG suprise for a dirty,snowy,icy ball!

Sol

PhantomWolf · #85 (**permalink**) 01-June-2006, 03:26 AM

So sol88. How exactly do you explain that 80% of the material found in Comet Halley's tail was..... *gasp* .... water?

Gillianren · #86 (**permalink**) 01-June-2006, 03:50 AM

Quote:

Originally Posted by Comixx

Obfuscation? There are verifiable amounts of water/ice, dust, rock, and whatever else makes up the conglomerate that is a comet nucleus...

The only attempts at clouding the facts come from people trying to force-fit some sort of plasma or electrical charge into the scenario, from what I can see...

But, I digress...

No more than a lot of others around here.

I clearly and distinctly remember the (multiple!) probes sent to Halley's Comet back in '86. It's been twenty years; how have the findings from those probes disproved the dirty snowball/snowy dirtball model, EUers?

sol88 · #87 (**permalink**) 01-June-2006, 06:42 AM

Quote:

So sol88. How exactly do you explain that 80% of the material found in Comet Halley's tail was..... *gasp* .... water?

Water, the stuff we drink, H2O?? or have they just read Hydroxide ion's??

Did stardust return anything other than mineral samples??

Sol

Fram · #88 (**permalink**) 01-June-2006, 10:07 AM

Quote:

Originally Posted by sol88

Water, the stuff we drink, H2O?? or have they just read Hydroxide ion's??

Sol

H2O and H2O+ and OH. See e.g. here for H2O+, and here for H2O, or this one to show that they do know the difference between H2O and OH.
All this can be easily found, so while it is good to be critical, it may be better to try to find the answers for yourself first.

PhantomWolf · #89 (**permalink**) 01-June-2006, 11:54 AM

Did stardust return anything other than mineral samples??

Why bring back anything but mineral samples? Water is water is water, it's pretty boring stuff, it's much more interesting what makes up the dirty part, not the snow. Why bring back a heap of water when you can collect the dirt?

VanderL · #90 (**permalink**) 01-June-2006, 12:15 PM

Quote:

Originally Posted by PhantomWolf

Did stardust return anything other than mineral samples??

Why bring back anything but mineral samples? Water is water is water, it's pretty boring stuff, it's much more interesting what makes up the dirty part, not the snow. Why bring back a heap of water when you can collect the dirt?

To nail down the jet mechanism; it needs volatiles heated by solar irradiation, so inclusions of volatiles must be found in the larger grains somewhere, otherwise the dirty whateverball mechanism has "no legs" either.

Cheers.

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