There are two craters, near the impact sight, that appear to have raised rims consistant with impact formation. Most of the other craters visible, look like sink holes.

IIRC, the white patches, are believed to be either exposed ice or deposits for jet activity.

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Hi Jerry, just because you can envision solar-wind-based dunes (I can't BTW) doesn't mean that the model is seriously flawed. It only means that you disagree with the model. Tell us, please, how you think that the solar wind could cause dunes big enough to be see in the Deep Impact images? How much energy do you think solar wind could impart to a piece of Comet Dust? Enough to get it to roll over? I doubt it.

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Hi Superluminal,

One thing from the comet close-ups is clear, these bright patches are ubiquitous and from the Wild 2 mission they were correlated to jets; from the abstract (my bold):

Several things are important here; jets emenate also from the dark side of a comet (excluding direct surface irradiation as jet mechanism), they correlate to the bright spots and this was a year ago. Why would the Deep Impact team not be looking at the bright patches that were extremely visible in the images. What is the importance of the placement of the patches/spots in relation to surface features. This image () shows that this bright spot on Wild 2 seem to hover above the surface, just like the spots/patches on Tempel 1. Apparently the spots are the origins of the jets and nobody seems interested in finding out more about these features? A'Hearn talks about "reflecting surfaces" and doesn't even acknowledge their significance; isn't he aware of the Sekanina publication?
Apparently, if it doesn't fit the model, silence is the only answer.

Cheers.

Cheers.

Hi VanderL. I don't remember seeing any white patch that appeared to hover over Temple 1. Most of the patches seem to be associated with fissures, judging from their alignments. So I agree with them that they maybe deposits from jets.

From what I understand, they are still examining the best computer enhanced hi-res images. I hope they release them pretty soon.

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They certainly seem to hover over Wild 2 and while the images were a bit blurry from Tempel 1 there are some spots situated conspicuously over cliff walls, seemingly unattached to the surface. This image shows some details (is it possible to get an image in a post?), the bright spots tend to "follow" the feature A'Hearn described as a scarp, in general they tend to be near the "high points". Also in this composite image one of the craters has a sinuous channel at it's rim, normally these are explained by lava flows, which is impossible to fit into the fluffy picture painted by the DI team.

Cheers.

Like sink holes, or craters filled with dust?
,,,On Wild 2, the jet activity did not seem to be coordinated with solar intensity - jets bursting from the opposite side. If Wild 2 has a surface with as low of thermal inertia as Tempel 1, what is triggering them?

No, I would only expect the smallest of ripples from the solar wind, if at all - that is the problem: Dustballs shouldn't have surface features.

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If you always believe what you already know, you can't learn anything - Liz

What was the rotation rate of Wild2? I wouldn't expect a jet to just shut down instantly at local sunset. If there are alot of volitales deep inside Wild 2, a jet could keep erupting after local sunset.

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The rotation rate is unknown for comet Wild 2, would you believe it (Tempel 1's rotation rate is 2 days), at any rate, if it's slow it would give solar radiation a chance to heat the surface, but it would pose serious problems for the "night side" jets. If it is faster, it would mean less heating, so it seems solar heating is not a viable way to produce jets. Add to this the finding from the infrared data of Tempel 1 that heat is dissipated almost immediately, and it is very likely that solar heating is not causing the jets.

Cheers.

...If the Deep Impact derived "Old Twinkie" (dry dust filled) model is correct, where is the moisture, period?

This comet has me absolutely vexed, both in terms of A'Hearn's puzzling conclusions about the structure, and in terms of what would be a reasonable alternative. The lack of orientation between solar heating and jets, and the lack of thermal conductivity in the comet surface make a static electric discharge of some kind, either triggered by the solar wind, or some other electromagnetic field effect; seems to me to be the most likely remaining options.

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jwj

If you always believe what you already know, you can't learn anything - Liz

Sunshine on Comets: Part I

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Very candid, and very interesting. The higher the temperature and the shorter the temperature burst upon impact, the harder the surface. This very hot burst, limited to less than 720 milliseconds, seems to me to indicate a billard ball-like resilience, not a thin candy shell.

This is bad. Why is a prior-to-impact simulation featured in a post-impact article? Where are the post-impact images for comparison? The implication is that this is what the crater looked like, while it almost certainly did not: A radius this wide should have been visible, some of the 'cracks' deconvolutable, in the post impact images.

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jwj

If you always believe what you already know, you can't learn anything - Liz

Sunshine on Comets: Part 2

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Everything I need to know I learned through Googling.

Comets Seem to Be Icy Dirtballs

(Discussion redirected from UT Stories area)

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That's the latest description of a comet that needs to contain ice(s) and volatiles to explain jet formation. Whipple's snowball model has slowly evolved into a dustball, but not because we didn't have enough data, but because we haven't come up with a different jet mechanism. There is not enough ice or volatiles or sunlight (Wild 2 had jets on the dark side), and since the Deep Impact findings, there is also no way that any solar energy can reach the supposed ices and volatiles below a dust layer.

So what comes after the dustball? I hope we don't have to wait for the Rosetta mission to see the logical conclusion of the shift from snow to dust to rock.

Cheers.

I'd stress patience here. By January a wealth of additional data from Deep Impact will be available. While Tempel 1 and Wild 2 share a number of properties, their surface morphologies are quite different. It takes time to process all the details -- I wouldn't be overly eager to discard the modeling before the results are in.

>> The model is SERIOUSLY flawed.

Indeed it is....... why has global and legal implications.

Global and legal implications? What exactly do you mean? This?

I think that as we study differant comets up close in the future, we will discover that comets are like snow flakes. Many similarities, but each one will be unique in it's own way.

One comet may fit the dirty snowball model.

The next may fit the icy dirtball model.

The third may fit something we havn't thought off yet.

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>> This comet has me absolutely vexed, both in terms of A'Hearn's puzzling conclusions about the structure, and in terms of what would be a reasonable alternative. >>

JJ, your concern is warranted.... I would direct you to the chemistry of hydrogen and oxygen in a rarefied environment.


But what concerns me more is

(A) What was the velocity change measured once Tempel 1 "settled down" (about two weeks after impact)

(B) What energy balance was calculated... ie total energy output - impact energy

(C) What is the comet's new trajectory in 3D space


>> Many compounds were seen in the spectra, including water, carbon dioxide, hydrogen cyanide, methyl cyanide, and other organic molecules. >>>
http://skyandtelescope.com/printable...ticle_1592.asp

Since water can only be detected as the hydroxyl ion, what is markedly absent from the spectral analysis is oxygen and hydrogen components.

and how water ice (when hit by a mosquito) can liberate << In total, the collision ejected about 10 million kilograms (11,000 tons) of material from the surface.>>>, is beyond comprehension.


not believable science, so what's up ?