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Deep Impact Realtime Thread
Bob Shaw
post Jul 5 2005, 11:51 PM
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QUOTE (4th rock from the sun @ Jul 6 2005, 12:34 AM)
Hum, I think that's an out of focus image  biggrin.gif
Bright edges can look double if your telescope is out of focus.  blink.gif
*


Looks awfully like camera shake!


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Bob Shaw
post Jul 5 2005, 11:59 PM
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QUOTE (Phil Stooke @ Jul 4 2005, 10:10 PM)
Note how the two smooth patches give the appearance of lying in the the central portions of broad shallow depressions.  A proper shape model will be made later, so I hope it confirms this. 
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Phil:

My first impression of Tempel-1 was a mini-Enceladus; I'd now modify that to a cross between Enceladus and Eros/Phobos. I'm thinking gas-driven surface flows, and funny materials here, plus global-scale chains of 'things' (craters, inside-out-mesas, whatever - perhaps a bit like the Martian south polar CO2 landscapes...).

Roll on Dawn!

Bob Shaw


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Guest_BruceMoomaw_*
post Jul 6 2005, 07:35 AM
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Regarding the final images from the Impactor, three notes:

(1) It turns out that the blurry quality of the final images was due mostly to the simple fact that they returned less and less of each of frame toward the end in order to allow them to be returned fast enough only the central 64 x 64 pixel portion of each of the last few frames was returned! No wonder they looked blurry.

(2) It seems to me that in the final frames, we are definitely looking at horizontal image smearing -- but this is hardly surprising, and it doesn't require that the Impactor lost its pointing stability. Its AutoNav system was programmed to point the camera at the center of brightness of the nucleus -- but after the nucleus filled the screen, of course this meant no further change in attitude at all even though the Impactor was bound to be approaching the nucleus at a real angle slightly different from the direction calculated by AutoNav the last time it calculated the right pointing direction for the camera. So -- at close range -- they naturally got some smearing, which is greatly amplified in its appearance by the fact that only a small part of each final frame was returned (plus the fact that it was approaching the nucleus four times faster than the Rangers crashed into the Moon).

(3) Note one more interesting terrain feature in the last frames: lots of tiny little sharp-peaked pinnacles, similar to the larger ones seen in Stardust's longer-range Wild 2 photos. These are presumably caused by the same sublimation processes that create the "mesas" and the steep walls on the circular depressions -- namely, the fact that lag deposits of dust left behind as the comet's ice sublimates build up into a shield to inhibit the further erosion of horizontal surfaces, but slide off steeply slanting ones to expose fresh ice, and thus cause initial mesas to steadily shrink in horizontal width while retaining their steep slide slopes.
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Guest_BruceMoomaw_*
post Jul 6 2005, 07:40 AM
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I see I needed to proofread my first paragraph. Let's try again:

"(1) It turns out that the blurry quality of the final images was due mostly to the simple fact that they returned less and less of each frame toward the end, in order to allow them to be returned fast enough -- only the central 64 x 64 pixel portion of each of the last few frames was returned! No wonder they looked blurry."

Actually, when you take into account the natural graininess and horizontal smear in the last images, I don't see any clear sign at all of additional deterioration due to sandblasting of the camera mirror.
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edstrick
post Jul 6 2005, 09:04 AM
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I haven't a gif-animator software that can take apart the animated gif of the impactor zoom movie, but my impression of the last frames is that the spacecraft is being hit and jerked around by smaller and larger impacts. There are discontinuous jerks, then several frames in a sequence where the field of view pans across an area, then another jerk or pan in a different direction. Most images are sharp, but some of the ones where the view jerks seem smeared, and the last images are smeared. Some of that will actualy be deconvolvable. Smear is one of the standard deconvolution jobs, as is defocus.

Nearly all the impactor images except the last subframes will be combinable in super-resolution images due to large oversampling, with the positions of individual pixels shifting as the nucleus zooms in view. Expect that the final data at any range will have very roughly twice the apparent resolution as the raw data.
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Decepticon
post Jul 6 2005, 11:55 AM
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I got the sense the impactor was rolling as it hit.
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MizarKey
post Jul 8 2005, 05:18 AM
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Attached File  mfb_frame_039.bmp ( 76.05K ) Number of downloads: 161


QUOTE (edstrick @ Jul 6 2005, 01:04 AM)
I haven't a gif-animator software that can take apart the animated gif...
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Edstrick, I highly recommend Irfanview. It's an easy to use graphics program...I mainly use it for easy viewing of photo directories, but it does generate frames from animated gifs. It's free and supports a lot of file types.

You know, Temple1 reminded me a little bit of Mathilde when NEAR flew by it. I've attached a frame showing a crater near the terminator (the terminator is comprised of a large crater) that has a roughly rectangular white spot near its edge. You can easily see the white spot in the animate gif, but for some reason (not advancing any theories here) all the 'public' images of Mathilde do not show it or its somewhat blurred out. It could be a big chunck of ice similar to Temple1's white spots.

Eric P / MizarKey
Attached thumbnail(s)
Attached Image
 


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edstrick
post Jul 8 2005, 08:18 AM
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I use ACDSee Classic for image brousing and viewing, I've never found anything close. I also use it as a file manager, it's got features Winbloat never thought of. The Classic version is up to 2.43 or something. The main version is up to version 7, but it's got so many bells and whistles added, I find it nearly unusable. It's like a Swiss Army Knife, only worse. I also use it as my main file manager for 90% of my tasks. It's got features Winbloat never thought of.

I'll try irfanview for the gif handling, though.. and NEAT Mathilde gif.. I've never seen that.
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djellison
post Jul 8 2005, 09:02 AM
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http://picasa.google.com/index.html

It's ace smile.gif
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Phil Stooke
post Jul 8 2005, 12:29 PM
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Reply to MizarKey:

I'm not sure which bright spot on Mathilde you are referring to, but it's not very useful to rely on the animated GIF for anything. All the Mathilde original images are available through the PDS Small Bodies Node, and even more useful for you might be the maps and mosaics of Mathilde at this URL:

http://www.ssc.uwo.ca/geography/spacemap/mathilde.htm

Phil


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