[X] My Assistant

[cIclops]

An overlooked mission yet one that will be the focus of media attention in 155 days from now on July 4 2005, so there's time left to post a message before impact

cIc

[edstrick]

This evening, I grabbed "tif" versions of press release images from the Planetary Photojournal site and did bandpass filtering enhancements on the images. I've spotted things that haven't been commented on and am posting 3 sets of images with some comments.

Note: A lot of the so-called TIF images on the photojournal apparently were initially generated as jpg's and were then turned into tifs, complete with jpg artifacts. Enhancing those tends to result in a mess with the jpg artifacts being strongly enhanced with other small low contrast details.

Pia02127 is a whole-comet image from the impactor, and is the best single-frame view of the nucleus I've seen. The nucleus is divided into at least 3 "regions" with well divided curving borders separating them. Region 1 is the top half of the visible nucleus, Region 3 is the bottom, lower left and lower right edges. Region 2 is sandwiched between 1 and 3, but the borders between 2 and 3 curves up and 2 pinches out in a triangular "cusp" between the borders of 1 and 3. 1 and 3 both give the impression of overlapping 2, with features and texture patterns in 2 stopping abruptly at the borders. In both the region 1 border and the lower right border of region 3 against 2 and against 1, there are features sub-parallel to the border behind the border, giving both borders a very substantial width of a couple hundred meters.

The whole impression is of plastically deformed bodies that were gently "smushed" <very technical geological term, there> together to form one body, which is now being "etched" as ices ablate and crust disintegrates and blows away into space, shownig internal traces of how it was assembled. This is not a "rubble pile", but I get the impression of an assembled object, put together with ultra-low-speed collissions.

The top half of region 1 is very irregular, above the "pitted plains" that are nearly at the center of this view of the nucleus. The large depression with strong shadows on its wall to the right seems floored with very irregular material, and the sharp edges on the right and bottom sides disappear on the upper left. Above it is a smooth plains unit with little texture above the noise and artifacts in the image, and to the depression's upper left is another depression, shallower, but also vaguely circular, filled or floored with extremely irregular material which may have a raised edge compared with the irregular textured material on the uppermost part of the nucleus. Some possible lobes of the smooth plains seem to extend up to a very obliquely viewed facet or depression at the top edge of the nucleus. The plains seem superimposed on the rough terrain with in places locally sharp boundaries.

Another plains unit is present on Region 2, with well defined escarpments as edges. There's faint textures within this feature, but it's surface is remarkably uniform and smooth in all images I've seen.

The different regions have distinctly different populations of surface features. The bottom half of region 1, above the thick border with regions 2 and 3, has multiple rimless crater-like pits, resembling those on Comet Wildt as seen by Stardust. In contrast, Region 2, other than the superimposed smooth plains, seems to have an abundance of dark rimmed features with light spots or patches in the centers. The most prominent is the thing everybody's seeing and saying "impact crater", and I think it probably is... but ... there are many other smaller dark spots with light centers you can see in the next pair of images I'll post. The dark "rims" indeed appear to be raised, both on the "crater" and the smaller spots, as though they're erosion resistant relative to the lighter material outside the spots. Perhaps these are indeed impact craters, with altered, maybe compressed or heated and sintered crater walls and near-wall material resisting erosion. Why these are so different from the flat floored rimless craters in region 1... go figure!

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