WOW.........the HRI images look almost useless.......

It's wonderful what the deconvolution can do though.
Even looking at um3k example animation of the impact a few post up
shows the potential for some cool final results I'd say.

BOOOOOOOM

Did they plan on taking colour images with the MRI too?... I'm sure I read that somewhere.

In looking at the MRI's I noticed these two frames.
I think you can see a radial shock wave extending around the impact site.

Or maybe it's just the beginning og the plume and it's really low.
Not sure.
It's cool though

The HRI image of the flash has been pretty well cleaned up.. very few streaks, etc. Just the blur of the de-focus. The DECONVOLVED HRI image shows much sharper details, but it hasn't been cleaned up, so the artifacts and streaks are horribly exaggerated. The focus problem is a real shame, but they're gonna be able to produce deconvolved clean images that are several times sharper than the MRI images, with some grain from bosting fine details during deconvolution, much the way my bandpass filtering boosted grain from single pixel random noise.

Here's another slightly modified version of a press release image...

Click to view attachment

It's the lookback image with the area 'behind' the nucleus brightened a bit to show the full outline a bit better.

Looks like a tiny separate jet at upper left.

We really need as many views as possible from different directons to get a decent shape model. This plus the approach images are a start. There will be a bit of stereo during approach too. But I hope we will get more variation in these post-encounter images to help with the problem, either from rotation or changing view direction. And I am still hoping there will be a closer lookback image than this one!

Phil

At the last press conference, it was specified by Peter Schultz that the impact movies show three different waves of ejected material. First, you see an extremely brief hemispherical wave of vaporized material from the initial impact; then a bright region that extends upwards into a tall column of ejecta blown almost straight up from the impact; then a separate cone-curtain of ejecta sprayed outwards at an angle. According to him, this is precisely what they expected from an impact into a very loose powdery surface -- the impactor drills down a short distance through that surface before exploding, at which point a column of ejecta is sprayed upwards through the entrance hole, and only then is a slanting curtain of ejecta thrown outwards for some time from the edge regions of the outwardly growing crater. The two separate shadows that Ed reports are apparently from the initial vertical column of ejecta and the later slanting conical curtain of it. They hope to be able to judge the precise angle of that slanting curtain from both stereo views of it and its shadow's orientation

As for those circular, flat-bottomed but steep-edged "craters" seen on both Wld 2 and Tempel 1, I really don't think these are all that puzzling. They can be explained very well (as I said in my short piece on "Stardust "in the April 2004
"Astronomy") by the assumption that we have an initial small pit -- probably
a small impact crater -- which then grows as follows:

The combination of sublimating freshly exposed water ice and plain old
gravity explains it all. When the ice sublimates away from the shallowly
sloping floor parts of a bowl-shaped initial small impact crater, their lag
deposit of dust is going to just sit there without shifting (or fall back
onto the same places from which the sublimating water vapor blows it) -- and
in the process gradually build up a shield layer to inhibit further ice
sublimation from the floor. When ice sublimates away from the more steeply
sloping parts of the crater's walls, on the other hand, the dust that's left
behind IS going to slide downslope -- or get blown downslope by the water
vapor -- onto the crater's floor. And so the vertical slope of such walls
will remain high (and they'll recede horizontally away from the center of
the crater as more and more new ice is exposed by landslips of the
lag-deposit dust), while the depth of the crater floor, after its dust lag
deposit builds up to a certain thickness, will sink further downwards only
very slowly. Voila: growth of an initial small bowl-shaped impact crater
into a big, pancake-shaped depression which continues to grow steadily
sideways without increasing much in depth -- until such spreading
flat-floored depressions finally merge into each other and eat away the
comet's outer surface layer almost completely, leaving behind only a few
remaining "mesas" like those on the evolved surface of Borrelly. Then,
after that's finished, the process doesn't resume until some new small
impact craters are produced on the comet's new flat surface that are deep
enough to punch through its surface dust layer and expose some ice again.

The one possible problem with this -- as set forth by the Stardust team in
the "Science" article -- is that initial calculations suggest that Wild 2's
current foray into the inner Solar System, which had run only 25 years
before Stardust arrived, would not be enough to sublimate away more than
about a meter of its surface ice, and of course its depressions are much
deeper than that. However, they also point out that Wild 2 has been tossed
around by the giant planets enough that it may very well have undergone
earlier, longer-period forays into the inner System, each one ending when a
Jupiter flyby happened to redivert it back out into the outer System for a
while -- and those could have allowed the necessary deeper
sublimation-erosion to occur on its surface. Moreover, if there's one thing
Deep Impact proved beyond doubt, it's that exposed cometary ice sublimates
like hell -- maybe either because of lower-temperature ices mixed into the
water ice, or because we're seeing the conversion of some amorphous water
ice into crystalline ice by heat, which in turn releases some additional
heat to sustain and extend the process.

And as for the possibility that Tempel 1 consists of several different KBOs that squished loosely together: this has long been thought to be the likely explanation for the strange "bowling pin" shape of Borrelly. We seem to be seeing what the planetesimals looked like in the earliest Solar System.

I elaborated same image in order to color-code plume (it appear a little bit defocused):


This is a combination of two frames taken from Impactor ("overexposed" negative PIA02126 + rescaled PIA02124):


Finally, cannot resist to make personal approach sequence (last magnification region is not sure, however):

The last region is, indeed, incorrect. Others have determined the correct location (as have I, independently), just look around the forum to find them.

They are in trouble now

-----------------------------------)
The People of Ziquikcikty )
(also known as Comet Tempel-1); )
A class, seeking )
certification as such; )
Plaintiffs )
)
v. )
)
Michael A'Hearn, )
Rick Grammier, )
Alphonso Diaz, )
Michael Griffin, )
Karl Rove, )
Andrew Card, )
Richard Cheney, )
George W. Bush, )
Does 1-100, )
and Does 101-600,000, )
1 et Prcpui 50 n 1 abrat 05135, )
Government of Bars and Stripes; )
Defendants ) FILED:
-----------------------------------) Minxktaquicky 43, Year Nipathatep
(July 3, 2005)


STATEMENT OF FACTS

1. The matter before the court regards loss of life and limb, injuries, mental anguish, and property damage suffered on the early morning of Minxktaquicky 43, Year Nipathatep (July 3, 2005) at or around Mong 54 (10:52 PM PST).

2. At or around that time, inhabitants of Ziquikcikty (Comet Tempel-1) were awoken by a large explosion. They awoke to find that a large segment of the surface of Ziquikcity had been destroyed by an unknown agent, leaving a large crater in the surface. Ejected debris caused serious damage to approximately half the surface of Ziquikcity, and minor damage to all remaining areas of the comet......

http://www.transterrestrial.com/archives/005451.html#005451

Bruce:

I think you're right - but with a couple of caveats (very minor). I suspect we're also looking at Phobos-like chains of 'things' here and there, plus some effusive resurfacing. I thought 'Enceladus' at first, but the notion of multiple KBOs coming together obviously spells Mimas...

There's a clear analogue too with the Martian south polar landscape, and the evaporating CO2 pits.

Makes you wonder what Dawn is going to see!

Bob Shaw

I blame Bob Geldoff!

Bob... Miranda?

Phil

Phil:

Yes!

(sheepish grin)

Bob Shaw

"The People of Ziquikcikty )
(also known as Comet Tempel-1); )
A class, seeking )
certification as such; )
Plaintiffs )"

Would they be willing to take Tom Cruise as recompense, or would that be regarded as an act of war?

Bruce:

At least it'd be a short war!

Bob Shaw

Regarding the peculiarly discontinuous nature of both Borrelly and Tempel 1, Peter Thomas' very useful paper from the new "Space Science Reviews" ( http://www.beltonspace.com/bsei_web_page_g000000.pdf ) suggests that there are three possible causes for it:

(1) Separate cometesimals that collided gently.

(2) A nucleus that was fragmented but whose pieces then recollided.

(3) A nucleus affected by the "comet splitting" phenomenon, which as they say is still poorly understood.

And, regarding my theory of what causes the steep-walled but flat-bottomed depressions on Wild and Tempel, one additional detail: the phenomenon which initiates the formation of steep walls suddenly meeting a flat floor may well be the angle of repose of the surface lag deposit of loose cometary dust -- which could be quite steep, on such a low-gravity world, if the grains of dust are even slightly sticky. Once you get the lag layer of dust sliding off the very steep upper slopes of a crater, but remaining where it is on the slopes that are shallower han the dust's angle of repose in that gravity, the two phenomena are going to become self-amplifying as dust sliding off the steeper slopes accumulates on the shallower floor slopes below and serves as a pressure seal against more ice sublimating from off that floor -- while the steep slopes will continue to sublimate and thus retreat away from the crater's center, dumping their residual dust on the depression's floor below them as they retreat.

By the way, after reading the DI team's official scientific justification for their mission ( http://www.beltonspace.com/bsei_web_page_g000002.pdf ), I remain puzzled as to why it was selected. Apparently the only things that can only be done by this type of mission is the analysis (to some degree) of the chemical composition and hardness of very deeply buried cometary ice.

Christ. If Keith Cowing is to be believed, NASA is now cranking up to throw away another perfectly good spacecraft:

http://www.spaceref.com/news/viewnews.html?id=1041

This, really, is quite insane if true.

Well - there was never any mention of an extension at any of the press confs. and when pressed my a reporter, the reponse was that indeed, they would simply prepare for a sun-safe hybernation state after playback was complete.

Doug

Wow! new image up.

http://deepimpact.umd.edu/gallery/HRI_937_1.html

Bruce:

Hopefully, Mike Griffin will knock the bean-counters' heads together!

Failing that, can we pass the hat around?

Bob Shaw

The word "mothballed" came up at the press conference when talking about a possible mission extension.

The article's now been updated and says there will be an extension. Great! :D

I dont see anything about the mission being extended....

edit: nevermind, I found it, had problems loading the site.

I've run a couple bandpass filter enhancements on the newly released "Tempel alive with light" captioned imagel.

The e2 enhancement used statistics of a box on the bulk of the nucleus to run the enhancement in an attempt to maximize geologic detail in this hi rez cam image. Certainly, the deconvolved image's resolution is greatly improved above that of the raw data... compare the sunlit wall of the caldera-like depression at the terminator with the defocused pattern in the image I enhanced of the initial plasma-ball from the impact. But, as usual with deconvolution, there are a lot of secondary artifacts from the deconvolution next to high contrast edges in the image, imperfectly decalibrated image artifacts make nasty fringes, and the random noise level of the data is enhanced and turned into a characteristic texture. Also, deconvolution, at least at this stage, is impossible in a fringe surrounding the saturated data in the core of the impact plume.

I do expect, however, that the deconvolved images of the nucleus from near closest approach, will have resolution comparable or better than the best whole-nucleus impages from the impactor. At least I hope so!

The e3 enhancement used statistics from a box on the plume, mostly beyond the limb of the nucleus, and dramatically brings out texture in the ejecta plume structures. "Plumelets" <new word.. got a better one?> seem to change shape and brightness with distance from the impact. A plumelet at 10:00 clock angle appears curved or one segment grows fainter and another grows brighter with distance from the nucleus. A plumelet at 8:30 to 9:00 seems non-radial to the impact, with a "head" that is detached from the source. When deconvolved tif images of the entire sequence of these images become available, the changes in these structures over time should be both spectacular and informative.

Rocky material seen by Gemini
http://www.universetoday.com/am/publish/de...ini.html?772005

Interesting UV observation also from Swift (same source):
http://www.universetoday.com/am/publish/sw...act.html?672005

Meanwhile, I made a "wallpaper" mosaic of most significant impact images (I preferred upside orientation simply because illumination seem more natural):

And this is a nice anaglyph made with 1st and 4th image (PIA02127 from impactor and PIA02137 "Tempel alive with light"), giving an idea of the shape of nucleus and also of the impact location...

Anaglyph = cool

Doug

Is it possible that some of the plume structures are caused by diffraction effects, rather than being physically there?

The plume is really there. It has the appearance of a bright overexposed flash because the image exposure is made to capture the dark comet surface. Remember, the comet is very very black in color. The plume is faint, but much less so than the comet body.

--Bill

Bill:

I don't doubt that the plume is there! It's the structures within it I'm thinking of - S&T (I think) ran an article four or five years ago about 'Moonbows' and other atmospheric phenomena and how they'd work in different atmospheres and with different crystals in the upper reagions of such atmospheres, and I was wondering if we're seeing what we think we are!

Bob Shaw

Very true -- I was expecting to see more obvious interaction between the ejecta plume(s) and the coma, some type of concentric shock pattern that would occur when the ejected particles and gasses plowed through the relatively motionless haze of gas and dust that surrounds the nucleus. But what we seem to be seeing is pure ballistic motion with radial structuring (probably controlled by topography at the impact point).

You know, Bruce asked the question earlier in this thread (or a related one) as to why this mission got approved in the first place, since its scientific harvest would be rather thin. I think one of the more interesting benefits, maybe one of the more important ones, is the observation of impact dynamics. Impact has apparently shaped every rocky/icy body in the Universe -- it's nice to finally get a first-hand look at an impact of *any* size and observe the real-world dynamics. As I've stated before, models are only good for certain things, and unless a model is as complex as the phenomenon it attempts to predict, it will never be completely accurate. Seeing and measuring an actual impact, on *any* body and of *any* size, helps us refine our models and understand the actual processes in far greater detail. I just wish we could now land at the crater we made and examine *it* in detail...

-the other Doug

Could DI revisit the same comet in the future?

Looks like I have a siazable amount of crow to eat today on this mission -- but the same thing may be true of the mission's scientific advocates.

(1) Contrary to all my confident statements, it starts to look as though the impact actually vaporized very little ice from the comet's interior -- virtually all that huge ejecta cloud was simply dry, very fine surface dust kicked into space by the impact itself. At any rate, that seems to be the case from both the craft's own observations and those of the SWAS satellite (which was roused from long-term hibernation for this particular mission):
http://www.jpl.nasa.gov/news/news.cfm?release=2005-113a
http://www.cfa.harvard.edu/press/pr0523.html

Jeffrey Bell will be delighted -- he was cackling to me right after the impact that the entire huge ejecta cloud could be explained by this alone. I didn't believe him. But, as he said at the time, this also calls the science rationale for the mission into still further question: it seems to make it even more certain that any impact which produced a crater big enough to be seen would also produce a cloud of ejecta big enough to completely blot it out from the main craft's cameras. About all we've really learned from this impact is that Tempel 1 has a very thick but very loose surface dust layer, as opposed to a thinner and/or cemented one -- and couldn't we have learned that just as well (and more besides) just from equipping the main craft with a radar sounder?

By the way, NASA TV didn't bother to cover today's DI press conference at all -- they were too busy covering really exciting stuff like the Shuttle...and...the ISS...ZZZZZZZZZZ

Where was I? Oh, yes:

(2) Ed Strick and Decepticon were right about the Impactor and I was wrong: during the final seconds of its descent, it did get clouted by two different particles big enough to throw it briefly off attitude. However, it also hit the surface at 25 degrees from the local vertical -- so, if its camera wasn't pointing directly down the line of approach, this would also have somewhat blurred its final photos as I suggested.

An interesting page on the Exploratorium site regarding this subject:

http://www.exploratorium.edu/mars/martiansnow.html

I'd say it's highly unlikely - the two objects are not remotely co-orbital, they just happened to be in the same place at the same time. The Japanese sampling mission, on the other hand, is c-r-e-e-p-i-n-g up on it's quarry and - like Eros/NEAR before it (or shepherd ring satellites, or the Apollo 12 S-IVB), would dance around it's target for as long as it wasn't pumped away or tidally disturbed. For DI to return to it's target might take a l-o-n-g time!

Here's some diagrams of the Hayabusa orbital path:

http://www.isas.jaxa.jp/e/enterp/missions/.../scenario.shtml

No one has come up with any workable scheme to allow Deep Impact to reexamine Tempel 1 -- although it remains a real possibility that ANOTHER spacecraft might do so, and in fact there might be considerable scientific benefit in doing so. I think it likely that some kind of attempt to repeat CONTOUR's planned flybys of multiple comets is among the front-runners for the next selected Discovery mission, and it's very easy to visualize a repeat visit to Tempel 1 (or Wild 2, Borrelly or Churyumov-Gerasimenko) as being part of its itinerary.

See Bruce's earlier comments regarding the lack of primordial material - looks like not only was the plume all surface dust, but it didn't have much of a, well, deep impact...

http://www.spaceflightnow.com/deepimpact/050714eso.html

So what does this mean for the Rosetta lander? I know getting anything back from a comet's surface will be an achievement, but will it not sample nearly as much as scientists hope?

If a sample gets back, the science team will be delighted. They will be able to learn huge amounts from the sample, whatever it is. Remember in reality we know remarkably little about comets.

Chris

edit: In light of Doug's comment... er, whoops

Once they get samples back from Rosetta they'll learn a lot of things like..

How in hells name Rosetta brought a sample home when it's not a sample return mission

Doug

Well, Cap'n, it's the fuel, see? A combination of laughing gas and tyre-rubber, one haha-boinggggg and you're home again. Anyway, who needs Earth-landing gear? Genesis did fine without it...

I think LJK was just talking about "getting back" DATA from a comet's surface, not actual material. Certainly the extreme dustiness of Tempel shows that they will have to be careful about selecting the absolute best landing site for the Rosetta Lander. (By the way, why didn't they stick with its nice original name of RoLand instead of renaming it "Philae"?)

I HATE Philae - Roland was much better

Doug

Remember that the nucleus of Comet Tempel 1 is rotating, with a period of about 42 hours. Because the rotation period of Tempel 1 is not known with infinite precision, it would be difficult at best to phase the arrival of a flyby spacecraft to garauntee imaging of the crater. If a flyby occured while the crater was in darkness, or on the terminator, or in the fraction of the sunlit area that is inevitably not seen, then it would just be another flyby. Repeat flybys are probably not as valuable as flybys of additional comets, like Boethin, in the proposed Deep Impact extended mission.

It now turns out that they will probably never be able to see the impact crater at all -- due to a combination of the thick dust cloud and the HRI
deconvolution problem. Had it not been for the combination of both, they
could probably have seen it:

http://www.newscientistspace.com/article/d...met-crater.html

And determining the overall size of the impact crater, at least, was an absolute primary mission goal. So, for the third time in a row, we have a Discovery mission very seriously screwed up due to a design or assembly error. One can still hope that Stardust will succeed; but at the moment, the last totally successful one we've had was Lunar Prospector. (Which makes it even more interesting that
the Senate just voted to keep the Discovery cost cap at an artificially low $350 million, in order to continue funding Shuttle/Station -- although I don't know whether that provision will hold in the final House/Senate
compromise.)

Bruce, the jury is still out on this one. It often takes years for the really good science from a mission to be processed and digested. Perhaps they will find the crater, perhaps not. Is it dissapointing, yes, but there is still a lot of valuable science to be gleaned from this mission, despite its possible failure on one goal. I think you are starting to sound too much like Jeff Bell.