Sorry - I can't find a player for this clip.

__________________
jwj

It's ok not to know. We should try harder to find out.

You could use QuickTime or QuickTime Alternative.

Didn't I read there was a jet seen just prior to impact?

__________________
Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

http://www.spaceref.com/news/viewpr.html?pid=18095
This article is what Jerry was referring to, the heat inertia is low, meaning the heat from the Sun is gone when the comet surface turns into shadow. If this comet's heat inertia is anywhere near comet Wild 2's heat inertia it totally invalidates any model of jet production based on solar heating. On Wild 2 specifically, jets were emitting from the dark side and if we get any news on the jets from Tempel 1 I suspect it will confirm this impossibility.

To show what I mean: this website shows results from all the telescopes that imaged the impact.
http://deepimpact.umd.edu/collab_pub/imagep.shtml

Click on "Images" and look at the result from the NOT telescope in Spain:
Image caption:
I'm not sure which side of the comet is turned towards the Sun, but it seems the right side (after impact) shows a "shell" presumably lit by the Sun. If the Sun lights the comet from the right, it would be interesting to see from which specific points of the comet's surface the jets emanate. It needs triangulation, I hope it will be published soon. Another thing that strikes me as odd is the absence of any mention of the "bright patches" (in the recent Science articles) and the insistence of the team that no new jets were formed. The image above clearly shows otherwise, the existing jets remained, and new (short-lived) jets emerged. My guess is that the findings don't "fit the bill", and common practice is leave out the difficult issues whenever possible.

Cheers.

Just a Deep Impact update:

NASA - Mission Update - November 2005

__________________
0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 ...

Thanks for the link,

I'll try to find what I'm looking for (what causes cometary jets, and what are the bright spots/patches seen in close-ups of comets), but I'm not very hopeful.


Cheers.

I may be mistaken, but there is absolutely no news in this update, merely some whining that it is hard work to measure the size of the crater (duh, you can't measure the crater size until the dust settles and not with a comet in between!). Where are all the results of the triangulation measurements of the jets, the acknowledgement for the lack of water and explanation for the bright patches and the "double flash"? I guess the team has, after almost 6 months' work, only released the data that fit the preconceptions (ice and volatiles) and refuses to speculate on the data that don't fit the now obsolete "snowball" model.

I asked the DI team directly about the origin of the jets and bright spots, several times, but didn't even get an acknowledgement that the question was received.

Cheers.

There is no question they are downplaying the surprises. These include:

1) virtually all of the ejecta was dust with very little water vapor.

2) The dust is fairly high in iron content. (Remember, comets are thought to consist of only primal material found at the edges of the solar system when it formed. Most of the iron should be in the inner solar system.)

3) The minerals found take significant temperatures ~400+K to form. Again, this was not expected.

While it is true many in the field had been leaning towards an "Icy dirt ball" rather than a "dirty ice ball". the results contraindicate long-standing solar models. If you couple this with the amount of iron showing up on Pheobe, and possibly other saturn moons, the trend is undeniably at odds with the consensus model of solar evolution.

__________________
jwj

It's ok not to know. We should try harder to find out.

41 days, 6 hours, 14 minutes, 17 seconds til Stardust Return to Earth.

Only 1224 days, 4 hours, 12 minutes an 2 seconds before the data from the Stardust mission will be released (if it "lands" in one piece).

Btw where are the Genesis data?

Cheers.

According to the timeline, sample analysis occurs September 2004 through September 2007. I don't know if that's been updated to accommodate the sample's disheveled state on arrival.

__________________
0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 ...

Nothing about progress reports, or news releases? I can't imagine any project that takes 3 years of sample analysis and releases it's data all at once, surely not every analysis takes this long?

Cheers.

Hello everyone. I'm new, just tooling around and found my way here.

In case you're interested, Dr. Schultz is here at the Ames Vertical Gun Range this week conducting some experiments related to Deep Impact. I cannot go into too many specifics (he keeps these things tightly to himself until numbers are crunched and such), but I can answer general questions.

As for me, I am an engineering tech here at NASA Ames, and have been one of the three operators of this and other light gas guns for the past 5+ years.

Just thought I'd say hello and see if I could provide some insight into the research related to this event.

Hi Superheat,

Welcome to the forum, I hope you can give some extra dimension to this Deep Impact thread, there's many questions and I hope you stick around to answer a few.

Here's some for starters: the Deep Impact flyby camera showed an early flash (as Dr Schulz mentioned these were also seen at the Ames facility experiments) showing up in only one frame, meaning it lasted less that 50 mseconds, followed by several frames where "nothing happens" and then the plume starts erupting. How can this time be several frames (at least 100 msec) long? Do you know the specific numbers? At the speed of the impactor such a delay would mean it could have travelled almost a kilometer deep? That seems hardly possible, do you know what could have caused such a delay, maybe the early flash was not produced on impact, but before impact for whatever reason?

Cheers.

Welcome. [My education is m.e.] My general question is...that's a vertically downward gun, right? [I won't ask about pumpkin ballistics.]

Wouldn't penetration, even in talc-like material, require a narrow body? It was Newton who reasoned the displacement material would be accelerated to the speed of the object, roughly; so the cross section to mass ratio must remain small for serious penetration.

__________________
Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Thanks for the warm welcome!

I'll answer George's question first, and follow up with VanderL when I can get some answers from Pete :-)

The gun is indeed configured to fire vertically, at angles from 15-90 degress with respect to target materials and gravity. Also, the largest projectile we can safely load into this particular gun is 0.25", and most of the research prior to DI was 0.25" Pyrex, though we are shooting mostly 0.125" projectiles this week. As far as penetration, generally speaking, impacting fine pumice at 6km/sec will yield a crater of approximately 2.5" deep. The bucket we're shooting into is about 6" deep, and the typical projectile is melted away before reaching the bottom.

I hope this is helpful, and I will find out more when I speak to Pete.

Regards.

2.5" deep would seem shallow for something at 6km/s (> 13,000mph). However, based on Newton's principle, it doesn't sound so shallow. Since the DI projectile was neither long nor skinny, should'nt we expect it to have very limited penetration?

__________________
Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Limited in depth, yes. Fragments of the projectile often penetrate much further, usually close to the bottom and rarely follow a straight trajectory through the material. The amount of excavation can be considerable, but there is a fair amount of relational computation that took place between the experiments here and the actual event. Even after several years of research, I still don't grasp the concept.

Hoping to make up for my lack of cratering physics knowledge, how about a nice picture of Pete profiling a crater in the impact chamber? This was shot by me on 8/20/02 during some early DI research.

Image

Thanks, Superheat. We like to encourage the use of smaller images. I use Image Shack to host large images. You can then insert their thumbnail/link image. This reduces the board's load.

It is nice to see how you profile the crater. This image seems to show a broad crater for the size projectiles you mentioned. Interesting.

__________________
Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.