25 Sep 06 Update?

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greuti
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25 Sep 06 Update?

Post by greuti »

According to the update from 25 Sep - CAPTEM Recommendations ("How do you work with a $200 million collector?") - the current status of the Stardust@home search was presented to the CAPTEM Stardust Oversight Committee at the Lunar and Planetary Institute near NASA Johnson Space Center in Houston... Quote: "The question at issue was: how do we further investigate the candidate interstellar tracks that Stardust@home collaborators -- you!! -- have identified, with minimal risk to the collector?"

I'm a bit confused about this update and it poses a question to me:
Am I right? The same tiles of aerogel in the collector captured on two sides either comet particles or IS particles, didn't they? If so we have here still the same aerogel tiles as in the investigation of the comet particles.
What's now the difference in the handling of IS particle tracks to comet particle tracks that were already determinated and extracted? Are the experiences that were gained on the other side of the collector not yet enough?

GelDelve

Re: 25 Sep 06 Update?

Post by GelDelve »

greuti wrote:I'm a bit confused about this update and it poses a question to me:
Am I right? The same tiles of aerogel in the collector captured on two sides either comet particles or IS particles, didn't they? If so we have here still the same aerogel tiles as in the investigation of the comet particles.
What's now the difference in the handling of IS particle tracks to comet particle tracks that were already determinated and extracted? Are the experiences that were gained on the other side of the collector not yet enough?
My understanding is that there were two different trays of aerogel, a much deeper one for the comet particles and a thinner one for the interstellar ones (not IS, since I think that is being used for particles coming from our own solar system). They were mounted back to back and faced into the correct positions to collect the particles each were designated to collect at various points in the space flight. I think the two trays were separated and are being subjected to different reviews and processes.

You do raise an interesting inquiry about having the comet side of the aerogel to compare with the interstellar side. It would seem that since they have already extracted items from the cometary tray, the experience could well apply to this side. I can think of at least two reasons why it may not be so and urges extra caution: 1) If I remember correctly, the interstellar side is made up of an aerogel that is less dense than the comet side (that would probably make the aerogel's structure weaker and easier to collapse from the process of extraction) and 2) The interstellar particles are significantly smaller and, thus more difficult to extract compared with the area that is disturbed by the extraction process. That, I believe, makes them extremely reluctant to damage the aerogel by attempting an extraction without more assurance that an actual particle might be extracted.

the moon
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Post by the moon »

I'm curious why it would be so bad if they damaged the collector. The way he talked it was like they plan to reuse it. But for what? Are they putting it on another satellite?

Mighty Pete
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Post by Mighty Pete »

No No the IS particles are very close to the surface. The gel is very damaged at this shallow depth. There is a chance much damage could be done to the particle they try to extract or others that may be close by. They want to preserve the angle of entrance as much as possible so they can extrapolate where the particle came from. There is no going back once it's extracted. Basically they said do everything possible first and practise on the backup unit. Get as much information as possible collected first. It's very thin too only a single cm. The comet dust collector is closer to a inch thick.

Other words, no Oops... D'oh !

It's going to be very difficult, I think they have been discussing this for over 10 years. I seem to remember them discussing trying to find the dust before even the launch in the first 100 microns of the surface because of how banged up that part gets.

It's already cracked everywhere and one wrong move and it could shatter.

DustBuster
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Post by DustBuster »

the moon wrote:I'm curious why it would be so bad if they damaged the collector. The way he talked it was like they plan to reuse it. But for what? Are they putting it on another satellite?
I think the concern is not for the collector, but the samples in the collector- these are irreplaceable (unless you've got your own oversight committee, millions of dollars and a number of years to wait around to complete another mission).
It's basically a one-shot deal- and with only 45 expected particles to be found, they don't want to risk damaging even one sample.
greuti wrote: Are the experiences that were gained on the other side of the collector not yet enough?
The other side of the collector contains cometary samples wereas the side in question was used to collect interstellar matter and are not the same.

greuti
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Post by greuti »

The other side of the collector contains cometary samples wereas the side in question was used to collect interstellar matter and are not the same.
I dont know if I understand you correctly, however, in my question I've written the same, didn't I? What do you mean exactly by "are not the same"? Is GelDelve right?

However, that what Pete has written seems to be plausible. Even so, wasn't it the same problem with very small cometary samples which also were (or still are) very close to the surface?

Mighty Pete
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Post by Mighty Pete »

The cometary samples had more mass so they are deeper in the gel. You'd think there would be a few in the top 100 microns though.. I already said that months ago when they said they're are not exactly sure what they will look like. Seems there should be some good samples in the first 100 microns on the other collector to me. My impression was there was only one collector and they used both sides but that does not seem to be the case. I've asked for clarification but never got any. Like where they bolted together or did the holding device actually have the ability to switch the two around as in one safely stored while the other was exposed... Can't seem to find more info on it.

I found this again but it does not really answer the question. The picture there shows it as one piece so if that's the case how did they take it apart? It says there is two collectors one 1 cm and one 3cm. Like is this interstellar dust search tying up the comet side also or has that been removed already? If so how did it come apart? Was the two bolted together?


http://stardust.jpl.nasa.gov/mission/capsule.html
Last edited by Mighty Pete on Fri Sep 29, 2006 3:56 am, edited 1 time in total.

Wolter
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Post by Wolter »

There is indeed 1 collector with 2 sides. One side contained a 3 cm thick layer of aerogel for cometary dust collection. The other side contained a 1 cm thick layer of aeogel for interstellar dust collection.
In this drawing you see the collector folded away in its container, the purple layer is the cometary side while the orage layer is meant for IS particals.
butImage

When exposed both sides were out there and the spacecraft was directed so that the correct layer faced the correct direction.
Image
This and many more on http://stardust.jpl.nasa.gov/mission/capsule.html
Just dusting... Image

greuti
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Post by greuti »

Ah thanks, so far I don't advanced so deep into the stardust site...
If I'm right then there're two grids that were mounted together to one collector.

I guess this pic
Image
in (Gallery - Cleanroom Photos) http://stardust.jpl.nasa.gov/photo/cleanroom.html shows the two grids still mounted together.
Last edited by greuti on Fri Sep 29, 2006 6:55 am, edited 1 time in total.

fjgiie
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dust depth

Post by fjgiie »

From Zack Gainsforth we find the thickness of the tiles of Aerogel which is one centimeter. (0.01 meter)
http://stardustathome.ssl.berkeley.edu/ ... ight=#7317
Zack Gainsforth wrote:The depth just has to be deep enough to capture the particles and not let them punch through the other side.
Let us be conservative and guess that the scientists wanted to be sure that the IS dust did not punch through and say that the dust would only go one fourth of that one centimeter. (0.0025 meter)

The microscope can only focus down to 100 microns at most = 0.0001 meter
0.0025 m / 0.0001 m = 25

Our dust would be 25 times deeper than the point where the focus on the microscope goes. Some may be more shallow, maybe only 10 time the depth of our focus. Who knows? We have not found any yet. Surely deeper than 100 microns.

This is just for scale and order of magnitude - not to be precise

fjgiie

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