Why haven't any tracks been found yet?

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Why have no tracks been found?

A
3
21%
B
3
21%
C
8
57%
 
Total votes: 14

Nikita
DustMod
Posts: 994
Joined: Wed May 17, 2006 8:33 pm
Location: Indiana, USA

Post by Nikita »

GelDelve,

Wow! You really epressed this well! This is an example for me of the unexpected part of the expect the unexpected! I never thought of anything like this. I wonder if an impactor would be big enough, hard enough or fast enough to damage the collector. Interesting. I look forward to seeing how your theory may come into play.
After long thought, I came up with all the specs as just being dust bunny poop. I'm tellin' ya, those bunnies have to come from somewhere! :shock:
From dust we come

greuti
Posts: 200
Joined: Fri Aug 11, 2006 10:11 am
Location: Switzerland

Post by greuti »

You mean there is yet poo-poo anywhere else than only on Earth! :shock:

GelDelve

Post by GelDelve »

Nikita wrote:After long thought, I came up with all the specs as just being dust bunny poop.
That was my other theory!

DustSabre
Posts: 63
Joined: Sat Dec 09, 2006 4:51 pm

Post by DustSabre »

D. We have not looked long and hard enough yet
I don't think that's the answer; In my events, I'm finding that even the tiniest specks, buried in the most obscure places, and so small you can hardly see them, are still getting a good deal of agreements on them. It proves that we are looking everything over extremely carefully, and I personally don't think any track could possibly slip by us unless it were literally atoms across. :wink:

I vote that the biggest problem hampering our speed is that people aren't being trained to locate the particles if they're there. All the tests and calibration movies are so obvious that you'd have to be blind to miss most of them. I can often tell, just from the picture type and quality, when I'm viewing a calibration movie. :?

eshafto
Posts: 6
Joined: Thu Nov 02, 2006 7:50 am
Location: Livingston, New Jersey, USA

Post by eshafto »

F) Because not enough people have recognized My Pet Track as being of interstellar origin, despite my having posted it twice (once to low-angled tracks and once to I think I may have found...).

Well, I have no shame, so I'll plug it here, too:
http://stardustathome.ssl.berkeley.edu/ ... =6979778V1

the moon
Posts: 177
Joined: Thu Aug 03, 2006 12:34 am

Post by the moon »

Well among the other interesting information in the short paper from the recent update post,
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1457.pdf
the most revealing thing I think is that they anticipate that the real IS tracks will be as big, if not bigger then even the largest calibration movie tracks. This does not bode well for reasons B and C. If it's true, that would mean any track will be very obvious, and we certainly haven't seen anything like that yet.

Other interesting info from the paper if you're too lazy to read it:
All the calibration movies are made from a single track, resized and rotated many times. This surprised even me, all this time I thougtht there was at least 10 different tracks that merely all looked similiar. But when I took another look at the CMs today, they are in fact all the same track.

Oh and apparently, while you're dusting, you are no longer a human being, but rather a large multichannel instrument. It's strange, I don't feel any different.

fjgiie
DustMod
Posts: 1253
Joined: Sat May 20, 2006 8:47 am
Location: Hampton, SC, US

Update of 13 Mar 2007

Post by fjgiie »

the moon wrote:Well among the other interesting information in the short paper from the recent update post,
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1457.pdf
the most revealing thing I think is that they anticipate that the real IS tracks will be as big, if not bigger then even the largest calibration movie tracks. This does not bode well for reasons B and C. If it's true, that would mean any track will be very obvious, and we certainly haven't seen anything like that yet.
Only the multiplier will be larger...from the paper:

These track diameters correspond to particles sizes
of ~ 0.3 − 1.5μm, using the tracktoparticle diameter value
(~ 9) reported by Burchell et al.[2]. (This ratio is likely to be
larger for the SIDC since the aerogel densities are lower and the
velocities are higher than in the Burchell et al. experiments.


If the new multiplier is 10 then a 0.2μm particle will make a track only 2μm which is close to our smallest CM tracks we see now.

The other fact that was new to me was the distance we see down into the aerogel tile, which is stated as 200μm as movie depth. Therefore at times we can see 2% into the 1 centimeter thickness aerogel tile. I myself had thought 1.2% earlier. Each movie frame bites ~ 5μm and not the 3μm that I had thought earlier.

scopdrvr
Posts: 14
Joined: Tue Jan 30, 2007 6:26 pm
Location: Lafayette, IN, USA

Post by scopdrvr »

Wow! Each movie frame bites only 5 microns? That's the width of a red blood cell! I fervently hope when the bad focus movies are retaken, that they increase the depth to 10 microns at least! I don't think it will affect our ability to identify tracks, and it should allow almost all of the movies to include the surface and enough depth to find or exclude a possible track. In fact, as was mentioned in the suggestion thread, they could probably start doubling the depth between focus levels now and get a much better yield for the tiles that remain. Any other opinions?

greuti
Posts: 200
Joined: Fri Aug 11, 2006 10:11 am
Location: Switzerland

Re: Update of 13 Mar 2007

Post by greuti »

We used a single image of a submicron carbonyl iron grain
that was fired into an aerogel collector using the Heidelberg
tandem Van der Graaf dust accelerator at 20 km sec− 1


Can somebody tell me please, is there a difference between 20 km sec−1 and 20 km/sec ? If yes, what difference?

greuti
Posts: 200
Joined: Fri Aug 11, 2006 10:11 am
Location: Switzerland

Post by greuti »

scopdrvr wrote:In fact, as was mentioned in the suggestion thread, they could probably start doubling the depth between focus levels now and get a much better yield for the tiles that remain. Any other opinions?
Yeah, if it is possible, to double the depth would be great! But I guess, there are good reasons for the current 5 microns steps.

fjgiie
DustMod
Posts: 1253
Joined: Sat May 20, 2006 8:47 am
Location: Hampton, SC, US

Post by fjgiie »

greuti wrote:Can somebody tell me please, is there a difference between 20 km sec−1 and 20 km/sec ? If yes, what difference?
Yes, the answer is no.

http://en.wikipedia.org/wiki/Metres_per_second

greuti, I believe it's like a doctors prescription, can only be read by certain people. km per sec, or km/s is same as km s-¹ or km·s-¹.

The -¹ gets rid of the /

My guess is that this can be blamed on acceleration
m/s/s becomes m·s-² (superscript or exponent)

Also informative SI

[edit] Edited to place exponent in place of -1[/edit fjgiie]

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