aerogel

[doc]

I do not fully understand what is happening here. Does the gel close in over an entering partical? If not why do most of the tracts come into focus beneath the syrface? Do they come in at an angle? If the gel does not close over then why are some of the surface openings that penetrate a ways and have edges looking like tracts not considered tracts?

[DustBuster]

The surface of the impact in the aeorgel can be quite small (depending on the particle size) and can leave very little indication of entry, however, directly beneath the surface it's expected to make a track many times its own size as it slows and stops in the aerogel, thus making the 'carrot' shape that is detectable with the stereomicroscope we are hoping to find.

[ZackG]

As DustBuster says, it creates the carrot shape below the surface of the aerogel and doesn't create a big hole at the surface. This is actually the way the aerogel is "carved out" and it doesn't really fill back in at the top. This has to do with the fact that the particle is supersonic on entering the aerogel. You may notice from some of the pictures of the cometary particles, that often the carrot ends but the particle is a bit further down. The end of the carrot is when the particle becomes subsonic.

By comparison, you may have seen shows on TV where a projectile creates a bigger hole out the back of a wall, while there is only a small hole in the front. (Mythbusters comes to mind for some reason...) If you know what you're doing, you could probably rig up an experiment using foam and some sort of projectile to get a feel for it. It would make for a fun afternoon, I'm sure!

[Mighty Pete]

A picture is worth a 1000 words. Or just two, No Track, This is a track but it's a comet dust track The ones we are looking for are way smaller.



This is the comet side of the collector. We are not looking at that side. We are looking at the other side. But it gives you a idea what the tracks look like from a side view:

[bmendez]

See also these side-on views of tracks in the cometary collector on Stardust: http://stardust.jpl.nasa.gov/images/2trackposter.jpg

-Bryan

P.S. Try firing BBs into jello for a fun demonstration.

[Mighty Pete]

Well that explains a lot. The branches coming off of the main part. I guess that odd shaped object I clicked on was not such a bad idea after all. It only had a single vote. Me, Was in the glass and went very deep. After I clicked on it I stared wondering if it was maybe one of those very deep foggy areas I seen on other movies. It was a track shape but it had those branches..

Thanks for the pics.

The top one is the one I clicked on:

http://stardustathome.ssl.berkeley.edu/ ... d=467978V1

94 views and a single vote so far.

Could also be another one that entered the glass from the back side too. If it is that would be the second one I found. The other one is posted in I think I found a track thread.

This page:

http://stardustathome.ssl.berkeley.edu/ ... &start=300

[sb126k]

By comparison, you may have seen shows on TV where a projectile creates a bigger hole out the back of a wall, while there is only a small hole in the front.

The reason for that can vary, though, depending on the type of bullet. A hollow point bullet will leave a bigger exit hole no matter what, simply by design. I do see your point though.