Update: 27 Mar 2007 - Extracting Candidates

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bmendez
Stardust@home Team
Stardust@home Team
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Location: UC Berkeley Space Sciences Lab
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Update: 27 Mar 2007 - Extracting Candidates

Post by bmendez » Tue Mar 27, 2007 11:45 am

During the week of March 12th, most of the Stardust@home team were in Houston for the Lunar and Planetary Science Conference. Dr. Westphal also stayed for the CAPTEM meeting.

Dr. Westphal presented the latest from the Stardust@home project. This generated intense interest and excitement: people were very impressed with the dedication and hard work of the roughly 23,000 "dusters" -- you have collectively searched nearly 40,000,000 images. Even more important than this is the amazing sensitivity of dusters to small tracks -- roughly 75% of the smallest calibration tracks are found by dusters. Since we need only about 10% to identify a track, dusters are more than seven times more efficient than they need to be! Naturally, there was also intense interest in the several dozen candidate interstellar dust tracks that we have found so far. We emphasize that we don't know what these are -- at this point they are simply "features of interest."

There was considerable discussion about the next steps in determining whether or not any of these candidates are indeed interstellar tracks. It has become clear that before any further progress can be made, these tracks must be extracted from the collector for analysis. We learned from the Stardust cometary collector tray that it is very difficult to get much information about tracks while they are still in the tray. The Berkeley group proposed an approach that we hoped would address some of the concerns of previously considered approaches. The idea is to use a micromanipulator mounted on the side of the Stardust interstellar collector tray to extract keystones (tiny wedge-shaped sections of aerogel surrounding a track) directly from aerogel tiles while still in the tray. This eliminates the need to remove entire tiles from the tray, which is probably risky. It also removes concern from having to mount a micromanipulator over the tray, since it could shed particles during extraction.

The Cosmic Dust Laboratory will be shut down to interstellar tray scanning for about two months starting next week to catch up on allocations of interplanetary dust particles (IDPs). During this time, we will modify the scanning system to accommodate a micromanipulator -- the main job is machining a new mounting plate for the interstellar tray -- then we will practice doing extractions of ''picokeystones'' on the Stardust interstellar flight spare tray. These will enable us to image the tracks, and determine trajectories. The next steps will depend on what we find!

While scanning in Houston is shut down we will be uploading high magnification movies from several tiles for searching in the VM. We will also be uploading new calibration movies to go along with these new movies.


Image
Extraction at Berkeley of a keystone from a tile on the Stardust cometary dust collector.

Image
A tiny particle track (from a particle with a mass of only about a picogram, one trillionth of a gram) extracted in a "picokeystone" (a little keystone on a bigger keystone).

Image
View of a picogram particle track in a picokeystone in a Scanning Electron Microscope (photo credit: Giles Graham, Lawrence Livermore National Laboratory)

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