Update: 3 Nov 06 - Site Problems and an Evaluation Plan

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bmendez
Stardust@home Team
Stardust@home Team
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Joined: Wed Apr 19, 2006 11:28 am
Location: UC Berkeley Space Sciences Lab
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Update: 3 Nov 06 - Site Problems and an Evaluation Plan

Post by bmendez » Fri Nov 03, 2006 5:45 pm

1) More new candidate evaluation comments from the Berkeley Team have been posted to the database this week. You can see them by viewing your My Events page. Progress on this has been slower than hoped, but the Team is going through them very carefully and moving as fast as they can.

2) This past week saw a number of problems with the website. It went down for scheduled maintenance once, the server hiccuped and froze once (which was remedied this morning), and many people have noticed a marked slowing in the download speeds of focus movies. This slowing in focus movie downloads appears to be caused by heavy traffic being experienced by Amazon Web Services. They are busily working to upgrade their system to handle increased loads and assure us that the problem should go away shortly.

We thank everyone for their inquiries about these problems and ask that you continue to let us know if other such problems persist.

3) Last week, the Stardust@home director, Andrew Westphal, presented a plan to CAPTEM
in Houston for the first steps in the evaluation of the interstellar dust candidates that Stardust@home "dusters" have identified. These tests will be done on the flight spare tray, not on the actual Stardust Interstellar Collector. We proposed to do three tests, and, in anticipation of the likely success of the one of the tests, install two new pieces of equipment.

The first test is motivated by the very limited image quality that we currently have using reflected illumination. It is a testament to the skill of the Stardust@home "dusters" that they have been able to search these challenging images! We cannot currently use transmitted illumination because of aluminum foils that cover most of the backs of the aerogel tiles. So we will do a test to see how the tiles react to folding back the foils. If they are not disturbed, then we will install the transmitted illumination, which should give much better image quality. We may even decide to scan from now on using transmitted instead of reflected illumination.

The second test is motivated by the possibility that we will have to eventually remove tiles from the tray. The aerogel tiles on the cometary tray are now routinely removed without difficulty or damage to the tiles, but these tiles are 3 cm thick, while the interstellar tiles are 1 cm thick, and so may be more fragile. We need to do some preliminary tests on the flight spare tray to uncover any unexpected problems.

The third test is motivated by the possibility that we may decide to extract tracks from the tray without removing tiles. We cannot use the same techniques that we have been using on the cometary tray, using automated micromanipulators, because of the danger of particle contamination. But we may be able to use the stage itself to move the collector with respect to the sharp glass needles that we use for "machining" the aerogel. We will find out if this approach works.

CAPTEM approved these plans. Now we have to get to work on these tests -- stay tuned!

For the interested, here are the details:

Test 1. Evaluate folding back foils on flight spare tray
On the flight spare, carefully make a focus map of a specific aerogel tile, with respect to some fixed references, e.g.: silicon chips glued to the frame as has been done with the flight tray. Remove the tray, and carefully fold back the foil on the back of that tile with a second observer watching the tile from below to look for any pieces that could come off. Replace the tray on the scanning microscope to redo the focus map, evaluate the change in altitudes of the tile surface, and measure the rotation of the tile. The results of this evaluation will be presented to the SOC and CAPTEM for consideration before any further steps are taken.

Test 2: Practice tile extraction on flight spare tray
We should also proceed with the practice extraction of a tile from the flight spare. Focus maps should be made of the tile before and after extraction to evaluate any distortion that might occur during extraction.

Test 3: Keystone extraction test of flight spare using microscope stage
Using a non-Stardust tile, we should test extracting tracks in keystones using a needle fixed to the microscope head and only the microscope stage for motion. Because the interstellar and cometary dust aerogels are different, it is possible that they will require somewhat different methods for extracting keystone shaped sections of the aerogel. We propose to use both the flight spare tray and a non-Stardust aerogel tile with tracks in it for this test.

Action item. Install new tie-down, install transmitted light
In anticipation of a successful outcome of test 1, transmitted illumination should be reinstalled on the scanning microscope. Currently this is not possible because a tie-down going through the base of the microscope goes through the transmitted illumination housing. We propose to replace the current tie-down with a new tie-down that will allow for the reinstallation of the transmitted illumination.

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