Update: 14 Feb 2007 - Results from the Foil Unfolding Tests

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Stardust@home Team
Stardust@home Team
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Joined: Wed Apr 19, 2006 11:28 am
Location: UC Berkeley Space Sciences Lab

Update: 14 Feb 2007 - Results from the Foil Unfolding Tests

Post by bmendez » Wed Feb 14, 2007 3:49 pm

As was discussed in earlier updates, we have been conducting tests to determine if it will be feasible to fold back the aluminum foils on the backside of the Interstellar Dust Collector. The reason we want to be able to do this is so that we can better scan the collector with light being transmitted directly through the backside rather than shining light through the top and reflecting it back up with a mirror. This will also allow us to make scans of candidate fields of view at higher magnification (25x or even 50x rather than the 10x optics currently used).

The major concern with folding back the foils is that the tiles might shift as a result, causing us to lose information about the direction from which any discovered particles came. The aerogel collector was oriented during flight to point directly into the uncoming stream of interstellar dust particles. So the interstellar dust particles should impact the top of the aerogel at an angle of 90 degrees to the surface (straight in).

After tests were done with the flight spare collector, showing minimal shifting or tilting, a test was done on the real thing (tile I027). The amount of tilt measured for this tile was as much as 10 times larger than on the flight spare. The overall shift of tilt measured was about 2 degrees.

This isn't terrible news, however. The collector pointing was not exact for the two collection periods during space flight and there is some natural spread expected in the directions of the oncoming dust particles. Overall, the expected minimum spread in possible impact angles is 10 degrees. So a 2 degree shift in the tile is not too bad.

Right now, the curator of the collector is deciding if this acceptable to carry on and begin unfolding more tiles, or if it should be discussed further by CAPTEM.

The images taken on tile I027 using transmitted light at 25x magnification are of superb quality. There are no strange optical effects at the edges as had been seen using reflected light. The team feels that this is definitely the way to go forward with rescanning fields of view that had bad focus and to look at individual candidates in more detail.

This is an image of the upper left corner of the collector before the foils were folded back on I027.

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