The problem is that the surface of the aerogel is rough and cracked when viewed through a microscope. I don't think it's the 7 years in space that is responsible - I've seen the collector up close and it looks as good as the day it launched. It's due to the way aerogel is manufactured starting from a thick set gel.
Andrew has written a new program which automatically judges where the surface of the aerogel appears in each focus movie. It should be close to the top so that you are searching for interstellar dust tracks in the aerogel. We've been going back over all the tiles scanned so far.
We've plotted the results up and I thought I would share them. Here's how the new images work:
Each image is a representation of 1 aerogel tile and each point represents a focus movie:
Green points - the focus is good enough
Red points - the focus is too high. Most of the movie is above the surface
Blue points - the focus is too low. The surface is right at the top
Black points - no focus. The movie has missed the surface altogether
White - no data
If a tile has a lot of red, blue, black or white points we have to rescan it.
The latest tile is I032. It looks good, so I'm uploading the focus movies right now
Anna
image updated 18July06