Discovery Program 2006 and Missions Of Opportunity |
Discovery Program 2006 and Missions Of Opportunity |
Guest_AlexBlackwell_* |
Jan 3 2006, 10:19 PM
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#1
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Guests |
I'm not sure exactly which forum this fits in but NASA has just released the AO for Discovery Program 2006 and Missions of Opportunity. See the Discovery Program Acquisition Home Page for more details. Click on the "Discovery AO" link to download the PDF.
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Nov 1 2006, 10:03 AM
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#2
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
Yup - we had that discussion a while back about star scanners being out of focus to produce a little ring of the star which is easier to identify with software than a sharp star and cosmic ray hits etc.
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Nov 1 2006, 04:15 PM
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#3
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
we had that discussion a while back about star scanners being out of focus to produce a little ring of the star which is easier to identify Actually, I was the one who suggested that in both cases so it should be taken with a grain of salt. I do, however, seem fairly certain I read that somewhere -- most likely a writeup on Cassini. -------------------- |
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Nov 2 2006, 04:31 AM
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#4
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Junior Member Group: Members Posts: 87 Joined: 19-June 05 Member No.: 415 |
Actually, I was the one who suggested that in both cases so it should be taken with a grain of salt. I do, however, seem fairly certain I read that somewhere -- most likely a writeup on Cassini. Yes, indeed, star trackers and star cameras do blur the images of the stars. As you said, this does enable the system to find the "centroid" or center-of-gravity so to speak of the spot, to a small fraction of the pixel dimension. Defocus is one way to do this blurring, and is definitely used on commercial products. Others have (and may still) use a camera that just doesn't form a good image, although the blur still has to be round (to a first approximation). Using focus requires very stable systems, so that the blur spot doesn't grow or shrink too much. There are papers in the professional literature (AIAA proceedings for instance) on the software that determines orientation in space from an image of stars. Extremely clever programing, although some are even more clever than others. |
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