Juno at Jupiter, mission events as they unfold |
Juno at Jupiter, mission events as they unfold |
Jul 5 2016, 07:53 PM
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#31
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Merciless Robot Group: Admin Posts: 8785 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
This topic will consist of discussion of Juno operations post-JOI until end of mission, currently anticipated in Feb 2018.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Aug 9 2016, 05:29 PM
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#32
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Senior Member Group: Members Posts: 2542 Joined: 13-September 05 Member No.: 497 |
To be honest, I'm not really sure what you're trying to do here. IMHO, the small-disc Jupiter images are not great for assessing fine-scale distortions because they don't cover a large area of the field and there's not a straightforward error metric that you can minimize, like residuals in star images would have. Unfortunately we haven't taken RGB star images because of TDI limitations, but maybe we need to look into what we could do along those lines.
Be warned that spin axis knowledge may need to be refined post JOI and PRM burns because of s/c balance changes. There's also some evidence of nutation effects that I have yet to track down. Mods: I think that this whole discussion should be moved to the "Juno PDS data" subforum, and that subforum be renamed to better reflect a detailed technical discussion of Juno instrument specifics. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Aug 9 2016, 07:35 PM
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#33
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
To be honest, I'm not really sure what you're trying to do here. IMHO, the small-disc Jupiter images are not great for assessing fine-scale distortions because they don't cover a large area of the field and there's not a straightforward error metric that you can minimize, like residuals in star images would have. Unfortunately we haven't taken RGB star images because of TDI limitations, but maybe we need to look into what we could do along those lines. Be warned that spin axis knowledge may need to be refined post JOI and PRM burns because of s/c balance changes. There's also some evidence of nutation effects that I have yet to track down. Thanks for each bit of info! The short answer regarding Jupiter's small disc images: Think of many of these images - or better their centroids in each band - superposed into one image: The result is kind of RGB star images with highly accurate pixel position data. The difficulty with the small Jupiter images is, that they are on a narrow range of x-coordinates. But they are very suitable to constrain the camera parameters. Another set of Jupiter images with different x would result in a second narrow parameter subspace. Intersect both constraints, and you get a good geometric camera calibration. I may also use SPICE, and cruise and EFB images to obtain the missing constraints. I take the data as they are available; RGB star images would be helpful, too; but I'm confident to find a work around, if necessary. [More advanced: Think also at the identity theorem for holomorphic functions as a related idea: It says, that for a certain class of functions, a function is determined by its properties of any local area.] At hindsight, additional Earth / Moon images days or weeks before and after EFB would have been useful; next time, maybe. |
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