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Jim Bell Q'n'a, Questions Please
algorimancer
post Aug 14 2006, 12:45 PM
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Here's a quick question for Jim or anyone else who knows... when we see a series of pancam pics of the sun, followed by a regular series of pancam pics, while I assume that the pics of the sun are used to renormalize the rover orientation, is that renormalized orientation applied to the immediately following series of pancam images, or is the processing done on earth and sent back to Mars, so that the renormalized orientation applies to the NEXT series of images? Also, how accurate is the sun-based orientation (+/- degrees azimuth/elevation)?
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mcaplinger
post Aug 14 2006, 02:56 PM
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QUOTE (algorimancer @ Aug 14 2006, 05:45 AM) *
when we see a series of pancam pics of the sun, followed by a regular series of pancam pics, while I assume that the pics of the sun are used to renormalize the rover orientation, is that renormalized orientation applied to the immediately following series of pancam images, or is the processing done on earth and sent back to Mars, so that the renormalized orientation applies to the NEXT series of images? Also, how accurate is the sun-based orientation (+/- degrees azimuth/elevation)?

I thought that most of the Sun images were being used only to estimate tau. I can't be sure from http://anserver1.eprsl.wustl.edu/anteam/me...ate_systems.ppt (page 13) if the processing is onboard or not, and I don't know the frequency with which they make these refinements. There has to be some onboard processing to provide coarse initial azimuth, but I'm not sure about fine adjustments.

There's a lot more information in http://trs-new.jpl.nasa.gov/dspace/bitstre...8/1/05-0560.pdf but I haven't read through it yet.

Also see Eisenman, et al, "Sun sensing on the Mars exploration rovers", http://ieeexplore.ieee.org/xpl/abs_free.jsp?arNumber=1035391 if you have IEEE access.


--------------------
Disclaimer: This post is based on public information only. Any opinions are my own.
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algorimancer
post Aug 14 2006, 03:59 PM
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Thanks, those were exactly the references I was hoping to find. Trying to reconcile the site-to-site azimuth variation that I have encountered with the AlgorimancerPG utility.

(edit...)
After reading through the papers, it appears that the gist of it all (from my perspective) is that the rover orientations are calibrated to within 1.5 degrees, and recalibration is needed about every 20 Sols, quite possibly on the occasion of a major panorama acquisition. This is loosely in agreement with my own estimates based upon the apparent variation azimuth of the Twin Peaks (30-odd kilometers to the east) over some tens of Sols. Good to know. On the other hand, pancam orientation seems to be good to better than a tenth of a degree, but it is not clear to me what bearing this has on the rover orientation itelf, beyond assisting in its determination.
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Tesheiner
post Aug 24 2006, 08:06 AM
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JB is in charge of Emily's blog this week, and posted this interesting article about their daily work on MER.

http://www.planetary.org/blog/article/00000679/

PS: Doug, if you find a better place for this post just move it there.
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remcook
post Aug 24 2006, 09:05 AM
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it also gives some comments about the whole photography thing, the subtitle of his book. Jim Bell's blog entries have been quite good so far!
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djellison
post Aug 24 2006, 09:26 AM
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My fav glogger to date - I must admit. But I'm loath to pass judgement on the 4 so far...because I'm ever aware that I'm only 5 weeks away.

Doug
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remcook
post Aug 24 2006, 10:08 AM
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you'll do great, I'm sure. At least you've got a large fanbase :-)
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Pertinax
post Oct 12 2006, 02:22 PM
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Another halo related question....

If I remember correctly, in the new software recently installed on the rovers recently there are improved provisions for auto cloud detection / imaging.

IF that is a fair statement, are there any plans to (or would it be difficult to) do any multispectral (L2,5,6 for ex) imaging of any clouds detected, particualry those within 05 to 50 degrees of the sun. Second and similarly, any possibility for high (temporal) resolution solar imagery when clouds are detected to be within say 05 degrees of the sun in order to learn more of the variable optical depth of the clouds? The first would further assist in halo element detection for H1, H2, and H4 type cirrus (http://www.srh.noaa.gov/jetstream/synoptic/h1.htm). The second would be nice just to better understand the observed clouds on mars.


-- Pertinax (the halo nut)
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