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Juno development, launch, and cruise, Including Earth flyby imaging Oct 9 2013
Gerald
post Mar 17 2014, 02:48 PM
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The likely phase shift for efb17:
Attached Image


I've compared a cleaned and enhanced version of efb17 with a combined efb14,-15,-16 image visually, starting with Sirius, narrowed down the phase shift candidates by some Orion stars, and used a couple of other bright stars for confirmation.
The likely phase shift from efb16 to efb17 is close to the threefold of the phase shift from efb15 to efb16.

About 95% of the specks in the cleaned efb17 seem to be cosmic ray hits. A few percent seem to be stars, sufficient to select a likely phase shift.

Thus far, I didn't find a reliable criterion to distinguish (most) cr hits from stars, when just looking at one image (efb17).
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gndonald
post Aug 3 2014, 02:36 PM
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Found an interesting video on youtube covering the mission up to 2013:

Juno - Halfway There and Home Again

Only 701 days to go till Jupiter orbit.
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mcaplinger
post Sep 8 2014, 09:05 PM
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A paper about Junocam in Space Science Reviews is online at http://link.springer.com/article/10.1007/s...hor/onlineFirst


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gndonald
post Jan 6 2015, 06:11 PM
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Visited the official site and there has not been any new news about Juno since 2013.

545 Days to Jupiter

Lets hope the spacecraft is still functional...
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Explorer1
post Jan 6 2015, 06:22 PM
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Regular mission statuses are posted here:

http://www.nasa.gov/mission_pages/juno

and on the twitter feed: https://twitter.com/NASAJuno

Everything is fine; Newton and Einstein are at the wheel, as they say.
The same can't be said for the multiple redundant websites as sources of mission information (some folks have a field day with highlighting that sort of thing).
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mcaplinger
post Jan 6 2015, 06:53 PM
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QUOTE (Explorer1 @ Jan 6 2015, 11:22 AM) *
The same can't be said for the multiple redundant websites...

I know of two "official" websites: the NASA website http://www.nasa.gov/mission_pages/juno/main/ and the project website http://missionjuno.swri.edu/ Both have been updated more recently than 2013 and I'm not sure I'd call them redundant.

If you're referring to the JPL website http://www.jpl.nasa.gov/missions/juno/ it just has links to the two above.


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Explorer1
post Jan 6 2015, 07:43 PM
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Maybe that was the wrong word for me to use; overlapping instead? I'm not sure which one gndonald was referring to as not being updated.
It's inevitable that some repetition happens given that both universities and governments are involved in most missions, and each wants to have a website to share news. For a mission's uneventful cruise phase, Twitter is more than adequate.
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elakdawalla
post Jan 6 2015, 08:35 PM
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May be a reference to http://juno.wisc.edu/, which for a long time was the top Google result for the Juno mission even though it hasn't been updated in forever. Fortunately it's been falling in Google search results recently so fewer people wind up on it. I don't know why it still exists when it's not being updated but I've been told "it's complicated." Anyway the mission is healthy and the NASA and SWRI pages are the up-to-date sources.


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Paolo
post Mar 27 2015, 09:22 PM
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an interesting paper on today's arXiv; The crucial role of HST during the NASA Juno mission: a "Juno initiative"
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Paolo
post Jul 7 2015, 07:05 PM
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a Juno status update

and this is unexpected:

QUOTE
Following a detailed analysis by the Juno team, NASA recently approved changes to the mission's flight plan at Jupiter. Instead of taking 11 days to orbit the planet, Juno will now complete one revolution every 14 days. The difference in orbit period will be accomplished by having Juno make a slightly shorter engine burn than originally planned.


and also
QUOTE
The revised plan lengthens Juno's mission at Jupiter to 20 months instead of the original 15, and the spacecraft will now complete 32 orbits instead of 30. But the extra time doesn't represent bonus science for the mission -- rather, it's an effect of the longer orbital period and the change in the way Juno builds its web around Jupiter.
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mchan
post Jul 7 2015, 08:10 PM
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Interesting from the status update -

QUOTE
The revised cadence will allow Juno to build maps of the planet's magnetic and gravity fields in a way that will provide a global look at the planet earlier in the mission than the original plan. Over successive orbits, Juno will build a virtual web around Jupiter, making its gravity and magnetic field maps as it passes over different longitudes from north to south. The original plan would have required 15 orbits to map these forces globally, with 15 more orbits filling in gaps to make the map complete. In the revised plan, Juno will get very basic mapping coverage in just eight orbits. A new level of detail will be added with each successive doubling of the number, at 16 and 32 orbits.


The revised flight plan sounds analogous to a progressive .jpg vs. a baseline .jpg for the original flight plan.
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Gerald
post Aug 24 2015, 05:37 PM
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QUOTE (mcaplinger @ Sep 8 2014, 11:05 PM) *
A paper about Junocam in Space Science Reviews is online at http://link.springer.com/article/10.1007/s...hor/onlineFirst

The paper is very helpful. After fixing the sign of the K1 value in the Brown-Conrady model (section 4.7), I was able to create a rather well-aligned version of efb12, purely with 2d transformations (no explicite or implicite 3d shape model of the Earth used) :
Attached Image

There are lots of issues in this version of the image, but I'm unaware of any published version of efb12 with a better alignment of the rgb channels. So I thought it's worth to post this intermediate version.

This post is mainly intended as a feedback, that there seem to be ways to align the rgb images down to an accuracy of one pixel or even better.

===

I can't rule out, that I'll do some write-up of the processing techniques beyond usual umsf posts, as things get more complex before or during the Jupiter encounters, in a paper-like style. What's the preferred way to make them available? Via pm/email to the Junocam staff, via attachment in a umsf post, on an own private website, or submission to arXiv, ... just in case?
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hendric
post Aug 24 2015, 05:56 PM
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Personally, I prefer on UMSF or arXiv, the other mediums tend to be a little brittle, with links often breaking or disappearing.


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mcaplinger
post Aug 24 2015, 10:10 PM
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QUOTE (Gerald @ Aug 24 2015, 10:37 AM) *
There are lots of issues in this version of the image, but I'm unaware of any published version of efb12 with a better alignment of the rgb channels.

Frankly it's hard to tell how well-aligned the color channels are, since for some reason there seems to be little or no color variation in the overlap -- it just looks like a blue-tinted monochrome image.

I spent a lot of time trying to get the full map-projected image color channels to line up, without complete success, so I'm interested to hear what you're doing.


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Gerald
post Aug 25 2015, 12:39 PM
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Here a sketch of the 2d geometrical processing I've used for the above EFB12 version:

Step 1: Decomposition of the source image efb12_tif into filtered and masked subframes, as they are assumed on the camera CCD chip.
Album of subframes.

Step 2: Distortion of the subframes, with the following assumptions:
- optical center at x = 824, y = 296, with (0,0) the lower left corner,
- pinhole horizontal FOVs of 60.03° for red, 60.03° for green, and 59.90° for blue for 1648 pixels, hence a small chromatic aberration, absolute angle values may need some further adjustment by using stars,
- radial Brown-Conrady distortion with K1 = -3.839251e-8 (sign!), Kn = 0.0, for n >= 2,
- projection to a longitude/latitude representation with the camera the center of the sphere, spin axis the polar diameter, equator at half the width of the distorted output subframe.
Album of distorted subframes.

Step 3: Merge of the subframes.
- (Translational) displacement per subframe: -1.8 pixels along x, 114.7 pixels along y.
- pixels are averaged per rgb channel, only non-black channel values are considered.
I've posted a cropped jpg version of the merged image above. The whole png would have been about 10 MB.

Generally, interpolation is bilinear, if none of the four involved pixels is black in the relevant channels, else the result is black.
Being less restrictive results in lines as processing artifacts.
The images aren't significantly supersampled in the provided version. Therefore there is some loss of information due to the two bilinear interpolation steps.

Parameters are chosen with respect to the software. Annihilation of errors of the software that way can't be ruled out entirely.


Why does it work? The total parallax per subframe of the Earth due to the relative spacecraft motion is about 1.8 pixels (along x). The difference of the distance between the spacecraft to different points on the surface of the Earth is only a fraction of the distance between spacecraft and Earth. The per frame parallax error is hence only a fraction of 1.8 pixels.
Caution: Naive map projection would result in a distorted map. Spacecraft motion needs to be considered when projecting.

==========

I'm working on more than a dozen of Junocam-related tasks, but I shouldn't raise expectations before it's implemented and tested. Currently my focus is on trying a (tentative) quantitative analysis of the ghosts / light scatter / stray light.
If it works, it can remove more camera artifacts than it adds processing artifacts; to be investigated.

Edit: You're right with the color variations. Thanks! I'm looking for the cause.
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