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Juno Perijove 48, January 22, 2023
mcaplinger
post Jan 28 2023, 04:48 PM
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https://www.nasa.gov/feature/jpl/nasa-s-jun...lyby-of-jupiter

QUOTE
The JunoCam imager aboard NASAís Juno spacecraft did not acquire all planned images during the orbiterís most recent flyby of Jupiter on Jan. 22. Data received from the spacecraft indicates that the camera experienced an issue similar to one that occurred on its previous close pass of the gas giant last month, when the team saw an anomalous temperature rise after the camera was powered on in preparation for the flyby.

However, on this new occasion the issue persisted for a longer period of time (23 hours compared to 36 minutes during the December close pass), leaving the first 214 JunoCam images planned for the flyby unusable. As with the previous occurrence, once the anomaly that caused the temperature rise cleared, the camera returned to normal operation and the remaining 44 images were of good quality and usable.


The good images have been posted to missionjuno.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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mcaplinger
post Jan 29 2023, 03:54 AM
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To correct some misimpressions I have heard in various channels:

The Junocam instrument paper says that
QUOTE
A platinum resistance thermometer (PRT) on the camera focal plane is read by the spacecraft to
provide temperature knowledge for radiometric calibration.

Since PDS release 8, the focal plane temperature is given in the metadata for each image. It is not correct (always says 0C) in earlier releases and in the missionjuno metadata for regrettable but unintentional software bookkeeping reasons.

I wish I could describe our ongoing diagnostic efforts in more detail, but I can't for various reasons that those of us who have worked on these missions are all too aware of.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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Antdoghalo
post Jan 29 2023, 06:33 AM
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Sorry your awesome camera is having problems, It has been a real trooper given what it was meant for and what its going through. Io torus is not friendly to spacecraft!


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Gerald
post Jan 29 2023, 06:27 PM
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QUOTE (mcaplinger @ Jan 28 2023, 05:48 PM) *
The good images have been posted to missionjuno.

Could you please release at least one of the invalid raw images, if they aren't completely saturated by noise?
I'd like to see whether thermal noise can be filtered out or smoothed to a level where meaningful image data can be extracted.

A private access would be ok, if a public release appears inappropriate.
Of cours only when you have time.
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mcaplinger
post Jan 29 2023, 10:18 PM
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QUOTE (Gerald @ Jan 29 2023, 10:27 AM) *
Could you please release at least one of the invalid raw images, if they aren't completely saturated by noise?

Everyone should stop assuming that somehow this is a choice I can make, it's above my pay grade.

If the images showed anything useful in terms of scene content, we would have pushed harder to get them released.


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vjkane
post Jan 29 2023, 10:42 PM
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There are good engineers working the issue(s). I wish them the best, and with their skills and luck, we will have a functioning camera for the close Io encounters.

Whatever happens, wow! for all the great images so far, and many thanks to those who have processed them for our enjoyment.


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Gerald
post Jan 29 2023, 11:47 PM
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QUOTE (mcaplinger @ Jan 29 2023, 11:18 PM) *
If the images showed anything useful in terms of scene content, we would have pushed harder to get them released.

Thanks a lot, Mike!
You might imagine that I happen to get similar questions via email.

Here are PJ48 drafts:
PJ48 drafts

I'll upload other processed versions here over the next few days:
PJ48
Some copies will also be submitted to the missionjuno site.
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StargazeInWonder
post Jan 30 2023, 12:46 AM
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It's an understatement to say that JunoCam has become one of those systems that has significantly outlived the design requirements, whether you measure by years or orbits. It's been great so far and if we get a few images of the closer Io encounters, that will be fantastic.
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Decepticon
post Jan 30 2023, 02:47 AM
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Wait the imager has totally failed? Or did it fault?
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Brian Swift
post Jan 30 2023, 04:58 AM
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PJ48 Reduced Resolution Exaggerated Color/Contrast Collage
Attached Image
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Brian Swift
post Jan 30 2023, 05:33 AM
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Jupiter and Ganymede PJ48_215 Crop
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volcanopele
post Jan 30 2023, 02:38 PM
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Glad to see that the camera overall is still okay, so there is hope! I just want you to know Mike how great the images have been from JunoCAM and how useful the Io images have been so far, yes even at 44 km/pixel. Really pulling for you all to come up with a solution or workaround for this issue.


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stevesliva
post Jan 30 2023, 04:44 PM
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QUOTE (Decepticon @ Jan 29 2023, 09:47 PM) *
Wait the imager has totally failed? Or did it fault?


The tape got stuck during part of the flyby. /joke

Sounds like there is a mode where the camera is alive and recording images, but they're noise. Reasons not entirely explained yet. And it relates to how long it's been active with "how long" having large error bars. But the camera has eventually come around and taken images in all cases. AFAICT.
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Gerald
post Jan 30 2023, 08:29 PM
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Here is PJ48, image #216, roughly illumination-adjusted, and gamma-stretched, I think to the 2nd power of radiometrically linear (gamma=4 wrt. square-root encoding)
Attached Image

I've used linear radiometric weights derived from PJ47. Usually, using the weights of the preceding PJ is ok. But this time the reddening seems to be significantly stronger. This suggests that the camera experienced a higher radiation dose than for previous PJs. I'm going to quantify this more accurately, before I'll perform a second run with updated weights.
But overall, the CCD sensor is looking fine. Just the optics appears to be darkening faster than it used to do so before.
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Bjorn Jonsson
post Jan 31 2023, 12:07 AM
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QUOTE (Gerald @ Jan 30 2023, 08:29 PM) *
But overall, the CCD sensor is looking fine. Just the optics appears to be darkening faster than it used to do so before.

This is very interesting - I may have noticed hints of this already in the PJ47 images. The change was probably not as fast back then as it appears to be now though but I haven't analyzed this in any detail yet. I noticed *lots* of radiation noise in some of the PJ47 southern hemisphere images and this might be of significance. From this post:

QUOTE (Bjorn Jonsson @ Jan 18 2023, 11:08 PM) *
BTW I noticed that some of the PJ47 southern hemisphere images are extremely noisy. My software automatically removes spikes but doesn't do it very aggressively. I used to consider images where the software removed ~5000 spikes as very noisy but for image PJ47_113, about 25,000 spikes were removed. I am fairly sure that this is (by far) the largest number I have seen.

It now occurs to be that maybe I should have used different color correction for the PJ47 northern hemisphere images than I used for the southern hemisphere images. I remember I was slightly surprised by the bluish color of a PJ47 northern hemisphere image. The high northern latitudes are more blue than areas closer to the equator but despite this I was a bit surprised. I now think that by using the southern hemisphere images to determine the correction I may have 'overcompensated' for the image reddening when processing the northern hemisphere images. I may take a look at this soon since it is clear that I will be spending less time processing PJ48 images than I was expecting.
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