Juno Perijove 58, February 3, 2024 Options

[volcanopele]

Looks like Masubi lives!

[Bjorn Jonsson]

These images are awesome. They must be by far the best images ever obtained of specular reflections on Io. This is image 26 enlarged by a factor of 2. North is up. I haven't been this excited by new planetary images for a long time (but they appear at a terrible time for me - it's now roughly 3 am where I live!).



A plume is visible at lower right. This part of the image is heavily processed and has been brightened significantly relative to other parts of the image to show the plume more clearly.

[volcanopele]

Improved versions using a global control network

[Daniele_bianchin...]

sorry if the question has already been posted,
What are those that look like lakes filled with?
and does Loki contain magma or a liquid?
Daniel

[StargazeInWonder]

According to previous temperature measurements, the greater part of the surfaces around Loki, while definitely warmed by internal heat, were far too cool to be liquid.

In fact, coincidentally, they are roughly comfortable for human presence!

https://www.sci.news/astronomy/map-loki-pat...n-io-04854.html

So that would be compatible with a solid surface that is glassy.

On the other hand, Io brings uncertainty across time and fine scales of space, so maybe what we're seeing now is different.

[john_s]

Yes, wonderful images. It's interesting that the northernmost patera of Mazda Catena, the site of a strong specular reflection here, was very likely also the location of a specular reflection seen by Voyager 1 45 years ago here. The temporary brightening was interpreted at the time as a blueish cloud emitted by the patera, but it's more likely that it was a specular glint, that was strongest at the time when the blue filter image was taken.

The most striking thing about the Loki specular reflection is how uniform it is- that's telling us something interesting about the resurfacing process.

John

[ngunn]

Wonderful images of a wonderful world. Thanks to all for posting. Jason, I notice that the horizon/limb topography seems to be missing or at least muted in your versions compared with, for example Brian Swift's post 41 which has more the feeling of being in a real landscape. (The horizontal orientation helps too.) This encounter calls to mind the excitement of New Horizons at Pluto even though it's not our first look at Io.

[mcaplinger]

Jason, I notice that the horizon/limb topography seems to be missing or at least muted in your versions compared with, for example Brian Swift's post 41 which has more the feeling of being in a real landscape.

If these are map-projected products without an underlying DTM, then the relief at the limb will get mostly lost -- that's an inevitable consequence of this type of processing that Brian's method avoids.

[volcanopele]

Just two different methods of processing the data. I use ISIS which has the issue of it trimming the images off at the limb when you map project them. But on the other hand they are very useful products for dropping them into ArcGIS.

[Bjorn Jonsson]

A map-projected comparison of images PJ57_24 and PJ58_26:

[antipode]

Has anyone managed to actually spot an impact crater on any of these new images?

As far as I know, no one ever has, but they must be there even if resurfacing is common.

Also, Bjorn, are those specular reflections off peaks at the bottom of your right hand (new Juno) image?

P

[Phil Stooke]

We just recently had a first suggestion of an impact crater in old data:

https://eos.org/articles/amateur-astronomer...le-crater-on-io


Juno would not be able to see craters like that one.

Phil

[Brian Swift]

PJ58_23 with plume. Jupiter-shine illuminated.

[StargazeInWonder]

"Twenty-kilometer diameter craters are made by kilometer-size impactors; such events occur on a Galilean satellite about once in a million years."

https://pubmed.ncbi.nlm.nih.gov/11878353/

Io's surface is "no more than a couple of mission years old."

I don't know what a fair extrapolation is for the rate of cratering for that could be seen in these images, but it seems like it would be very optimistic to hope to see one, and zero is the likeliest number. The ambiguity in appearance adds to the difficulty. (Even on Earth, the cause of origin of weathered, extant craters can be ambiguous, and we're not observing them from orbital distances!)

[Bjorn Jonsson]

This is an updated plot of the values I use for correcting the color in the JunoCam images. It shows the now well known reddening of the images as the mission progresses. Interestingly, the reddening trend became more irregular once the first JunoCam anomaly occurred at PJ48. In particular, the images temporarily became less red after PJ48 but are now again getting redder - there was a very large change (reddening) from PJ57 to PJ58.



There was a very rapid reddening from PJ47 to PJ48 (i.e. immediately before the PJ48 anomaly) and again from PJ53 to PJ54. The third large change is PJ57 to PJ58. I suspect these all correspond to a lot of radiation. Smaller changes might simply be a coincidence or they might be associated with lower levels of radiation or (in some cases) mitigation measures like heating the camera between perijoves as was successfully done before PJ57 in response to the PJ56 anomaly.