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Io, Still A Mystery Moon
jasedm
post Jul 15 2008, 03:47 PM
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Thanks VP.
I thought I'd seen an image some time back of an Ionian crater, but I think it may have been an old Voyager shot of an Europan one (Pwyll maybe).

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MarcF
post Aug 4 2014, 08:50 PM
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New data for an old topic:
Three massive volcanic eruptions occurred on Jupiter's moon Io within a two-week period in August of last year.
http://www.nasa.gov/jpl/news/jupiters-moon...0804/index.html
"We typically expect one huge outburst every one or two years, and they're usually not this bright," said Imke de Pater, professor and chair of astronomy at the University of California, Berkeley, and lead author of one of two papers describing the eruptions. "Here we had three extremely bright outbursts, which suggest that if we looked more frequently we might see many more of them on Io."

"These new events are in a relatively rare class of eruptions on Io because of their size and astonishingly high thermal emission," Davies said. "The amount of energy being emitted by these eruptions implies lava fountains gushing out of fissures at a very large volume per second, forming lava flows that quickly spread over the surface of Io."

Regards,
Marc.
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Toma B
post Aug 24 2014, 09:24 AM
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Io is definitely my favorite moon of Jupiter if not in all Solar System.
I was just wondering is there a possibility to acquire good images of Io once Juno gets to Jupiter in July 2016?


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The scientist does not study nature because it is useful; he studies it because he delights in it, and he delights in it because it is beautiful.
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Bjorn Jonsson
post Aug 24 2014, 01:04 PM
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This has been discussed elsewhere and the answer is no. Junocam is a wide angle camera - at a distance of e.g. ~500,000 km from Io Junocam's resolution is ~400 km/pixel. There will be no close flybys of the Galileans, this is a mission that's focused on Jupiter.
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mcaplinger
post Aug 24 2014, 04:04 PM
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QUOTE (Bjorn Jonsson @ Aug 24 2014, 06:04 AM) *
There will be no close flybys of the Galileans...

Correct. In the nominal orbit the closest approach to Io is a little under 200,000 km.


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Phil Stooke
post Aug 25 2014, 04:01 PM
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Right... but to be more specific, a previous calculation was that Io at best would appear only 16 pixels across. That's not much, but it will allow large features to be seen, including large eruption deposits. It is reasonable to expect that the small number of images we might expect from the closer passes by Io will let us see a few recent surface changes, such as the effects of the big eruptions just reported.

Phil



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volcanopele
post Aug 25 2014, 04:54 PM
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To be honest, ground-based observatories can do a better job. That being said, the IR instrument on Juno could acquire useful data over Io's polar regions.


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tedstryk
post Aug 25 2014, 05:10 PM
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I would imagine that some of the plumes might look neat at a high phase angle even at such low resolution. I wonder if it would be possible to take some framelets of Io on a few successive rotations for stacking purposes to reduce noise and maximize usability. And it would seem that at its closest, should that be looking down at a pole, it would still be moderately useful for looking at albedo changes in those foreshortened regions.


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mcaplinger
post Aug 26 2014, 04:19 AM
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QUOTE (Phil Stooke @ Aug 25 2014, 09:01 AM) *
a previous calculation was that Io at best would appear only 16 pixels across.

The Junocam images of the Moon during Earth flyby are very similar to the best approaches of Io in terms of size and resolution.

It's too early to say what the satellite encounter distances and times will look like for the real mapping orbit. By intent we don't get that close -- see http://www.trylam.com/files/AIAA_2008-7368...uno_Mission.pdf


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jccwrt
post Sep 22 2015, 06:13 AM
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Sorry if this is the wrong thread, but I didn't see one about the reprocessing of Io images.

As you may know, some of the Voyager 1 images taken during the Io flyby are heavily smeared due to movement of the scan platform. Thanks to machi's tip about using the Parallel Iterative Deconvolution plugin for imageJ, I realized that some of these heavily smeared images could be restored to at least some degree.

Just as Voyager 1 was about to make its closest approach, it took two three-frame longitudinal scans of the Moon, centered at around 300 degrees west and 5 degrees west. Judging from volcanopele's mosaic page, these images have a resolution somewhere around 400m/px. (Jupiter Viewer seems to output a wrong range to Io - 400,000 km - so I can't use that to calculate the resolution better).

So without further ado, the deblurred mosaics:


Io Longitudinal Scan 1 by Justin Cowart, on Flickr


Io Longitudinal Strip 2 by Justin Cowart, on Flickr

The most severe smearing was in the first frame of each sequence, so I'm guessing that's a result of imaging before the scan platform had entirely stabilized after slewing. Unfortunately I wasn't able to recover fine detail, but some of the larger features spanning several pixels have been recovered to some degree. At any rate I'm just happy to see some fresh new Io pictures I hadn't seen anywhere else on the web!
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machi
post Sep 22 2015, 03:03 PM
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Nice work!
In terms of freshness those aren't the first attempts to reprocessing those images.
Some of older images are here.
I did few mosaic, Bjorn Jönsson did few of them, Jason (Volcanopele) did lots of them (best high-res global mosaics of Io on the net) and Paul Schenk did exquisite mosaics for his Atlas of the Galilean Satellites.
There are probably even more of them from other authors.


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jccwrt
post Sep 22 2015, 03:39 PM
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Thanks for those links! I'd done some googling and searches though the various Io threads in this subforum for other examples of these pictures and came up empty-handed.

I'd really also like to thank you for sharing that tip about Deconvolution, using it feels like I've been turned into a wizard with magical image restoration powers!
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tedstryk
post Sep 22 2015, 05:00 PM
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Amazing work! The Voyager 1 smears have been a set that I've never been able to crack. I've never been able to get rid of the smear without destroying detail visible from the part of the exposure that wasn't smeared.


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Bjorn Jonsson
post Sep 23 2015, 10:21 PM
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Great mosaics! I ran into somewhat similar problems when desmearing some of the less smeared Ganymede images - maybe the scan platform motion is more irregular in these images than in the more smeared images, thus making the less smeared images more difficult to desmear (contrary to what one would expect).
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jccwrt
post May 29 2016, 05:05 PM
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I worked on one of the approach sequences taken by Voyager 1 on March 4, 1979. I believe that these series of images was the one where Linda Moribito noticed the faint eruptive plume from Pele and discovered Io's volcanic activity.


Full-size here

I got a slightly better S/N ratio on the images because there were three clear filter images, and two images through each of the filter sets. I used the OGV combination. I've boosted the brightness and contrast of the space around Io a little to make the plume a little more obvious.

It's striking how much brighter Pele's plume is at UV and blue wavelengths. Is that more from the sulfur content, or is there a psuedo-auroral emission from the ionizing radiation?
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