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Juno Extended Mission, Perijove 34-76
volcanopele
post Jan 13 2021, 03:36 AM
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Here is the simulation of the best Europa view I found:

Attached Image


Closest approach is over the nightside. Best views over the sub-Jupiter hemisphere.


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Decepticon
post Jan 13 2021, 07:35 AM
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Very excited to see Europa and Io!

Does Amalthea come close to being imaged?

Very curious to the fallout from Io on its surface.
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volcanopele
post Jan 13 2021, 03:33 PM
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QUOTE (Bjorn Jonsson @ Jan 12 2021, 06:40 PM) *
The two close Io flybys look interesting to me since the ground tracks posted above are over a relatively poorly imaged area.

Keep in mind that most of the "poorly imaged area" will be in darkness. The terminator will be at around 330 W, so features like Ra and Loki will be illuminated. That being said, the PJ31 images of Io, while not that great in terms of resolution, do suggest to me that JunoCam might be able to do decent Jupiter-shine imaging. Mike would be better placed than me in knowing how well the JunoCAM sensor might perform when imaging a target that is illuminated at 1% of Solar. the effective resolution would be lower due to poorer signal-to-noise, but I don't know how much "play" sequence planners have in adjusting exposure time to deal with the weaker illumination conditions.


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mcaplinger
post Jan 13 2021, 04:07 PM
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QUOTE (Decepticon @ Jan 12 2021, 11:35 PM) *
Does Amalthea come close to being imaged?

Juno gets to within 42000 km of Amalthea on 2025-07-13 but it will only be 8 pixels or so across.

Remember that the encounters with the Galileans are as much about changing the orbit as about doing satellite science, and Amalthea is not useful for the former.


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volcanopele
post Jan 13 2021, 04:31 PM
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And even with JIRAM, Amalthea would be 25x12 pixels in size. still, it could get some disk-resolvable NIR spectra.


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mcaplinger
post Jan 13 2021, 04:52 PM
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QUOTE (volcanopele @ Jan 13 2021, 07:33 AM) *
JunoCam might be able to do decent Jupiter-shine imaging...

The main issue with the encounters is the spacecraft spin and the maximum cadence of imaging. So we can't take images as quickly as we might like, it may take 2-3 spin periods between images. And we have data volume constraints as well. We could use a lot of TDI for nightside imaging, but it frankly hadn't occurred to me to try it, and I'm not sure how well it would work. But this is something we could try for the earlier Io encounters to see if they would be worthwhile for the close ones.


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Antdoghalo
post Jan 13 2021, 11:28 PM
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I think what would be cool is an end of mission plunge down the road that flies by Amalthea and gets that image Galileo wasn't able to get.


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Explorer1
post Jan 14 2021, 01:15 AM
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That would be awesome, but even if orbital dynamics allowed it, how much time is there to transmit data to Earth during such a final plunge? Amalthea is pretty close to the planet, and the PIs of the other instruments would not want the pipeline hogged, I'd bet!


On a related note, I am wondering how EOM disposal will occur; if the main engine still can't be fired, will it be gravitational assists from a moon that push the last perijove down into the clouds (like Cassini's final encounter with Titan? Or will there be an RCS manouevres at apojove?
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Bjorn Jonsson
post Jan 14 2021, 01:28 AM
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QUOTE (volcanopele @ Jan 13 2021, 03:33 PM) *
Keep in mind that most of the "poorly imaged area" will be in darkness. The terminator will be at around 330 W, so features like Ra and Loki will be illuminated. That being said, the PJ31 images of Io, while not that great in terms of resolution, do suggest to me that JunoCam might be able to do decent Jupiter-shine imaging. Mike would be better placed than me in knowing how well the JunoCAM sensor might perform when imaging a target that is illuminated at 1% of Solar. the effective resolution would be lower due to poorer signal-to-noise, but I don't know how much "play" sequence planners have in adjusting exposure time to deal with the weaker illumination conditions.

I also wonder if the SRU camera might be useful here. Judging from its images of Jupiter's nightside illuminated by Ioshine it seems to work well under low light conditions. The SRU's resolution (16.4 deg FOV and 512x512 pixels) is comparable to JunoCam's. Europa plume search might be interesting too but I have no idea if this (or SRU Io imaging at close range) is feasible. However, I noticed that the extended mission description recommends archiving engineering instrument data.
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volcanopele
post Jan 14 2021, 02:21 AM
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Animation of Io encounters as promised...

https://www.youtube.com/watch?v=xic5OjuhorA


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Antdoghalo
post Jan 14 2021, 03:37 AM
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I think the best part will be seeing hotspots and aurorae.


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Adam Hurcewicz
post Jan 14 2021, 08:55 AM
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QUOTE (volcanopele @ Jan 14 2021, 03:21 AM) *
Animation of Io encounters as promised...

https://www.youtube.com/watch?v=xic5OjuhorA


Great animation.


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mcaplinger
post Jan 14 2021, 03:54 PM
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QUOTE (volcanopele @ Jan 13 2021, 06:21 PM) *
Animation of Io encounters as promised...

Very nice work. You're definitely better at setting the Cosmographia viewpoint than I am.

You can see from this how these encounters might benefit from a little off-pointing of the spin axis, if this is allowed.

As a public service, you might consider doing animations of the Ganymede and Europa close encounters as well, if you have time.


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