Juno Extended Mission, Perijove 34-76 |
Juno Extended Mission, Perijove 34-76 |
Sep 2 2020, 08:05 PM
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Senior Member Group: Moderator Posts: 3241 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
At today's Outer Planet Assessment Group (OPAG) meeting, Scott Bolton gave a presentation on Juno, providing an update on the mission and providing more information on its extended mission proposal. The proposal has been sent to NASA and they expect a final decision later this year.
The proposed extended mission starts where the current one ends at perijove 34 in June 2021 and continues through orbit 76 in September 2025. The continued northward progression of the perijove latitude, and continued lower altitude of the ascending node, is going to enable a lot of great science both at Jupiter (higher resolution views of Jupiter's poles) and of its satellites. Most excitingly for me, Juno will perform several flybys of the Galilean satellites. This includes a 1000-km encounter with Ganymede next June during PJ34, a 320-km encounter with Europa in late 2022, and TWO Io flybys in early 2024 at an altitude of 1500 km. There are also a number of "Voyager-class" encounters with Ganymede, Europa, and Io between mid-2021 and mid-2025. The PDF for Scott Bolton's presentation can be found on the page for the OPAG meeting: https://www.lpi.usra.edu/opag/meetings/opag2020fall/ -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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Jan 13 2021, 01:40 AM
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IMG to PNG GOD Group: Moderator Posts: 2254 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Ganymede was actually fairly well imaged by the Voyagers since V1 flew by Ganymede when outbound whereas V2 did so when inbound. Later Galileo filled some gaps (plus limited 'postage stamp' hi-res images).
However, there are some really poorly imaged areas on Europa because only one of the Voyagers (V2) obtained moderate resolution images and most of the many Galileo flybys occurred over the antijovian hemisphere (also the HGA problem prevented the return of lots of gap-fill images from non-targeted Europa flybys like G7). The coverage is especially poor near longitude 130 degrees and there are also some 'annoying' patches of low resolution coverage near longitude 70 degrees and longitude 320 degrees. I haven't checked the new Juno SPKs yet (e.g. spk_ref_210111_251021_210111.bsp) so I don't know if Juno has opportunities to image these areas at better resolution but I suspect not. The two close Io flybys look interesting to me since the ground tracks posted above are over a relatively poorly imaged area. Of course this is exciting but I suspect the satellite data from JIRAM or even the magnetometer may turn out to be far more interesting than the JunoCam data. That said, I'm especially interested in seeing the JunoCam coverage of Jupiter's north polar region. The north pole will soon be in sunlight which is great and saves me from becoming frustrated by the fact that the north pole will be in darkness when JUICE arrives at Jupiter and will still be in darkness at the end of the mission (there is an inclined phase during JUICE's tour, allowing it to view the polar regions). So we get to see the north pole during summer after all. |
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Jan 13 2021, 03:33 PM
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Senior Member Group: Moderator Posts: 3241 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
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. -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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Jan 14 2021, 01:28 AM
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IMG to PNG GOD Group: Moderator Posts: 2254 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
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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