Juno- Satellite Observations Options

[Ken Arromdee]

I know this mission is not meant to study any Jovian satellites, but is Juno going to, by chance, pass near enough to any satellites (particularly small, not well imaged satellites) that it could take any useful pictures of them? (Or will it be possible to finagle the final de-orbit burn to send it past a satellite for this purpose?)

[centsworth_II]

At the press briefing it was stated that although Juno will not get close to Jupiter's moons it will be taking pictures and because of it's polar orbit will get never before seen looks at the moons.

[Gerald]

In the Planetary Radio talk I've referenced, Candy Hansen mentioned, that Juno is planned to get close to one of the Ring moons. But since those moons are tiny, the moon is expected to show up as a small spot only.
--- Might be, that positional data of the moon can be refined this way.

[I'd think, this thread should better be merged to the Jupiter approach thread.]

[Glenn Orton]

I know this mission is not meant to study any Jovian satellites, but is Juno going to, by chance, pass near enough to any satellites (particularly small, not well imaged satellites) that it could take any useful pictures of them? (Or will it be possible to finagle the final de-orbit burn to send it past a satellite for this purpose?)

We may get some observations of satellites, but it's not the focus of the mission, and anything we obtain will probably not rival anything obtained by a previous mission regarding spatial resolution. I think the Juno engineers will consider 'finagling' a very low priority compared to making a successful plunge into the atmosphere to protect Europa from encounters with the Juno spacecraft. Our opportunities to get any observations of satellites is limited by our polar orbits, as has been noted already. In fact, our best continuous images of the Galilean satellites may be taking place right now with what we call the Approach Movie. This will be released on July 4.

[nprev]

MOD NOTE: Edited topic title to make it a generic thread for Jovian satellite observations by Juno. Since there aren't likely to be very many, this may suffice for the mission. However, if subtopics are required we'll split them off as needed.

[Steve G]

New images of Ganymede from Juno.

https://www.nasa.gov/feature/jpl/nasa-juno-...edes-north-pole

[volcanopele]

Decided to start a new topic [I see there was already a topic from four years ago so I'm merging the two] for the discussion of Juno observations of the Galilean satellites, mostly because many of the best observations are by JIRAM and data from that instrument takes a few months to a year to show up in the PDS. There have been observations of moons via JunoCAM at lower resolution that have been useful, like observations of the Chalybes plume at Io.

The other day, the JIRAM team had a press release showing off their observations of Ganymede from PJ24:

https://photojournal.jpl.nasa.gov/catalog/PIA23988

They don't say in the caption but I presume that the blue and green channels use L band data (3.455 µm) and the red channel uses M band imaging (4.78 µm). Let's take a look at the M band data since there are more surface feature contrast:



at first glance that doesn't really look much like Ganymede does it? What if we do a quick invert of the brightness values?



Okay, now it is starting to look like the Ganymede we know. The bright regions in the original image are the dark "Regios" (specifically, the one of the right in each image is Perrine Regio). The dark spots in the original image are bright at visible wavelengths and are the icy ray of relatively fresh impact craters. This invert method works because water ice absorbs light at 4.78 microns, so ice rich areas are dark while comparatively ice-poor regions are bright. So inverting the 4.78 micron images gives something that better resembles visible light images.

For a comparison, here is a Cosmographia preview of the middle image:

[JRehling]

That's a cool demonstration, Jason. If you wanted to take it one step further, another factor determining luminance across the image is the phase angle, so if you divided those by images of lambertian spheres at the same phase, you'd get a closer match to the local albedo. (Mainly, the terminator would not seem excessively bright.)

[Antdoghalo]

Unfortunately it didn't hit the small unmapped region near the north pole on the other hemisphere. It is nice to see Juno can image the Galileans with detail. Even if low resolution, any imagery of that area would be suitable to fill in the roughly 3 percent of Ganymede Galileo missed. Juno's orbit is adequate to imaging the unmapped areas around the poles.

[Decepticon]

Any more future bonus moon images?

[volcanopele]

Finally got around to adding a Juno section to my small webpage of Io images:

https://pirlwww.lpl.arizona.edu/~perry/Juno/

Mostly consists of JIRAM data though there are a few JunoCAM images thrown in. Tried to maintain a standard format of the summed JIRAM image on the left and a gradient map version overlaid on an Io basemap on the right. Images are magnified 10x from the original data.

For PJ57 and 58, there are some sample JunoCAM preview images, though keep in mind that JunoCAM will not get all those images due to data volume considerations and other constraints.

[volcanopele]

Updated the above page to include images from PJs 40, 41, 43, and 47. Sorry that took a bit longer than expected.

https://pirlwww.lpl.arizona.edu/~perry/Juno/

[volcanopele]

Another update to my Juno image page, now with JunoCam images from PJ51 and JIRAM data from PJ47. I also updated the hotspot map.

https://pirlwww.lpl.arizona.edu/~perry/Juno/index.html

[Antdoghalo]

Do you plan to map the Juno images too?

[volcanopele]

I do have JunoCam maps in Arc Pro. Maybe I'll release a few with PJ53.