Ganymede Flyby - PJ34, June 7, 2021 Options

[mcaplinger]

We will be releasing the PJ34 data per our usual process. Recall that we can't release standard products until we get the reconstructed C kernel, and we don't release partial images until every effort has been made to retransmit them. For the Ganymede imaging, we'll be trying to generate the map-projected standard products but it's not clear how well that will work (may be sensitive to SPK errors or our software might just choke); if it doesn't work then we will just release the raw products.

All that adds up to the data showing up on missionjuno no earlier than 8 June and hopefully no later than the day after, barring unanticipated events. And note that I haven't looked at the specifics of the DSN schedule so I'm not sure when the raw data is expected on the ground.

In theory we could post the raw data without waiting for the C kernel, but that would be outside our normal flow and might preclude ever posting the map-projected images if they do work, so I wouldn't count on it for now.

[mcaplinger]

My simulations of the first two Ganymede images, subject to spin phase and timing/nav errors.

[Brian Swift]

Thanks for the update Mike. I assume everyone is pretty excited about the Ganymede encounter, I certainly am.
Glad to hear the plan is for a normal data release. (Though I can certainly understand projects wanting to be more restrictive to maximize a news-cycle impact.)

Looks like my mapping images are consistent with you’re simulated images, so at least I don’t have the illumination coming from the opposite direction.

Can you say if the Ganymede images will be less compressed than typical Jupiter images given their novelty.

[mcaplinger]

As with many high-value Jupiter images, the plan is to take the Ganymede images with lossless compression.

We always compress at as high a quality factor as we can given the goals and constraints of each PJ pass.

[Steve G]

Would have any of these flybys been possible had Juno successfully completed the Period Reduction Maneuverer to the nominal 14 day science orbit, assuming an extended mission was granted?

[Explorer1]

An interesting what-if, but the increased radiation damage taken during those orbits makes it hard to be certain. Funny to think the mission might already have been over by now but for the engine problems!

[mcaplinger]

Would have any of these flybys been possible had Juno successfully completed the Period Reduction Maneuverer to the nominal 14 day science orbit, assuming an extended mission was granted?

No idea, it depends mostly on the delta V required to trim the orbit. I didn't have the impression that it took that much delta V but I could be mistaken.

AFAIK the dose per orbit is not much different between the 53-day orbit and the 14-day orbit, you just accumulate it faster with the shorter orbit. There's no way to know how the nominal mission with the PRM would have gone.

[stevesliva]

https://spaceflightnow.com/2020/10/12/juno-...jupiters-moons/

The 53-day orbit meant Juno operated at a slower scientific cadence, but the longer orbit is what allows the mission to venture near Jupiter’s moons in the 2020s, Bolton said.

Note: not a direct quote from Bolton; author's words.

[Decepticon]

https://www.nasa.gov/feature/jpl/nasa-s-jun...s-moon-ganymede

[vjkane]

https://spaceflightnow.com/2020/10/12/juno-...jupiters-moons/

Note: not a direct quote from Bolton; author's words.

I heard Bolton say equivalent words in meetings.

[Steve G]

Ganymede is the only large moon with the exception of Iapetus that has significant albedo variations like Earth's moon. Even Mercury is relatively bland. It is a fascinating world, and I'm looking forward to the results that I am certain will be fascinating.

[TrappistPlanets]

My simulations of the first two Ganymede images, subject to spin phase and timing/nav errors.

i want to make a mosaic from the real images when we get them tomorrow, but how am i going to fix the distortions as seen in your simulation of 2 of the pics?

[mcaplinger]

how am i going to fix the distortions as seen in your simulation of 2 of the pics?

There's nothing different about the Ganymede images and they have to be processed the same way as any other Junocam image.

The simulation was just a rough stitch of the simulated frames with the overlap removed and doesn't closely resemble either the real raw data or our map projections.

As discussed above, the earliest you can expect the data on missionjuno is sometime on Tuesday 8 June. I honestly don't know if playback will be happening between the Ganymede encounter and the perijove pass (I hope so), but checking https://eyes.nasa.gov/dsn/dsn.html to see if there is high-rate downlink from Juno will be a clue.

[JRehling]

In all the excitement about visual images of Ganymede, I lost track of how Juno's main instruments will provide at least four new (or best-yet) kinds of science regarding Ganymede, taking surface spectroscopy in new wavelengths and doing some subsurfacing microwave sounding, which is a big deal – penetrating the ice of a jovian moon is a major goal for Europa in particular and Juno will be the first opportunity to do so, first getting data from Ganymede and then, hopefully, differential data that is comparable at Europa. Finally, occultation of radio signals is not something new but 2021 technology is an advance over Galileo results; moreover, with the variable nature of Jupiter's and Ganymede's particles and fields environments, more data at new lat-lon locations is always valuable.

That data won't all be analyzed this week, but should be available eventually if the encounter goes well.

[Antdoghalo]

NASA's Eyes show flyby happening right now.