17:53 is a backup against timing errors or possible unrecoverable loss of 17:52.

There are constraints on how close the sets can be and I don't think the last set can be moved in.

But I hear you and I'll see what I can do.

Pretty, but the FOV is rather important. 17:49 just doesn't have much of Io in it.

Astrobotic is now saying



This seems odd to me, since usually such a valve would open just once and then a downstream regulator would maintain system pressure at the desired safe level. But it sounds like they tried to avoid needing a regulator by just burping the valve open briefly (in hindsight maybe not such a good idea.)

Normally all of that is determined by analysis and then the testing is done with a lot of extra margin to cover all uncertainties. https://blogs.sw.siemens.com/simcenter/spac...oustic-testing/

And it's not like Vulcan is that different than Atlas in that regard.

What is a little odd is that Peregrine was supposed to be launched with two prototype Kuiper satellites, but after all of the delays, those were launched separately. There didn't seem to be any place to put them on the Centaur, but it seems implausible that they changed the configuration enough to impact Peregrine unfavorably.

If Astrobotic decides this was a vibe-induced failure, I'm sure there will be some finger-pointing.

I'll look at it. Keep in mind that all of these times are +/- 15s and I can only take four images in a set before incurring an additional delay. I could start the third set earlier but only at the cost of dropping the last image it currently has, which I was reluctant to do. I tend to not value the nightside images that highly, but maybe that's the wrong bias to have.

Thanks. But without seeing where the Junocam FOV is along the ground track, it may be hard to understand why I picked the times I did. Visualizing this on a flat map is tough, as I well know. These times were a product of going back and forth in Cosmographia repeatedly, looking at the evolving FOV coverage.

I haven't heard anything, and there is not much public detail about Peregrine's propulsion system. But it started right after the system was pressurized and was large enough to disturb blankets. I can think of three root causes: 1) damage during launch vibration (hopefully unlikely since the spacecraft was vibe-tested); 2) propellant migration causing a small explosion that blew a hole in the plumbing; 3) pressure regulator failure leading to overpressurization. Assuming https://www.nasa.gov/stmd-game-changing-dev...in-space-talos/ describes what they ended up flying, the main engines were MON-25/MMH biprops but how the attitude-control thrusters (presumably monoprops) were tied in, I have not seen.

My initial cut at PJ58 image timing for Io is:

2024-034T17:32:00, two images, high and low TDI, RGB
2024-034T17:39:00, two images, high and low TDI, RGB
2024-034T17:50:00, four images, first high TDI, three low TDI, RGB
2024-034T17:56:00, two images, high and low TDI, RGB

high TDI will be 6, low TDI will be 2.

All image spacing is 60 second. All compression is lossless. I thought about taking one-band images but due to various constraints I couldn't make it work without compromises.

Feel free to provide feedback. But keep in mind that the FOV of Junocam rapidly slides across Io near closest approach, so if I did something that seems odd, I might have done it intentionally.

Landing almost certainly off the table.

Sounds like a stuck thruster or bad prop system leak. Fingers crossed but it is not sounding good at all.

https://twitter.com/astrobotic/status/1744389634568724791

Closest to what? Io? Io C/A was over the nightside and we didn't try to take any images.

The paper itself is here: https://academic.oup.com/mnras/article/527/4/11521/7511973

Note that the paper references Bjorn's work at https://www.planetary.org/articles/uranus-n...olor-difference so this is old news for this forum. At least the super-saturated Voyager images are, and I'm not totally convinced by the tristimulus discussion in the paper -- yet another "what does this look like to the human eye" conundrum.

Compare the progression of black offset and noise during PJ56 (a lot) with that in PJ57 (practically none). Even if PJ58 proceeds like PJ56 did (which we hope is unlikely) most of the change would happen after the Io encounter.

We hope.

I'll do what I can. There are a whole bunch of constraints. Io goes through the FOV rapidly around 17:50 and we can only command a maximum of four images at fixed cadence before incurring a 30s delay. I can't improve the nightside coverage at the cost of degrading the dayside, the best of which happens around 17:51:30.

I'm surprised that people are getting a lot out of the TDI 2 nightside images. I guess they're better than nothing but I was expecting at least TDI 6 would be required if not more, which means the dayside would be blown out for sure.

(Started a new thread to avoid cluttering up the PJ57 thread with PJ58 discussion.)

Are you sure? The outbound sub-spacecraft point was about 40N,30E for PJ57 and it's about 0N,15E for PJ58. The inbound imaging on PJ58 is pretty poor resolution while the illuminated limb is still in the Junocam FOV.

http://www.unmannedspaceflight.com/index.p...st&p=254962 and subsequent posts.

Very few missions have archived the raw bits as received from the spacecraft; PDS puts the responsibility for archiving on the instrument teams. It usually works better than this.

It's more equatorial but the same hemisphere.

The Jupiter images have been posted to missionjuno. I think we're still waiting on some partials for the approach images, some which are pretty neat (GRS with a distance Io).

Have to think about that. There are timing/cadence tradeoffs between TDI and number of bands. Could do green on one spin, red on the next, probably.

Depends on your definition of "probe". I personally wouldn't count any Earth orbiter and not any Earth-observing satellite. If you allow Earth orbiters, why count Chandra and not HST?

Is there really useful color information in the Jupitershine part of the image? A quick look at pj57-031 (the only image with TDI of 6) suggests to me that the green channel by itself is telling you most of what there is to know. Certainly the blue channel is pretty noisy.

We will almost certainly take more nightside images on PJ58, but my inclination is to go with longer TDI and only one channel (green, or perhaps red.)

I thought it was stated somewhere (OPAG?) that disposal was no longer required with the current orbit, so I suspect it's the latter. Depending on ongoing spacecraft health and funding availability, of course.

Yes, certainly.

Buried in the Facebook comments from NASA Solar System Exploration:



Credit to Jamie Carter at Forbes.com for actually finding that comment and reporting it.