The mission description PDF is now online.

Enceladus 3 Flyby

Yes, nice to see the imaging footprint details. The basemap has kind of a familiar look to it

Should be interesting to see some new areas being imaged at higher resolution than in previous encounters (both northern and southern).

I'm a bit confused about the what the highest resolution of the images will be. This description claims that the ISS will take images up to meter-scale, but I can swear on that I saw another description somewhere that said that the images taken will at most be 200 meters/pixel. While I guess that's technically meter scale I'd like confirmation on that.

Adam, there's a more detailed mission description here that details the resolution of the NAC whether it's 'prime' or 'ride-along' throughout the encounter.

There's now a multi-person blog about the Enceladus encounter on the Cassini web site. Just three posts so far (including one from me ), but more will be posted soon.

John.

One of you guys on the Cassini team needs to please get ahold of the webmaster for the official Cassini site, and tell them that the date on the simulator (Where is Cassini now?) is out of whack.

Tried sending a discreet email this afternoon, but ...

Although there is a Contact Us/Feedback link on pretty much every NASA page, I've never had any feedback from any message/email i've ever sent.

I kind of lost track of when the C/A distance was set to 50 km as opposed to the 38 km figure stated earlier. What were the reasons the altitude was raised?

Great idea on a blog, too. Looking forward to new entries!

Although this one: Enceladus Approach Maneuver canceled
scared the heck out of me until I realized it referred to a correction
maneuver on the way to the Enceladus encounter.

Thanks for pointing out the problem with the "Where is Cassini Now?" page- I just sent in a note about it.

The close approach distance on Rev. 61 was raised due to a desire to be a little more cautious about the plume hazard, I believe. We'll review the plume data from this flyby in order to decide whether to maintain the planned 21 km approach distance on Rev. 88.

John.

Whoa! 21 km? Talk about threading the needle there...

You've really got to admire the accuracy with which the navigation team's flying a spacecraft some 1.5 billion km away.

Technically speaking, we should admire it *after* the flyby. BEFORE the flyby, we can still admire their bravery though. :-)

--Greg

Well, in all honesty, they've proven this time and time again. The most recent cancellation of the final targeting maneuver just shows how good a hold of the trajectory they really have.

Well, I know for a fact that Alice Wessen (head of Cassini outreach) has personally attended to that very task until very recently, and it's now in someone elses hands. If you've got a specific case in point, let me know and I'll pass it on.

Dave 'the navigator' Seal is working on the simulator to get it sorted. There's server shifts and recompiles involved.

Doug

I always pray that they're remembering to aim 21 km above the SURFACE, not from the center!

Simulator is fixed!

Also got back a nice reply from the Cassini Team.

I assumed that it was something easy to fix, and therefore they were simply unaware. Turns out they were really dealing with some issues on it, and several people had emailed them.

Just in time for the flyby, too.

LINK

The first of many ...

March 9

March 10

I noticed that Cassini's cumulative trajectory plot is now significantly smoother. Looks like they decreased the time tick interval (at periapsis only?) by which they draw the trajectory using linear segments. It looked ugly at periapsis before because that's when the S/C covered the greatest distance per time unit. Also, I don't remember seeing anything else than Titan in the lower right view before. Neat.

According to the official blog on the JPL Cassini Huygens web site, the spacecraft has begun it's data download to the Deep Space Network. The download will take about nine hours.

Some flyby raws are up. Check this shot in particular. Those 'central mounds' in the larger craters are most intruiging!

beauty!
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=146107

Is all the snow just randomly "hot" pixels?

Am I correct in assuming the illumination from the "bottom" is actually saturnshine primarily from the planet's southern nightside which, in turn is softly illuminated by reflected ringshine? See this image for an illustration, only in this case the rings would be nearly perfectly edge-on (not sure how much they contribute to lighting) and the sunlit crescent wouldn't be visible.

Also, the two additional illumination sources on the "top" side of the moon (seen in other, even longer exposure shots) would be two of the neighboring satellites?

David, the majority of those dots (actually short streaks) are stars.

The illumination from "below" is Saturn-shine (possibly ring shine...). The illuminator to the right is Tethys with some light from Dione (both are pretty much in the same direction). The illuminator to the lower left is Rhea.

Here's a mosaic (click for full size):

This would have to be a sort of ring-saturn-shine if that's what you meant, doubly reflected and dim light off of the cloud tops. Enceladus is in such a low inclination orbit, 0.019 deg (compared to Mimas' 1.51 deg) that the main rings are effectively invisible. I wonder how much light the broader F ring would diffuse and if it would be comparable in brightness to the light flux from the night side?

CDA bad news...

Nice work um3k, I was waiting to see which of the resident image wizards would come up trumps first on this north pole mosaic

End of : http://youtube.com/watch?v=7P2NMem2llQ





Doug

The JPL website must be getting hammered...I'm having a hard time getting in to the raw images. Wish I could grab them and set up a mirror somehow...

--Emily

The flyby blog appears to be down as well...

I've decided to keep away from the NASA site, and just wait until somebody smart from UMSF has had a look at them.

I haven't been able to get a look at the raws since I came home from work, 3 hours ago...

Still, shouldn't complain, I guess; it's a sign that this fly-by has got a LOT of people out there intetrested in space exploration. We can't have it both ways!

Thanks to everyone who's posted images here. I'd have seen NOTHING otherwise!

Some quick "Hmmmm...."s... looking at um3k's excellent image...

1. What happened to the rest of these craters?
2. Ooh look, a "chevron" like on Miranda...!
3. Weird... re-frozen cryo-volcanoes..?

Click to view attachment

I've seen only a single image so far. It's extremely slow with frequent errors. UMSF is extremely slow today as well (even slower than yesterday). I'm not sure I'll be able to post this message without errors ;-).

I find the TryAgain firefox plugin helps when sites are getting bombed:
https://addons.mozilla.org/en-US/firefox/addon/2462

Of course, that means I'm exacerbating the issue more than my share. But I'm selfish.

The crater to the upper left of the two marked seems to have something similar. It'll be interesting to see how many craters have this effect, and if its in anyway related to size.The image that pops into my head is a large impact producing a temporary lake of liquid water underneath it, which powers cryovolcanism.

If I'm not mistaken, those two craters were apparent back in the Voyager imagery and led to various explanations like viscous relaxation of ice which (unlike other icy sats) seemed to be warmer and thus less rigid. Very few, if any of the craters on Enceladus have your typical crater-bowl-look seen on other worlds.

Or it punches through to a liquid layer and the open throat is the source for upwelling.

Just like the Evil eye of W Quivira or Coats Facula on Titan?

I can't wait to measure the ratio of inner diameter vs. rim diameter. It looks pretty similar.

-Mike

wow… everything is real tied up. i guess nobody here has anything else from other sources?

anyone find out if these dots are all “hot pixels” or otherwise?

Gordan is right. Those distinctive Enceladan craters with up-domed floors, where the domes are heavily fractured, are very easy to explain through the process of "viscous relaxation," where the crater looked normal (bowl shaped or whatever) when it formed, but over time, and with help from heat conducting from the interior, gravity causes the ice in the crater to flow (in the solid state -- no volcanism or anything required here) to equalize the gravitational potential. Short-wavelength features take longer to relax because the strength of the ice comes in to play, so you get the most deformation acting on the longest wavelength, which is the up-down-up of the crater rim-floor-rim. As the floor domes upward, there are extensional stresses along the top of the dome, so it fractures. This is basically the same kind of stress regime that is being proposed to explain the "spider" feature in the center of Caloris as seen by MESSENGER on Mercury.

I looked around for some papers on viscous relaxation on Enceladus and this is what I came up with that's in the public domain.
http://www.lpi.usra.edu/meetings/icysat2007/pdf/6051.pdf
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/2237.pdf

Mgrodzki, as ugordan pointed out here, those are stars. It's a long exposure becuase of the eclipse.

--Emily

ah… i just saw emily’s post. its super-exposed from rings shine, saturn shine… etc. so those could very well be stars picked up by the sensitive exposure.

I took um3k's image (Stu's annotation added) and zoomed in on "3":

Click to view attachment

Click to view attachment

Side by side comparison with the T25 RADAR image of the "Evil eye" W Quivira feature on Titan (annotated and unannotated versions). The ratio of inner bulge and outer rim diameter are real close, even though "Evil eye" feature on Titan is ca. 5x bigger.

The central domes look larger and a little bit rougher ("bulgier?") than normal. Topography would help illuminate this (that's a stretch for a "shape from shading" pun). Maybe these are central dome craters where the rebound just didn't know when to stop?

-Mike

[EDIT: Just saw Emily's post. Fracturing would make the central domes look rougher. Might also explain the Evil eye of Titan if it is indeed a fractured-up central dome crater.]

Since these places have names, we might as well be using them. Stu's "3" is Aladdin. The adjacent, more angular-outlined one is Ali Baba. Here's the Voyager view:

Click to view attachment

--Emily

Still can't get on the raw images site... has anyone ever known a lock-out like this before? I can't remember having this much trouble getting at the Iapetus close fly-by images...

MAybe we just have to wait for every space enthusiast in the US with a computer to go to bed!

It's unusual. I've exchanged emails with folks at JPL and they are working on the problem. They say that although it seems as though it's traffic-related, they've tested with much higher demand and not had problems, so it's a bit of a stumper.

FWIW, I do get pages to appear as long as I wait long enough.

--Emily

A short animated version of the Enceladus approach from the raw images.
Click to view attachment
Enjoy
Astro0

Post-encounter press release
http://saturn.jpl.nasa.gov/news/press-rele....cfm?newsID=824

Three-image mosaic
http://ciclops.org/view.php?id=4865

I thought some of the rough images would make a cool animation… especially (oddly enough) because of the motion blurry frames.

check it out: Plume Diving: The Approach