On the CICLOPS page it says 4m/pixel, though with some blurring it might be about 8m resolution.

http://www.ciclops.org/view/1250/Boulder_Strewn_Surface?js=1

You will find those two on Emily's blog site, where she has posted all the Enceladus pictures from Cassini flybys.

Here is the link.

They are near the bottom, under caption ISS_011EN_ICYEXO001_UVIS

These pictures were taken under less challenging conditions than this flyby, with a lower relative speed.

The distance to target was between 500 to 600 km.

Edit: They were taken from a range to target of 319 km, while Cassini was at an altitude of 208 km above Enceladus. The resolution of the NAC was 4 meters/pixel, with a little smear.

Yeah, those super-close images weren't originally on my page, because for some reason in Bjorn's database a bunch of the geometric data, including the range to target, was missing for that observation. (The range is what I use for the select query to get the best images.) Thanks to Holder for pointing out they were missing. I just went and checked the headers of the files and found that the geometric information is there, and it's different from what shows up on the Cassini raws website. My page has been re-updated with the geometric information. The resolution is about 5.5 meters per pixel after 2x2 binning, but there's also significant motion blur. I'm guessing the difference in the numbers may have to do with there being some slant angle to the Cassini observation, which isn't important if you're far from your target but if you're this close it means the range is longer than the range to nadir.

--Emily

Doc, the definitive guide to ISS is found in Porco et al.'s 2004 article in Space Science Reviews. The following site includes a link to a .pdf version of the paper: http://ciclops.org/sci/reports.php#ISS

When they say x meters/pixel, is that the average resolution in the image? Maximum? Minimum? Particularly if the boresight is off-nadir, there could be appreciable differences within the image.

I'd say they quote the resolution at the middle of the image. The NAC FOV is sufficiently small that resolution won't vary much except for very oblique angles.

I know, I know, here I go again, laying on weepy, over-sentimental "Little House On The Prairie" feelings and emotions with a trowel, giving another robot tree-huggy feelings...

THROUGH THE PLUMES…

What strange, warm-water wonderland will lie beneath me
as I fly high overhead?
Below me, rushing past – a snow-globe scene,
a fractured, cratered wintry plain of gleaming
ice as hard as stone, criss-crossed with groaning
fissures that open and close like the bone-
dry maws of some fearful buried beasts
that feed on vacuum, and scream in pain
each time they feel Great Saturn’s pull…

Peering down upon the gravity-sculpted ground
I’ll feel a million Terran eyes upon me,
wondering what wonders I will see
when I fly into bright sunlight once again:
miles-high plumes of tinkling, twinkling vapour
shining bright against the endless night
of space? Racing through them might my face feel
the gentle touch of Enceladean dust?
Tomorrow I will know, and as snow falls softly
on the moon below I watch it grow and grow and grow…

© Stuart Atkinson 2008

[quote name='Stu' date='Aug 10 2008, 05:31 PM' post='123231']
I know, I know, here I go again, laying on weepy, over-sentimental "Little House On The Prairie" feelings and emotions with a trowel, giving another robot tree-huggy feelings...

Stu.. you just keep on being weepy robot tree-huggy.... plenty a folks can quote the facts....
not many can give us the feel.

Craig

Hear, hear!!! UMSF's Poet Laureate has a job to do, which he does exceedingly well: documenting the unprecedented drama and beauty implicit in humanity's exploration of the Solar System. We can't be there ourselves; he takes us there. Well done, sir!

Take for example the case cited above:

"They were taken from a range to target of 319 km, while Cassini was at an altitude of 208 km above Enceladus. The resolution of the NAC was 4 meters/pixel, with a little smear."

The camera is specced at 5.99 urad/pixel, so at a range of 319 km, wouldn't the resolution be 319000*5.99e-6 = 1.9 m/pixel (assuming a nadir shot)?

As for "the bone-dry maws of some fearful buried beasts that feed on vacuum," Cassini can only tell them "say cheese."

That's one of your best Stu.

I can almost picture Christmas carolers out for a sleigh ride on the snows of Enceladus.

Hmmmmmmmmmmmmmm...

"fissures that open and close like the bone-dry maws of some fearful buried beasts that feed on vacuum, and scream in pain" I hope they do not scream "Tekeli-li! Tekeli-li!" Just joking... Stu... I get the same feel as you but am not talented enough to express it.

What marvel's will we eventually find there? What wonders lie under those portals to subterranian seas?
A spelunkers dream (or nitemare).

Craig ... a Lovecraft fan

In some cases geometric data is missing from the LBL and index files for super-close images for some reason. I've seen it happen for some of the Enceladus flybys, including (if memory serves) the very close nontargeted flyby in February 2005, some of the later targeted flybys and also the very close nontargeted Tethys flyby.

Does anyone know if the ultra-close images to be obtained during the upcoming flyby are BOTSIMs? This is not mentioned in the flyby descriptions I've read (I haven't checked everything yet though).

In any case this seems to me to be the most complicated Cassini flyby so far and one of the most exciting and interesting ones as well - good luck to everyone involved.

Yep, but that image was binned 2x2 so the effective pixel scale is 2*1.9 m/pixel, exactly as advertised.

Only the last skeet shot image shown in the attached image from the Looking Ahead article contains a CL1/CL2 BOTSIM. There is a botsim at the start of that trigger, but it is over the nightside.

The reason there aren't more BOTSIMs might lie in what I wrote about earlier - they're twice as data intensive so might limit the speed at which ISS can take images, which in a high speed flyby is most undesirable. This is due to the fact the SSR recorders and their support system (what was it - the CDS?) can handle up to 384 kbps (I think). It doesn't physically prevent snapping a new picture, but the ISS generated packet buffer is emptied slower into the SSR if both cameras are generating much data and new images have to be "queued" until the buffer is emptied.

As a matter of fact, it's not unusual for CCD frames to have a delayed readout (there's a PDS image flag by that name) if the telemetry pickup is slower than the speed the camera reads out lines from the CCD and encodes them. This messes the dark current calculation as the rest of the image just sits on the CCD for a period of time and one can actually see higher dark currents starting at a certain line in some WAC raw images if you really brighten them.

But, I digress...

Ah, I missed that earlier comment.

Using NAIF data to figure the ground speed of the ISS boresight during this flyby, I get this graph:



The "skeet shoot" is over around 21:11:09, then the 8-tile mosaic starts (not all of the latter shown).

Well, Bob Shaw, who hasn't posted in over a year, would appreciate that. As do I.

(The images of the myriad of dark circular storm centers in Saturn's southern atmosphere remind me of the eyes of the Shoggoths.)

Better late than never, I have copied Emily's timeline into the realtime simulation

The distant (~450,000 km) images from today's 3 hour "early" downlink seem to be do down. At a quick glance I didn't notice any plume material but the automatic contrast stretch messes things up so this may not mean anything.

NAC image with Enceladus nicely centered:

http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=165786

Scanning around somewhere near Enceladus:

http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=165828

Wouldn't it be kind of weird seeing the south pole plumes while looking down onto the north pole?

I agree with you that it seems weird to be looking for plumes when you're looking down on the north pole, but that observation is described in the mission description as "Inbound Enceladus plume observations (distant)".

--Emily

The plumes are big so they should be there poking above the nightside limb. They may not be conspicuous here due to the viewing/lighting geometry (brightest part behind the limb, phase angle not high enough etc.).

They probably *are* poking behind, but at that point they're very faint and diluted. I wouldn't expect to see them even in calibrated imagery, a simple sunlit sliver is enough scattered light to drown out anything near.

The first image--a WAC image at 21:07:19--will be framed something like this:



From the Verbiscer writeup:



Looks like some material from that fissure could easily be up in the sunlight but silhouetted against the night side? I think from the NAIF data the angle of the shot is something like 40 degrees from the local vertical.

lots of blank white images of Enceladus in the raws...I wonder what's the cause of those.

JPL news release:

Someone on Enceladus was having fun pointing a laser pointer in Cassini's camera!

If i'm reading the timeline from the Mission Description page correctly, the images we have are from the first (3 hr)downlink (pre encounter). The second (5 hr) downlink should have reached the ground a few hours ago. The third (9 hr) downlink is currently in progress and should finish about 7 hours after the time of this post. Hopefully there are a bunch of images on the completed second downlink which they will post soon.
-Floyd

No images from the second downlink that I can see. I'm sure they will all show up in the 9 hour downlink (which actually starts up in a little under 1 hour).

See post 45 above - looks like it will be tomorrow morning before the very close shots appear (but we may get the Northern hemisphere shots prior to that )

I know that My point was that the "we may get northern hemisphere images earlier" idea looks to not be correct. But it will just carry over to this next playback.

Why tomorrow morning? Anne Verbiscer said 1800 UTC today. Which is in a little less than two hours.

Not sure where 1800 UTC came from. The 9 hour long playback hasn't started yet (20 minutes to go!). The images from that playback will show up on the JPL raw images page and the CICLOPS page at 0530 UTC (or thereabouts, that's the earliest) Tomorrow. No images other than the 2.5 km/pixel distant "plume tendril" observations are available at the moment.

I guess the ISS playback wasn't scheduled to start until about an hour into that 9 hr long playback or something.

How come there'll be such a long delay for the raws? Typically they show up as soon as they get down, you can sometimes actually catch the raw page being updated every minute with new images.

The images on the raw images page shows up 4 hours after the playback ends. That isn't part of the real-time stream.

We are all getting spoiled. Remember how agonizingly slow it was waiting for Galileo images to get downloaded (at around 3 images per day)? Worse than that, during the first few orbits they were saved up until a press conference announcing the latest discoveries.

But at least you could eventually get to all of the images on the web, as opposed to the old days of Voyager where only a subset were published in magazines or books.

So.... much as I really, really, really want to see the closeups of Enceladus, I guess I'll just have to wait another 24 hours or so.

Que sera ? Big disappointment or images like this artist's painting :
http://saturn.jpl.nasa.gov/multimedia/imag...fm?imageID=3039

Approach images are now going to the raw image page. More will be coming!

Yay! I was hoping they'd pull something like this to cut down the wait for the public. Looks like outbound images at that, I thought we'd be seeing the inbound imagery first as that was scheduled to be downloaded first.

Hey, those are receding shots, e.g.:

N00118300.jpg

"N00118300.jpg was taken on August 12, 2008 and received on Earth August 12, 2008. The camera was pointing toward ENCELADUS at approximately 202,865 kilometers away..."

Is the science advisor being briefed?

Camera still works! (*whew*)

Looks like no bugs on the windshield, too!

They got the subject in the frame (fingers crossed)!

Some inbound shots there now...

What do pictures like this show? Plumes?


Paolo Amoroso

Yep, a couple from 109,000 km out. Actually almost all the money shots will be outbound, past closest approach. Should be a couple more inbound at around 40,000 km though.

Paolo:

Stray light, most likely from Enceladus itself. This is the reason I'm skeptical any plumes can be seen while sunlit terrain is actually in the frame, be they silhouetted against the blackness of space or not. The plumes are very tenuous.

The team is working to manually post a few of the images that are in the raw image cue. We know you're all waiting.. patiently..

There are a few more up -- looks like they are not the skeet-shoot, they are frames from the post-CA multispectral mosaic...
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=165845
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=165847
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=165848
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=165849

--Emily