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Unmanned Spaceflight.com > Outer Solar System > Saturn > Cassini Huygens > Cassini PDS
machi
Helene from distance ~7000 km. Date 18.6.2011. Red, green a blue (BL1) filter. Resolution is ~42 m/pix.

EDIT: I uploaded new version of the image without three prominent specks of noise.
Phil Stooke
Beautiful - people, it really repays enlarging it and panning around that amazing surface.

Phil

tanjent
Regarding the term "panning" Phil, I can't enlarge it enough for panning because the whole image still fits comfortably on my screen.
Did you download a more detailed version from a different location? No complaints; I just want to be sure I am successfully following your suggestion.
What I can see at the present resolution is indeed fascinating in both its detailed dust effects and in the macro resemblance to a really spooky skull.

Phil Stooke
I downloaded this and opened it in Photoshop, enlarged the view and moved around within it. Any other image viewer would do. I often find that merely enlarging a file by two or three times lets me see much more in it without any processing.

Phil
Stefan
Wonderful!!!
And what a bizarre little world...
Ian R
Great shot, Daniel (BTW, north is down in this view).

To pan and zoom this image without opening any software, you can use the zoom.it website:

http://zoom.it/LdNG
elakdawalla
Oh now that is a very cool tool. The original image is only 1000 pixels across, much smaller than my screen. But somehow, when I zoom, I notice features that I did not notice when it was at "actual size." Like: there are not very many craters visible, but each one seems to be modified in a different way, depending on where it was located and (presumably) how old it is.
tasp
Maybe print a b/w version (on regular paper, not photo sock) and see if the kidlings want to color one for us to see?
Ian R
Ooooh! Now I want a pair of Helene photo socks for Christmas!
machi
"Beautiful"
"Wonderful!!!"
"Great shot"

Thanks!

QUOTE (Ian R @ Apr 6 2012, 06:12 AM) *
BTW, north is down in this view


Good point, I forgot on any orientation corrections.

QUOTE (elakdawalla @ Apr 6 2012, 06:44 AM) *
...there are not very many craters visible, but each one seems to be modified in a different way, depending on where it was located and (presumably) how old it is.


It is questionable, if resolution of Helene's images (not only this one) is generally sufficient for clear distinguishing between age of smooth regions and age of "scratchy" surface.
This "scratchy" surface looks like some kind of older, harder crust, but it is only my idea, because I don't know about any scientific paper about geology of Helene.
Mariner9
absolutely beautiful! thanks for posting this.

My firdt reaction is "Wow!". A moment later it was "Huh? What the....?"

will be most interested to hear what the science folk have to say about this. Is it a flying rubble pile? Or would "flying dust pile" be closer to the truth?
Phil Stooke
An older harder crust that is being stripped away does look like the best explanation for this. If the crust lies over loose regolith, that might allow downslope movement to undermine the crusty patches and gradually eat away at them. But why do we have a crust like this? The surface of Calypso may be similar.

One of the big puzzles with these small moons is why they are so different. Janus and Epimetheus seem to have patches of dark smooth material in depressions. Helene and maybe Calypso have extensive evidence of downslope movement like this. Hyperion is incredibly rough, Telesto very smooth.

Phil

volcanopele
QUOTE (machi @ Apr 7 2012, 03:09 AM) *
It is questionable, if resolution of Helene's images (not only this one) is generally sufficient for clear distinguishing between age of smooth regions and age of "scratchy" surface.
This "scratchy" surface looks like some kind of older, harder crust, but it is only my idea, because I don't know about any scientific paper about geology of Helene.

Exactly. I haven't seen work yet on crater counting on Helene (and between the different terrains) but the differences in the appearance between craters in the bedice and in the smoother, dust covered regions could be the result of either post impact modification or differences in initial target properties.
Bjorn Jonsson
As machi's great color composite reveals, Helene's color is pretty bland in visible light. Color differences are somewhat more pronounced if IR3-GRN-UV3 is used as RGB. Here is an enhanced IR3-GRN-UV3 composite; color differences become obvious by greatly increasing the color saturation:

Click to view attachment

The color of the smooth terrain is clearly different from the color of the 'grooved' terrain (different composition?). The grooved terrain is more yellowish.

It should be noted that the bright colors (especially red and blue) that are visible at several locations near the limb are not real features. Due to Cassini's rapid motion and the time between the GRN image and the other two images I had to warp the images to get a proper color composite and this was especially difficult near the limb. I probably need a high quality shape model of Helene to be able to do this properly (there are many nice stereo pairs of Helene and the shape of Helene's limb could also be used for constructing shape models).
machi
LSD Helene! laugh.gif
algorimancer
QUOTE (machi @ Apr 10 2012, 07:13 AM) *
LSD Helene

I initially read that as "Latin Square Design" -- clearly a bit too immersed in the world of stats smile.gif

Definitely a really cool pic -- I think back to the pictures from Pioneer and Voyager, which gave us only a hint of things to come.
Phil Stooke
OK, this is just fooling around, it doesn't mean anything, but an eyecatching view anyway. What would the great mountain ranges of Helene look like from a viewpoint on the opposite side of the valley?

Phil

Click to view attachment


elakdawalla
Ski Helene!
tedstryk
Mt. St. Helene?
rogelio
Just for fun: Assuming a free-fall drop of 2 km and using Heleneís gravity figure below (1/5000th that of Earthís), ballpark figures for your skierís terminal velocity speed would be less than 10 km/h after a 20 minute run-out
http://solarsystem.nasa.gov/planets/profil...p;System=Metric

Phil Stooke
That's my kinda skiing! Slow and steady.

Phil
machi
Final product of my efforts.
Animation of the Cassini's flyby of Helene:

YOUTUBE

More here.

nprev
Fan-TASTIC, Daniel!!!! ohmy.gif
jamescanvin
Oh my goodness, that is unbelievable.
Bjorn Jonsson
Great work. And in way I'm even more impressed by the enhanced color composite than the movie since it can be extremely difficult to perfectly align the color channels for closeups of an irregular, small target like Helene.
tedstryk
Simply beautiful. Great work, Machi!
machi
QUOTE (nprev @ May 5 2012, 02:16 AM) *
Fan-TASTIC, Daniel!!!! ohmy.gif

QUOTE (jamescanvin @ May 5 2012, 10:08 PM) *
Oh my goodness, that is unbelievable.

QUOTE (tedstryk @ May 6 2012, 08:13 PM) *
Simply beautiful. Great work, Machi!


Thanks!

QUOTE (Bjorn Jonsson @ May 5 2012, 11:56 PM) *
Great work. And in way I'm even more impressed by the enhanced color composite than the movie since it can be extremely difficult to perfectly align the color channels for closeups of an irregular, small target like Helene.


It's never perfect for irregular bodies, but it can be done with ImageJ + UnwarpJ or via manual warping. I used both methods in this animation.
Malmer
Not as good as machi's but still something...

Created a partial shapemodel and used it to register images and create a surface map.

http://youtu.be/_thh_oXgQoc

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