CICLOPS: Cassini Imaging Central Laboratory for OPerationS
The North Polar Region of Enceladus

The North Polar Region of Enceladus
PIA 08409

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The North Polar Region of Enceladus
PIA 08409

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  This three-image mosaic is the highest resolution view yet obtained of Enceladus' north polar region. The view looks southward over cratered plains from high above the north pole of Enceladus.

Cassini's March 2008 flyby of Enceladus was designed to directly investigate the ongoing plume activity at the moon's south pole, but the path of the spacecraft allowed investigation of older evidence for internal activity near the north pole.

Compared to much of the moon's southern hemisphere -- the south polar region in particular -- the north polar region is much older and covered with craters. These craters are captured at different stages of disruption and alteration by tectonic activity and probably past heating from below. Many of the craters seen here are sliced by small parallel cracks that seem to be ubiquitous throughout the old cratered terrains on Enceladus. The mosaic also shows a variety of impact crater shapes, some with bowed-up floors and smaller craters within, very likely indicating that the icy crust in this area was at some time warmer than at present. While this conclusion was previously reached from NASA Voyager spacecraft images, these new data provide a much more detailed look at the fractures that modify the surface. This data will give a significantly improved comparison of the geologic history at the satellite's north pole with that at the south pole.

Two prominent craters in this view, Ali Baba and Aladdin (the two overlapping craters near center), are among the largest craters known on Enceladus.

Several areas of much younger terrain are visible in this mosaic, including Samarkand Sulci, an area of disrupted terrain that runs north-south at left of center, and the "leading hemisphere terrain," a region, seen at right, filled with tectonic fractures, ridges and "ridged terrain."

Samarkand Sulci slices through some prominent craters that were seen in Voyager images. At that time, it was thought that the portions of the craters that extend into Samarkand were completely destroyed by whatever process formed Samarkand. However, Cassini images show remnants of the crater rims that have survived. This new insight provides a benchmark for measuring how tectonic processes modify older terrains, and will also help imaging scientists develop a more accurate timeline for the geologic history of these terrains.

Lit terrain seen here is on the Saturn-facing hemisphere of Enceladus (504 kilometers, or 313 miles across).

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on March 12, 2008. The view was acquired at a distance of approximately 32,000 kilometers (20,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 115 degrees. Image scale is 176 meters (577 feet) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission, visit and the Cassini imaging team home page,

Credit: NASA/JPL/Space Science Institute
Released: March 13, 2008 (PIA 08409)
Image/Caption Information

Alliance Member Comments
Red_dragon (Mar 25, 2008 at 3:46 AM):
It's a possibility. Anyway, both Enceladus and Dione seems to lack the "sulcus" present on Ganymede, so things have worked different there.

I guess if something was active in Titan, it would have been detected by the VIMS team and perhaps the CIRS team, and so far, it seems no "hot spots" have been detected on Titan.
One interesting possibility would be that Titanian cryovolcanism works "on impulses"; today is inactive or at least mostly so, but in other epochs is at work.
carolyn (CICLOPS) (Mar 24, 2008 at 12:43 PM):
Sergio. The Latest Comments section is meant to provide a global view of all the new comments on the site. To see the complete comment, go to the individual Image Release page (by clicking on the link on the left of the Latest Comments table) and then scrolling to the bottom. That's where you can add a comment also.

If people think we should change this way of doing things, and go to a regular forum, let me know. But I once asked the Alliance members this, and those who answered said the way it was now was ok.
Sergio (Mar 23, 2008 at 4:01 PM):
Hi folks. This is only to highlight that you should revise the CSS styles that rule the table in which the comments list are shown, because all comments longer that 2 rows can't be read into my browser.
The third line has gone.
Leave the table cells free to resize in height.
Thanks is advance
Mercury_3488 (Mar 21, 2008 at 5:23 PM):
Hi Red-dragon,

Yes Cryotectonics would explain very well what Carolyn has described on Dione & Enceladus. I remeber a similar thing with Jupiter's planet sized moon Ganymede, that the Voyager images suggested cryovolcanic flows, but then the Galileo Orbiter showed these areas to be furrowed ice.

Perhaps we are seeing similar on Dione & Enceladus?

Regarding Titan I think image PIA09176, Ganesa Macula, imaged by the Sythetic Aperture Radar, is almost certainly a 180 KM wide, 1.5 KM tall cryoshield volcano, complete with a 20 KM wide summit caldera & flows. What we do not have evidence of though is, is it still active?

I hope we get to see the Hotei Arcus SAR results soon, another possible cryovolcano???

Andrew Brown.
Red_dragon (Mar 21, 2008 at 8:53 AM):
High quality comment, Carolyn. So, instead of cryovolcanism we have "cryotectonics" (at least Titan seems to have cryovolcanism or at least hints of it, according to SAR imaging).

And, talking about Titan, really impressive the release about its subsurface ocean. I guess that GSEs that were done during T11, T22, T33, and T38 should confirm its existence, since SAR was the instrument used to detect it.

carolyn (CICLOPS) (Mar 19, 2008 at 10:33 AM):
Folks.....patience, patience. It will take some time to pore over all these images and address all the questions you have come up with. There are many of them!

But let me say that we have not seen any evidence for cryovolcanism on Enceladus or Dione or any of the saturnian satellites. Nothing has flowed on the surface, despite the fact that in some places, especially on Enceladus, it would seem to the untrained eye to be so. My team members who are experts in geophysics and geology tell me that all morphological features on Enceladus and
the other satellites can be explained by tectonics. Even the complete erasure of the cratering record. And on Enceladus, some alteration is explained by past heating events and, in the south, present heating. But not a shred of cryovolcanism anywhere.

So, it illustrates the power of carrying the capability to see to greater and greater detail. In Voyager images, we concluded that the smoother terrains on Enceladus, and the wispy terrain on Dione, were the result of cryovolcanism. But with the exquisite resolution offered by Cassini, we now know we were wrong.

Makes one humble.
Mercury_3488 (Mar 19, 2008 at 7:39 AM):
I also like that comment by Harry regarding the variety of moons & those that think they are boring needs a cup of coffee. Very true indeed.

Looking at the images from this pass as well as earlier ones, still suggests we are looking at cryovolcanism driven by fossil impact heat & some from the Saturn & Dione tidal flexing.

Perhaps one mothod on its own is not enough, but together, the result is all to see.

I hope we get to see the Synthetic Aperture Radar images of Hotei Arcus on Titan soon, but this latest Enceladus encounter will keep us busy for a long while.

When will this 'revelation' be announced? I too am impatient to know, what it is.

Andrew Brown.
djbarney (Mar 18, 2008 at 11:04 AM):
That "needs to get a cup of Coffee" comment from Harry made me laugh out loud.

My first impression of this image was one of revelation. Up close and personal. Mysteries revealed and then new mysteries.

I could whine and moan about lack of media coverage, but I won't, and anyway, it's too late now. The discovery has been made. The data is there. The deed is done. It's there for anyone to wonder at.

Time for another cup of Coffee ("there's Coffee in that Nebulae" as Captain Janeway said).

DJ barney
dpingree (Mar 18, 2008 at 11:03 AM):
Incredible as always!
But, I'm impatient!! Why does it take so long to post images of the fly-bys? We haven't even seen the results from the last Titan pass:-(
Maybe someone could post a lesson here that describes the process of acquiring, processing, and publishing science results so that morons like me won't feel so put out when it takes weeks to see something?
Mercury_3488 (Mar 15, 2008 at 4:43 PM):
Hi bruno_thiery,

Need to look again, but I had seen somewhere that the ridges / striations in Samakand Sulci & Sarandip Planitia are between 200 - 300 metres in height & that the surface gravity of Enceladus is roughly 1/200th G or one half of one percent of Earth's, so not very strong.

I think on the whole, tidal influences of Saturn & Dione appear popular causes as to the current activity.

I sometimes wonder if what we are seeing is only temporary? To me it looks like continuing outgassing from a huge impact event & the heat is fossil heat from said impact.

The Tiger Stripes & surrounding area looks to me like hardening skin on paint in a paint pot with no lid.

The northern hemisphere with softened impact craters, would suggest to me that impact energy was temporarily converted to heat, thus softening ice away from the impact site.

Neighbouring inner Mimas also the scene of a huge impact creating the Herschel Crater, was on a pure brittle ice moon, that nearly shattered. Enceladus is very different, somewhat denser & differentiated, behaved very differently.

I cannot help but think that this is impact related, happening fairly recently in the geological past.

We'll know more to either reinforce or dismiss this idea in the coming encounters.

Andrew Brown.
bruno.thiery (Mar 15, 2008 at 4:33 AM):
I do agree with Red_Dragon, who posted the comment a few days ago I think: a mosaic like this makes a day.

When looking a this, a few questions pop up.
1. On top of the image, where Samarkand Sulci touches the horizon, the terrain is very rugged. Does anyone know the height of these cliffs?
2. Is it possible to extrapolate, from this height and from the resistance of the ice (I guess ice flows, even deep frozen ice like that one), a maximum age for these cliffs? The initial height is unknown, but is surely capped by gravitation. Not very precise...but might give an indication?
3. Is it possible to have a global ocean beneath the surface, and still have some old cratered terrains? By contrast, Europa is young everywhere.
4. And finally, there is often great prudence in the explanations of the forces reshaping of Enceladus. For sure, some books and articls suggest tidal forces from Saturn and Dione. But it is never as clear cut as the explanations for Io's volcanism. What's the point?
If you have ideas, I would be glad to read them.
Have a nice day all.
Harry (Mar 14, 2008 at 10:35 AM):
Thanks for the heads-up! I should spend more time reading the captions and less time staring at the images. As you suggest, sometime in the dim past the slumped crater curvatures suggests the region was warmer. How warm and how long ago would be great issues to study. The interior prominences may also be Enceladus versions of Eratosthenes & Tycho (craters w/central peaks) on the Moon.

An interesting postulate to test would be if the interior & surface are or have been differentiated sort-of like the crust and core of Earth with a "greasy" mantel allowing relative movement. If so, why is the south still active and the north frozen? What would drive the movement - gravitational tidal forces generated by the orbit? Who knows and what instruments could the next generation of scientists send to Enceladus to extract answers?

Again, thanks for the opportunity to comment and congratuatlions on Cassini team's successes! Harry from Houston
carolyn (CICLOPS) (Mar 14, 2008 at 9:29 AM):
Harry: you are looking at the northern region of Enceladus. The southern hot zone is far away, in the other hemisphere. But it was likely that the whole of Enceladus was warmer, to some degree, in the past.
Harry (Mar 14, 2008 at 9:04 AM):
Such an awesome image! I expect there will be many papers written on the interpretations of this terrain.

I wonder if the prominences in Aladdin & Ali Baba are extinct geysers. Infra red imaging showing the extent of the southern hot zone would be wonderful.

The "faults" of the Samarkand Sulci perimeter seem to be gapped. Quasi-parallel extension zones implies that the center may be a subduction zone. Hopefully the radar imaging might provide some elevation details of the region to help interpret what is happening. Obviously, the internal sturcture of Enceladus must be differentiated.

So many new and wonderful concepts to test. It is hard to imagine: Sector 6 containing moons so different as Hyperion, Titan and Enceladus along with the rings all around the same planet. Anyone thinking these moons are simple structures with a boring history needs to get a cup of coffee!

Congratulations again on such wonderful science. Harry in Houston
VAE (Mar 14, 2008 at 6:00 AM):



Red_dragon (Mar 14, 2008 at 2:43 AM):
You did it again. I tip my hat to all the people involved in this epic mission. The raw images are really fantastic -as well as this mosaic, of course-. This has been nearly so exciting as the Iapetus flyby (and not more, just because I had other things to worry about).
You know, the Cassini-Huygens mission is more than just a space mission; as well as the Voyager mission, it's a legend, the history of two intrepid explorers whose odyssey will live forever in the history of space exploration.

Excellent work!. Now, it's time to analyze all the data and see what surprises has Enceladus in store for us.