... FLIES BY SATURN'S TORTURED MOON MIMASOn its recent close flyby of Mimas, the Cassini spacecraft found ... seen in the new images.The new Mimas images are available at http://ciclops.org, ... available ...
... and images of Saturn's icy moon Mimas obtained by NASA's Cassini spacecraft ... the spotlight, but it turns out Mimas is more bizarre than we thought ... infrared spectrometer, which mapped Mimas' ...
... affected by the gravity of the moon Mimas. This process is commonly believed ... Saturn's rings due to the moon Mimas. Resonances in Saturn's rings ... particles orbits. In the case of the Mimas ...
... gravity of the nearby larger moon Mimas disturbs their orbits. Gravitational ... in Saturn's magnificent rings. Mimas provides a regular gravitational ... orbits due to their resonance with Mimas, ...
... moons orbit between much larger Mimas and Enceladus.Moons surrounding ... Methone, is in such a resonance with Mimas and appears to have undergone ... 4 are dynamically locked with Mimas gives us a ...
Cassini's closest flyby of Mimas on August 2nd revealed it to be one of the most heavily cratered Saturnian moons, with variations in color across its surface but little if any evidence for internal activity.
This time the IMAGES with high and very high resolution ( official ones and raw ones ) returned of a Enceladus flyby were greater than from any previous close Enc flyby - but all the other close flybys had also great Enc pictures. When I made a search for the latest Hi-Res Enc Images on the Cassini Mission Main Page ( http://saturn.jpl.nasa.gov/ ) some hours ago, I found over 200 of them ! But the Image 'Boulder-Strewn Surface NAC View' ( many older ) is very remarkable and a new look, too.
These Hi-Res Images of Enc with its icy, alien surface were GREAT !!!
THAT is exploring new territories ! ( new worlds ! )
Now I think we know too less of the interior of Enc to explain exactly why it has got this surface. I think the crust ( of course icy ) is thin in the south ( roughly 2 km to 250 meters ). Under the crust there is ( probably ) a subsurface ocean of liquid H20 being roughly 273 to 277 K. How deep is this ocean ? I have no idea. Is it global or local ? I just don`t know.
The surface in the south with its 'tiger stripes' ( 'sulci" ) lets me think of the sulci being rather similar to Earth's rift zones but on Enc there are far more ones than on Earth. And I also think that on Enc the activities and the locations of those sulci are shifting very rapidly compared to Earth. Of course the south polar region is geologically very young.
Then I need this subsurface ocean for my theory because I suppose that the outer mantle of Enceladus is this ocean that has got very many convection cells that are driving all the active 'sulci' . So there are plates on Enc and they are moving like at plate tectonics ( more or less ). Often we're seeing compressed ice terrain at the areas adjacent to the most active 'sulci' - that is something like Enceladan mountain formation . perhaps there is happening subduction because the surface mustn't increase in area.
The surface is 95 to 99 percent pure H20 ice. It's very bright. Some few patterns of Enceladan activity remind me a bit of common features at Earth's glaciers.
The inner mantle could be a mixture of ice and rock or water ( ?? ) , ice and rock. The core could be rocky. I think the core is only rock, with no water and no ice. Because the interior of Enc is far hotter than it 'should' be, I believe this moon to be differentiated ( crust, mantle, core ) completely. I think that in the south the crust is thinnest below the large ( active ) 'sulci'. There water or water and ice mixed is penetrating the crust through cracks generating this moon's famous geysers.
Today we have no temperature values at all of Enc's Interior making it even more difficult for me to think how its interior is like - especially how much water there is and if there's life in the upper mantle.
But this is all only guessing. Now we know very few about the interior of Enc. Its density is now believed to be 1.6 g/cm3.
For A New Saturn mission there is needed an unmanned lander ( at least ) for Enceladus. ( of Saturn's moons ) That one shall be like the ( today neither finished nor launched ) Europa orbiter ( lander ) landing on Europa and then melting thru the Europan ice crust and then if there is water it shall continue as a small submarine with a chemical laboratory. Of course it has to transmit its finding to Earth when diving in Europa. Or a Enceladus Rover that could drive/climb around and follow the warmth by its temperature sensors. Then it shall melt thru the thinnest part of the southern Enc crust. If there were water pockets it would find them.
That is now just dreaming.
I wrote a lot but now it's finished.
The activity of Enc compared to Mimas is a mistery.
And Io's activity at Jupiter is also partly misterious because it's explained not completely by tidal heating.
All the latest images of the 2008 Halloween Enc flyby were very interesting !
I love this shot of Janus!
I fully understand the need to focus on Titan, and the results of all the flybys have been stupendous, but I must say, imaging of the small moons is very interesting to me. Also, the other large moons, Iapetus in particular, are of great interest to me. Iapetus is a mysterious object, and even with the two close flybys, remains so. The imaging of its equatorial mountain range was quite literally, stunning! I spotted multiple landslides of enormous scale on the flanks of the mountain range, but I've not seen any discussion of those amazing slump features.
There is one other really dramatic landslide in evidence on Iapetus, within one of the large craters. This large crater is approximately 375 miles across, and features a smaller, 75 mile diameter crater within it, that appears to have impacted such that it's rim is almost exactly tangent to the inner rim of the larger crater. This smaller crater is nearly half filled with an enormous landslide that propagated off the rim of the larger crater, which at this location is about 15km high! From the looks of the landslide, it appears to be perhaps 5km thick? When that landslide cut loose, it's impossible to imagine the forces involved...truly an awesome feature on Iapetus!
The best image I've seen of it is at the following address...
Great examples of massive slumping are evident on many of the moons, including the bright splat crater on Rhea, which has large lobular flows off of it's crater walls. That one in particular brought a question to my mind, which is, where did the energy come from to soften that material enough to cause the mass slippage? The crater floor is peppered with small craters, but the landslides are free of craters, which indicates that the slumping occurred long after the formation of the crater, and at least geologically speaking, perhaps not so long ago (a billion years?)...which makes the question of where the energy came from even more interesting. I thought, other nearby impacts, but the lobular form of the slides would seem to indicate liquefaction occurred...which would seem to indicate thermal energy transfer? The related image (wide angle) that I've looked at was taken on November, 26, 2005, is as follows...W00012124...an amazing image to be sure. So...anyone have theories on how those lobular flows were formed, in such a low energy environment?
One other moon that has been woefully missed, in terms of hi-resolution imagery, is Mimas. No hi-res imagery of the crater Herschel have been captured, only medium res. It's clear from the medium res imagery that this crater has been filled with mass slumping...but the lack of hi-res imagery makes it very frustrating. And while this post might indicate otherwise, I'm NOT obsessed with landslides!
I think I've written enough for now...
It is reckoned that Enceladus has rolled over. Jupiter's moon Io is another point. Some of the larger plumes on Io like Tvashtar are in the higher latitudes than the equator.
Dione also appears to have extentional faults & graben too. It is thought that Dione is partially responsible, for the heating of Enceladu, but Dione too, appears to have been very active at some point. Dione is approx 30 times the mass of Enceladus. What caused Dione to be active? Rhea??????? Yet Rhea appears as dead as a dodo, with not much happening there other being cratered.
it's interesting to see the pattern outwards from Saturn.
Mimas. Inactive cratered.
Tethys. Inactive, cratered.
Dione, has been active, possibly still is on a small level.
Rhea. Second largest of Saturn's moons, inactive, cratered.
Titan. Possibly very active, with cryovolcanoes & tectonic activity.
Iapetus. Inactive, cratered, but with a huge equatorial mountain belt, possibly home to some of the highest peaks not on Mars & Io.
Some parts of the south polar region on Enceladus does resemble Europa in may respects, yet Europa is approx 500 times Enceladus's mass.
It is interesting to see how similar landforms appear on bodies that cover a woide range of size & mass.
You think this is boring? What about Mimas?!!! It's a good thing there's Herschel crater or there would be no drama at all on Mimas. Now, as a member of a collection of bodies, it and the other `boring' moons provide valuable points of comparison in their mass densities, compositions, cratering records, etc, so they really aren't as boring as they look. In fact, they are quite valuable and we're glad to have the opportunity to explore them. But for exquisite geological formations and that instinctive `I wanna go there' emotion they evoke, it's hard to beat Enceladus, Titan, Iapetus, and even Dione.
It is surely a question that has been asked a thousand times, sorry for that.
The Herschel impact crater on Mimas is always presented with much awe as the result of an event that nearly shattered this moon.
But Odysseus is even larger compared to he size of Tehtys. Is Ithaca chasma the scar of this terrible impact, or is it unrelated? If it is unrelated, then are there signs of the stressful event elsewhere?
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.
I wonder if the active area in the south is a remnant of a giant impact basin? The area & striation seem to be circular around the curcumferance, with the Tiger Stripes, looking like hardening skin on paint in a paintpot with no lid?
The cratered north to me does not look primeval, yes there are a lot of craters, but they are softened, like many on Dione, Jupiter's Ganymede & the Uranus moons Titania & Oberon, certainly being cryovolcanic bodies in the past, until fairly 'recent' times geologically speaking.
The sharp demarkation between the cratered & 'newer' terrain you picked up on, seems to suggest to me that the ice crustal thickness, increases suddenly from south to north, perhaps also an impact consequence?
The neighbouring moon Mimas was nearly destroyed in the collision that created the Herschel Crater, but then Mimas is near enough pure ice, that was brittle. Enceladus being composed with a larger amount of rock, perhaps even differentiated behaved differently, the huge impact scar, filled with cryolava instead, creating this weird surface & dichotomous morphology?