Approaching Iapetus - what makes it two-faced?

[tdamskov]

Hm. I think you're right that things might be complicated but perhaps in even more interesting ways. How about this... Here's a moon that's primarily composed of H2O and CO2 ice. Very high albedo as seen towards the poles. Along comes disintegrated carbonaceous object / or Saturnian primordial ring which deposits a fairly thick pile of dust on one side, mainly on the equator. This stuff is almost like tarry sand. Subsequent cratering of the equatorial dustpile (evident from the images) ballistically disperses quite a bit of this dusty material further towards the poles, primarily collecting in hollows of craters. Perhaps the tarry dust/sand material tends to stick together slightly when it's heated by the sun? That might account for the sharp black/white edges. It might even bake out gases (Vogon's colouring agent) which would expand around the dust puddles.<br /><br />The subsequent dispersal of the dusty material would also account for the extremely rounded and soft terrain around the equator. However, what worries me is the fact that I see no "revealing" craters on higher latitudes where the impacts have dug away the dust to show pure ice below. Then again, impacts into the ice would create temporary clouds of gas (vaporized ice and co2) and the resulting winds might be able to carry enough dust to partially cover the recent crater with a thin layer.

 

[jaxtraw]

Do we have any shots of Voyager Mountains that show parts of them to be composed of/covered in "white stuff"?

 

[anthmartian]

Apart from the odd tiny patches there is a lack of white on the Voyager Mountains.<br /><br />I have updated the site pages. I am mostly playing catch up here as i have been a bit busy today.<br /><br />I hope some of these images can help the discussion. <img src="/images/icons/smile.gif" /><br /><br />http://anthmartian.googlepages.com/iapetusencounter<br /><br />http://anthmartian.googlepages.com/thisislandearth <div class="Discussion_UserSignature"> <p><font color="#000080"><em>"Traveling through hyperspace ain't like dusting crops, boy! Without precise calculations we could fly right through a star, or bounce too close to a supernova and that'd end your trip real quick, wouldn't it?"</em></font></p><p><font color="#33cccc"><strong>Han Solo - 1977 - A long time ago in a galaxy far far away....</strong></font></p><p><br /><br />Click Here And jump over to my site.<br /></p> </div>

 

[Smersh]

3488<br /><font color="yellow">Mind you I am thoroughly enjoying this encounter very much indeed. </font><br /><br />Absolutely Andrew! I can't believe what I'm seeing here. Anth tells me it's Titan next - that should be fun too. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <h1 style="margin:0pt;font-size:12px">----------------------------------------------------- </h1><p><font color="#800000"><em>Lady Nancy Astor: "Winston, if you were my husband, I'd poison your tea."<br />Churchill: "Nancy, if you were my wife, I'd drink it."</em></font></p><p><font color="#0000ff"><strong>Website / forums </strong></font></p> </div>

 

[jaxtraw]

What's bugging me is there doesn't seem to be any "mixed" material anywhere, i.e. "dirty ice". It's all totally one thing or the other. Why haven't impacts churned the two together? This says to me that the carbonaceous covering, or the white ice covering, which is doing the covering, must have been laid down after all cratering ceased.

 

[halcyondays]

<<<<br />http://anthmartian.googlepages.com/iapetus010september2007et3-enhanced-.jpg/iapetus010september2007et3-enhanced--full.jpg <br /> />>><br /><br />Absolutely amazing pictures, and thanks to everyone here.<br /><br />For a spectator like me, I am trying to work out scale and distance. For example, from the picture I quote here, which seems to be one of the very best, can I have some idea of how far it is from the left to the right of the image, how high the mountains are and the diameter of the craters ? Many thanks.

 

[franontanaya]

Ok, posting link instead of the image.<br /><br />New images included the IR filter and the full resolution image I was missing, so I compossed them again. Please, don't look too close to those borders between dark and light surface, each channel seems taken from a slightly different height so I had to adjust them a bit.<br /><br />N00092009 + IR + GRN + UV<br /><br />About the coating... my first idea was that Iapetus crust is dirty ice, as if much of the ice sublimated away and left the impurities behind, which aren't sent down to the core by the missing ice tectonics or vulcanism. Then, some of the dirty ice that still sublimates gathers over the dirty layer in some clean ice patches.<br /><br />Or maybe the underlying ice, as it is heated by the dark coating, "exudates" through it and then freezes... <div class="Discussion_UserSignature"> </div>

 

[robnissen]

This has been one of favorite threads ever in SDC. I think the hypothesis and comments here have been awesome and I really like the fact that by following this thread we know almost as much about Iapetus as anyone in the world. (The pros have only had a couple days to digest the data that we are getting at the same time.) I especially want to thank everyone who has taken the time to post pictures on other cites. (BTW, SDC, please FIX your image posting problem!!)<br /><br />Again, I just want to say this has been a spectacular thread, and I want to thank everyone for making it so.

 

[silylene old]

Fran: very very interesting! <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[webscientist]

I've just seen the latest image of Iapetus with the inky stains on a bright terrain. What do those dark patches represent ? <br />At first glance, I would say it is liquid even if the absence of atmosphere makes the hypothesis unlikely.<br />Do you think it is possible that the bright blankets maintain enough pressure for a liquid like methane to appear? And who thinks that those darks patches are liquids deriving from a subsurface sea beneath the ice blanket?

 

[anthmartian]

I would also like to say this has been a fantastic thread to contribute to, and be involved in.<br /><br />Some of the ideas and theories about this moon have blown me away. So have all the contributions. <img src="/images/icons/smile.gif" /><br /><br />Due to the image problems here, i have as you know hosted and featured Andrew Browns images on my web site. I have now decided to extend that to other members contributions. If any of you see your work on my site, and wish it removed i will take it down right away. Or if you object, please say so here and i will pass by your work.<br /><br />I do not usually feature other peoples stuff on my site. Infact it was a policy of mine from the start that i would not feature straight copies of any image, only ones which i have worked on myself.<br /><br />But, due to the problems here with images, coupled with the huge interest and stimulating content of this topic, i felt it best to include as much as i can from members. Anything to help this topic flourish further.<br /><br />Some of you may know i am involved in bringing content featured here and on my site to DVD video. Some members here and myself hope to release a SDC DVD. I plan to make this topic and all the images from the encounter into a video feature for that venture ( you can find links to my Youtube channel with previews and sample movies for this on my site. )<br /><br />So, all those who wish their content to be used on this project, please let me know here or by e-mail anthmartian@gmail.com I can download content posted here, or i will gladly recieve anything new, or video file attachments, whatever you turn out. <img src="/images/icons/smile.gif" /><br /><br />I have added a new Encounter page to my site...<br /><br />http://anthmartian.googlepages.com/iapetusencounter2<br /><br />Page 1 is here...<br /><br />http://anthmartian.googlep</safety_wrapper <div class="Discussion_UserSignature"> <p><font color="#000080"><em>"Traveling through hyperspace ain't like dusting crops, boy! Without precise calculations we could fly right through a star, or bounce too close to a supernova and that'd end your trip real quick, wouldn't it?"</em></font></p><p><font color="#33cccc"><strong>Han Solo - 1977 - A long time ago in a galaxy far far away....</strong></font></p><p><br /><br />Click Here And jump over to my site.<br /></p> </div>

 

[JonClarke]

I just have no idea what is going on. The surface looks very old because of the intense cratering, and yet the colour difference looks so superficial. It does to appear to have any thickness. It could be paint. <br /><br />A wonderful example of Haldane's proverb - the universe is not only stranger than we imagine, it is stranger than we can imagine.<br /><br />It is a great cridt to the NASA, ESA and Italian team that we can enjoy the fruits of this marvellous mission, even if we don't understand them - or aleast I don't. And thanks to everyone for posting the links!<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[franontanaya]

"If any of you see your work on my site, and wish it removed i will take it down right away."<br /><br />No problemo for me, mine are just cheap and dirty mixes and crops, and these images were NASA's public domain anyway.<br /><br />About the dark patches on the icy side, they are just underexposed I think. I guess those craters are like sun ovens, they'll reflect the light and melt the bottom. Also, maybe the sublimating ice from the sides is replaced by the sublimated ice from the bottom as it expands up, so the bottom ice is the first one to vanish without being replaced. <div class="Discussion_UserSignature"> </div>

 

[3488]

Hi everyone,<br /><br />I'm back now. Have had a bad spell with my condition, but feeling much better now.<br /><br />I would like to say an enormous thank you to every one who has continued this thread in my<br />short absence.<br /><br />The post closest approach images are just amazing, the bright trailing hemisphere, looks<br />like another moon altogether. <img src="/images/icons/laugh.gif" /><br /><br />I quite like these: Iapetus from 18,646 KM & Iapetus from 81,420 KM & Iapetus from 79,464 KM & Iapetus from 75,388 KM<br />& Iapetus from 22,283 KM.<br /><br />This one, a crop & enlargement of the of the 22,283 KM view showing the terminator of Iapetus.<br /><br />The rifts & canyons are impressive in the low sun.<br /><br />Iapetus from 42,073 KM. Showing the giant crater.<br /><br />Iapetus from 76,091 KM. Showing giant crater to terminator.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[theuniverse]

<img src="/images/icons/laugh.gif" /> Thank you very much Andrew Brown aka 3488 <img src="/images/icons/laugh.gif" /><br /><br />Some times its hard to tell if these surfaces are white on black or black on white. I think for the black on white hypothesis though it is just the shadow from the terran altitude variations that is causing the black to appear on the white. <br /><br />I enjoyed reading this forum it was very interesting. Thank you everyone for your constructive criticism's and your comical humour it has been fun <img src="/images/icons/laugh.gif" /><br /><br /><font color="purple">"The fool doth think he is wise, when the wise man doth know he is a fool"</font>-William Shakespeare

 

[CalliArcale]

The part that's blowing my mind is the apparent "splattering" of dark stuff around the transition area between Cassini Regio and the white, trailing hemisphere. It looks positively unreal. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[anthmartian]

Welcome back Andrew. I hope everything is ok, or improving. <img src="/images/icons/smile.gif" /><br /><br />Some of the last batch of links you posted are among my favourites. Simply stunning! I managed to stitch four of that recent release of images together here.<br /><br />http://anthmartian.googlepages.com/iapetus-mon2-col.jpg/iapetus-mon2-col-full.jpg<br /><br />I am onto page two of this encounter now on the site. Page 2 features other SDC members contributions too.<br /><br />http://anthmartian.googlepages.com/iapetusencounter2 <div class="Discussion_UserSignature"> <p><font color="#000080"><em>"Traveling through hyperspace ain't like dusting crops, boy! Without precise calculations we could fly right through a star, or bounce too close to a supernova and that'd end your trip real quick, wouldn't it?"</em></font></p><p><font color="#33cccc"><strong>Han Solo - 1977 - A long time ago in a galaxy far far away....</strong></font></p><p><br /><br />Click Here And jump over to my site.<br /></p> </div>

 

[jaxtraw]

Glad you're feeling better, Andrew <img src="/images/icons/smile.gif" />

 

[h2ouniverse]

Hi Andrew,<br /><br />Hope you are fine.<br />I missed yesterday evening (too much work). And just discovered the Dalmatian effect . How exciting!<br />Some craters look as if formed by the black bombardment (with the ink in the center). Others not. <br /><br />Let's hope the spectrometer measurements will be realeased soon...<br />regards

 

[h2ouniverse]

Does anybody know whether the equatorial ridge goes significantly over the white hemisphere?

 

[3488]

Thanks Anthmartian, joel & jaxtraw.<br /><br />I have had a pretty rotten 36 hours or so, but I am feeling very much better now.<br /><br />Got taken home from work yesterday, when I suddenly became ill. No warning, <br />just a sudden deterioration.<br /><br />However, I am back now.<br /><br />I quite like this one: Iapetus from 23,404 KM. <br /><br />This one is a blowup & crop from the 23,404 KM image, clearly showing slumping within <br />the crater, a canyon & the splattering effect of the dark areas. This is a LARGE<br />image, approx 2.8 MB.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[3488]

Hi joel,<br /><br />Yes that is a good question. I have tried to find that out myself.<br /><br />This image from 14,322 KM, showing the transition from the Cassini Regio<br />onto the bright hemisphere.<br /><br />Here is a cropped enlargement of the equatorial region of above image from 14,322 KM. <br /><br />To me it looks like the Voyager Mountains do not continue far onto the trailing hemisphere.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[franontanaya]

I never saw a cosmic ray do that:<br /><br />http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS33/N00092248.jpg<br />http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS33/N00092249.jpg<br /><br />It doesn't match the camera exposition, like if it was moving in both shots from left to right. Star trail I guess. <br /><br />(The glare is an artifact, or at least it isn't blurred in the first shot.) <div class="Discussion_UserSignature"> </div>

 

[h2ouniverse]

Thanks Andrew for the info,<br /><br />However it shows clearly that the dark sputtering is posterior to the formation of the ridge...<br />(That, plus the numbers of craters on the ridge, and under the dark material).<br /><br />What is surprising is that it does not look like a set of impacts. And if it was due to myriad of tiny bodies loaded with tholins, then ... <br />Btw, it's not the first time finally that we see Dalmatian aspects.<br />Hyperion is not far...<br />Remember this picture? <br />http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=1764<br /><br />Regards.

 

[3488]

Yes I remember Hyperion.<br /><br />A nice close up here of Hyperion from 2,228 KM, clearly showing the <br />same sort of dappling effect as on Iapetus.<br /><br />Vogon says that both Hyperion & Iapetus are tainted by gasses escaping from Titan.<br /><br />That would make sense.<br /><br />Another idea, although I suspect is now rejected was dark material coming from Phoebe.<br /><br />Anyway, any ideas about this canyon on Iapetus? Impact fracturing or even limited geological activity?<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>