Approaching Iapetus - what makes it two-faced?

[Smersh]

WOO - HOO !! - As you guys across the puddle sometimes say. <br /><br />Anyway, some of us here are British so - Jolly good show chaps !! <img src="/images/icons/wink.gif" /><br /><br />Today's the day ... <br /><font color="yellow"> <br />NEWS - News Releases - 2007<br /><br />Cassini Prepares to Fly By Walnut-shaped Moon<br />September 5, 2007<br />(Source: Jet Propulsion Laboratory)<br /><br />PASADENA, Calif. - Cassini will make its only close flyby of Saturn's odd, two-toned, walnut-shaped moon Iapetus on Sept. 10, 2007, at about 1,640 kilometers (1,000 miles) from the surface.<br /><br />This flyby will be 100 times closer than Cassini's 2004 encounter, and will be the last time the spacecraft will aim its instruments at this moon.<br /><br />Iapetus (pronounced eye-APP-eh-tuss) has a ridge of surprisingly large mountains -- the so-called "belly-band" -- that lies directly on top of the equator. The moon also has a distinct difference in the brightness of its leading and trailing hemispheres, one as bright as snow and the other dark as tar. The irregular shape, the mountain ridge and Iapetus' brightness contrast are among the key mysteries scientists are trying to solve. </font><br /><br />Full story here. <br /><br /><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>

 

[anthmartian]

Andrew : Absolutely amazing!!! <img src="/images/icons/smile.gif" /><br /><br />I have colour versions of these latest images on my site. The above image from 208,378 KM, and also an earlier one from 268,243 KM.<br /><br />http://anthmartian.googlepages.com/thisislandearth<br /><br />One image ( 268,243 KM ) is true colourized from Red, Blue, and Green, and then enhanced somewhat. <br /><br />The other ( 208,378 KM ) is a simulated colour image made from a shaded monochrome picture, and another enhanced in the same way i processed my New Horizons imagery. Those two were combined to form one. i am very pleased with the resulting image.<br /><br />But, working with such astounding images makes things easy! <img src="/images/icons/smile.gif" /> <br /><br />Amazing to think we are going to see views 127 times closer than the closest view so far seen! I am really liking the way we can see that drifting of the bright material into those craters already. <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>

 

[anthmartian]

Things are getting seriously exciting now! Images in from 62,331 KM as i type. <img src="/images/icons/smile.gif" /><br /><br />I have just posted this new image ( others to follow ) on my site.<br /><br />http://anthmartian.googlepages.com/thisislandearth<br /><br />New Image : Taken on September 10, 2007 and received on Earth September 10, 2007. The camera was pointing toward IAPETUS at approximately 68,551 kilometers away <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>

 

[3488]

Thank you very, very much Anthmartian. <img src="/images/icons/laugh.gif" /><br /><br />This is getting REALLY Exciting now. We are only just over TWO HOURS away <br />from closest approach. <img src="/images/icons/laugh.gif" /><br /><br />The viewing angle will change enormously as Iapetus will wax from the slim crsecent,<br />that has been apparent to a fully lit disk.<br /><br /> Iapetus in Saturnshine. 68,478 KM.<br /><br />Hi Vogon, what do you maske of the Voyager Mountains in Anthmartian's excellent images???<br /><br />Blow up of Voyager Mountains. <img src="/images/icons/cool.gif" /><br /><br />Needless to say, I will come back again later. <img src="/images/icons/shocked.gif" /><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>

 

[Smersh]

Thanks Andrew! That one of the voyager mountains is unbelievable ... just about to post them over at LTL. <img src="/images/icons/wink.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>

 

[3488]

It sure is Smersh.<br /><br />Incredible image.<br /><br />I will be doing more later & keep a watch on Anthmartian's excellent website too. <br /><br />There WILL be some real crackers on there, I am telling you now.<br /><br />http://anthmartian.googlepages.com/thisislandearth <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>

 

[anthmartian]

Due to the problems here regarding images i will be posting my own images along with Andrews images on my site. we chatted about this last night and thought it would be the best way around the problems ( yes this stuff is all planned you know!!! lol )<br /><br />http://anthmartian.googlepages.com/iapetusencounter<br /><br />New images will also pop up on the front page as usual.<br /><br />http://anthmartian.googlepages.com/thisislandearth<br /><br />I am just setting things up for what should be a busy and frantic time ahead. An awesome time though! <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>

 

[vogon13]

It sure is 'beat up' !!<br /><br />The view I (think) I really want to see would be 180 degrees around from that one.<br /><br />We are looking west up the ridge, I want to look east down the ridge.<br /><br />It sure is zorched with craters, ghastly !<br /><br />(I used HP Image Zone to turn picture "right side up", helps enormously in studying picture.)<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[3488]

I agree, it does look extremely beat up.<br /><br />Cleary, very, very, ancient.<br /><br />Cannot tell just yet, what the Voyager Mountains actually are just yet. <br /><br />That ridge is very severly ZORCHED. <img src="/images/icons/shocked.gif" /><br /><br />But I think by this evening, we will see.<br /><br />Don't know when the images will start returning.<br /><br />Judging by the approach, pretty quickly. <img src="/images/icons/laugh.gif" />.<br /><br />Anyhow, closest approach has just ocurred.<br /><br />Here sim of Iapetus as seen from Cassini @ 2:15 PM UT.<br /><br />Here sim of Iapetus as seen in greater detail from Cassini.<br /><br />This is really thrilling stuff.<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>

 

[jaxtraw]

My first impression of the pic of the mountains is that despite the very heavy cratering, they started off very symmetrical and smooth with a clearly defined central "spine". This may mean nothing, just blathering while I await the rest of the piccies <img src="/images/icons/smile.gif" />

 

[silylene old]

So far, IMO the equitorial mountains look "exuded", and not deposited by the collapse of a ring. I can't wait for more pictures! <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>

 

[3488]

Hi silylene.<br /><br />Yes it does look exuded so far. But the real acid test will come when the higher<br />resolution images come in. I do not know when that will be, but it is just over <br />four hours now since closest approach, so hopefully not too much longer now.<br /><br />What I have noticed, which still IMO still keeps the Collapsed Ring theory alive<br />at the moment is the fact the craters appear to cut deep, on the Voyager Mountains<br />& I think I may have found a landslide (not sure though), but hopefully will be clearer<br />later when the high resos start coming in.<br /><br />If I am correct on both counts, than the Voyager Mountains are just a huge ring of <br />rubble pile, consistant with a Collapsed Ring.<br /><br />However if I am wrong, & the Voyager Mountains are stronger, than a cryovolcanic<br />origin cannot be ruled up.<br /><br />I will look for<br /><br />1). Large ice boulders / slipage / landslides / drilled in craters / layers for collapsed Ring origin.<br /><br />2). Flows & summit ridges / craters & some excavated ice boulders from impacts for cryovolcanic origin.<br /><br />3). Faulting / fracturing / some excavated ice boulders from impacts for rifting / compression.<br /><br />My bet at the moment is still on option 1.<br /><br />Please do not forget: http://anthmartian.googlepages.com/thisislandearth <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>

 

[vogon13]

The 'fluting' on the sides of the ridge seem to mostly be resultant from impactors.<br /><br />(that is expected pretty much regardless of the manner of formation of the ridge)<br /><br />Angle of repose of the sides of this segment of the ridge are very hard to determine from the devestating subsequent cratering damage. It looks like a sand castle structure at the beach trampled by 10 subsequent volleyball games. <br /><br />I had not anticipated a level of cratering so heavy as to have obliterated the evidence we are looking for to differentiate between the various ridge formation ideas.<br /><br />{Note: forshortening in the view we have now does emphasize the irregularities in the surface due to cratering, perhaps a higher viewpoint for the rest of the pictures will help}<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[nimbus]

Their raw images gallery is taking a cue from SDC's... <div class="Discussion_UserSignature"> </div>

 

[vogon13]

I see at least 3 major landslides slumping out from the ridge. With limb picture rotated for space = up, 2 slides on left and one on right. Biggest one is at top left by the large discontinuity in ridge, other is towards terminator, and is very distinct, but much smaller. The one on the right is 1/2 way down the length.<br /><br />(this list is not inclusive) <br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[3488]

I think that you are correct Vogon.<br /><br />I still favour a rubble pile (Collapsed Ring) for the origin.<br /><br />I too had not anticipated THAT level of cratering damage. I still think that <br />there is still enough left for the true answer to reveal itself.<br /><br />Just hope that the high reso & better orientated images will not be long in coming now.<br /><br />The WAIT is killing me (metaphorically).<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>

 

[vogon13]

{to reiterate: slides and slumping do not preclude any idea regarding formation of the ridge, other than the structure is obviously not hollow.}<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[3488]

Thanks Vogon, your evaluation with what we have so far, matches mine.<br /><br />I can see the landslides you are referring too. Quite obvious now really.<br /><br />I had tentatively identified the largest one.<br /><br />I would have thought a cryovolanic origin would make the ridge more solid, so<br />I think that now we can begin to reject that one, unless the high resos show otherwise.<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>

 

[jaxtraw]

Not sure if this has any meaning but--<br /><br />I don't see any white in the image so far (difficult to tell of course) which I'd expect to see exposed by cratering IF the dark material is a dusty covering of some kind. Is the dark material much later, after all "hill creation" and cratering? Is it a result of processing of the surface, craters and all? Does it suggest that the hills are made from the "dark stuff"?<br /><br />I don't know. Ignorance is my only virtue in this discussion <img src="/images/icons/smile.gif" />

 

[anthmartian]

I think it's safe to say, its the white that is the substance doing the covering. If not, the only other explanation is that the darker covering is extremely new indeed. Too new for there to be no craters leaving white marks.<br /><br />The white material must be from within Iapetus, or collected from another moon. If its from within, then surely that opens up a lot of possibilities as to what the bulge could be. Something simular to what we see on Europa maybe? Could this have been a fracture that slowly built up as something piled up on the outside from within it? <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>

 

[3488]

Hi Anthmartian.<br /><br />AFAIK, the dark material is a thin covering over a 'cleaner' ice crust.<br /><br />I see your point though about the lack offresh craters burrowing under the<br />dark dust.<br /><br />I would suspect that the cratering rate this far out in the outer solar system is<br />rather slow at the current time.<br /><br />Back during the December 2004 / January 2005 encounter, the large basin<br />with the landslide, showed whate ice on the slumping wall, with the dark dust, being<br />just a veneer.<br /><br />Hopefully later on, we will see further evidence of this.<br /><br />Just checked the schedules, newer images should have arrived @ Goldstone. The Madrid <br />station will recieve more tomorrow morning. Don't know when the highest reso images <br />will arrive.<br /><br />I do not know how long it takes for the images to appear on the Web??<br /><br />The Voyager Mountains are just not making any sense right now. Deep fluting & evidence of<br />landslides & drilled craters looks like a 'heap' of loose material to me. But we'll<br />soon see.<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>

 

[anthmartian]

Andrew : I left out the part where i meant to say " i know nothing!" lol<br /><br />The cratering rate must be very slow as you say. Thats what threw me out. I would have definatelly expected some of the craters to be newer than the dark coating. There certainly is a lot of mystery here. <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>

 

[3488]

Hi Anthmartian. You do not know nothing. Far from it.<br /><br />Iapetus is one of those objects that has had a complex early history, that will take an <br />awful lot of research to unpick.<br /><br />Iapetus from 1,478 KM & 1,316 KM & 5,983 KM.<br /><br />Enlarged horizon views from 1,316 KM & here. <br /><br />Enlarged portion of view from 1,478 KM.<br /><br />Iapetus Crater enlarged view from 1,478 KM<br /><br />Terminator view of Iapetus from 1,623 KM.<br /><br />Cropped & enlarged portion of Iapetus Terminator view from 1,623 KM.<br /><br />Crater from 1,316 KM view. That crater looks pretty deep. The ice crust of Iapetus is indeed<br />very thick & is of great structural strength. Clearly we are looking at a landscape that has<br />probably not changed much since well before multicelluler life began on Earth.<br /><br />http://anthmartian.googlepages.com/thisislandearth <br /><br />It looks lik <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>

 

[vogon13]

The 60,000 + km range picture of the terminator with the ridge extending out around the equator ties in to the pictures we got in 12/2004.<br /><br />The row of 3 craters parallel to the ridge and to the north side, with the center one being square, is visible in the new image, and the old mosaic.<br /><br />Sadly, this part of the ridge is where the trifurcation starts, (the most intersting bit) and it is very, very heavily damaged with craters.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[silylene old]

Wow, I just got to see the newest batch of pictures. IMO, it still looks 'exuded'. But I agree that an 'exuded' appearance would be hard to distinguish from depositionl + slumping. <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>