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Fraser
2007-Jul-06, 05:40 PM
One of the most bizarre objects in the Solar System has got to be Saturn's moon Hyperion. From the pictures taken by Cassini, this tiny moon looks like a sponge you might buy at the Body Shop. ...

Read the full blog entry (http://www.universetoday.com/2007/07/06/spongey-hyperion-coated-with-hydrocarbons/)

antoniseb
2007-Jul-06, 06:48 PM
Looks like a big hunk of pumice.

bluehorse
2007-Jul-06, 11:22 PM
Could this be a captured comet core? The "craters" look like exhaust openings for gases that sublimated out in the past. This might explain the hydrocarbons at the bottoms - stuff that didn't escape.

EDG
2007-Jul-07, 02:17 AM
Can I say "you've been EDG_'d?" ;)

http://www.bautforum.com/showthread.php?t=61619

I was surprised this didn't show up on UT earlier...

Brian Backlash
2007-Jul-09, 06:59 AM
This is the best blog ever. I've been reading it for about a year now, and I needed to just hop on and thank you for doing such a wonderful job digging up some of the most interesting science items and discussing them in an intelligent way.

Jerry
2007-Jul-09, 01:22 PM
Isn't the extremely spongy look limited to one side? If so, why would cratering be so differentiated?

John Mendenhall
2007-Jul-09, 06:45 PM
Isn't the extremely spongy look limited to one side? If so, why would cratering be so differentiated?

Jerry - try not to get too excited, but here's a speculation from one of the most rabid mainstreamers, namely me.

Many solar system objects show differentiated hemispheres. How about if the entire solar system passed through a protoplanetary disc, or similar, at very high speed? The exposure time would be brief, and for objects tidally locked, one side would take a beating. Once we examine a lot of solar system bodies, the idea can be tested by seeing if they all exhibit differentiation at about the same time.

Regards, John M.

Jerry
2007-Jul-09, 08:56 PM
Explanations for one moon in orbit about Saturn require some level of consistency with other objects in orbit about Saturn, or a reason that they are not. This is turning out to be a very weird place.

The cratering patterns on Iapetus are broadly similar on the 'dark side' and on the 'light side'. Our moon, luna, is somewhat more cratered on the dark side, but I think the moons of Saturn are, in general, not widely differentiated in the crater patterns. Hyperion is not in tidal lock. It looks to me like Hyperion has a unique crater pattern on one side, but not the other. Also, according to Wiki, the dark side of Iapetus and the dark material on Hyperion are similar: Why would this material be found on one side of Iapetus, but all over Hyperion...or is it? Very curious.

Palomar
2007-Jul-10, 12:43 PM
Could this be a captured comet core? The "craters" look like exhaust openings for gases that sublimated out in the past. This might explain the hydrocarbons at the bottoms - stuff that didn't escape.

That's a very interesting thought! :)

---

Image of the Day : Candy-Colored Cup-Shaped Craters of Carbon Dioxide Ice (http://www.space.com/imageoftheday/image_of_day_070709.html)


cup-like craters filled with hydrocarbons. These substances may indicate a more widespread presence of basic chemicals necessary for life in our solar system.


also discovered solid carbon dioxide (dry ice) mixed in unexpected ways with the ordinary ice. Images of the brightest regions of Hyperion's surface show frozen water that is crystalline in form, like that found on Earth.


In this map, blue shows the maximum exposure of frozen water, red denotes carbon dioxide ice ("dry ice"), magenta indicates regions of water plus carbon dioxide, yellow is a mix of carbon dioxide and an unidentified material.

3488
2007-Jul-10, 12:52 PM
It appears that the Hydrocarbons on Hyperion are similar to those on Iapetus & Phoebe.

I think without doubt, that Phoebe is a captured giant comet, from the Kuiper Belt. Asteroid 5145 Pholus & Comet Chiron, also have very darkened hydrocarbon surfaces.

It appears to me anyway, that Phoebe (& others) imported these hydrocarbons into the Saturn system.

Since Phoebe's capture (whenever that was), impacts have blasted some of the hydrocarbons from the surface, where later they spiralled in towards Saturn, where Iapetus, got its dark leading hemisphere, & Hyperion captured dark material in its craters.

The dark material within the craters, absorb more sunlight than the surrounding ice, thus these warmer crater floors, 'burn' deeper into Hyperion, giving this tumbling moon the 'sponge like' appearance.

That is my take of it anyway. Perhaps I am talking rubbish???

Andrew Brown.

OneHotJupiter
2007-Jul-10, 01:39 PM
I like the comet core theory , Hyperion is one of the most fascinating objects in the Staurn system , if not the entire solar system and this is the kind of discussion I love to see on this forum.

Does anybody know if Cassini has anymore work scheduled as far as this interesting moon goes?

3488
2007-Jul-10, 01:54 PM
Maybe. I had seen somewhere else that Hyperion may have formed as a moon around Titan, but was pulled away by Saturn.

Not proven I know. Hyperion could like Phoebe, be a captured comet. One idea I have also heard about, is that Hyperion was more like Mimas, a small spherical object, that got hit hard, just shy of shattering completely, forming a huge crater & causing Hyperion to tumble.

The very low density of Hyperion, does suggest caverns & cracks within the main ice body.

Cassini if i recall, is not scheduled to make any more close encounters with Hyperion, not at least during the primary & so far extended mission
(two with Enceladus, & one each with Dione, Helene & Rhea are on the cards).

However, opportunities will arrive when Hyperion will be well placed, so by all means, Cassini is not really done with Hyperion yet.

However I do think that we have seen the best stuff, though.

Andrew Brown.

Jerry
2007-Jul-10, 05:26 PM
The dark material within the craters, absorb more sunlight than the surrounding ice, thus these warmer crater floors, 'burn' deeper into Hyperion, giving this tumbling moon the 'sponge like' appearance.

That is my take of it anyway. Perhaps I am talking rubbish???

Andrew Brown.
That is consistent with the first theories that emerged to explain this surface, but not the one in this article. See more detail in:

CASSINI SCIENTISTS WRING OUT THE DETAILS ON SPONGY HYPERION (http://ciclops.org/view.php?id=3303&js=1)

According to Deep Impact Scientists, Tempel 1 has about the same density as Hyperion ~0.5g/cc. However, the 'apparent' craters on the surface of Temple 1 look nothing like these deep holes on Hyperion.

That is what is cool about the extended mission of Stardust, to revisit Temple 1. If Deep Impact left a big Hyperion-like crater, there is order in the universe...

However, since Temple 1 is passing much closer to the sun between visits, The best we may be able to do is determine how much the overall geography was impacted by this searing encounter.

3488
2007-Jul-10, 08:32 PM
Thank you very much Jerry for your brilliant post & link to CICLOPS.

I often look at that site, but have not done so for a few days. Yes that is very different to the idea of the dark crater floor burning into the surface.

That extremely low density does show that Hyperion is full of voids. The impacters will just push material in rather than create impact craters as we are used to seeing on dense coherent bodies like The Moon, Mars & Mercury.

This reminds me a lot of Main Belt Asteroid 253 Mathilde. When the NEAR/Shoemaker spacecraft encountered 253 Mathilde, on route to asteroid 433 Eros, one of the huge surprises were enormous depressions, some over 50% of the diameter of the asteroid.

Of course common sense dictates, why does 253 Mathilde still exist? The late Gene Shoemaker monitored the tracking of the NEAR spacecraft & realised that its density at the very most was that of water ice!!!!!!!!

Clearly 253 Mathilde was a rubble pile held together by mutual gravity. Since then we have found that the Jupiter moon Amalthea is a rubble pile, asteroid 25143 Itokawa is one also & now Hyperion.

I am beginning to wonder if many of the smaller icy moons of Saturn, Uranus & Neptune are just icy rubble piles. Perhaps Nix & Hydra orbiting Pluto & Dysnomia orbiting Eris are too?

A shame reallly that Cassini will not be making any more close encounters. I would like to see Phoebe again really close up too, perhaps the other side as last time during the approach to Saturn.

Has Hyperion been smashed up & re-assembled?

Images below.

1). Hyperion from 14,867 KM.
2). Hyperion from 8,671 KM.
3). Hyperion tumbling.
4). Hyperion false colour.
5). Hyperion from 2,555 KM. The smallest details are aprrox 14 metres across. Some boulders can be seen at top right.
6). 'Crescent' Hyperion.

Andrew Brown.

antoniseb
2007-Jul-10, 08:47 PM
Clearly 253 Mathilde was a rubble pile ... asteroid 25143 Itokawa is one also & now Hyperion.

Wait a minute, Hyperion may have lots of voids, but it has structure, and looks nothing like Mathilda or Itokawa. I don't know if there is a term for what Hyperion looks like, but for now let's call it a crystal palace. It has voids, but it is has self-supporting structure at least thirty kilometers thick on the surface.

3488
2007-Jul-10, 09:46 PM
What do you suspect has happened?

If the surface is of the consistency to allow meteorites to 'burrow' deep craters, than surely the surface cannot be solid?

Unless it is a deep icy 'regolith' over a solid crust, under which are voids. Really strange object.

The close up images of Hyperion, do look quite crystalline. However, how would crystalline ice form on Hyperion?

There is no evidence of present or past cryovolcanism, or could it be impact generated?

I do agree, Hyperion looks nothing like 253 Mathilde or 25143 Itokawa. But all three show remarkably low densities.

Images below:

1). 253 Mathilde.
2). Hyperion.
3). 'Crescent' 253 Mathilde.
4). 'Crescent' Hyperion.

Two very different objects.
253 Mathilde a type C (Carbonaceous) Main Belt asteroid.
Hyperion, an irregulalrly shaped & tumbling icy moon of Saturn.

Both objects share the fact that both are of very low density & may well have large internal voids.

Andrew Brown.

antoniseb
2007-Jul-11, 12:31 PM
What do you suspect has happened?
I haven't speculated much, so my model is pretty rough and full of holes. My first guess is that Hyperion may be an object such as became the KBOs when ejected to the outer solar system, but that it went through some period of being heated, which resulted in release of the most volatile materials, but that somehow (I don't know how) the materials had not been homogenized in the initial creation of the object (which I guess came in alternating phases of accreting volatiles and less-volatiles). So, when the later hot period happened, structure was left behind when the volatiles escaped.

That being said, I'm pretty open minded to any other model. Mine is just a hand-waving explanation with nothing but "it looks like" to back it up.

3488
2007-Jul-11, 01:11 PM
Thank you very much antoniseb, for your answer.

I too am flummoxed. Your explanation makes sense, regarding the potential for large internal voids & caverns. They must exist, as
Hyperion has an overall density of only 0.55 Gcm3.

Interesting if Hyperion like Phoebe did originate in the Kuiper Belt???

It seems quite an oxymoron that Cassini may have beaten New Horizons to a KBO, with the Phoebe encounter in June 2004 & maybe again with Hyperion.

Andrew Brown.

antoniseb
2007-Jul-11, 01:42 PM
Interesting if Hyperion like Phoebe did originate in the Kuiper Belt???
It is my understanding that in earlier days of the solar system, objects that we call KBOs were in the zone now populated by Jupiter and Saturn, and were cast out by the migration of Jupiter and Saturn inward. I'm not too surprised to see Saturn with a few of these objects as moons, but wouldn't think of them as KBOs that migrated in after being ejected. I think they were captured before the population was removed from the area.

3488
2007-Jul-11, 01:58 PM
Hi antoniseb.

I don't know.

As far as I understood it, the Kuiper Belt formed roughly where it is now. The planetary formative process was so slow beyond Neptune, that only these objects could form. Eris & Pluto are the largest as yet found.

I could be wrong, perhaps it did migrate outwards, or even the Kuiper Belt is a product of both processes.

The solar system is getting weirder & more complicated, the closer we look & the more we learn.

Fascinating stuff though. Would not want it otherwise.

Andrew Brown.

PsyberDave
2007-Jul-15, 01:31 AM
Here's an interesting picture of Hyperion showing the presence of water and carbon dioxide. The captured comet idea seems more probable with these data. http://www.nasa.gov/multimedia/imagegallery/image_feature_867.html

OneHotJupiter
2007-Jul-15, 03:17 AM
Too freakin' fascinating , to me Hyperion has always been the strangest looking object in the Sol System , I hope more attention is soon paid to this freaky moon!

dgavin
2007-Jul-15, 06:06 AM
I haven't speculated much, so my model is pretty rough and full of holes. My first guess is that Hyperion may be an object such as became the KBOs when ejected to the outer solar system, but that it went through some period of being heated, which resulted in release of the most volatile materials, but that somehow (I don't know how) the materials had not been homogenized in the initial creation of the object (which I guess came in alternating phases of accreting volatiles and less-volatiles). So, when the later hot period happened, structure was left behind when the volatiles escaped.

That being said, I'm pretty open minded to any other model. Mine is just a hand-waving explanation with nothing but "it looks like" to back it up.

jUst a thought, maybe it was a close encounter with one of the gas giant's that caused a period of internal heating and out gassing. It maybe one of those objects that survived a breif enounter in the roche limit of another.

3488
2007-Jul-16, 02:17 PM
I had heard a theory that Titan may not have formed in orbit around Saturn, but at one of the Lagrange points. Over millions of years
Titan drifted towards Saturn, due to orbital pertabations with Jupiter & Uranus.

Hyperion may have been Titan's moon.

I do not know about this, it was something I saw elsewhere. It does seem that Titan's & Hyperion's orbits aorund Saturn are reasonably close to one another.

Titan 1.221 Million KM. Hyperion. 1.481 million KM. So 260 thousand KM difference.

As I said I do not know.

The CO2 ice is interesting. This does point to an interplanetary origin, as far as I know, the other major Saturn moons do not display this. Only Phoebe, apart form Hyperion seems to show it & Phoebe almost certainly is an interloper.

Andrew Brown.

antoniseb
2007-Jul-16, 02:51 PM
Titan may not have formed in orbit around Saturn, but at one of the Lagrange points.

This could explain Triton's strange orbit around Neptune better than Titan's orbit around Saturn, but both seem plausible enough. Interesting idea.

3488
2007-Jul-16, 03:37 PM
Hi antoniseb.

I agree with you 100% & thank you for not just dismissing what I say.

Triton is definately an interloper within the Neptune system. I do not think that there is any doubt about that at all.

Titan, I am not sure. It is odd though, that Titan is so large, when you compare Titan to Rhea & Iapetus, the second & third largest Saturn moons. Then there is another quite large size gap, down to Tethys & Dione.

Having said that, I would not dismiss the idea that Titan & Saturn once shared a Heliocentric orbit in their youth & later on Titan was trapped within Saturn's Hill Sphere.

If so, than indeed, Hyperion could well have been Titan's original moon. Saturn's gravity overcame Titan's Hill Sphere, at whatever distance Hyperion orbited Titan at, but Hyperion being on a very similar trajectory to Titan, would end up in a similar Saturncentric orbit, which is exactly what we do have & see.

Also there is roughly a 3:4 resonance between Hyperion & Titan. Every four orbits around Saturn, Titan completes, Hyperion completes three.

The more I think about this, the more I think it may be true.

Titan & Hyperion, just seem to ring a bit false in regard to the rest of the Saturn system. Phoebe, yes, definately an interloper. Titan & Hyperion, hightly likely in my opinion.

Hyperion is just getting weirder & weirder, the more we all seem to think about it.

Andrew Brown.

thothicabob
2007-Jul-16, 04:53 PM
What do you suspect has happened?
The close up images of Hyperion, do look quite crystalline. However, how would crystalline ice form on Hyperion?


Hyperion's surface reminds me of the 'hoar frost' you see forming in the north on cold mornings (with bits of the ground pushed up one to several inches on top of ice crystals). Of course, 'extremely cold' here is somewhat more toasty than out there, and I don't know if other materials could react in the same way under more extreme conditions, but...it's an observation, is all. Thought I'd share. :)

3488
2007-Jul-16, 09:11 PM
Thank you for sharing that.

Possible.

Perhaps Hyperion does have a temporary atmosphere when a large impact occurs.

You are correct. Even the coldest places on Earth, are hot compared to Hyperion. The AVERAGE surface temperatures on Hyperion are roughly minus 180 Celsius / 93 Kelvin.

At this temperature, water ice is as hard as solid rock.

I would not think of Hyperion & atmosphere in the same sentence, but this object is so weird, perhaps this can happen under certain conditions.

There is no sign of any cryovolcanic activity, either active or dead, but I wonder if any outgassings are occuring here?

Thank you all for your thoughts.

Andrew Brown.

thothicabob
2007-Jul-16, 09:21 PM
I would not think of Hyperion & atmosphere in the same sentence, but this object is so weird, perhaps this can happen under certain conditions.


In a sense, it seems that Hyperion IS essentially a hunk of "frozen atmosphere". :)

thothicabob
2007-Jul-16, 09:33 PM
After posting the above, an odd question came to me: what WOULD happen to the atmosphere (and ocean) of a planet (that had them) that suffered enough of an impact to shatter it, and scatter its pieces?

Of course, there'd be intense heat involved initially (and perhaps a brief period of knashing of teeth, but probably not enough time for rending of clothes), and it would take some time for all the pieces to dissociate (assuming a sufficiently powerful impact at the right velocity/angle), but not long afterwards, there'd be rapid cooling.

Now, I am NOT suggesting this is Hyperion's origin; the question is sort of tangental. But could the 'atmosphere' condense and freeze into solid objects?

3488
2007-Jul-16, 09:36 PM
You are probably not wrong there.

If Hyperion was warmed & sublimed, yes it would be gas.

The more & more I think about it, more cometary Hyperion does become.

At only 0.55 grammes per cubic centimetre, average density, I would find it very hard to believe that htere is much or even any solid rock or metal enclosed within.

Hyperion must be the least dense of all the solid bodies known within the solar system.

Even Phoebe, which is almost certainly a captured comet / KBO, the density creeps up to 1.17 G/cm3, high enough for Phoebe to be free of voids & have a bit of rock contained within.

Andrew Brown.

Below: Hyperion (left) & Phoebe (right).

m1omg
2007-Jul-18, 10:59 AM
If it is 40 percent empty space, could be gigantic ice caves here?

3488
2007-Jul-18, 11:09 AM
I think so & Antoniseb thinks so too. I quite like his Ice Crytal idea. To be honest, I cannot think of anything better. :cool:

These would be huge caverns. Perhaps one day, we will send a lander that cen borrow through the ice to them.

Seismometers on the surface, with perhaps a directed impact with a spent booster may reveal if these caverns exist.

I think they do. :cool:

Andrew Brown.