A nice shot of Hyperion

http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=33556

This moon is very diffrent looking compared to the other smaller moons.

Could this moon be broken chunk off another sat?

They think that unlikely, but they DO think that something big hit Hyperion itself and blasted a lot of material off it (most of which then probably hit Titan).

That irregular shape gives Hyperion another peculiar distinction -- since it's in a pretty eccentric orbit close to Titan's (with an exact 3:4 period ratio), Titan's periodic tuggings acting on its irregular shape mean that it rotates in a completely chaotic way. That is, not only its rotational period but its rotational direction keep changing in a virtually completely unpredictable way: it speeds up and slows down, tumbles in different directions, and sometimes even reverses direction! As that very great SF writer Poul Anderson pointed out in one of his last stories ("Scarecrow"), this means that landing on it will be unusually difficult -- the surface will keep sliding around at a fair speed underneath your descending ship in a way that cannot be predicted from one moment to the next. So far it's the only chaotically rotating moon we know of in the Solar System: there were some initial suspicions that Neptune's moon Nereid might be one, but more recent measurements suggest that it may have a regular (if non-synchronous) rotational period after all.

That chaotic tumbling also seems to have caused Hyperion itself to be coated over its entire surface with dark material similar to that on the leading side of Iapetus (and probably coming originally from Phoebe or one of the other little irregular moons) -- Titan apparently intercepts all the remainder of this inward-spiralling stuff before it can reach any of the light-colored inner moons.

It is arguably the fourth oddest of Saturn's moons, and it will be interesting to see what Cassini makes of it during its one close flyby in late September.

I hope we get a good look at most of the surface. Full surface mapping of all major moons is something I'm looking forward to.

I keep thinking Hyperion's got an interesting story to tell, if only someone can figure out how to get it to talk to us...

Does anyone here know if there's a consensus on the origin of Hyperion's eccentric orbit? Would a more-or-less spherical Hyperion have been pumped up into its current orbit by Titan, or is the eccentricity the result of whatever whacked it into its current odd shape?

After Titan, Iapetus, and.... is Enceladus or Pheobe your third oddest? Just curious.

http://www.planetary.org/saturn/hyperion.html

We have one close flyby of Hyperion - not too far off either, Setpember 26, 2005, altitude 1000km.

"After Titan, Iapetus, and.... is Enceladus or Pheobe your third oddest? Just curious."

Actually, I'd tie Iapetus and Enceladus for second. We now know Phoebe to be just the biggest member of a veritable cloud of small captured irregular satellites, which are probably very similar to the captured irregulars that we now know orbit Uranus and Neptune. After Hyperion, I'd probably rank the Janus/Epimetheus pair, those perpetually starcrossed -- or orbit-crossed -- lovers which are obviously the two pieces of a single moon that got cracked in two by a major impact (or perhaps into more fragments, which later re-coalesced into two rubble piles). By the way, J. and E. will carry out one of their every-4-years orbital altitude exchanges this year.

JPL seems to feel the way I do. In 1997 they prioritized Cassini's flyby targets besides Titan as follows: Enceladus, Iapetus, 2nd Enceladus flyby, Dione, Hyperion, Rhea, 3rd Enceladus flyby.

There is also a 166,000 km Hyperion flyby on June 11.

Which ought to provide slightly better than 1km resolution, if I'm doing the math right. Voyager 2's closest approach was 431,370km.

Another look at Hyperion:

http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=35559

This moon has just been a pain to get a nice pic of.

Looking at this image and Voyagers I expect this moon to have big surprises.

Guys, Gals check this out!

Not bad...

http://ciclops.lpl.arizona.edu/view.php?id=904

http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=35611

More Hyperion

Here's a update. http://photojournal.jpl.nasa.gov/catalog/PIA06623

A few new ones:

Do I see the central peak of a crater casting a shadow? And the bright traces of the crater's ruined rim at upper right? Since Hyperion's 1,543,330 km away, these "features" are near the limit of resolution - which makes them all the more fun to speculate about!

There's also a much closer one, from "only" 768,869 km. My putative Hyperion-sized crater is, conveniently enough, not visible in this view.

Gsnorgathon, yes, you do see a central peak. Compare this with the Voyager image sequence - at, for instance,

http://www.ssc.uwo.ca/geography/spacemap/hyindex1.htm

- and you can see a hill in the centre of that circular region, and its northern rim which is called Bond-Lassell Dorsum. The rest of the rim is not very clearly defined.

Also compare the 'much closer view' with the best Voyager images. The limb shape is the same but reversed left to right - this bew view is of the opposite side.

Phil

Drat! And here I thought I'd made a Great Discovery. So much for Gsnorgathon Mons... I really liked the ring of that. :@(

Phil - as a cartographer, you must know a thing or two about nomenclature; is Bond-Lasell Dorsum likely to become just plain old Bond-Lasell (since craters don't seem to get "Crater" appended to their names)? And do you suppose that big crater was created on Hyperion before or after Hyperion got smacked by whatever smacked it into its current eccentric orbit and chaotic rotation? (Or did Hyperion get smacked?)

Hi - I don't think the name has to change. The crater itself does not have a name (it wasn't recognized as a crater when the few names were assigned). This is similar to many lunar mountain ranges, with individual names.

A few new Images of Hyperion:

http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=47478

I noticed that Cassini passes fairly close to Hyperion today , at around 15:00 UT, see link below.

http://space.jpl.nasa.gov/cgi-bin/wspace?t...orbs=1&showsc=1

Here is a composite view of the images taken during the August flyby of Hyperion.

Click to view attachment

It is lower resolution than the June flyby (I also posted a composite of those images), but still better than Voyager resolution. It very conveniently fills the gap in Hyperion rotation that was missing in June.

The most prominent feature is the long curving scarp, Bond-Lassell Dorsum. Since it has a mound at its center I interpret it as the remains of a crater with a diameter about 80% of the long axis of Hyperion. Some people doubt that such large craters can be formed without destroying the target, but this is, I think, based on a misunderstanding of the physics of the cratering process. The crater is excavated by an expanding hemispherical shock wave, which loses energy as (i) some is used to eject debris, and (ii) it is spread out over a larger surface. By the time it gets to full crater size it has lost much of its disruptive power (or it wouldn't be at full crater size...) Only if the shock wave is still capable of digging a crater after it has fully traversed the target does the target get blown apart completely.

Deimos and Vesta both have craters this size, relative to their mean diameters, at their south poles. (Rapid rotators would preferentially reorient to place a giant crater at a pole).

Phil

Spelunker's paradise?

*One of the best Hyperion images yet, IMO. I wish they would/could create a "movie" of Hyperion; if not entirely from all angles (which might be impossible, considering flight path, schedules, etc.) then from as many as possible. Hyperion can look so very different from pic to pic.

What is the approximate timescale of Hyperion's chaotic rotation? Would it actually change rapidly enough to make spacecraft landings hazardous, as suggested in Anderson's short story? Are we talking weeks, years, centuries or what?

If it really _does_ change rapidly, one advantage of the chaotic rotation is that we will be able to get maps of the whole moon a lot sooner than will be the case for the other major moons (due to their polar regions being in the dark).

On an unrelated note, I kind of enjoyed the discussion in this thread regarding the ranking of the moons with regard to how interesting they are. This of course raises the question of which major moon is LEAST interesting (leaving out the tiny rocks since they are already at a disadvantage).

My vote would be for Rhea, but even Rhea has a "dark area" and those two adjacent basins. It sure isn't in the same league as Umbriel or anything like that. (Yeah. A white crater. Ya-hoo.)

The idea that Hyperion rotates chaotically comes up so often that it really does need correcting. Back in the 80s Hyperion was said to be in chaotic rotation, and a google search today turns up lots of references to those statements. But look at this paper:

Thomas, P.C., Black, G.J. and Nicholson, P.D., "Hyperion: Rotation,
Shape and Geology from Voyager Images", ICARUS 117: 128-148, 1995.

and you will see the current view. The rotation is not chaotic, it is the same type of rotation experienced by Halley's nucleus, asteroid Toutatis and (no doubt) lots of other slow rotators: a "slow long axis" mode, rotating about the long axis instead of the short one, but with rapid precession about a steeply inclined angular momentum axis. This will undoubtedly be refined with Cassini data, but if you look at the motion of the terminator in both the June and August flybys, they are quite consistent with rotation about the long axis.

Phil

*I've most often seen Hyperion's motion referred to as "tumbling." As we know, it does have a "long, looping" orbit.

Hyperion Hoopla

Is one of my favorites regarding this moon from the NASA/JPL Cassini site.

Another, rather amusing:

Does look like a face...particularly the Pringles Potato Crisps "guy."

P.S.: Saturn's most intriguing moons? Titan and Enceladus.

Thanks for the reference, Phil. Our library's web server is down for repairs right now, but I'll check it out come Monday. Sounds interesting.

And...the "Face on Hyperion"? Geez, don't anybody let Richard Hoaxland find out about it!!! He'll find some crazy way to connect it with his Super-Sixty-Sided Iapetus Death Star theory for sure. (Can someone please take away that guy's JPEG compressor before he hurts himself with it?)

[Long after the fact edit: Altered Hoaxland's name to keep Googling kooks away, here and in other posts.]

Rob:

No, give him a BIGGER one, with sharpened ends!

Bob Shaw

Hyperion has a face? I'll bet it's not as convincing as the Nose of Prometheus! Yes indeedy, check out the best Voyager image of Prometheus, and there at the north pole is a gigantic sculpture of a nose. It must be 50 km long at least. And not just any nose... it's Elvis's for sure. But the north pole is in shadow at this season, so Cassini can't check it out. Coincidence? I think not!

Phil

Yeah, we all know that Cassini himself was never a fan of Elvis - he even went so far as to call him 'nothing more than a pelvis-shaking titillater of horny loser broads'. How Cassini could argue with the life-affirming melodic declaration that is JAILHOUSE ROCK, I'll never know! DON'T STEP ON MY BLUE SUEDE SHOES, YOU AIN'T NOTHIN' BUT A HOUND DOG, A MOTHER CRIES... IN THE GHETTO

Hmm. I was not aware that a giant replica of Elvis' nose had been found on Prometheus. You learn something new every day in this forum.

This raises the question of where the rest of him has gone. Is it possible that his sideburns ended up draping over Iapetus? Could Telesto and Calypso be his detached ears? Is Hyperion a giant replica of the last cheeseburger he wolfed down? We can only wonder.

On the whole, this revelation would probably be of great interest to the Hoaxlandites, for two reasons. First, the Voyager photo of Prometheus is fuzzy enough to make JPEG tampering unnecessary, which would save them a lot of time and effort. Second, any discovery of a giant nose immediately raises the prospect of some outlandishly contrived connection with Easter Island, the details of which would likely keep them occupied for some time to come. (Everyone needs a hobby.)

Did Elvis ever visit Easter Island, perhaps during his time in the Army? If not, it should be possible to make something up. A "transdimensional gateway" would probably suffice.

Maybe I'll write this up, and submit it for peer review at the Weekly World News.

The Hoaglandites have been missing quite a few bets over the last few years anyway. Eros looks like a giant bedroom slipper; Borrelly like a bowling pin; and there are at least two heart-shaped craters on Mars and one on Eros. Nor must we forget that feature on Mars that looks exactly like a gigantic bas-relief of Kermit the Frog sitting on a branch and singing, thereby proving not only that there was intelligent life on Mars but that they worshipped Muppets.

The 'H' on Titan is the best. Someone actually believes it's artificial, because there is an H shaped lake in the Sahara

Doug

The branch-sitting Kermit proves only that the Martians could a) see into the future, loved cloth green frog-like representations, and c) loved to form mountains into whatever tickled their fancy. All evidence thus far has clearly pointed to this conclusion (such as the patch of Mars that had the winning lottery numbers for the Minnesota State Pick 5 for 4/9/2003 and of course the three-mile-high hieroglyphics spelling 'RA IS GREAT, CAN'T GET ENOUGH OF THAT COCA-COLA'). Oh yeah and the huge billboard made of light and dark sand that says 'Mars - Come for the sparkling beaches, stay for the truffles', though this proves more that the local tourism board was once quite vital!

Actually, I think that conscious entities create the details of reality as they observe them (68.27%). And ultimately it all comes down to what started it all, but if we knew that, nobody would ever do anything, and that would be dull, and I imagine whatever started it all figured that out long ago.

I had not seen that image of Kermit the Frog Planitia before, but it sure is good for a chuckle isn't it.

Keep on chucklin', chuckle-o.

Resurrecting an old thread... to post a new image of Hyperion from the Oct. 06 orbit. This is a composite of eight frames from that orbit, with some contrast stretch.

Phil

Click to view attachment

Some threads back. I pointed out a "peninsula" jutting out into the equatorial dark belt on Titan a ways east of Xanadu that really does look like the playboy bunny symbol... I've been calling it Cape Heffner ever since...!

I will probably get banned for this since it might attract kooks, but dang, it looks like some sort of microorganism in that image!

Don't feed it any caffeine, or it will be a Hyper-ion.

Ted, Ed, go to thine rooms...