Cassini at Hyperion

Take a look at the false-color image of Hyperion at


http://saturn.jpl.nasa.gov/multimedi...m?imageID=1762

Note the bright, obliquely-angled surfaces forming a tilted, elongated
'C' shape. Does this look like an artifact of the image processing? A
partial rim of a degraded old super-crater? The longer I look at it,
the more puzzling it is.

"Monte Davis" wrote in message
...

Take a look at the false-color image of Hyperion at



http://saturn.jpl.nasa.gov/multimedi...m?imageID=1762

Note the bright, obliquely-angled surfaces forming a tilted, elongated
'C' shape. Does this look like an artifact of the image processing? A
partial rim of a degraded old super-crater? The longer I look at it,
the more puzzling it is.

The fact that there are few impacts visible on the walls of the "crater" is
really, really strange. That implies that the walls are young, but the
central portion has an appearance similar to the rest of the surface. If
it's a crater, how could the floor be old? If it's a degraded crater, what
is the mechanism of degradation that allows walls with such a young
appearance?

It looks something like a slump structure of some kind -- but Hyperion is so
small that I'm hard put to imagine the gravitational mechanics of any slump.

I'll look for images of the other side of the moon. It's remotely possible
that this is a "contrecoup" feature, generated by a impact on the far side
that blew out a ring on the side we are viewing here. But it's profoundly
unlikely that the "floor" would have settled back into the ring with so
little disturbance.

Interesting mystery.


Jim McCauley

"Jim McCauley" wrote:

Hyperion is so
small that I'm hard put to imagine the gravitational mechanics of any slump.

Yup. When you don't have the, uhh, global simplification of gravity
strong enough to pull things into a sphere, all sorts of one-of-a-kind
weirdness are likely to ensue.

Jim McCauley wrote:
"Monte Davis" wrote in message
...

Take a look at the false-color image of Hyperion at



http://saturn.jpl.nasa.gov/multimedi...m?imageID=1762

Note the bright, obliquely-angled surfaces forming a tilted, elongated
'C' shape. Does this look like an artifact of the image processing? A
partial rim of a degraded old super-crater? The longer I look at it,
the more puzzling it is.

The fact that there are few impacts visible on the walls of the "crater" is
really, really strange. That implies that the walls are young, but the
central portion has an appearance similar to the rest of the surface. If
it's a crater, how could the floor be old? If it's a degraded crater, what
is the mechanism of degradation that allows walls with such a young
appearance?

It looks something like a slump structure of some kind -- but Hyperion is so
small that I'm hard put to imagine the gravitational mechanics of any slump.

I'll look for images of the other side of the moon. It's remotely possible
that this is a "contrecoup" feature, generated by a impact on the far side
that blew out a ring on the side we are viewing here. But it's profoundly
unlikely that the "floor" would have settled back into the ring with so
little disturbance.

Interesting mystery.


For some reason, my previous reply did not get posted. The Feature you
are talking about is the left side of what appears in the Voyager pics
as a heart(valentine)-shaped ridge (scarp?). The right side is beyond
the terminator and continues over the limb as seen in the recent
Cassini pics. Just below the "V" of the valentine is a group of 4 large
craters that are visible in the Voyager pics, too.

The more I look at the new pics, the odder Hyperion seems. Part of it
is that we're not used to the physics of this size-range of bodies.
Gravity does still work here, don't worry (look closely at that
scarp/ridge, and you can see in several places the fan-shaped
signitures of landslides). It's getting pretty obvious that something
catastrophic has occured in the Saturian system in the relatively
recent past. My feeling is that a large moon was struck by another
large body, perhaps in the final stage of the Formation Era. Hyperion
was left as the largest chunk with a hell of a lot of debris scattered
all through Saturnian orbit. Still leaves a lot of questions, though.

wrote:


The more I look at the new pics, the odder Hyperion seems. Part of it
is that we're not used to the physics of this size-range of bodies.
Gravity does still work here, don't worry (look closely at that
scarp/ridge, and you can see in several places the fan-shaped
signitures of landslides). It's getting pretty obvious that something
catastrophic has occured in the Saturian system in the relatively
recent past. My feeling is that a large moon was struck by another
large body, perhaps in the final stage of the Formation Era. Hyperion
was left as the largest chunk with a hell of a lot of debris scattered
all through Saturnian orbit. Still leaves a lot of questions, though.



Is what we are thinking is some sort of slump feature actually the
object that struck Hyperion? If the collision was at very low velocity,
and both Hyperion and what hit it are more loose conglomerations of
material held together by gravity rather than solid bodies, then a
object hitting it may just make a dent in its surface and end up
deposited on the bottom of the dent in a distorted form. The thing in
the crater may be the back side of the impacting object in a fairly
undisturbed (if flattened) state.

Pat