New Iapetian image series Options

[ugordan]

No, it really is November 2005. The January 2006 encounter was more distant, in fact I've got the entire sequence assembled into an image and an animation. It can be found here.
The distant approach images from November and January are pretty similar, but if you look closer the January images show more of the Snowman in sunlight.

[Rob Pinnegar]

That November 2005 image is interesting for another reason. Look at the 8 o'clock position on Iapetus' limb. You can see one of the large basins in profile. This one isn't normally as easy to pick out as some of the others.

It looks to me like the upcoming April 15th shots of Iapetus might have a chance of catching the big Roncevaux Terra basin in a similar profile.

[TritonAntares]

Hi,
here some infos about the upcoming far-encounter:

april 15 -> 2 clear und 19 color images
april 17 -> 1 clear, 6 color and 3 WAC-images
april 18 -> 2 clear, 34 color and 2 WAC-images
april 21 -> 2 clear, 6 color and 2 WAC-images

Resolution (NAC) will be about 14 km/pxl.

Bye.

[TritonAntares]

So,
NASA's Solar System Simulator shows this:



Bye.

[ngunn]

More food, Iapetus hounds:
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=107531

[Rob Pinnegar]

For fans of Roncevaux Terra, the first set of Iapetus images from this very distant encounter are now up.

As I'd hoped, it looks as if the big trailing-side basin can be seen in profile as a "flat spot" on the moon's limb at about the 4:00 position. There seems to be a central peak visible.

There are also a couple of dark spots visible that may not have been seen before. And (once again) we get a tantalizingly fuzzy look at the Snowman crater system.

No sign of the bellyband on the moon's limb -- but 2.2 million kilometres is very long-range -- it may just not be that high at that particular point. We'll find out in a few months.

[ugordan]

More food, Iapetus hounds

Wow. If there's one Iapetus image that's radically different from all previous Cassini images of this moon, it's this one.

[TritonAntares]

Ahh,
there they are...

Here two takeouts, ~3x enlarged:

Distance: 2,258,272 km
Filters: BL1 and CL2


Distance: 2,258,232 km
Filters: UV1 and CL2

The trailing-side basin must have been a really big hit.
Interesting is also huge step/rim in the north polar region.
Is there a hidden basin? A tectonic fracture? Or what else?
Curious to see the moons almost bright side,
doesn't look like Iapetus...

Bye.

[Rob Pinnegar]

Interesting is also huge step/rim in the north polar region.
Is there a hidden basin? A tectonic fracture? Or what else?

I noticed that too. I think it's probably a topographic feature that looks brighter than the surrounding area because it is tilted towards the Sun. We saw this kind of thing in the south polar region last year.

[TritonAntares]

I noticed that too. I think it's probably a topographic feature that looks brighter than the surrounding area because it is tilted towards the Sun.
We saw this kind of thing in the south polar region last year.

I remember such a structure from this saturnshine image:

Date: 2004-10-22
Distance: ~1.6 million km

Could be the same or a different one...
I'm not quite sure, wasn't this region observed during the Newyear's flyby 2005?
There were some saturnshine images...

[Phil Stooke]

This is a composite of four of the new images. I recall that stereo viewing of Voyager images of this northern bright area revealed apparently tectonic lineaments in this area - probably one of the old NASA TM reports on the geology and geophysics program.

Phil

[ngunn]

If I'm not mistaken all these features show up very well on the Iapetus mosaic map on CiCLOPS. The big basin complex lower centre at about longitude 320 and the ones up north at about longitude 0. If I'm totally wrong please tell me gently.

[TritonAntares]

Any idea for these structures? Real or artificial image errors?

[alan]

Iapetus is a relatively small part of the image thus the image is more likey to get overstretched by the algorithm they are using. Thats what appears to have happened to the bright patches which are located in the area which is receiving the maximum sunlight.

[Rob Pinnegar]

Thanks for the composite, Phil.

In addition to the poorly known parts of Iapetus that are near its limb on this sequence of photos, we're also getting a much better look at some topography on the terminator. There are a couple of big craters on the northern terminator that have been hinted at in previous images but for one reason or another just haven't been very visible before now.

Over the course of the next few days these craters will become more visible. Cassini seems to be "chasing" Iapetus for the time being -- it will maintain about this distance for the next week or so. Perfect time for shooting stereo pairs!