[X] My Assistant

[Rob Pinnegar]

According to the schedule on the main website, Cassini is gearing up for the "petal rotation" part of its tour. Consequently, it will be crossing the orbit of Iapetus several times between now and next spring.

Sadly, there are no close fly-bys (or should that be flys-by?) of Iapetus during this period, or in the subsequent parts of the tour between now and the close flyby scheduled for September 2007. However, just looking at some animations of the Cassini tour, it looks as if Cassini might get within a million kilometres of Iapetus once or twice during that period. Of course, Iapetus' orbital inclination to Saturn's equator complicates this, so it's hard to tell.

For those of you who have the software to do the calculations: What are the closest distant flybys of Iapetus between now and September 2007? Will any parts of Iapetus be seen at higher resolution than previously?

Also, what are the odds of a second Iapetus close flyby during the extended mission? I guess it's a bit problematical due to orbital-mechanical considerations and the fact that it would take up a lot of Cassini's time. However, I vaguely remember someone saying, a couple of months back, that it was under consideration.

[Decepticon]

For some reason, the big impact basin visible in Ted's picture (circled here in red) doesn't show up in Steve Albers' map of Iapteus. The large crater in the southern lighter terrain isn't there either.

Is the map incorrect, or am I looking in the wrong places? 

This has been driving me nuts. I think your right. This crater is partly hidden from other impacts.

If we are right the crater is over in this area.

[Rob Pinnegar]

I believe that the impact basin from Ted's image is the one that can be seen in the lower-left part of the right-hand side Iapetus image from the above post. (One of the red lines terminates right in the middle of this basin.)

Its northernmost extent is almost exactly on the equatorial belt. It's not as well defined as the other two basins in Cassini Regio. In fact you can see it best in the above thread by looking at Steve Albers' map WITHOUT enlarging it -- that's my experience at least.

I still can't see this purported 850-km basin (which has been mentioned in other places as well, not just here), which should be over 1.5 times the diameter of the big basin from the above image. It must be very old and beat up to be so poorly defined. Either that or I'm setting a new world record for obliviousness. (It wouldn't be the first time.)

[tedstryk]

While working on some of the new Cassini images, I admit that I have been frustrated, largely due to the fact that I am so used to 8-bit (or worse) imagery. So to make myself feel better, I decided to finish up my Voyager 2 Iapetus flyby sequence. Here is a super-resolution series using the best 7 shots from Voyager 2 (each consisting of 9 images for grayscale and OGV color). Some of them had good color data, for some, particularly the more distant shots, smeared color data had to be used, giving a poorer result. I know Cassini has taken better images, but I still think that it is really a pretty sequence. Still a bit of work to do on the color - the quality of raw data varies so much that it is hard to balance in some of the images.