Titan´s July flyby cancelled?

[danielj]

I am puzzled.I received information that Cassini will be near Titan on July 2,but in Cassini?s site,it is said that the next flyby will be only on October.What happened?
It means that the next Cassini images will be released only on October?While this,the Cassini will do nothing!?

[selden]

Daniel,

There's "near" and then there's "near".

They're describing two different types of "flyby". The one that just happened was at a distance of about 300,000 km. The one in October will be at a distance of about 1,000 km.

To see the difference, install Celestia v1.3.2pre8 and follow Cassini.

[Evil Dr Ganymede]

Today's flyby is most definitely going ahead (or has gone ahead). Though note that because of a solar conjunction (the sun's between Earth and Saturn this week) we won't be getting most of the data back from it til next week - hopefully they'll downlink some images today and tomorrow before that happens though.

[chris]

There are raw images from encounter online already. Here's an intriguing one:

http://saturn.jpl.nasa.gov/multimedia/i ... ageID=6986

It's going to be very interesting to watch tomorrow's press conference on Titan where they'll presumably unveil the processed images. We may find out for certain if Titan has oceans of liquid methane and ethane.

--Chris

[lostfisherman]

The images, uncalibrated as they are, are coming in thick an fast. I read that this most recent "flyby" was toward the Southern pole, could this be an ice cap or is it just me?

http://saturn1.jpl.nasa.gov/multimedia/ ... ageID=6964

[Matt McIrvin]

The images, uncalibrated as they are, are coming in thick an fast. I read that this most recent "flyby" was toward the Southern pole, could this be an ice cap or is it just me?

http://saturn1.jpl.nasa.gov/multimedia/ ... ageID=6964

It's more likely a cloud. Astronomers have been seeing bright clouds near the south pole of Titan for some time now. It's summer in that hemisphere and the south pole has been in continuous sunlight for several years, which might have something to do with it.

Those raw pictures are tantalizing. I've been messing with them in GIMP trying to pick out details-- some of them have barely visible, faint linear marks that look like rivers or cracks or something... even with this IR/polarizer filter, it's hard to see through all that smog. I'm sure that more diligent image processors than I will be hard at work on them. I suppose you'd want to start by subtracting or dividing out a synthetic image of a featureless sphere, to make the background even in brightness across the image; that's part of how this team managed to get surface details out of old Voyager visible-light pictures:

http://www.lpl.arizona.edu/~jrich/vgertitan.html

[Evil Dr Ganymede]

Well, I'm stumped. I'm a planetary geologist who has stared long and hard at images of planets and I don't have a bloody clue what I'm looking at in those images - are we seeing clouds or surface features? I thought I saw a dark feature that looked a bit like a Marineris style rift valley in one of the images... And why are they so blurry - is the atmosphere still interfering with the view at these wavelengths?

At 300,000 km range the images should be a lot sharper and more hi-res than that - I mean, this image of Ganymede was taken by Galileo at a distance of over 600,000 km...

EDIT: From rumours I've been hearing, it seems that the IR camera is indeed not as effective as penetrating the atmosphere as they hoped (good thing they bought along a radar imager, to be used later!) - there's too much smog in the way. However, there is apparently going to be a press conference/release in the next few days that will reveal some very interesting stuff...

[Matt McIrvin]

This is the most interesting one of the lot:

http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS02/N00006513.jpg

Rivers? Canyons? Europan cracks? Canals built by intellects vast and cool and unsympathetic? Anyone's guess, I suppose, but you can see more of them if you put a heavy unsharp mask on the image with a wide radius.

[Evil Dr Ganymede]

This is the most interesting one of the lot:

http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS02/N00006513.jpg

Rivers? Canyons? Europan cracks? Canals built by intellects vast and cool and unsympathetic? Anyone's guess, I suppose, but you can see more of them if you put a heavy unsharp mask on the image with a wide radius.

The thing to the right of the dark patch in the bottom left is what I thought looked like a rift valley. Though I'm hoping it's a lake of some sort.

Frankly, if we get confirmation that there is liquid of some sort on Titan's surface then I'll be very excited indeed - largely because it means the post-doc I'm doing actually has a point

[Guest]

Hi All,

My, danielj does start some interesting threads these days... .

Intrigued by what lostfisherman said about an ice cap and Evil Dr G said about clouds, I searched through yesterday's raw images of Titan for the most contrasty ones, and had a go at upping contrast.

Then I realised that there are 'triplets' in these photos, so I combined them into colour taking each as an RGB component. Have a go yourself! I assume the lowest contrast are the bluest, but you'll find they might not be in numerical order. Of course, not being calibrated, and not knowing what filters were used for each, the colours are very false, but you really start to see very fixed features from one triplet to the next.

Triplets I've found are:

1. N00006513, N00006514, N00006515 - these are for the one that Matt McIrvin recomended as most interesting. At lower left is the very dark 'lying H' feature picked out in the ESO photos. You can easily find this on the new map at far right. This feature is on Titan's Equator. The 'Mariner valley' feature (just lower left of centre) Evil Dr Ganymede notice is at about 30°S. To right, you can see more patches, and also some things that are thin and straggly.

2. N00006569, N00006570, N00006574 - The 'lying H' has now rolled off to the limb (lower left), and the same patches and thin and straggly features are better seen. These (I think) are within the (highland?) area called Xanadu. I wonder if we're looking at rifts cutting through a highland area like Aphrodite on Venus? Then at the top, we have a large dark feature, and just the edge of the 'cloud'/'ice-cap' feature shown in lostfisherman's link. But, this is better shown in the third triplet...

3. N00006550, N00006551, N00006552 - This is actually my favourite! The 'cloud'/ice-cap' feature is more included at right, but look between it and the hook-end of the dark area at the lower right! Between the end of the large dark area and the collection of bright splodges is a winding line - it's the most river-like thing I've seen off Earth.

It's difficult to tell exactly but after following Cassini in Celestia it looks like these photos are taken several hours apart. The bright splodges do not seem to change shape from picture to picture though. One thing is clear, the splodges are right at the south pole. I wonder if these slodges are some kind of white ethane snow on mountains, and the snow is melting into an ethane river, flowing into a sea... Sorry, Evil Dr Ganymede, I favour lostfisherman's interpretation!

I think all these photos are in infra-red. Clouds actually appear black in IR pictures of Earth - they trap heat and have cold tops. The weather forecasts you see on TV use IR negatives to make the clouds appear white!

So, another thing I'm wondering is that there seem to be virtually no clouds in Titan's atmosphere - it's all just smog. If that's the case, then maybe Huygens is going to get very good views on the way down!

Note these images have segments of the limb of Titan in lower left and right. I rotate the images 90° clockwise so that Titan is 'lit' from the left - it'll help orient you in Celestia for how Cassini saw Titan during yesterday's flyby.

This complete speculation brought to you by ...

Spiff.

[Spaceman Spiff]

Argh! Another duff login!

Spiff.

[Spaceman Spiff]

I what I thought was Xanadu isn't... It's a different area on the side facing Saturn. Xanadu is the bright area seen with Hubble, but is on the far side from Saturn.

Hmm, is Xanadu an official name yet?

Spiff.

[Ynjevi]

Hmm, is Xanadu an official name yet?

No... First time I heard the name was when Cassini first time mapped the moon in spring. It'll probably take a few years before the IAU officially names the surface features on Titan.

---

BTW, don't forget next Cassini news briefing at 10:00 a.m. PDT (17:00 p.m. UT).

[Matt McIrvin]

I thought Xanadu was more or less centered on the leading hemisphere, the direction of Titan's motion around Saturn.

One thing that the recent Cassini global map (and those heavily munged old Voyager pictures that were recently revealed to contain more surface information than previously believed) have helped me realize is that the 1990s Hubble maps also actually show more real detail than I originally thought they did. It was hard to compare the Hubble with the ESO/VLT or Keck maps because their areas of best coverage were different. But Hubble actually picked up part of the Lying H that cuts into Xanadu on the northeast, and the long eastern extension of Xanadu south of the equator leads into the bright patch south of Lying H that VLT saw. Also, what the Hubble astronomers called "the Sickle" is part of the long arc- or ring-shaped feature connected to the east of Dragon's Head.

[symaski62]

je vois titan ? la mer avec brille.... soleil.

je sais MER!!!!!!!!! titan

merci.....

[Evil Dr Ganymede]

Well, even though I want them to be there, I was skeptical that there'd be oceans there (just because something is possible doesn't mean it necessarily exists after all), but that opinion is getting rapidly eroded with these images... but we still don't have any proof that the dark things are bodies of liquid. So I'll be skeptical to the last!

[lostfisherman]

It looks like Matt McIrvins thoughts were correct about Titans polar region, they are clouds. They are described as a "cloud field", and are thought by the ciclops website to be composed of methane. Over a period of 5 hours you can make out some change in their appearance here.
(Pick a resolution)
http://ciclops.lpl.arizona.edu/view.php?id=250

There are some other Titan mosaics here, very impressive!
http://ciclops.lpl.arizona.edu/ir_index.php?id=6

I wonder what software they have because those pictures are far better than those I saw on the raw imaging site, maybe I need more practice on GIMP

[Evil Dr Ganymede]

I strongly suspect that they used ISIS (or VICAR?) - USGS planetary imaging software (VICAR is JPL, IIRC, but I don't know if it's still in use)

[symaski62]

[Evil Dr Ganymede]

symaski62 - is that image is made by combining the three filters found here? Have you done something to the images? Because when I combine them they don't look anything like that (the green image is very deteriorated in quality)