Titan's changing lakes Options

[ngunn]

Today's big news?
http://ciclops.org/view/5471/CASSINI_FINDS...ILL_TITAN_LAKES

Changes in the south polar region were announced late last year. Is there more to this story now??

[ngunn]

That's brilliant, thanks VP.

[Jason W Barnes]

I actually much prefer that these press releases coincide with actual scientific papers; it increases the signal-to-noise. Any damned idiot can put out a press release, but without a peer-reviewed paper to back it up it's just gum-flapping. This is the first time that this discovery has been announced. You here of the cognescenti know of it from Dr. Turtle's DPS talk, but this is the first public release.

The ISS team did this one right, and by the book, so don't give them crap for it!

- VIMS Jason

[ngunn]

The ISS team did this one right, and by the book, so don't give them crap for it!

No-one's doing that - certainly not me. I'm 100 percent delighted with what they (and all the other instrument teams) do. The images and map associated with that release are new to me. If they were posted here before, I missed them. Until now I didn't know exactly where the newly 'flooded playa' was, and I found the comments in the article most interesting.

Not so long ago there were people here (not the mission scientists) saying that Titan doesn't receive enough solar energy to empty and fill the lakes on a seasonal basis. I'm hoping 2009 brings us more, and that this is just the beginning of Cassini's record of Titan's surface changing with the seasons.

While you're on the line - can you shed any more light on the question of using the ISS polarisers to look for sky reflections in the lakes? There probably are reasons why it isn't worth trying but I can't discover them.

[Jason W Barnes]

While you're on the line - can you shed any more light on the question of using the ISS polarisers to look for sky reflections in the lakes? There probably are reasons why it isn't worth trying but I can't discover them.

Well, since the lakes are at the poles the incidence angle is always going to be 70 degrees or higher. Therefore to see a specular reflection, you'll need to look with emission angle of 70 degrees or higher as well. As you know from processing the ISS data, the empirical atmospheric correction that they do does not produce reliable surface photometry this close to the limb. Look at Mezzoramia in the Turtle et al. paper -- the brightness looks quite different between these two flybys, when there's every reason to think that it hasn't actually changed at all.

Another reason is that you'd need a very specialized encounter geometry in order to be in position to see the specular reflection. I can't speak for ISS. But as for VIMS, we've made the decision that if we were in such a geometry, we'd rather be looking straight down at the ground with 0 emission angle, as that would mean new territory at fine resolution.

This type of observation may have been rendered moot by the T49 RADAR altimetry pass -- we'll have to wait until that's been released to find out. Hope this helps,

- VIMS Jason

[ngunn]

That is indeed most helpful. Although I'm still not clear why the direction of the sun should be a constraint if one is only looking for a reflection of the hazy sky, I can well appreciate how the other difficulties might mount up.

What is the RADAR turning up I wonder? Like many others I await that too with eager anticipation.

Patience is needed there I know, but the upcoming flyby will provide plenty of excitement in near-ish real time. Seatbelts fastened, a quick wave at the lake and in we go!

[rlorenz]

What is the RADAR turning up I wonder? Like many others I await that too with eager anticipation.

Patience is needed there I know

LPSC abstracts will be out soon - there will be something for you there