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Posted by: AlexBlackwell Oct 4 2006, 10:52 PM

The mission description document is now online (http://saturn.jpl.nasa.gov/multimedia/products/pdfs/20061009_titan_mission_description.pdf).

Posted by: volcanopele Oct 12 2006, 10:53 PM

Two cutouts from Monday's T19 Titan flyby show more lakes in the north polar region. In "http://photojournal.jpl.nasa.gov/catalog/PIA01943", methane and ethane have filled eroded river valleys, creating lakes that resemble Lake Powell and Lake Mead in the Southwest United States. In the second released cutout, http://photojournal.jpl.nasa.gov/catalog/PIA01942, several lakes appear to be have drainage channels, allowing methane from through the region to flow into the two large lakes at the top of the strip.

Posted by: JRehling Oct 12 2006, 11:36 PM

Before I finished reading your sentence, I clicked on that link, and thought, "Hey, that's Lake Powell!"

Posted by: volcanopele Oct 13 2006, 12:06 AM

In the "Titan's Great Lakes?" image, you can see channels that discharge into large lakes at the top of the frame. I've highlighted some of the channels in the attachment below, in red. I've also highlight the flood plain of the main channel:

Posted by: tty Oct 13 2006, 06:16 AM

Here on Earth coastlines looking like that would be interpreted as being the result of water recently invading river valley systems and not yet having had time to modify the morphology.
Lake Mead or Lake Powell as you say, or a transgressive "Ria" coast like parts of England or Ireland, or the Carolinas inside the sand barrier.
Is it methane flooding season on Titan?

tty

Posted by: Thorsten Oct 13 2006, 12:11 PM

Wow! The cutouts from this radar pass are not only scientifically interesting, but also of incredible scenic beauty!
(At the risk of doing something quite silly, I have attached an artistic interpretation of one of these north polar channels, meandering over miles and miles through a hilly landscape with deeply cut valleys or wide floodplains and finally draining into a good-sized lake. (The human observer to the left is purely speculative)).

Posted by: ugordan Oct 13 2006, 12:16 PM

Isn't he also Chinese?

Posted by: climber Oct 13 2006, 12:37 PM

I don't know how "others" behave but, I personaly need to see a representation of what spacecrafts "see", either in visible light or IR or UV ..or Radar. Some people here are VERY good to create pictures from those spacecrafts data, some put some poetry inside those pictures, some show Earth scenary that remind them what they see on other planets, and some others post artistics representations (as you say). All deserve the same THANKS for helping our brains to get a sense of the reality, even if only a sense. So, thank you Thorsten, you know you're not SO far in the representation of what Titan looks like.

Posted by: ngunn Oct 13 2006, 02:00 PM

I am still seeing details within the darkest parts of these images. Could somebody (volcanopele?) please indicate the outlines of the areas you think are actually standing liquid surfaces at the time of imaging?

Thorsten there is nothing at all silly about your line drawing - keep them coming.

Posted by: ugordan Oct 13 2006, 02:16 PM

It's plain to see which areas in the RADAR images are much darker. The fact that we're seeing details in those regions as well could simply indicate the lakes are shallow so we actually get a radar reflection off the bottom. Remember the radar beam penetrates through liquids fairly well, only a substantially deep lake would give back very little echo -- probably several meters in depth.

Posted by: Thorsten Oct 13 2006, 03:01 PM

A similar conclusion was reached in the case of the “Kissing Lakes” (PIA08740).
Lighter patches in one of the lakes were considered as an indication that this lake is shallower, with radar signals penetrating through the liquid and reflecting off the lakebed.

http://www.newscientistspace.com/article.ns?id=dn10163&feedId=online-news_rss20

Posted by: volcanopele Oct 13 2006, 03:06 PM

Very nice drawing Thorsten! Mind if I pass this along to our local Titan group?

The RADAR team is interpreting variations within the lakes to indicate that they are sensing the lake bottoms in some places. This would indicate that these lakes are quite shallow, maybe on the order of a few 10s of meters.

Posted by: ngunn Oct 13 2006, 03:08 PM

Yes I've been keeping up with the posts on this, and it's still far from obvious to me at what point on the images you actually get your feet wet.

Posted by: volcanopele Oct 13 2006, 03:31 PM

Here are the outlines of the lakes PIA01942

Posted by: MahFL Oct 13 2006, 05:57 PM

Are they 100 % certain they actually have wet lakes, or just dry lake beds ?

Posted by: volcanopele Oct 13 2006, 06:16 PM

No they are not 100% certain. We know that the lake beds contain a radar absorbing material, which have some sort of internal structure. Now that doesn't conclusively mean shallow, liquid methane, but given the morphology and associated structures, this appears to be the most reasonable hypothesis.

Posted by: ngunn Oct 13 2006, 10:18 PM

Thanks for the lake bounday map and other interesting comments. I agree that the image suggests two different types of surface with a boundary more or less as drawn. I particularly like the 'river estuary' but I'm not so sure about the two isolated lake patches on the right. However there is a heck of a lot of detail within the 'lake' including continuations of apparent drainage features. Doesn't look deep enough to sail a boat to me.

I agree that lakes are plausible, even likely, and that they could look like this, but I have a nagging doubt that the same appearance could be produced in other ways. I just want the case nailed down - solid evidence of liquid, so to speak, and I think we're still waiting (not what you'd guess from the press releases).

Posted by: Sunspot Oct 13 2006, 11:09 PM

Such As?

You cant possibly think that the features in this image could be formed by anything other than a moving liquid?

http://photojournal.jpl.nasa.gov/jpegMod/PIA01942_modest.jpg

Posted by: antipode Oct 13 2006, 11:37 PM

Note the 'groove' that is the radar dark continuation of the major north south drainage channel well into what appears to the the lake proper? this feature reminds me of the Warburton and Kalaweerina 'grooves' that are obvious on isobaths on the map of Lake Eyre, Australia's largest lake. The lake is normally largely dry, but after big rains it can fill mainly through the aforementioned rivers, which have caut 'grooves' into the lakebed. Even when the surrounding lakebed is dry, the grooves can hold water.

I've include a low res map, north at the bottom. The grooves are clear at the bottom of the map as major deflections in the isobaths. The lake is around 150km north to south.

It looks to me like that lake (on Titan!) might be substantially larger when fully flooded.

P

Posted by: ngunn Oct 14 2006, 01:50 PM

Indeed not, it obviously was formed that way. I think evidence for moving liquid is overwhelming at the Huygens landing site too. The question is when? Now? Last week? Last year? A hundred (or a million) years ago? It's entirely possible that we are looking at real rippling lakes and actively flowing streams. If it turns out to be so no-one will be happier than me - but that is exactly the problem. The history of astronomy is littered with discredited theories born of wishful thinking, especially in the matter of liquids. So until it's nailed I'll continue to play devil's advocate.

Posted by: Thorsten Oct 15 2006, 08:52 AM

Just a little joke! As CBS informed us in June that Chinese astronauts will land on Dione in 2024, I thought they might as well do a stopover on Titan! I would have liked to add a NASA Titan-Montgolfiere but the Chinese will obviously be faster!

http://www.unmannedspaceflight.com/index.php?showtopic=1216&st=330

Posted by: Thorsten Oct 15 2006, 08:56 AM

I would be honored, volcanopele! (Sorry for the late reply)!

Below are two drawings, inspired by the radar image “Titans Great Lakes (PIA01942)”. The one to the left deals with the idea that the long dark channel at the left of PIA01942 is surrounded by extensive flood plains. The second one shows the bright landforms at the top protruding into the “lake” that could be the eroded hilltops of flooded landforms. (As the speech balloons indicate I am working in my free time on a little comic strip in which Titan plays a small but significant role.)

Posted by: mchan Oct 15 2006, 09:34 PM

I think he or she is Titanese. At lease that is what the Chinese characters say.

Posted by: Gsnorgathon Oct 16 2006, 02:52 AM

So - can those in the know point those of us who are in the don't-know to discussions of how far Cassini's radar penetrates various hypothetical Titanese fluids? I know that any such discussion is fraught with uncertainty, but I'd like to get an idea, at least, as to how much uncertainty there is about just how deep we might be seeing below the surface of these lakes.

Posted by: volcanopele Oct 16 2006, 03:04 AM

IIRC, it's on the order of 25-50 meters in liquid methane.

Posted by: ugordan Oct 16 2006, 07:12 AM

Of course, that would probably assume pure liquid methane. Any contaminants will probably reduce the figure. It's not totally unreasonable to assume a lot of organic stuff is dissolved/dispersed in the lakes.

Posted by: tty Oct 16 2006, 06:25 PM

I wonder if most organics would really have that much effect on radar penetration. What would really stop radar is ionic compounds that make the liquid electrically conducting.

tty

Posted by: ugordan Oct 16 2006, 06:43 PM

True, but what about fine, dusty particles mixed in the lakes? Not dissolved but solid particles? There would have to be a major concentration of those dispersed in the methane to affect radar, but it's a thought...

Posted by: peter59 Oct 9 2007, 06:30 PM

See more, enjoy more !!!

Swath T19

and Targeted Distant Look (T19)

Posted by: peter59 Oct 10 2007, 04:32 AM

and T20 Targeted Distant Look (NW Xanadu, Tortola Facula)

Posted by: Juramike Oct 10 2007, 04:42 AM

Very cool!

Any idea of the coordinates of the distant targeted look?

-Mike

Posted by: peter59 Oct 10 2007, 07:05 PM

I can't open radar images greather than 100 MB (256 pixels/deg). Volcanopele,
can you update your http://pirlwww.lpl.arizona.edu/~perry/RADAR/ page ?

Posted by: volcanopele Oct 10 2007, 08:59 PM

Sure, but it will have to wait until I get back to Tucson this coming weekend.