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T16 RADAR SAR Swath, Land o' lakes
volcanopele
post Jul 24 2006, 09:33 PM
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Much to my surprise, a chunk of the T16 Sar swath as been released:

http://photojournal.jpl.nasa.gov/catalog/PIA08630

An abundance of lakes can been seen. Some appear to be crater lakes (or sinkholes), like the lake at far left on the top cutout. That lake appears similar to Crater Lake in Oregon, with a little island in the middle (you can kinda see the attenuation of the signal surrounding the island as the methane gets deeper). Some lakes appear quite distinctive from the surrounding terrain, like the features on the right part of the bottom cutout.


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Guest_AlexBlackwell_*
post Jul 24 2006, 09:39 PM
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QUOTE (volcanopele @ Jul 24 2006, 11:33 AM) *
Much to my surprise, a chunk of the T16 Sar swath as been released:

http://photojournal.jpl.nasa.gov/catalog/PIA08630

An abundance of lakes can been seen

I know Jason and some of the other Yahoo! planetary_sciences alumni will remember the following wager that someone made with a few of us just over two years ago:

"I have wagered $20 that Titan's surface lacks Cassini-resolvable bodies of liquid."
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volcanopele
post Jul 24 2006, 09:42 PM
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Was that me? I forget now laugh.gif

But to be honest, they didn't find "bodies of liquid", they found features whose morphology is best explained by lakes... Though finding features consistent dry lake beds (with presumably large pebbles) next to smooth terrain in the same basins, would seem to clinch it (for me anyway).


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Guest_AlexBlackwell_*
post Jul 24 2006, 09:45 PM
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QUOTE (volcanopele @ Jul 24 2006, 11:42 AM) *
Was that me? I forget now laugh.gif

No, it was someone else. Both you and I took the bet :-) See Messages #14584 and #15285 in the old group.
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ugordan
post Jul 24 2006, 09:47 PM
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Wow, this is it!
Finally here we have a body we can (almost certainly) say has ponds of liquid, other than our fair planet!
Theorizing lakes exist is one thing, actually seeing them is another. Maybe I'm making too much of this, but this feels to me as equally important as seeing Enceladean plumes clearly for the first time. We're at the mid-point of the primary mission and Titan just became a little more familiar place.

Hats off to the RADAR team for a swift release!


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David
post Jul 24 2006, 09:48 PM
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This is fantastic stuff. I'd be even happier if I could see one of the surface channels discharging into a lake so as to remove all doubt...
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djellison
post Jul 24 2006, 09:59 PM
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The largest body in the top right actually has some channels around its periphery - within the confines of what one might call the 'lake' but between that edge and the darkest part of the lake in the middle - you can just see them

Doug
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The Messenger
post Jul 24 2006, 10:02 PM
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Can it be stated with certainty that these are not liquid water lakes, or perhaps frozen water lakes?

18 months ago everyone was quit certain that there could not be liquid water geysers near the south pole of Enceladus. Do we have enough spectral/temperature data to say this is not water near the north pole of Titan?
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volcanopele
post Jul 24 2006, 10:20 PM
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They do get radiometry at the same time they acquire SAR coverage. If these were lakes of liquid water, they would of course show up as VERY warm areas compared to what they should be.

While I would dismiss the notion that these are water lakes until we hear otherwise from the RADAR team, I do note that some of the lake depressions look an awful lot like Ionian calderas.


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belleraphon1
post Jul 24 2006, 11:18 PM
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To quote Emily from her Planetary Society blog

"WOO HOO" ...... indeed!!!!!!!!!!!!!

But what will it take to confirm that what we see are indeed liquid lakes? Should we look for evaporation over time? What are the radiometric and scatterometry characteristics that could nail this down (are there any)?

Agree with Jason that these have the visible character of some of the calderas on Io.

How VERY COOL (pun intended)!!!!!!!!

Craig
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Rob Pinnegar
post Jul 24 2006, 11:31 PM
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Okay. Let's assume that these are lakes.

There are a bunch of them near the north pole but not many at the south pole; just Ontario Lacus, which, last I heard, could just be mudflats at the present time. Making a further assumption that this isn't a coincidence, here's some wild speculation:

(1) Does this mean these lakes are seasonal? If they are seasonal, the northern-hemisphere lakes would have to start to evaporate as we get closer to ring-plane crossing -- *IF* sunlight at Saturn packs enough energy to evaporate the lakes (I have no idea whether this is possible).

(2) The methane would presumably have to transfer from the northern to the southern hemisphere. So will we perhaps see a "rainy season" starting as we get closer to 2009?

I guess that any seasonality of Titanian lakes could also involve groundwater (groundmethane?) flow -- maybe no rainy season required.

Don't know if there's anyone out there who specializes in both planetary science and hydrology, but, if so, they're gonna love this.
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belleraphon1
post Jul 24 2006, 11:50 PM
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Agree here with Rob...

Close up monitoring of the seasonal changes is paramount. Will methane follow the dark..... evaporate in the sun and unleash brief methane monsoons at the lower latitudes until a new
equilibirum is reached at the southern pole as it retreats into a winter darkness...... ??????

This really speaks to an extended CASSINI mission as a precursor to future Titan missions.

Craig
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Bjorn Jonsson
post Jul 25 2006, 12:26 AM
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Now Titan is even more interesting than before, an extended mission even more important than before and as before, almost too many interesting targets to explore at Saturn. And probably at least 15-20 years until a new mission gets launched towards Saturn.

Will the northern lakes disappear and if so, when? Will lakes form near the south pole when it recedes into darkness and if so, when?

Hopefully Cassini lasts years beyond its primary mission, enabling it to observe seasonal changes (Titan and Saturn's blue northern hemisphere).
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Decepticon
post Jul 25 2006, 01:00 AM
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Does this radar swath go over the north pole?

I'm not sure what area was imaged exactly.



As for those lake like features...... WOOOO HOOO!! laugh.gif biggrin.gif
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Guest_AlexBlackwell_*
post Jul 25 2006, 01:23 AM
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QUOTE (belleraphon1 @ Jul 24 2006, 01:18 PM) *
But what will it take to confirm that what we see are indeed liquid lakes?

If by "confirm" you mean a point at which everyone unequivocally accepts a "liquid lakes" explanation for these particular RADAR data, then probably not until a probe actually lands in one, if then. In other words, I'm sure that up until that point there will be holdouts who will offer, for example, heuristic plausibility arguments positing alternative explanations.
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