[X] My Assistant

[Guest_Sunspot_*]

The imaging cameras haven't told us anything about the surface - except some looks dark and some looks light.

[nprev]

Well...maybe not with respect to topography, but the spectral properties of surface materials are at least equally important in terms of understanding the place as a dynamic system, of course.

Titan is a complex critter, arguably as complex as Earth in many key ways. We need to equitably divide time amongst all Cassini's resources in order to get the best possible picture of what's really going on...don't think we're there yet.

[Exploitcorporati...]

Certainly can't argue with that...the broad spectrum of coverage is critical for properly peeling this orange. Thanks for the insights regarding the channels south of the sea. I had no idea whether or not they were unusual, but they sure are pretty and well defined in the image.

[volcanopele]

The imaging cameras haven't told us anything about the surface - except some looks dark and some looks light.

The imaging cameras tell us a lot about the global-scale distribution of materials on the surface, something RADAR won't come close to. Sure RADAR can get details about specific areas, but it can't tell us the big picture.

[ngunn]

Here's a higher res grab of the new section.

I don't think the channel geometry is at all unusual. Any bit of random relief near the shoreline will divert a channel.

Phil

[attachment=10388:attachment]

Splendid new views, thanks guys. I think that deltaic deposition could also be a factor in diverting the lower reaches of the channels in unexpected directions.

[rlorenz]

The imaging cameras tell us a lot about the global-scale distribution of materials on the surface, something RADAR won't come close to. Sure RADAR can get details about specific areas, but it can't tell us the big picture.

That's fighting talk... and I believe substantially incorrect. If by big picture you mean large-scale
spatial relationships, remember that Radar swaths are very long, running in some cases from
equator to pole, and total SAR coverage is approaching 20% of the globe. As for conceptual
'big picture', that will ultimately rely on synthesis of data from all the different investigations, but as
for the contribution of specific instruments, the comparative lack of ambiguity (subjective, I suppose)
in Radar data has enabled it to provide secure identification of landforms and processes - the
publication record will bear me out.

The point that all the datasets contribute to our (incomplete, even after the XM) understanding
of this complex world is right on, and thus we seek a balance of coverage from the different
instruments.

[volcanopele]

True, actually figuring out what all the dark and bright stuff mean, yes, that requires a synthesis of all three datasets. My answer may have been a bit simplistic, but overall, ISS and VIMS are capable of imaging a far larger area each encounter than RADAR. But to say that "The imaging cameras haven't told us anything about the surface - except some looks dark and some looks light", I had to respond to that. So admittedly, my use of "big picture" was much less conceptual. It was more referring to the fact that ISS and VIMS will have greater global coverage by the end of the mission than RADAR.

Not to mention "They should use Radar on all the passes".

[Mongo]

Not to mention "They should use Radar on all the passes".

I really wish that the beancounters had not cut the scan platform. Imagine being able to use both RADAR and the imaging cameras on every pass...how much money was saved by that deletion anyways? I bet that the cost savings was insignificant, compared to the loss of observations.

Bill

[ugordan]

Imagine being able to use both RADAR and the imaging cameras on every pass...

I'm not sure it's that simple. I don't know what bitrate the SSR recoders can handle, but it's quite possible they couldn't cope with combined data rates of both SAR and imaging instruments anyway. I know ISS telemetry pickup rates were chosen accordingly to accomodate bandwidth limitations and the highest pickup rate for ISS is something like 384 kbps IIRC. And that's pretty much only usable when not using other instruments.

[Guest_Sunspot_*]

True, actually figuring out what all the dark and bright stuff mean, yes, that requires a synthesis of all three datasets. My answer may have been a bit simplistic, but overall, ISS and VIMS are capable of imaging a far larger area each encounter than RADAR. But to say that "The imaging cameras haven't told us anything about the surface - except some looks dark and some looks light", I had to respond to that. So admittedly, my use of "big picture" was much less conceptual. It was more referring to the fact that ISS and VIMS will have greater global coverage by the end of the mission than RADAR.

Not to mention "They should use Radar on all the passes".

But has the ISS told us anything about the surface other than some is dark and other parts light? It has taken SAR radar observations to tell us what those dark and light patches are. ISS it totally ambiguous when it comes to Titan.

And yes, I still think SAR radar observations should be given priority.

[ugordan]

How higher a priority would you like? The way I understand is that a typical flyby right now consists of optical sensing up to a few thousand km altitude and SAR takes control during closest approach. If anything, I'd say VIMS and RADAR fight for closest approach time, not ISS.

[volcanopele]

But there are still several other instruments that need C/A coverage, but yes, the majority should go to RADAR (just not every encounter). While it took RADAR to tell us what the bright and dark material are structurally, ISS and VIMS can provide more global coverage of the features seen by RADAR. For example, global wind patterns in the dark terrain by examining the orientation of bright features within the equatorial dark terrain.

[Guest_AlexBlackwell_*]

I'll throw some lighter fluid on the fire by going even further than Ralph: Based on the publicly released data, RADAR has told us more about Titan's surface to date than ISS and VIMS combined, notwithstanding the "global" coverage and limited spectral windows accessible by the latter.

There is a good reason that a dedicated Titan radar mapper is being put forth as a future mission concept.

[rlorenz]

I'll throw some lighter fluid on the fire by going even further than Ralph: Based on the publicly released data, RADAR has told us more about Titan's surface to date than ISS and VIMS combined, notwithstanding the "global" coverage and limited spectral windows accessible by the latter.

There is a good reason that a dedicated Titan radar mapper is being put forth as a future mission concept.

I won't disagree, and there will be a lot of neat new radar results in due course on the
data recently acquired.

It is important to remember that there is more to Titan than just its surface - its surface is clearly
modified by the tropospheric weather via aeolian and fluvial processes ; the stratospheric
circulation (polar hood and the downwelling of organic-rich gas) may be responsible for the
concentration of lakes at the poles, and the intiial formation of all that dark sand may be in
the ionosphere (see Hunter's recent paper on tholin formation)

RADAR was purpose-built to study Titan's geology ; ISS and VIMS may do less well in that regard
but also address the atmosphere (e.g. knowing how often and where the clouds happen).
Radio occultations, INMS observations etc. all contribute to the integrated picture, which is why
not all passes are devoted to surface observations, and only a subset of those have radar (next
SAR is T36 by the way :-( )

A follow-on mission - see the OPAG presentation - similarly cannot study the geology alone, but
needs to figure out the circulation, the organic formation at high altitude, the composition of the
surface, global topography etc. All these processes occur at different scales, hence we are
advocating a multiscale, multiplatform architecture - orbiter for 4 years plus a lander plus a balloon!

[nprev]

I won't disagree, and there will be a lot of neat new radar results in due course on the
data recently acquired.

(rubs hands together vigorously)...do tell, sir! We can hardly wait...

A follow-on mission - see the OPAG presentation - similarly cannot study the geology alone, but
needs to figure out the circulation, the organic formation at high altitude, the composition of the
surface, global topography etc. All these processes occur at different scales, hence we are
advocating a multiscale, multiplatform architecture - orbiter for 4 years plus a lander plus a balloon!

Right on. One thing we've learned is that early recon efforts provide virtually all the basis for future detailed investigations. We'd have to be extremely lucky to achieve the precise combination of instruments and strategy needed to fully eke out the answers to all possible questions on the first few missions to any planet, especially one as complex as Titan.