[X] My Assistant

[Juramike]

...we are advocating a multiscale, multiplatform architecture - orbiter for 4 years plus a lander plus a balloon!

SWEET!!

If we pass the hat around the table, can we pony up enough to send two?

-Mike

[rlorenz]

SWEET!!

If we pass the hat around the table, can we pony up enough to send two?

-Mike

You tell me - I assume you are a taxpayer.....
Rough costs (costing data was notably absent from the other flagship presentations!)
for a suite of options were given in the presentation. Obviously a second lander
or second balloon has a more modest cost increment than the first (you only have to
demonstrate the technology once, only have to write the software once, etc.).

There are a lot of descope options, or opportunities for international partnering.

[ustrax]

There are a lot of descope options, or opportunities for international partnering.

Is there any possibility of seing your project merging with TANDEM?
Or will they follow different paths?

[Juramike]

You tell me - I assume you are a taxpayer.....

(Actually, for my 2002 tax check to the IRS I scrawled in "More Mars Rovers" in the comment field.)

I hope it helped....

-Mike

[JRehling]

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.

It's not too far from the truth to say that the data we have on Titan right now is a bit like the union of the data we have on Ganymede or Europa (remote sensing in vis/IR) and on Venus (radar mapping plus atmospheric studies plus some in situ look from a lander). Anyone who says we wouldn't want to have the vis/IR look at Venus's surface is crazy... it's just next to impossible to get.

For airless Ganymede, vis/IR ends up providing a lot of what RADAR would buy you. Stereography and shape-from-shading provides some local topography (which is almost as wild on Ganymede as Titan). Spectroscopy in vis/IR has proven to be pretty dicey. Mars, Europa, and Ganymede has proven to be almost ciphers. Triton, Pluto, Mercury have been easier to get some results from, just luck of the mineralogical draw. I don't think VIMS is doing too much worse at Titan than Galileo and MGS did at their targets, despite the much more challenging atmosphere overhead.

RADAR is going to end up mapping a minority of Titan's surface in contrast to the essentially total coverage we have of Venus. Hectare for hectare, RADAR is preferable to just ISS or VIMS, but the real prize we'll come away with from Cassini is to have a full global map in IR with a lot of it ground-truthed with RADAR, which should let us do some inference about the other 65% of the globe. At the hazard that some truly unique geological provinces never get the RADAR treatment... which is what makes extended mission planning so important (and some luck regarding feasible geometry). If Magellan had missed Ishtar Terra, nothing else on Venus would have replaced it as similar. But most of the other locales on Venus are specimens of more general phenomena. So long as RADAR gets to check out the stuff that looks unique to ISS/VIMS, we can feel like Cassini gave us a great once-over. With RADAR taking blind peaks on its own, how would we know if we'd criss-crossed around an amazing unique province on Titan like Venus's Ishtar?

Note that we've seen some hints of temporal variation on Titan. I think we need to keep looking for those and keep alive the hopes of the super-payoff of seeing something like that from VIMS and then getting the closeup with RADAR to see what's venting.

[Guest_AlexBlackwell_*]

RADAR is going to end up mapping a minority of Titan's surface in contrast to the essentially total coverage we have of Venus. Hectare for hectare, RADAR is preferable to just ISS or VIMS, but the real prize we'll come away with from Cassini is to have a full global map in IR with a lot of it ground-truthed with RADAR...

I don't think anyone here disputes (at least with a straight face) the fact that Titan needs to be studied with a panoply of sensors. The synergy of the various Cassini data sets trumps any parochial assertions (viz., "my instrument is more valuable than yours").

However, the question presented was a narrow one: To date, which instrument(s) has/have provided the most information regarding Titan's surface? And I believe a fair reading would indicate the answer is RADAR.

[JRehling]

However, the question presented was a narrow one: To date, which instrument(s) has/have provided the most information regarding Titan's surface? And I believe a fair reading would indicate the answer is RADAR.

FWIW, ISS's work can be done at 2-orders-of-magnitude downscaled resolution from Earth, and that data would be correlated with RADAR if ISS and VIMS didn't exist. If we're scoring carefully. Radaring Titan from Earth would lose much more in the translation.

[nprev]

Just to be iconoclastic, what sort of information about Titan's surface would be considered most valuable? Radar certainly wins hands-down for topography as well as some limited information about surface permittivity, but it doesn't really tell us much about what the materials specifically are in terms of chemistry (other than any pure water ice outcrops it may encounter).

Admittedly, the latter question will require landers and/or blimps to answer decisively (if then; I wonder just how versatile and reliable an automated organic chemistry lab can be made). Until then, I think the Cassini team is wise to divide time between instruments in order to maximize a diverse data return during the primary mission.

Now, if we're talking extended mission...let's fire up the radar & leave it on!!! Getting the best possible radar map of Titan sounds like the best contender yet for an extended mission objective, with an encounter or two with Enceladus thrown in for variety...

[Thorsten]

Sorry to interrupt this fascinating conversation, but while I was eagerly waiting for the release of the T28, T29, and T30 radar results I played a little bit around with the small RADAR cutout from the Titan Flagship Study (page 5, bottom left) and the Lake Powell- like flooded drainage system from PIA01943 “Lakes and more lakes”.

BTW, last week my girlfriend had her first lesson as high school teacher in chemistry and had to talk for two hours on alkanes (particularly methane and ethane). So I suggested including a short lecture on the recently revealed lakes of Titan. Both, the pupils and the inspector were delighted by her lecture. Gives you a good feeling to know that there are now a dozen more people who have heard of the wonders of the outer solar system!

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[ngunn]

That's a great little inset. I love the way that channel starts as an outflow from the caldera-like feature.

[Littlebit]

Sorry to interrupt this fascinating conversation, but while I was eagerly waiting for the release of the T28, T29, and T30 radar results I played a little bit around with the small RADAR cutout from the Titan Flagship Study (page 5, bottom left) and the Lake Powell- like flooded drainage system from PIA01943 “Lakes and more lakes”.

The history of the canyons surrounding Lake Powell, and to an extent the entire Colorado river drainage, is worth mentioning: Much of the terrain is an ancient lakebed silted in with eons of sand. When the continental plate that this lake or seabed was formed on was lifted up, the sandstone cracked and was easily eroded into great wide canyons. Ok, it took millennia, but if the similar features we are seeing on Titan formed in the same way, plate tectonics are/were active players.

[Tom Tamlyn]

I really wish that the beancounters had not cut the scan platform.

I've read that the experience of creating the scan platform for the Galileo mission was so difficult and chancy that some engineers swore "never again." But perhaps that was just a rationalization for the budget issue.

TTT

[elakdawalla]

I thought that the "never again" sentiment had to do with half of the spacecraft being spun, and half despun. Shorts in the interface between the spun and despun sections are what caused most of Galileo's safing events.

--Emily

[Tom Tamlyn]

Right, thanks for refreshing my recollection. I had thought that having the spacecraft half spun, half despun was necessary for accommodating the scan platform. However, since (as I now gather) a number of other spacecraft have had scan platforms without being half and half, I'm obviously not on top of this issue. (sorry)

TTT

[belleraphon1]

Tom ... a scan platform was used on the Voyagers. The reason for the spun/despun on GALILEO was to accomodate scan platform instruments on the despun portion while allowing the particle fields instruments a 360 degree field POV on the spun section which was very important to those studies. This was meant to make everyone happy (scientists), but was a nightmare for the engineers.

With CASSINI losing the scan platform (for a typical penny wise pound foolish budget decision), this has vastly complicated the spacecraft operations and is one reason designing the encounter sequences can be so contentious...

Craig