As we see the very cool stuff come in from Cassini, one orbit at a time, I'm curious: at the end of the mission, what will the book on Titan be like?

What kinds of global maps will be available? What gaps will still remain?

It also depends what JPL does in the extended mission. I hope they focus on Titan and other moons.

I really don't know. But one thing I do know. We will have a full high resolution map of Titan from the south pole to about latitude 45 degrees by July 2008. The extended mission would probably extend the coverage up to the north pole.

The big data gaps will be seen at high resolution from Febraury 2007.

And I guess that they will make a map of Titan showing both the ISS and radar imaging as well.

The extended mission will not massively increase the coverage. Unlike the MERs, which have outlived their nominal lifetime by an order of magnitude, and the Pioneer/Voyager craft, Cassini has a hard stop built in when attitude control fuel runs out. The budget for fuel may be stretched, but it is essentially impossible for the extended mission to offer more than about half the number of Titan flybys provided by the primary mission. The extended mission will, however, take us through the equinox, allowing us to see the north polar areas in IR while the south pole disappears.

Just in terms of the three main instruments' mapping, ISS and VIMS will almost surely map the entire surface by the end of the extended mission, but the resolution will vary from place to place, especially for VIMS.

RADAR's SAR mode will not be able to provide effective coverage of more than roughly 25-40% of Titan. Now that they're experimenting with some long-range radar mapping, I suppose it's possible that low-resolution radar mapping could cover more of the surface, but the high-resolution stuff will cover just a fraction of Titan. A representative fraction, we can hope, but not the entire surface.

RADAR's radiometry mode will probably cover the entire surface, but the resolution is very low. Altimetry tracks will be even sparser than the SAR mapping.

At mission's end, Titan's surface will be in a sort of haves and have-nots situation: Some places will be imaged quite well by all three imaging modes (of course, one place was also imaged by Huygens). Other areas will be imaged only hazily by ISS and VIMS. Much of the science will come from studying the areas that are triple-mapped (quadruple in the case of the Huygens landing site), learning correlations between the different imaging modes' views of the same areas to construct models, and to hypothesize that the merely single/double-mapped areas follow similar trends. Also, areas that are seen in high resolution by ISS and RADAR will be "colored" with lower-resolution VIMS multispectral imagery, so we might presume that a low-resolution VIMS border roughly corresponding to a sharper boundary revealed by ISS is the same boundary... thus the one instrument will reveal the morphology [best] while the other reveals something about the composition of the surface units.

I have a Venus globe on my desk: Most of the surface was best imaged by Magellan's SAR, but there are some stripes that Magellan missed, and the mapping there is filled in with other radar surveys' data. When the post-Cassini Titan globe is put together, it will have global coverage, but you will notice the stripes and patches of highest-quality coverage that RADAR provided while the surrounding areas are "only" imaged by ISS and VIMS.

However, at 12-inch globe scale, ISS will cover many areas very sharply, so you'll also notice the discrepancy between places where ISS really "nailed" the coverage at subkilometer resolutions vs. the areas where oblique views are all we have.

JRehling has answered this question in terms of image coverage. I will add something on cartographic products.

I'm assuming Titan will follow the pattern set by other worlds.

First, soon after the end of the mission we can expect a preliminary global map from the U. S. Geological Survey at 1:25,000,000 scale (one sheet) or 1:15,000,000 scale (three sheets), probably ISS plus placenames. It might be accompanied by a mosaic of radar strips at the same scale, with many gaps.

Then, about 4 or 5 years later (these things take time) a global set of 1:5,000,000 quadrangles will begin to appear - 15 sheets covering the whole world, quite likely in several formats - ISS, radar, maybe a composite as well, and possibly a shaded relief interpretation as well. At this stage a global-scale geological map might be published too.

Then maybe 5 years after that, the same set of 15 quads will begin to appear as geological maps. This takes a long time... the Magellan geological maps at 1:5,000,000 are only now being published, one at a time. They are worth waiting for, though - these geological maps represent the culmination of years of analysis and summarize almost everything we know about the world.

The map scales and sheet layouts will probably be the same as for other comparably-sized worlds, Ganymede and Callisto. That's what I'm basing this on. Many good university map libraries have these maps - check them out if you get a chance.

Phil

There will be a huge list of new questions about the chemistry, physics and history of Titan. For other worlds we are used to getting the objective data and reaching broadly settled conclusions perhaps a few years later. This will not happen for Titan as it's just too complex. I think it will take generations to understand how Titan works - most inconvenient from an academic publishing point of view but a wonderful continuing adventure for the science community of the future.

Yeah. Things would get boring if we figured it all out.