Titan Review article Options

[rlorenz]

This just out. Not earth-shattering, but colorful - maybe handy as an up-to-date
Titan intro

http://www.jhuapl.edu/techdigest/td2702/lorenz.pdf

[JRehling]

Great synopsis. The points regarding the diversity of the chemistry were new to me.

I think the comment about mobility and exploration is dead-on, and the map of a possible groundtrack got my imagination going. I think I would expect greater return from a two-balloon mission than one lander + one balloon.

I'm reminded of how the original plan for Mariner 8 and 9 intended to place one in an orbit producing high phase angle imagery and the other into an orbit providing low phase angle imagery, so that the two data sets would complement one another. The failure of Mariner 8 spoiled this plan, but it was an interesting strategy.

So I wonder about a two-balloon mission that placed the two balloons not only at different latitudes, but also different altitudes. A lot of the diversity of Titan correlates with latitude, and a single balloon would run the hazard of permanently missing some of that diversity, even if it lasted a very long time.

So, off the cuff, I am thinking about a mission with an equatorial balloon that begins its mission at around 20 km altitude, and a polar balloon (preferably northern, at around 80-85N) at around 3-5 km. The northern lake districts provide diversity that would be interesting to probe extensively. The low altitude would mean narrower imaging noodles, so we would be rooting for it to complete many laps. Meanwhile, the equatorial balloon would have wider imaging at lower resolution. If it does have an extremely extended lifetime, it might be desirable to drop its altitude after it had circumnavigated Titan a few times. As for the polar balloon, it would be nice to have it migrate eventually to the mid latitudes, but this may not be possible. The balloons might be flown until they fail, or their mobility could be sacrificed in order to provide a "lander" somewhere. With two, we could split the difference, keeping one flying indefinitely while landing another.

At the end of a mission like this, we would have a lot of ground-truthing of most of Titan's interesting terrain types. We could select some high-value targets for the initial entry points (with much of what followed being left to the chance of circulation patterns). Of course, an orbiter would provide comprehensive mapping at resolutions intermediate between the balloons' and Cassini's. At the end, we'd have a rough global map, with enough ground-truthing to feel like we know the place pretty well. Then if we send another lander, we'd know where we want to send it. Right now, picking which places on Titan's surface NOT to explore if we only sent 1 or 2 landers feels like choosing which of your children you love least.