[X] My Assistant

[ngunn]

Thinking about all that methane rain descending on Titan's south pole, draining out into Mezzoramia and then - who knows where? - set me wondering . .

IF it seeps through a porous material it could possibly warm up at depth and re-emerge gradually at the surface as methane gas. This could be a peaceful process, like the emission of methane from a terrestrial marsh (or rubbish tip) rather than anything sudden or localised. Now suppose a large sheet of impermeable material is simply laid over the ground in such a place it might begin to trap methane underneath and become buoyant. Something like this is maybe what starts mid-latitude convection cells. Could it be possible to harness the phenomenon to lift balloons? Relatively cool balloons, smaller heat loss problems, very low power requirements. With a nitrogen atmosphere and methane both readily available on Earth the technology could be tested here.

[Doc]

Balloons are fine but has there been any talk on the prospects of using plane probes. That in my opinion is the final frontier of planetary exploration. An ariel surveyor is a tantalizing approach.

The same technology used for probing hurricanes can be used to perform such a project.
Mars is suitable for the first approach. Then Venus, Titan and then who knows where.

The technology is available. It is only a matter of willingness.

http://www.noaanews.noaa.gov/stories2005/s2508.htm

[centsworth_II]

...the prospects of using plane probes....

To me, an autonomous plane seems much more complicated and
prone to mission-ending mishaps than a balloon. I'd rather see the
lion's share of the engineering costs going into the instruments rather
than the platform.

edit: Remember Huygens? During it's descent it was flipped around
violently and somehow ended up rotating in the opposite direction
it was designed to. (Did they ever figure that one out?)
How would an autonomous plane handle those circumstances!

[centsworth_II]

Another advantage of balloon over plane on Titan:

At the tail end of Huygens' descent, the probe reversed course on it's
ground course. As far as I know that was unexpected and unexplained.
There is a lot of mystery in the winds of titan. A balloon could help study
wind behavior at various elevations. To a balloon, Titan's winds are a
natural object of study. To a plane, they are a hazard.

[rlorenz]

At the tail end of Huygens' descent, the probe reversed course on it's
ground course. As far as I know that was unexpected and unexplained.
There is a lot of mystery in the winds of titan. A balloon could help study
wind behavior at various elevations. To a balloon, Titan's winds are a
natural object of study. To a plane, they are a hazard.

This last remark is incorrect. Balloons and planes are both affected by wind.
The effects are inversely proportional in a sense to flight speed - I flew hanggliders
as an undergrad, and it was a lot bumpier than a commercial jetliner.

A balloon's trajectory is more or less completely determined by the wind, a
plane much less so. That makes a plane slightly less effective (though a
good IMU can help) in measuring the winds than is a balloon, but on the
other hand, a plane can go where you want it to.

In either case, winds on Titan are basically quite gentle, though it is true that
the wind reversal in the lower part of the Huygens descent was not widely
anticipated.

[centsworth_II]

This last remark is incorrect. Balloons and planes are both affected by wind.

My comment was too absolute, but in a relative sense I feel that a balloon
is cheaper to develop, longer lasting (more science), and less prone to mishap. (Just my 2 cents.)

...a plane can go where you want it to.

Doesn't the long communication delay eliminate any chance of determining
where you want the plane to go after it exits it's aeroshell? Only a preplanned
route could be used or you need to have a virtually intelligent autonomous
system. A balloon is much less maneuverable but there is much more time
available to plan actions (mostly elevation changes) to take advantage
of the balloon's slowly evolving circumstances.

I suppose a plane that takes off from a lander could be programmed to
fly a specific course, but a balloon could also be programmed to release
from a lander when the prevailing wind moved to a certain desired direction.
And the release and flight of the balloon remains much less prone to mishap
in my opinion.

[centsworth_II]

I'm sure someone must have mentioned the obvious compromise
between plane and balloon: A powered dirigible?

[ngunn]

I'm sure someone must have mentioned the obvious compromise
between plane and balloon: A powered dirigible?

Yes. It's all there in the Lorenz paper linked in post #4 which goes over the excitingly wide field of possibilities.