QUOTE (David @ Sep 9 2005, 03:05 PM)
And given that, at Jupiter's cloudtops, everything weighs more than two and a half times what it does no earth, you'd need something extraordinarily light. The task might be more practical on Saturn, where the gravity is less than earth's.
That also means the buoyancy is less. Hint: If you had a bathtub on Jupiter (filled with water and surrounded by STP air!), the same things would float there as on Saturn/Earth/Moon/Phobos/etc.
Unless you're worried about the thing falling apart under its own weight, the local g divides out.
In fact, Saturn's atmosphere is slightly lower in molecular weight than Jupiter's, making buoyancy there a bit harder.
QUOTE (David @ Sep 9 2005, 03:05 PM)
I wouldn't expect that an entry-probe with an imager would provide very spectacular images from
inside the clouds (though I'd be happy to be wrong); but if one had a downward-pointing camera, you could get invaluable images from the approach to the cloudtops, at much higher resolution than anything we have now, something like the approach images from Titan. Obviously they'd be more interesting if you dropped the probe into a raging storm, instead of a bland cloud-band!
My own terrestrial experience is that side-looking views of cloud formations can be pretty striking as you see the topside profile of them against the sky. One difficulty on Jupiter would be that there might be similarly-hued clouds behind those (there are layers on layers). Another thought is that the clear air above and between layers would still have some humidity (from various species), and even on a clear day, you can't see forever. A couple of hundred kms' line of sight would probably yield blankness no matter what cloud/sky mix were behind it -- although the "humidity" of a parcel of Jupiter air would have to vary depending upon... many things. A view might show the tops of local fluffy cumulus in front of what seems to be a blue sky that actually has lots more clouds behind it, but too far away to see through the vast distances of "air".
Another thought on in-cloud imaging is that onboard processing might be used to choose which of many images are worth sending up (the less blank the better). Thus, a probe might take dozens of images, then send one or a few later, before it dies.
Personally, the thing I'd most like to "see" from a dirigible would be mass spectrometry from cloud particles at all heights, and to find out what the coloring agents are in the clouds.