Q&A: More On Photographing Extra-Terrestrial T-Storms

Jul 5, 2004
New Jersey
Yeah, I know-I seem to have developed a reputation here as being rather stuck on this subject. :lol: :roll: :wink:

This will be the last one for a while-I promise. You folks must be bored. ;)

Once again, I ask the same scientist involved with the Cassini orbiter some questions on this subject. I don't plan to pester the poor man any more on this. :oops:

Fun stuff. :D
Mr. DelGenio,

Firstly, congratulations with the success you and your people had with
Hyugens. The photos are incredible, and the data is truly fascinating.

I have a few questions regarding the photography of gas giant thunderstorms.

Have scientists given consideration to a probe that can be dropped
into the atmosphere of a gas giant planet that is equipped with a
camera? I'm thinking about a probe that would be sort of a combo of
the Galileo probe and Hyugens. Given how huge thunderstorms are on
Jupiter, it must be an incredible sight-not to mention what a
fantastic view of the panorama we could see. I'm sure wind would be a
big problem, though, especially with Saturn's 1,000 mph winds.

What would be some of the difficulties needed to be overcome to pull
off something like that? Also, I seem to recall some photos of Earth
taken of its cresent, where we could see thunderclouds shooting up
into the sky. Has that been tried with Jupiter? Will that be tried
with Saturn, so we we could least get a view of its upper clouds?

Thanks again for your time. :)


Dear Saul,

Thank you for the kind words. I can't claim any credit for Huygens' success, as I'm on the Cassini Orbiter side of things. I of course was a *very* interested and excited observer.

In principle the type of probe you suggest would be great, but there are several practical problems. First, once one gets down below the upper level ammonia and ammonium hydrosulfide clouds on the gas giant planets, the illumination goes away pretty rapidly, faster than on Titan, which makes imaging difficult. The bigger practical problem is that t-storms on Jupiter, fascinating though they are, are a much less frequent occurrence than on Earth. T-storms on Earth are helping to move a good fraction of the excess heat that the Earth's surface absorbs upward to high levels where it can be radiated to space; globally it's something like 30 watts per square meter of energy that they carry, and much more in the tropics. On Jupiter there's only about 5 watts per square meter that needs to be removed fromt he interior, so t-storms need to happen less often to do the job they do. In our Cassini images of Jupiter we generally saw about 1 convective storm per global image mosaic. So placing a probe in just the right place and time on Jupiter to catch one of these would be almost impossible to pull off, though I admit it would be tremendous if it succeeded.

Your other idea about looking on the limb of the planet to catch the vertical structure of these things is a very good one. We will, over the course of the mission, be taking high phase angle (crescent) images of the Saturn limb at numerous times, to aid in the general analysis of cloud properties. If we are fortunate we might catch a convective storm at one or more of these times. The odds on Saturn are even lower than on Jupiter, since Saturn only has about 1 watt per square meter of internal energy to get rid of. But since we will image large areas of the limb repeatedly, sooner or later we might catch a break and see a convective storm there so we can learn more about its vertical structure. That's the beauty of an orbiter mission - you get lots of chances to see things, not just one shot. We'll start doing those crescent images of Saturn starting next year, when the Cassini oribits swing around so that their apoapses (we do most of our imaging near apoapsis because we need to be far away see a decent fraction of the planet) are on the nightside (right now the apoapses are in the morning, so the disk is a little more than half lit).

Tony Del Genio
I wonder what atmospheric height these alien thunderstorms reach, and another big question all ST members would love to know.....

Do they rotate?? :D