[X] My Assistant

[Tom Womack]

I've been wondering how you'd design a Meteosat system for Jupiter.

There is of course the initial question of why you'd want to ... the images would be intrinsically beautiful, it's an interesting domain of turbulent fluids, forecasting the weather on a second planet might help with forecasting on ours, but really it just looks pretty.

Jupiter-synchronous orbit is stupidly low and very radiation-filled, so you'd probably want to observe from the distance of Callisto, and you'd need three satellites at 120-degree intervals around that orbit. A camera like the one on Deep Impact would give a resolution of four kilometres (2 microradians at two million kilometres) on Jupiter, which is I think rather better than anyone's achieved before even at fly-bys. It would let you get very good observation of Ionian activity, with about an 800-pixel disc, though I suspect it wouldn't tell you anything very exciting about the less active Jovian moons.

I suppose far-Jupiter-orbit insertion is intrinsically too expensive for this to be a remotely feasible mission; I've not found very good details of what the outer radiation belts of Jupiter look like, it may be that Callisto orbit is still absurdly unfriendly compared to LEO.

[nprev]

Actually, as Ted points out, the amateur astronomy community does an excellent job of monitoring Jupiter's weather. Maturing CCD technology, etc. lets them produce imagery orders of magnitude better than the pros could do even fifteen years ago.

Therefore, sad to say, I don't see a compelling need for a dedicated Jupiter weather spacecraft or space telescope. Resources & effort would be better utilized by flying a next-generation Galileo-type mission, since the moons are much, much more difficult to observe from Earth.

[JRehling]

Actually, as Ted points out, the amateur astronomy community does an excellent job of monitoring Jupiter's weather. Maturing CCD technology, etc. lets them produce imagery orders of magnitude better than the pros could do even fifteen years ago.

It is great stuff for detecting changes in the big features over a period of days to weeks. I think it would be a compelling goal to run some surveys on the scale of hours, making sure that every feature on Jupiter is imaged at least once per jovian day when it is near subsolar longitude. That would allow us to track not only the big events but to characterize the dynamics of the much larger number of events among smaller objects. I don't know -- maybe a short survey tells it all; maybe Earth-based resolution is too poor -- but I'd think that a survey like that would push the envelope. Maybe it would only need to be done once to uncover the meaningful patterns. It seems to me like we don't know til we do it, and $10 million or so would be the ballpark of the cost.

Of course, watching a six-month movie of Jupiter's atmosphere at these resolutions could be a very pretty visual product lasting three minutes or so; I don't think anyone here would mind watching something like that. Cassini and Voyager produced versions of various resolution and duration... Earth-based observations would trump those in terms of temporal coverage.