Nasa Picks "juno" As Next New Frontiers Mission Options

[Guest_BruceMoomaw_*]

http://www.nasa.gov/home/hqnews/2005/jun/H...rontiers_2.html

Yeah, I know it ain't Saturn, but we don't seem to have any proper slot for Jovian news -- including yesterday's totally unexpected announcement that Amalthea's density is so low as to suggest that it's a highly porous ice object; maybe a captured Kuiper Belt Object reduced to rubble by infalling meteoroids. As Jason Perry says, this might explain those previously mysterious light-colored patches on Amalthea -- they may be its underlying ice, exposed by impacts that punched through the layer of sulfur spray-painted onto it by Io.

Scott Bolton has been pretty talkative to me already about the design of Juno. It certainly won't be as good in the PR department as Galileo or Cassini, but it DOES carry a camera -- as much for PR as for Jovian cloud science, according to Bolton. And since the latitude of periapsis of its highly elliptical orbit will change radically during the primary mission, I wonder if they might be able to set up at least one close photographic flyby of Io and/or Amalthea? (I believe, by the way, that this selection is a bit ahead of schedule -- and it certainly indicates that NASA's science program under Griffin won't be a complete slave to Bush's Moon-Mars initiative.)

[edstrick]

You really *do* want a very high power telescopic system on such a mission. A high inclination orbit will give close encounters with Io over a very limited range of orbital longitudes and thus illumination conditions. Even if you get 10 flyby's over 1 year, with Jupiter's 12 year orbit around the sun, the sun-angle at each flyby changes by 1/12 of 360 degrees.
The higher resolution the telescope, the better your monitoring coverage, and the better the detailed geologic mapping coverage from say 10,000 km. You haver longer "dwell" time at a given resolution if you aren't in a close periapsis flyby when you're getting that resolution.

An all-reflecting optics telescope can feed anything from ultraviolet to middle infrared with different instruments arrayed around a "pickoff mirror" at the focal point. That gives lower resolution imaging spectrometers more time at a given resolution as well. Imagine global VIMS coverage of Titan at 1 km/pixel instead of spot coverage at 2 km/pixel which Cassini is getting.