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.)

[Guest_BruceMoomaw_*]

The Juno instrument selection looks quite "reasonable". 

Camera, for cloud tracking and atmosphere structure,

A basic fields and particles instrument set covering all essentials.  Particle data's necessary to study magnetosphere dynamic effects on the magnetic field, to better separate external forcing from internal magnetic field sources.

UV spectrometer will probably have dual uses of upper atmosphere structure, composition and dynamics, and detailed imaging studies of the auroral oval and airglows.  Together with the fields and particles data, this maps the magnetic field down to the atmosphere top.

I'm more than a little surprised there's no imaging infrared instrument or mapping spectrometer.  Maybe the camera system's going to include a mid-infrared (1 micromter to 5 micrometers) detector.  The 5 micrometer band gives the deepest pemetration into hotspots and the like.

From Earth, we've crudely mapped microwaves from Jupiter's disk.  That's where we get the deepest electromagnetic spectrum remote sensing of the atmosphere.  Essential instrument.

Juno was deliberately created as a fusion of the three previous Discovery-class Jupiter mission concepts -- INSIDE Jupiter, the JASSI flyby, and the Jupiter Polar Orbiter -- and in fact the three proposal teams united for this mission. (I will never forget the Solar System Exploration Subcommittee meeting I once attended at which the PIs for INSIDE Jupiter and JASSI kept pulling me aside into corners to whisper derogatory things about each others' missions and encourage me to write them.) But if Juno is descoped, the instruments to go will be some of those associated with the magnetospheric investigations of JPO -- ALL the goals of the other two missions could be achieved with only two instruments: the magnetometer and the microwave spectrometer. The camera, according to Bolton, is the lowest-priority of the lot -- although I certainly intend to grill him more now on its capabilities, and on the possibility that they might be able to incorporate one or two flybys of Io and/or Amalthea (probably during an extended mission).

[tedstryk]

  The camera, according to Bolton, is the lowest-priority of the lot

Yes, but if it is small and simple, it is unlikely to be cut, given its PR value - There is no point in making cuts that don't save much money, weight, or power unless you are really desperate.