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Nasa Picks "juno" As Next New Frontiers Mission
Guest_BruceMoomaw_*
post Jun 1 2005, 10:10 PM
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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.)
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Guest_BruceMoomaw_*
post Jun 21 2005, 12:31 PM
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Actually, there are a hell of a lot of things they very badly want to get more closeup looks at Io for -- and they're listed both in Spencer's white paper ( http://www.lpi.usra.edu/opag/io.pdf ) and in William Smythe's previous essay "Getting Back to Io", which can be found at members.fortunecity.com/volcanopele/gbtio-1.doc .

On rereading both these essays, by the way, I've come to realize that I have very seriously underestimated the potential range of flexibility of orbital design for an Io Observer. Indeed, Spencer's paper actually points out that, if the Observer had the same radiation hardness as Europa Orbiter, it could make 100 Io flybys from an EQUATORIAL orbit, despite the fact that this would maximize its radiation dose on each flyby. So, simply by utilizing the radiation-hardened technology -- and, indeed, the spacecraft design -- of Europa Orbiter (and with much less fuel), we could devise a perfectly good combined Io/Ganymede/Callisto multiple flyby mission -- that is, our yearned-after "Galileo 2". (Indeed, with radiation hardness like that, we could use it to take a few close looks at Amalthea as well.)
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JRehling
post Jun 21 2005, 03:31 PM
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QUOTE (BruceMoomaw @ Jun 21 2005, 05:31 AM)
Actually, there are a hell of a lot of things they very badly want to get more closeup looks at Io for -- and they're listed both in Spencer's white paper ( http://www.lpi.usra.edu/opag/io.pdf ) and in William Smythe's previous essay "Getting Back to Io", which can be found at members.fortunecity.com/volcanopele/gbtio-1.doc . 


Indeed. Finding some impact craters is one of the ones that excites me more, because that would provide some sharp-shooting information regarding the cratering rate -- information that could be nigh impossible to find elsewhere in the jovian system.

QUOTE
On rereading both these essays, by the way, I've come to realize that I have very seriously underestimated the potential range of flexibility of orbital design for an Io Observer.  Indeed, Spencer's paper actually points out that, if the Observer had the same radiation hardness as Europa Orbiter, it could make 100 Io flybys from an EQUATORIAL orbit, despite the fact that this would maximize its radiation dose on each flyby.  So, simply by utilizing the radiation-hardened technology -- and, indeed, the spacecraft design -- of Europa Orbiter (and with much less fuel), we could devise a perfectly good combined Io/Ganymede/Callisto multiple flyby mission -- that is, our yearned-after "Galileo 2".  (Indeed, with radiation hardness like that, we could use it to take a few close looks at Amalthea as well.)
*


I'm still enamored of the orbit that makes use of two Io intercepts. If they were 180 degrees apart, then flybys could alternate in terms of geometry/lighting, and 50 "survived" perijoves would mean 25 looks at each hemisphere. Europa and Ganymede would cycle through 4 and 8 relative positions when the craft crossed their orbital radii, and that might mean regular flybys in fixed lighting conditions, if dumb luck wills it. If they were 120 degrees apart, then you could set the apojove so that the flybys would cycle through three relative Io positions: one third (~17) each with a flyby at two positions, and a third would have no Io flyby, but would likely enable some nice geometry for Europa/Ganymede (they would cycle through six and twelve positions -- it seems assured that at least four decent flybys of Ganymede, albeit in the same lighting condition, would take place).

I am ignoring the fact that the Galileans can yank a craft's orbit around. Those nudges could either be utilized to willfully vary trajectory geometry or could alternately be overcome with a little propulsion...

Indeed, if Europa Orbiter has a Galileo-2-ish midgame and an Io Observer had some of that worked into its primary mission, there'd be not much need for a dedicated-to-general-purpose Galilean/Jupiter craft in jovian orbit anytime soon. I suspect that, all things being equal, Io would end up trumping Ganymede/Callisto as a single priority, although the latter and larger pair would get the best coverage from any orbiter that was not specifically intended to be Io-devoted.
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Guest_vjkane2000_*
post Jun 22 2005, 09:10 AM
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QUOTE (JRehling @ Jun 21 2005, 08:31 AM)
Indeed. Finding some impact craters is one of the ones that excites me more, because that would provide some sharp-shooting information regarding the cratering rate -- information that could be nigh impossible to find elsewhere in the jovian system.
  I'm still enamored of the orbit that makes use of two Io intercepts. If they were 180 degrees apart, then flybys could alternate in terms of geometry/lighting, and 50 "survived" perijoves would mean 25 looks at each hemisphere. Europa and Ganymede would cycle through 4 and 8 relative positions when the craft crossed their orbital radii, and that might mean regular flybys in fixed lighting conditions, if dumb luck wills it. If they were 120 degrees apart, then you could set the apojove so that the flybys would cycle through three relative Io positions: one third (~17) each with a flyby at two positions, and a third would have no Io flyby, but would likely enable some nice geometry for Europa/Ganymede (they would cycle through six and twelve positions -- it seems assured that at least four decent flybys of Ganymede, albeit in the same lighting condition, would take place).

  I am ignoring the fact that the Galileans can yank a craft's orbit around. Those nudges could either be utilized to willfully vary trajectory geometry or could alternately be overcome with a little propulsion...

  Indeed, if Europa Orbiter has a Galileo-2-ish midgame and an Io Observer had some of that worked into its primary mission, there'd be not much need for a dedicated-to-general-purpose Galilean/Jupiter craft in jovian orbit anytime soon. I suspect that, all things being equal, Io would end up trumping Ganymede/Callisto as a single priority, although the latter and larger pair would get the best coverage from any orbiter that was not specifically intended to be Io-devoted.
*


I would love a mission that does everything you say (alternating encounter points, etc), but I worry about the orbital mechanics. Either each flyby would have to use a gravity assist to tweak the timing of the next enounter, or fuel would have to be burned to do so. This would be complicated by the fact that at least some of the encounters would have to use gravity assists to walk the orbit so that the movement of Jupiter (taking Io with it) doesn't move the encounter point.

The alternative idea of using polar orbits has its own problems. Roughly 1/3 of the surface below the encounter point can be imaged well. If you come in at Io's poles, half of this area is in darkness (although you should be able to pick up 1/2 of the other pole on the way out). In theory, you could just pass by Io on the sunward side, say 10,000 km out, and see the poles and the sunlit side. Unfortuantely, you then lose the gravity assists that allow you to walk the orbit to counter Jupiter's movement around the sun. Not too long after you entered orbit, you'd be passing on the dark side of Io.

Anyone know enough about celestrial billards (ie, using gravity assists) to know if these problems can be reasonably handled?
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Posts in this topic
- BruceMoomaw   Nasa Picks "juno" As Next New Frontiers Mission   Jun 1 2005, 10:10 PM
- - tedstryk   Great to hear. With the whole lunar program being...   Jun 1 2005, 10:44 PM
- - djellison   I take it this puts to bed the possibility of an N...   Jun 1 2005, 10:45 PM
- - Sunspot   Any proposals on what kind of camera?   Jun 1 2005, 11:39 PM
- - BruceMoomaw   No website yet, and I have no details on what kind...   Jun 1 2005, 11:51 PM
- - BruceMoomaw   Postscript: the mission selection actually was pla...   Jun 1 2005, 11:51 PM
- - Sunspot   They can't return to Jupiter without taking a ...   Jun 1 2005, 11:57 PM
- - edstrick   Atmosphere sounding instruments can also return ve...   Jun 2 2005, 06:49 AM
- - BruceMoomaw   Well, I can give you the full instrument list (alt...   Jun 2 2005, 10:37 AM
|- - garybeau   I would have thought / hoped the next Jovian missi...   Jun 2 2005, 12:39 PM
|- - tty   QUOTE (garybeau @ Jun 2 2005, 02:39 PM)I woul...   Jun 2 2005, 04:40 PM
|- - volcanopele   QUOTE (garybeau @ Jun 2 2005, 05:39 AM)I woul...   Jun 2 2005, 05:51 PM
|- - JRehling   QUOTE (garybeau @ Jun 2 2005, 05:39 AM)I woul...   Jun 6 2005, 03:26 PM
|- - tedstryk   I think the six-flybys analogy is a good one (seve...   Jun 6 2005, 05:02 PM
|- - Bjorn Jonsson   I vaguely remember reading somewhere that Juno wil...   Jun 6 2005, 05:26 PM
- - Chmee   Hopefully Juno wont have an umbrella style high ga...   Jun 2 2005, 03:03 PM
- - BruceMoomaw   Well, the Decadal Survey recommended -- and the ne...   Jun 3 2005, 01:17 AM
|- - Gsnorgathon   QUOTE (BruceMoomaw @ Jun 3 2005, 01:17 AM)......   Jun 3 2005, 02:16 AM
|- - Redstone   QUOTE (Gsnorgathon @ Jun 3 2005, 02:16 AM)Are...   Jun 3 2005, 02:32 PM
|- - Gsnorgathon   QUOTE (Redstone @ Jun 3 2005, 02:32 PM)... if...   Jun 3 2005, 09:58 PM
|- - garybeau   QUOTE The Jupiter icy moons' orbiter mission w...   Jun 4 2005, 12:18 PM
|- - tedstryk   I don't think getting to Europa is the biggest...   Jun 4 2005, 12:27 PM
- - BruceMoomaw   Jason is likely to be disappointed if he thinks of...   Jun 3 2005, 01:21 AM
|- - volcanopele   I never thought it would actually flyby Io, given ...   Jun 3 2005, 01:35 AM
|- - um3k   QUOTE (BruceMoomaw @ Jun 2 2005, 09:21 PM)it ...   Jun 4 2005, 02:38 AM
- - BruceMoomaw   BESIDES all that, there was one other major proble...   Jun 3 2005, 10:57 PM
- - edstrick   The Juno instrument selection looks quite "re...   Jun 4 2005, 09:04 AM
- - edstrick   Most of the P.R. talk on crashing Galileo into Jup...   Jun 5 2005, 01:56 AM
- - Decepticon   QUOTE ALL THESE WORLDS ARE YOURS EXCEPT EUROPA ATT...   Jun 5 2005, 03:29 AM
- - BruceMoomaw   I don't think the crashing of Galileo to ...   Jun 5 2005, 06:23 AM
|- - dvandorn   The other real difference between potential Martia...   Jun 5 2005, 09:30 AM
|- - garybeau   QUOTE (BruceMoomaw @ Jun 5 2005, 01:23 AM)Tha...   Jun 6 2005, 12:55 AM
|- - JRehling   Three miscellaneous comments for this thread, from...   Jun 6 2005, 01:30 AM
- - BruceMoomaw   QUOTE (edstrick @ Jun 5 2005, 01:56 AM)Most o...   Jun 5 2005, 06:32 AM
- - BruceMoomaw   While the new Solar System Roadmap (or, rather its...   Jun 5 2005, 06:53 AM
|- - tedstryk   QUOTE (BruceMoomaw @ Jun 5 2005, 06:53 AM)But...   Jun 5 2005, 10:35 AM
|- - Stephen   QUOTE (BruceMoomaw @ Jun 5 2005, 06:53 AM)But...   Jun 8 2005, 09:52 AM
- - BruceMoomaw   QUOTE (edstrick @ Jun 4 2005, 09:04 AM)The Ju...   Jun 5 2005, 07:09 AM
|- - tedstryk   QUOTE (BruceMoomaw @ Jun 5 2005, 07:09 AM)...   Jun 5 2005, 10:32 AM
- - Redstone   QUOTE (garybeau @ Jun 4 2005, 12:18 PM)The or...   Jun 6 2005, 02:17 AM
|- - Bob Shaw   Some comments on life on Mars (and elsewhere) and ...   Jun 6 2005, 01:58 PM
- - BruceMoomaw   Yeah, it will be -- which will certainly interfere...   Jun 6 2005, 07:27 PM
- - Myran   dvandorn wrote: "I think the most boring thi...   Jun 8 2005, 12:12 PM
|- - JRehling   QUOTE (Myran @ Jun 8 2005, 05:12 AM)As for sa...   Jun 8 2005, 04:47 PM
- - Decepticon   They are sending a Probe to Jupiter and according ...   Jun 10 2005, 02:03 AM
|- - JRehling   QUOTE (Decepticon @ Jun 9 2005, 07:03 PM)They...   Jun 10 2005, 04:30 PM
|- - tedstryk   Another factor to consider is that a decent Europa...   Jun 10 2005, 04:55 PM
- - Gsnorgathon   FWIW, a wee writeup at Astrobio.net, and the ever-...   Jun 10 2005, 05:30 AM
- - edstrick   Part of the problem is that *any* Europa orbiter m...   Jun 11 2005, 12:16 AM
|- - Decepticon   Even with Galileo type flybys would make me happy....   Jun 11 2005, 02:37 AM
- - Phil Stooke   Ted, I missed your Amalthea images until just now ...   Jun 11 2005, 03:21 AM
|- - tedstryk   QUOTE (Phil Stooke @ Jun 11 2005, 03:21 AM)Te...   Jun 11 2005, 03:30 AM
- - BruceMoomaw   Juno's orbit will go from only 4500 km above J...   Jun 11 2005, 09:04 PM
|- - MiniTES   QUOTE (BruceMoomaw @ Jun 11 2005, 09:04 PM)Ju...   Jun 15 2005, 02:51 PM
- - Phil Stooke   Spinning doesn't have to mean Pioneer 10-class...   Jun 15 2005, 03:28 PM
- - Decepticon   Can Juno at least take Movie like animations of th...   Jun 15 2005, 08:17 PM
- - BruceMoomaw   According to the Space.com article, it will indeed...   Jun 15 2005, 10:17 PM
- - BruceMoomaw   "...rathern using a filter wheel" is rea...   Jun 15 2005, 10:19 PM
- - Sunspot   Oh... thats a shame, I guess we probably wont ever...   Jun 15 2005, 10:46 PM
- - Phil Stooke   Actually we will see some good stuff in 2007 from ...   Jun 15 2005, 11:26 PM
- - edstrick   Why is it spinning? Field and Particles instrument...   Jun 15 2005, 11:27 PM
- - BruceMoomaw   Fear not! We WILL see excellent images of Jup...   Jun 16 2005, 02:26 AM
- - BruceMoomaw   Footnote: the reason that the radiation dose for a...   Jun 16 2005, 02:38 AM
|- - MiniTES   QUOTE (BruceMoomaw @ Jun 16 2005, 02:38 AM)Fo...   Jun 16 2005, 05:20 PM
|- - djellison   QUOTE (MiniTES @ Jun 16 2005, 05:20 PM)How th...   Jun 16 2005, 06:25 PM
- - edstrick   And.... It's moving perpendicular to the belts...   Jun 16 2005, 05:43 AM
- - BruceMoomaw   It would be more accurate to say that they intend ...   Jun 16 2005, 07:44 AM
- - Analyst   Bruce, I want your optimism when it comes to futur...   Jun 16 2005, 12:34 PM
|- - JRehling   QUOTE (Analyst @ Jun 16 2005, 05:34 AM)Bruce,...   Jun 16 2005, 01:53 PM
- - BruceMoomaw   Yup -- they've had solar panels planned for a ...   Jun 17 2005, 12:08 AM
- - BruceMoomaw   QUOTE (Analyst @ Jun 16 2005, 12:34 PM)Bruce,...   Jun 17 2005, 12:21 AM
- - BruceMoomaw   You'll notice that I HAVE backtracked from the...   Jun 17 2005, 12:25 AM
|- - vjkane2000   QUOTE (BruceMoomaw @ Jun 16 2005, 05:25 PM)Yo...   Jun 17 2005, 02:55 AM
|- - JRehling   QUOTE (vjkane2000 @ Jun 16 2005, 07:55 PM)The...   Jun 17 2005, 04:19 PM
|- - vjkane2000   QUOTE (JRehling @ Jun 17 2005, 09:19 AM)A dif...   Jun 17 2005, 05:23 PM
- - BruceMoomaw   It's a possibility -- but I suspect you're...   Jun 17 2005, 07:17 AM
|- - gpurcell   QUOTE (BruceMoomaw @ Jun 17 2005, 07:17 AM)In...   Jun 17 2005, 07:39 PM
- - edstrick   You really *do* want a very high power telescopic ...   Jun 17 2005, 07:22 AM
- - BruceMoomaw   Turns out I misread that white paper -- Europa Orb...   Jun 17 2005, 07:22 AM
- - vjkane2000   Cost is, of course, a major issue for any Jupiter ...   Jun 17 2005, 02:00 PM
- - BruceMoomaw   Damned if I know, especially with this president -...   Jun 19 2005, 10:29 PM
|- - Bob Shaw   Bruce: Are you talking about the Hubble II comple...   Jun 19 2005, 10:47 PM
- - BruceMoomaw   As for Van Kane's comments on the "Io Obs...   Jun 19 2005, 10:58 PM
|- - JRehling   Imagine the way Halley's Comet's orbi...   Jun 20 2005, 01:25 AM
- - BruceMoomaw   "Are you talking about the Hubble II complete...   Jun 19 2005, 11:54 PM
- - BruceMoomaw   (1) "Imagine the way Halley's Comet...   Jun 20 2005, 02:55 AM
|- - JRehling   QUOTE (BruceMoomaw @ Jun 19 2005, 07:55 PM)Ah...   Jun 20 2005, 08:55 PM
- - gpurcell   I've always thought that the best deorbit miss...   Jun 20 2005, 03:09 PM
- - BruceMoomaw   Actually, there are a hell of a lot of things they...   Jun 21 2005, 12:31 PM
|- - JRehling   QUOTE (BruceMoomaw @ Jun 21 2005, 05:31 AM)Ac...   Jun 21 2005, 03:31 PM
|- - vjkane2000   QUOTE (JRehling @ Jun 21 2005, 08:31 AM)Indee...   Jun 22 2005, 09:10 AM
- - BruceMoomaw   Well, keep in mind that Cassini's 45 close fly...   Jun 22 2005, 10:52 PM
- - BruceMoomaw   The presentations from the June OPAG meeting are n...   Jun 29 2005, 06:02 PM
|- - imran   Thanks for the links, Bruce. I am surprised too t...   Jun 29 2005, 08:37 PM
- - BruceMoomaw   This hardly means that they're not considering...   Jun 29 2005, 10:28 PM
- - BruceMoomaw   And, for one recent JPL study of a Titan aerobot m...   Jun 29 2005, 10:31 PM
|- - JRehling   QUOTE (BruceMoomaw @ Jun 29 2005, 03:31 PM)An...   Jun 30 2005, 05:20 PM
- - BruceMoomaw   Actually, we DO need more surface observation poin...   Jun 30 2005, 06:50 PM
- - tedstryk   QUOTE (BruceMoomaw @ Jun 30 2005, 06:50 PM)Ac...   Jun 30 2005, 06:58 PM
- - JRehling   QUOTE (BruceMoomaw @ Jun 30 2005, 11:50 AM)Ac...   Jun 30 2005, 07:15 PM
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