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Nasa Picks "juno" As Next New Frontiers Mission
volcanopele
post Jun 3 2005, 01:35 AM
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I never thought it would actually flyby Io, given the radiation concerns. But for Io, the key need is not necessarily high spatial resolution images, but high temporal and spectral resolution observations. So even consistent observations over a 2 year span can prove VERY useful for Io science.


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Gsnorgathon
post Jun 3 2005, 02:16 AM
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QUOTE (BruceMoomaw @ Jun 3 2005, 01:17 AM)
...
Hopefully they'll finally stop screwing around and fly the damn thing, now that O'Keefe's JIMO fairy tale has been taken back off the table.
...
*

I always thought JIMO sounded too good to be true. I hate it when I'm right about that kind of stuff.

Are there any informed critiques of JIMO on the web? I just figured it wasn't going to happen because of the everyone-gets-a-pony aspect, as opposed to actually knowing anything.
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Redstone
post Jun 3 2005, 02:32 PM
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QUOTE (Gsnorgathon @ Jun 3 2005, 02:16 AM)
Are there any informed critiques of JIMO on the web? I just figured it wasn't going to happen because of the everyone-gets-a-pony aspect, as opposed to actually knowing anything.
*


Not a detailed critique, but here is what Mike Griffin said to Congress about JIMO

QUOTE
The Jupiter icy moons' orbiter mission was, in my opinion, too ambitious to be attempted. Let me give a couple of specifics.

The vehicle would have required at least two heavy-lift launches to put into orbit, where it would have been assembled prior to its departure from earth to go to Jupiter. That would have been an extremely expensive undertaking, one which we have not performed before.

The nuclear electric propulsion system being developed for it does not presently exist, would not exist for some time and, if successfully developed, would have required approximately twice the world's annual production of xenon to be fueled -- to carry out the mission. It was not a mission, in my judgment, that was well-formed.

The original purpose of the Jupiter icy moons' orbiter was to execute a scientific mission to Europa -- Europa, a moon of Jupiter, which is extremely interesting on a scientific basis. It remains a very high priority, and you may look forward, in the next year or so, maybe even sooner, to a proposal for a Europa mission as part of our science line. But we would not -- we would, again, not -- favor linking that to a nuclear propulsion system.
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Gsnorgathon
post Jun 3 2005, 09:58 PM
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QUOTE (Redstone @ Jun 3 2005, 02:32 PM)
...
if successfully developed, would have required approximately twice the world's annual production of xenon to be fueled
...
*


LOL! Thanks, Redstone. Those are some good details.
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Guest_BruceMoomaw_*
post Jun 3 2005, 10:57 PM
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BESIDES all that, there was one other major problem that Griffin didn't mention and which would unique to JIMO among all NEP missions: the fact that it would simultaneously have had to be designed with new radiation-proof electronics for its Europa-orbiting mission. Jupiter's charged-particle radiation presents an entirely different kind of problem for electronics than the neutrons emitted by a nuclear reactor, and in any case the radiation from the latter -- on the end of a long boom, and with its own shield -- would be trivial in relative dosage anyway. Indeed, Jupiter's own radiation would seriously complicate the design of the reactor's own control electronics. This whole big problem, as I say, was unique to the JIMO proposal, and is further proof that it could have been advocated only by someone who didn't know anything whatsoever about actual engineering and could thus get suckered by dishonest underlings -- namely, O'Keefe.
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um3k
post Jun 4 2005, 02:38 AM
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QUOTE (BruceMoomaw @ Jun 2 2005, 09:21 PM)
it will approach at Ganymede's distance and make a Ganymede flyby to help brake itself into Jovian orbit (rather than using Io for that purpose, as Galileo did).
*

biggrin.gif

I was just pondering that concept. My idea, though, is even more ambitious: A Europa sample return mission that utilizes multiple flybys of Jovian moons in order to slow down enough to make a soft landing on Europa. A core sample would then be taken, which would be segmented into shorter pieces, and then launched into Jovian orbit, where it would be picked up by a larger orbiter. This would then conduct many more flybys in order to reach Jovian escape velocity. It would finally enter a solar orbit that would return it to Earth. The purpose of all the gravity assists, of course, is to use as little fuel as possible. cool.gif
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edstrick
post Jun 4 2005, 09:04 AM
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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.
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garybeau
post Jun 4 2005, 12:18 PM
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QUOTE
The Jupiter icy moons' orbiter mission was, in my opinion, too ambitious to be attempted.


The original concept for a Europa Orbiter was not a multi-billion dollar, nuclear propulsion behemoth, but rather a <1 billion scout mission with radar and imaging capabilities. The proposed mission had overwhelming support from both the public and scientific community.

http://www.planetary.org/html/society/pres...vey_results.htm

http://www.planetary.org/html/UPDATES/Pluto/plutoeuropa.html

It's only because of the shortsighted, politic driven decision making that that this mission has been "on again - off again" so many times.
Fortunately, NASA is not the only game in town any more. Maybe we will see an ESA Europa mission while NASA is trying to find its way. biggrin.gif

http://sci.esa.int/science-e/www/object/in...fobjectid=35982

I don't think getting to Europa is the biggest hurdle to overcome. I think one of most difficult challenges will be to get there without contaminating the moon with terrestrial organisms. I don't think that it is possible to completely sterilize a spacecraft and allow it to impact the moon. Enough fuel would have to be brought to allow it to leave the orbit of Europa when the mission is over and de-orbit into Jupiter the same way that Galileo did.

My apologies for getting OT.
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tedstryk
post Jun 4 2005, 12:27 PM
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I don't think getting to Europa is the biggest hurdle to overcome. I think one of most difficult challenges will be to get there without contaminating the moon with terrestrial organisms. I don't think that it is possible to completely sterilize a spacecraft and allow it to impact the moon. Enough fuel would have to be brought to allow it to leave the orbit of Europa when the mission is over and de-orbit into Jupiter the same way that Galileo did.

My apologies for getting OT.
*

[/quote]

I don't think the crashing of Galileo to "protect" Europa was worth it. I am extremely skeptical of the idea that the place might have life, and I think NASA's hyping of the idea distracts from the truly interesting aspects of Europa and the Jovian system.


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edstrick
post Jun 5 2005, 01:56 AM
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Most of the P.R. talk on crashing Galileo into Jupiter reffered to the planetary quarantine problem. They barely discussed the real reasons for the end of mission. 1.) The spacecraft was running out of orbit trim propellant. 2.) Radiation damage was making the spacecraft "sicker" and sicker. Things were progressively failing, going intermittant, flakey, etc. 3.) $$$$$... The mission was expensive to operate and track because of the enormous Deep Space Network effort to return a trickle of data from the omin antenna, after the main antenna failed to open.

But essentially, the spacecraft was dying.

I hear the same BS about evil NASA "killing" the Magellan Venus radar orbiter; but the spacecraft was literally falling apart when it was intentionally lowered into the atmosphere. Thermal cycling was causing the solder joints on the solar panels to break, and the spacecraft's was progressively and rapidly losing power at the end.
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Decepticon
post Jun 5 2005, 03:29 AM
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QUOTE
ALL THESE WORLDS ARE YOURS EXCEPT EUROPA ATTEMPT NO LANDING THERE USE THEM TOGETHER
USE THEM IN PEACE

- 2010: Odyssey -
Just kidding!

Before I kick the bucket I wanna see Full global mapping and a confirmation of a global ocean. < I'm Pretty sure it's there, I just wanna say Na Na Na Poo Poo to the Naysayers rolleyes.gif tongue.gif tongue.gif
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Guest_BruceMoomaw_*
post Jun 5 2005, 06:23 AM
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[quote=tedstryk,Jun 4 2005, 12:27 PM]
I don't think getting to Europa is the biggest hurdle to overcome. I think one of most difficult challenges will be to get there without contaminating the moon with terrestrial organisms. I don't think that it is possible to completely sterilize a spacecraft and allow it to impact the moon. Enough fuel would have to be brought to allow it to leave the orbit of Europa when the mission is over and de-orbit into Jupiter the same way that Galileo did.

My apologies for getting OT.
*

[/quote]

I don't think the crashing of Galileo to "protect" Europa was worth it. I am extremely skeptical of the idea that the place might have life, and I think NASA's hyping of the idea distracts from the truly interesting aspects of Europa and the Jovian system.
*

[/quote]

That possibility ain't "hyping": the science community itself has taken the idea extremely seriously for a couple of decades. Europa, after all, has lots of liquid water -- something which Mars has in tremendously more limited amounts.

And there's another factor, which I haven't seen mentioned in print although the scientists I've mentioned it to seem to agree: even if we find proof of present or fossil Martian life, we may have hell's own time proving that it didn't just descend from ancient Earth germs blasted to Mars via meteorites from Earth during the Solar System's earliest days (or, for that matter, vice versa). On the other hand, if we find Europan life, the odds will be overwhelming that it's native -- which means, since two worlds in a single Solar System will have separately developed life, that we'll know life must be common in the Universe as a whole, rather than being just an extremely rare chance development that happened to make one of its rare appearances in our own Solar System. For this reason, I have for years regarded the search for Europan life as MORE important scientifically than the search for Martian life.

As for the danger of contaminating Europa: the science community takes that very seriously, too. See the 2000 report by the National Academy of Sciences ( http://www7.nationalacademies.org/ssb/europamenu.html ) -- which points out that, since Europa has a unified liquid-water ocean, terrestrial microbes could spread all over that world far more quickly than terrestrial microbes could if they got loose on Mars. Proper sterilization of Europa spacecraft is extremely important, even given the fact that Jupiter's savage radiation environment will give us a lot of help in that regard.

That being said, providing Europa Orbiter with enough fuel to break back out of Europa orbit is simply impractical -- it will be hard to carry enough even to put it into Europa orbit in the first place. This is a difficult mission. We will, instead, just have to make sure it's properly sterilized (as we'll have to do in any case with all Europa landers).
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Guest_BruceMoomaw_*
post Jun 5 2005, 06:32 AM
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QUOTE (edstrick @ Jun 5 2005, 01:56 AM)
Most of the P.R. talk on crashing Galileo into Jupiter reffered to the planetary quarantine problem.  They barely discussed the real reasons for the end of mission.  1.) The spacecraft was running out of orbit trim propellant.  2.) Radiation damage was making the spacecraft "sicker" and sicker.  Things were progressively failing, going intermittant, flakey, etc.  3.) $$$$$... The mission was expensive to operate and track because of the enormous Deep Space Network effort to return a trickle of data from the omin antenna, after the main antenna failed to open. 

But essentially, the spacecraft was dying. 

*


Yep -- the Space Studies Board had done a detailed appraisal for NASA years earlier of just how much of an extended mission for Galileo was scientifically cost-effective. They ended up going for the most ambitious possible plan, except that they rejected the idea of trying to photograph Amalthea during its flyby on the grounds that the craft would almost certainly develop serious radiation collywobbles during that period anyway (which, indeed, it did). They did decide to add an imaging plan for its final Io flyby (something Jason Perry privately worked like hell to encourage) -- only to have that also ruined by a radiation reset of the sort that fouled up almost all of their Io flybys to varying degrees.

There is no way you can say that NASA threw away this spacecraft wastefully -- I'm amazed that it lasted as long as it did. (I'm even more amazed that they were able to squeeze so much valuable science out of it after the HGA disaster -- when I first heard about that in 1991, I figured that all of the mission except the entry probe was dead.)
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Guest_BruceMoomaw_*
post Jun 5 2005, 06:53 AM
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While the new Solar System Roadmap (or, rather its first draft -- it's about to undergo some minor revisions) has just been yanked back off the Web (along with all the other new Roadmaps) by NASA within a few days of being put there, I copied them all first. Two things about the Europa Orbiter:

(1) It will actually be the first of a new cost class of Solar System missions -- which were called "Intermediate" missions at the first meeting of the Roadmap committee when I attended it, but are now referred to as "Small Flagship"
missions. These are missions in the $700 million to $1.5 billion class. One thing that killed Europa Orbiter last time was the fact there was a $1 billion cost cap on it, and JPL concluded that it simply could not be done -- even in stripped-down form -- for less than about $1.2 billion. (The next two Small Flagship missions -- spaced at intervals of about 5 years -- will be to Titan and Venus.)

(2) One thing which the science definition team recommended strongly for JIMO could perhaps end up flying on this much smaller chemically-propelled mission: a small Europa lander weighing only a few hundred kilograms. It would certainly further complicate the mission -- but, given the very long intervals between Europa missions, we may well want to jump to this phase as fast as possible. (Exobiologist Jack Hunter once told me bitterly: "I'll be in a wheelchair by the time they land on Europa.") The Roadmap mentions it briefly as a possible addition -- and there was a very detailed design study done last year ( http://dosxx.colorado.edu/%7Ebagenal/OPAG/...port_Final2.pdf ).

It would use a flat-out full soft-landing system rather than airbags or other shock absorbers, on the grounds that the latter are just too heavy. Its two mandatory instruments would be a seismometer (to probe the thickness of the ice layer) and a mass spectrometer hooked up to a system for separating out various organic compounds (probably using liquid rather than gas chromatography) from the ice. The next two priority instruments would be a magnetometer (for more data on the ice layer thickness), and a surface camera -- that's probably as much as they could cram onto it. But the catch is whether they can design a lightweight sampling system for the mass spectrometer that could penetrate deep enough into the ice to get below the upper layer of Europan regolith where any biological organics have been unrecognizably scrambled by Jupiter's radiation -- probably a couple of meters. If they can't, I don't think a piggyback lander is worth flying.

But, with a lander or not, I think Europa Orbiter is finally definitely going to fly -- quite posibly as a collaboration with the ESA, which has recently officially declared itself very interested in such a teamup. NASA has finally been forced to get serious about this mission, as they finally were with the Pluto probe.
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Guest_BruceMoomaw_*
post Jun 5 2005, 07:09 AM
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QUOTE (edstrick @ Jun 4 2005, 09:04 AM)
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).
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