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Unmanned Spaceflight.com _ Jupiter _ Nasa Picks "juno" As Next New Frontiers Mission

Posted by: BruceMoomaw Jun 1 2005, 10:10 PM

http://www.nasa.gov/home/hqnews/2005/jun/HQ_05138_New_Frontiers_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.)

Posted by: tedstryk Jun 1 2005, 10:44 PM

Great to hear. With the whole lunar program being envisioned under the Moon/Mars program, it is good to hear this was selected. Also, it is nice to see another outer solar system mission entering planning...I mean, after New Horizons launches next year, we would have no outer solar system missions in development!

Posted by: djellison Jun 1 2005, 10:45 PM

I take it this puts to bed the possibility of an NH2 ?

Does Juno have a website ?

I'll create a Jovian section for the forum in a bit

Doug

Posted by: Sunspot Jun 1 2005, 11:39 PM

Any proposals on what kind of camera?

Posted by: BruceMoomaw Jun 1 2005, 11:51 PM

No website yet, and I have no details on what kind of a camera -- Bolton wasn't THAT talkative. I'll contact him again to see if a website is about to appear -- and, if not, I'll write my own article on the mission.

By the way, Doug, would it be possible for you to capitalize "Juno" in my original topic name? As usual, I screwed up on my capitalization.

Posted by: BruceMoomaw Jun 1 2005, 11:51 PM

Postscript: the mission selection actually was planned for last month. I'd lost track.

Posted by: Sunspot Jun 1 2005, 11:57 PM

They can't return to Jupiter without taking a decent camera blink.gif blink.gif

Posted by: edstrick Jun 2 2005, 06:49 AM

Atmosphere sounding instruments can also return very interesting images, witness infrared imaging spectrometers on Cassini and Galileo.

Also, some non-imaging instruments return truely spectacular images. The MOLA laser altimeter on Mars Global Surveyor is a non-imaging instrument, and it's "primary" data pre-flight tended to be described as the surface profiles from single passes, but the dense coverage it returned of altimetry data, *WITHOUT* gross artifacts in the form of pass-to-pass striping or the like results in truely spectacular images of Mars topography.

We'll see what we might make from non-imaging instruments that are interesting, when we have a payload list and some instrument details.

Posted by: BruceMoomaw Jun 2 2005, 10:37 AM

Well, I can give you the full instrument list (although not in much detail):

(1) Multi-channel microwave spectrometer (for very deep temperature, water vapor and ammonia profiles).

(2) UV imaging spectrometer (another version of the "ALICE" on Rosetta and New Horizons).

(3) Magnetometer

(4) Plasma detector ("JADE", or Jovian Auroral Distributions Experiment).

(5) Energetic particle detector

(6) Plasma wave detector

(7) Camera

Plus the radio science experiment -- which is actually the most important one on Juno, with the possible exception of the microwave spectrometer and magnetometer, given its ability to make gravity-field measurements so precise that they will settle both the question of whether Jupiter has a rocky core, but even detect the convection currents from very deep winds.

Nothing in there for images, except for the camera itself and ALICE (plus whatever maps they get out of the microwave instrument). As I say, this is a very important mission scientifically -- giving us our deepest look yet into Jupiter's innards -- but it won't have much charm for nonscientists.

Posted by: garybeau Jun 2 2005, 12:39 PM

I would have thought / hoped the next Jovian mission would have been a Europa orbiter. This is one of the few places besides Mars that holds any prospects for life. Whatever happened to Nasa's "follow the water" mantra. The Juno mission just doesn't stir up any passion.

Posted by: Chmee Jun 2 2005, 03:03 PM

Hopefully Juno wont have an umbrella style high gain antenna like Galileo! rolleyes.gif

Seriously, it will be great to see movies of Jupiter's weather and cloud patterns, something Galileo could not do because of the high gain antenna issue.

i am also surprised that a Europa mission was not selected. Must have been too much money.

Posted by: tty Jun 2 2005, 04:40 PM

QUOTE (garybeau @ Jun 2 2005, 02:39 PM)
I would have thought / hoped the next Jovian mission would have been a Europa orbiter. This is one of the few places besides Mars that holds any prospects for life.  Whatever happened to Nasa's "follow the water" mantra. The Juno mission just doesn't stir up any passion.
*


I could certainly imagine that life might exist deep in the Jovian atmosphere. A bit hard to get at though. wink.gif

tty

Posted by: volcanopele Jun 2 2005, 05:51 PM

QUOTE (garybeau @ Jun 2 2005, 05:39 AM)
I would have thought / hoped the next Jovian mission would have been a Europa orbiter. This is one of the few places besides Mars that holds any prospects for life.  Whatever happened to Nasa's "follow the water" mantra. The Juno mission just doesn't stir up any passion.
*

Actually, I'm glad to see a mission that does tow that line, astrobiologically speaking. In terms of a Europa orbiter, such a mission would be a flagship, billion-dollar class mission, a step up in pay scale from the New Frontiers missions. Believe it or not, I am fully behind the Europa orbiter, once I started thinking of it as a two-year Io mission with a 30-day extended mission in Europa orbit.

Posted by: BruceMoomaw Jun 3 2005, 01:17 AM

Well, the Decadal Survey recommended -- and the new NASA Solar System Roadmap document backs again -- a Europa orbiter; but it's too expensive to be an NF mission. Instead, the Roadmap report calls it a "small Flagship" mission -- that is, in the $700 million to $1.5 billion price range -- and strongly recommends it for a launch in 2014, maybe even with a small Europa lander added. 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. (Rumor has it that, due to his engineering ignorance, he was bamboozled into backing that grotesquerie by his pro-nuclear brother.)

Indeed, the Roadmap recommends two more small Flagship missions after that at 5-year intervals -- the first probably being a Titan Explorer (an aerobot to repeatedly sample the surface looking for organics, and relaying its data directly back to earth without a Titan orbiter), and the second being a Venus Explorer (some kind of long-lived surface vehicle using the temperature-resistant electronics that will hopefully be available by 2024 -- maybe a surface rover as the report recommends, but maybe instead a repeat-landing aerobot like the Titan mission). Then at some point in the 2025-35 period, it recommends one really big Flagship mission in the multi-billion dollar class, with several possible targets.

Posted by: BruceMoomaw Jun 3 2005, 01:21 AM

Jason is likely to be disappointed if he thinks of the Europa orbiter as "a 2-year Io mission with one month in Europa orbit". The plans for it, which have long ago been worked out in detail, call for it to make repeated flybys of Ganymede and Callisto during its 2-year orbital tour before settling into Europa orbit -- but NOT to get any closer to Jupiter than Europa, in order to minimize its radiation dose. The plan now is not even to have it make a close approach to Jupiter at its initial arrival -- instead, 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).

Posted by: volcanopele Jun 3 2005, 01:35 AM

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.

Posted by: Gsnorgathon Jun 3 2005, 02:16 AM

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.

Posted by: Redstone Jun 3 2005, 02:32 PM

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.

Posted by: Gsnorgathon Jun 3 2005, 09:58 PM

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.

Posted by: BruceMoomaw Jun 3 2005, 10:57 PM

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.

Posted by: um3k Jun 4 2005, 02:38 AM

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

Posted by: 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.

Posted by: garybeau Jun 4 2005, 12:18 PM

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/press/2002/survey_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/index.cfm?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.

Posted by: 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.

Posted by: 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.

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.

Posted by: Decepticon Jun 5 2005, 03:29 AM

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

Posted by: BruceMoomaw Jun 5 2005, 06:23 AM

[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).

Posted by: BruceMoomaw Jun 5 2005, 06:32 AM

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.)

Posted by: BruceMoomaw Jun 5 2005, 06:53 AM

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/ESSP_Report_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.

Posted by: BruceMoomaw Jun 5 2005, 07:09 AM

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).

Posted by: dvandorn Jun 5 2005, 09:30 AM

The other real difference between potential Martian and Europan life is that Martian life, if it exists today, is likely to be very, very simple -- bacteria at best. Whereas if Europa has developed life, there are fewer reasons to believe that it would *have* to be very simple. With an aquatic environment and enough heat from within the moon's rocky core, Europan life has no greater obvious evolutionary limits than Earth's sea life does.

As much as finding fossilized bacteria, or even live bacteria, on Mars would prove a point and be interesting in and of itself, it wouldn't give us a whole lot of data on how life might develop outside of Earth's influence. Multi-cellular organisms (or their equivalent) in Europa's oceans would demonstrate how life might be able to organize itself in different ways to those we see on Earth. For example, would genetic encoding be DNA-based? Or has Europan life found different ways to organize, evolve and propogate?

I think the most boring thing we could possibly find on Europa would be -- fish. Regular old fish, with scales and gills and DNA and everything. But it would sure hint at some common ancestor to life on both worlds, wouldn't it?

My bets are on truly alien life forms swimming in Europa's oceans, whether they look like fish or not.

-the other Doug

Posted by: tedstryk Jun 5 2005, 10:32 AM

QUOTE (BruceMoomaw @ Jun 5 2005, 07:09 AM)
  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.

Posted by: tedstryk Jun 5 2005, 10:35 AM

QUOTE (BruceMoomaw @ Jun 5 2005, 06:53 AM)
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.
*

I hope so, but I am biting my nails considering it seemed quite definite in the late 1990s...lets hope it doesn't get tied to a political push again.

Posted by: garybeau Jun 6 2005, 12:55 AM

QUOTE (BruceMoomaw @ Jun 5 2005, 01:23 AM)
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).
*


Thanks for all the info you provided. I hadn't heard about a Nasa/ESA cooperative effort for a Europa orbiter That's great news I hope the plans don't get stalled.

If leaving a Eurpan orbit is not practical, I guess the next best thing to do is leave it in orbit and let the intense radiation sterilize the craft. Once in orbit, how long would a spacecraft remain in an orbit around Europa? With little or no atmosphere, I would think a spacecraft would remain there for quite a few years. Are there other factors that would cause the orbit to decay such as tidal forces or resonant forces from the other moons?

I read the link that you provided from The National Academies on Preventing the Forward Contamination of Europa. I'm not sure if I share their optimism on the ability to satisfactorily sterilize a spacecraft. Even by their admission, a spacecraft will never be 100% free of biological organisms or spores, but only reduced to an acceptable level. I remember the surprise and disbelief when a piece of the Surveyor lander was brought back and Streptococcus bacteria were found to be still alive inside the camera. They were exposed to the vacuum of space, zero moisture, extreme temperature swings (night and day on the moon are 14 days long) and they were there for almost three years.
The biggest fear would be if the spacecraft missed it's orbital insertion target (i.e. Mars Climate Orbiter) and impacted directly into the moon. Without an atmosphere to slow it down, it would impact hard and pieces would most likely be buried under a protective layer of ice. I am still 100% for a Europa orbiter, but I think that we have an obligation to keep the risk of contamination as close to zero as we can. At least until we can confirm if any life currently resides there.

Posted by: JRehling Jun 6 2005, 01:30 AM

Three miscellaneous comments for this thread, from the concrete to the fanciful:

1) Orbits around Europa are very unstable due to the presence of other gravitational sources in the vicinity (the same is true of the Moon, but of course, Jupiter is much pushier than Earth gravitationally). So whenever the craft dies, it will not be long in impacting Europa's surface. Months, not years.

2) It is not believed that a europan ocean would have enough energy to support advanced life. That is surely somewhat speculative, but take that for what it is. The suspicions lean towards bacteria or nothing.

3) If (2) were wrong, the presence of, eg, fish would not point to a common origin. Earthly biota have reinvented key phylogeny properties many times. For example, "tree"ness has evolved very many times, on separate family branches. I think we can be dead certain (NPI) that fish would not make the ride from/to Earth to/from Europa on meteorites, in any form whatsoever.
If we do find life elsewhere, macroscopic resemblance would be a much less convincing evidence of common origin than molecular resemblance. Chirality to start with, use of the DNA codons vs. RNA codons in equivalent roles next. Someone with biology training past ninth grade could comment on others.

Posted by: Redstone Jun 6 2005, 02:17 AM

QUOTE (garybeau @ Jun 4 2005, 12:18 PM)
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.

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.
*


While a NASA only Europa mission may not be "on" right now, here's another Griffin quote made to the press on May 12:

QUOTE (Administrator Mike Griffin)
The Science Mission directorate wants to do a Europa mission, the National Academy of Sciences wants to do a Europa mission, I want to do a Europa mission. When we can afford it in the budget, we'll do it.


Sounds like a NASA mission is still on the cards, but we just need to wait a while. Remember Griffin is focussing on the manned program right now, the JUNO announcement notwithstanding. Once the ISS and CEV plans get settled in a few months, I'd expect Griffin to turn to the long-term detail of the space science program.

Posted by: Bob Shaw Jun 6 2005, 01:58 PM

Some comments on life on Mars (and elsewhere) and on Surveyor 3:

Life isn't divided into success and failure by 'simplicity' and 'complexity' - the only 'success' is survival of the organism through it's offspring (so human intelligence and fecundity may well not be good success strategies). The sophistication of 'simple' Martian/Europan life may not be obvious to a big game hunter, but a microbiologist might well disagree. Let's not get hung up on macro-organisms!

And sadly, there's a persuasive view of the Surveyor 3 camera which suggests that the bacteria found within it were due to laboratory contamination, so the jury has to still be out on the survival of spores etc in space.

Considering the early bombardment history of the planets, plus the recent claims of an equally early warm and wet Earth I'd be unsurprised to discover that life on Earth and Mars share a common ancestry (or are at least distant cousins, survivors of crustal reformatting by giant impacts and natural interplanetary flight).

If and when we ever see a substantial industrial base on the Moon, then that's the place to look for meteorites bearing the early signs of life - or maybe even smaller bodies, like asteroids, Phobos and Deimos, comets...

Posted by: JRehling Jun 6 2005, 03:26 PM

QUOTE (garybeau @ Jun 2 2005, 05:39 AM)
I would have thought / hoped the next Jovian mission would have been a Europa orbiter. This is one of the few places besides Mars that holds any prospects for life.  Whatever happened to Nasa's "follow the water" mantra. The Juno mission just doesn't stir up any passion.
*


Well, forget for a moment the sibling (parent) rivalry between Jupiter and the other worlds near it.
What we're talking about here is Jupiter -- one of the three most central planets to space exploration -- finally getting its Pioneer Venus, finally getting its Mariner 9. Among the worlds that have had orbiters (preCassini), one that is totally unique in structure and atmosphere. And with Galileo's Jupiter science having been a mere trickle, one that has been seen more like a world that's received six flybys than has ever been the subject of an orbiter's science in the way that Mars has received six, and Venus several (mainly Soviet, but two American).
It's got an atmosphere that is in some ways (thick water clouds, for one; sweeping storm fronts bearing rain) more earthlike than either Venus's or Mars's. A structure which is totally unlike that seen in the inner solar system. And note that Cassini is not giving Saturn the look that Juno would give Jupiter. Cassini's closest approach to Saturn already has taken place, and it wasn't even looking at the planet. Saturn's rings are both a barrier for close approaches and a factor that neutralize the particle environment that we want to see at Jupiter. Remember, Jupiter is our best analogue to most of the extrasolar planets we've discovered, and knowing it better could prove essential, obliquely, to our efforts to find earthlike planets sharing those systems with giant neighbors.
I don't think the first *real* Jupiter orbiter is a low-passion mission at all. With its camera a minor player, it may rank low in terms of (intended) eye candy, but planetary science is a forensic science, and fingerprints may seem less exciting than photos of a corpse, but they can be more telling about the history.
I'm excited about Juno -- even eye candy should be forthcoming. But I'm pretty curious about what's beneath the hydrogen. Whether it's 1 earth-mass or 30 earth-masses may have little visible effect at the surface, but the result will tell us a lot about origins. And given that the source of magnetic fields remains a bit of a mystery (eg, Mercury's; the large differences between those of the giant planets), more information on that matter is going to be welcome as well.

Posted by: tedstryk Jun 6 2005, 05:02 PM

I think the six-flybys analogy is a good one (seven if you count Ulysses Jupiter Distant Flyby a year or two ago which did yield some interesting particle and fields data, particularly with regards to dust from Io) in terms of data return, although it was over an extended period of time, so for things such as Io coverage, it at least had a long temporal baseline. I see it as a series of mini-flybys. I do hope that an Amalthea flyby can be squeezed into Juno. It will be penatrating in that far, and I don't see another spacecraft doing that for the forseeable future (I don't think it would be good to even risk an Io mission). It is a shame Galileo didn't take remote sensing data. Given its illness and how badly it got zapped however, had it been making turns to do imaging at the time of the encounter at first Io and then Amalthea, it would likely have at least safed, costing us the data on the near-Amalthea particles, a lot of particle and fields stuff, and we might have lost the spacecraft all together. The budgetary issues non withstanding, I would have loved Galileo images close to Amalthea, but I am skeptical the spacecraft could have pulled it off. I have been working on some of the images Galileo took, and it is a very interesting world, especially given the new shape-model release. I have worked hard on the high resolution E26 image, and you may have seen my result - it is faux-super-res, created by stacking various resamplings and processings of the same image. It creates a relatively sharp image despite oversampling, although it doesn't truly increase resolution. I also tried to correct overexposure in part of the image.
http://img106.echo.cx/my.php?image=amale26b2qo.jpg
Also, have worked on the only three Galileo color images of Amalthea, taken during the primary mission. I created color images using the various filter combinations available (the E4 data had a fourth filter available, but I didn't use it for color). I also used all available images (3 for G2 and C3, 4 for E4, although the E4 data was so distant it really wasn't worth it) to creat super resolution black and white images. I then overlaid the color data on these. Here is the result:

http://img299.echo.cx/my.php?image=galileocol5jl.jpg

Posted by: Bjorn Jonsson Jun 6 2005, 05:26 PM

I vaguely remember reading somewhere that Juno will be spin-stabilized, probably making it difficult to obtain high-res images of satellites like Amalthea or even Io during fast flybys. Or maybe I'm confusing Juno with something else (Inside Jupiter/JASSI etc.). Does anyone know if it will be spin-stabilized ?

Posted by: BruceMoomaw Jun 6 2005, 07:27 PM

Yeah, it will be -- which will certainly interfere with any imaging during a flyby, but would not make it impossible (or so low-quality as not to be worth the effort). Again, I intend to contact Bolton for more on all this in the very near future.

Posted by: Stephen Jun 8 2005, 09:52 AM

QUOTE (BruceMoomaw @ Jun 5 2005, 06:53 AM)
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.

On that last score I note that someone wrote in a recent scientific paper titled http://www.lpi.usra.edu/meetings/lpsc2005/pdf/2197.pdf:

QUOTE
The JIMO SDT report calls for a capability to sample to a depth of ~ 1 m. Our preliminary work suggests that it is unlikely that this will be accomplished under the present constraints. Innovative, light weight systems for active sampling to depths of several cm have been evaluated; a lander including such a system could weigh in at less than the allocated 375 kg. However, if the science community strongly desires sampling to depths of ~ 1 m, we believe it will be necessary to significantly increase the lander total mass allocation from its present level.

Should that prove to be the case, if you want to be able to drill even deeper ("a couple of meters") I guess that would mean an even bigger increase in the lander's weight.

Posted by: Myran Jun 8 2005, 12:12 PM

dvandorn wrote:

"I think the most boring thing we could possibly find on Europa would be -- fish. Regular old fish, with scales and gills and DNA and everything. But it would sure hint at some common ancestor to life on both worlds, wouldn't it?"

Its true that active swimmers would have to be streamlined to travel efficiently in water, but no or extremely little oxygen would mean no gills and active swimming less likely. (No photosynthesis possible under a mile of ice).

If there any life on Europa its more likely to be colonies of organisms gathered around warm springs getting their nourishment from chemical processes, what shape they might have im not qualified to even speculate about. The big question is if liquid water and volcanic heat is enough to get life started.

-"-

As for sampling and investigating deeper down: The idea of a robot that melts itself down to reach any possible ocean beneath the ice is a clever idea, but its not even on serious consideration so I wont see it in my lifetime.

Posted by: JRehling Jun 8 2005, 04:47 PM

QUOTE (Myran @ Jun 8 2005, 05:12 AM)
As for sampling and investigating deeper down: The idea of a robot that melts itself down to reach any possible ocean beneath the ice is a clever idea, but its not even on serious consideration so I wont see it in my lifetime.
*


(GOING STILL FURTHER OFF TOPIC, HERE)

Back in the salad days before we knew so much, it seemed possible to melt through the ice. But two compounded difficulties pretty much kill that idea. One, the ice is much deeper than we might have hoped. 20 km seems to be the direction that the evidence is pointing. Then, the factor that makes that especially lethal is that if the ice has any impurity at all, melting through it would cause the impurity to accumulate at the bottom of the hole, eventually creating a mass of salt or somesuch, which heating to 10C would not make go away.

Enceladus could stand in as a new arena for the exact same hopes. Cassini's early imaging seemed to deflate those hopes, for, although Enceladus showed young surface, it also showed considerable relief, which means the ice must be relatively thick (even when you allow for the very weak gravity). But, the last flyby of the south pole showed "tiger stripes" analogous to Europa's triple bands, and nonimaging instruments indicate that H2O seems to appear in Enceladus's vicinity at a considerable rate -- these results may combine to indicate that live geysers exist at high latitudes, which would provide a possible point of axis for a Enceladus Underwater Explorer (???). Not to help Myran too much, though -- I don't see that happening in our lifetimes, either!

Posted by: Decepticon Jun 10 2005, 02:03 AM

They are sending a Probe to Jupiter and according to this article Europa Ganymede and Callisto will not be studied?!?!


EUROPA should be Number 1 on the priority list.


I'm so upset by this article. http://www.space.com/searchforlife/seti_juno_050609.html

Posted by: Gsnorgathon Jun 10 2005, 05:30 AM

FWIW, a wee writeup at http://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=1596&mode=thread&order=0&thold=0, and the ever-popular "http://www.swri.org/press/2005/Juno.htm" of the spacecraft. Solar!

Posted by: JRehling Jun 10 2005, 04:30 PM

QUOTE (Decepticon @ Jun 9 2005, 07:03 PM)
They are sending a Probe to Jupiter and according to this article Europa Ganymede and Callisto will not be studied?!?!
EUROPA should be Number 1 on the priority list.
I'm so upset by this article. http://www.space.com/searchforlife/seti_juno_050609.html
*


For some reason, I can't load that article. I get a blank screen.

But, the reason why Europa has been shortchanged is organizational fumbling of a high degree. I can remember when Pluto and Europa were competing for a launch date that would have already taken place, and the winner of the competition was... neither.
Europa Screw-up #1 was to bundle three bizarrely dissimilar missions under a single planning structure (a Europa orbiter, a Pluto flyby, and a solar probe), even though the three had little in common except they were spacecraft that would not land anywhere.
Europa Screw-up #2 was to propose JIMO, aka Mission Impossible, so that we had to wait until it fell back to the ground when the gravity of common sense had counteracted the upward momentum of bad politics. JIMO was meant to be the sugarcoating on an expensive nuclear propulsion research program, which was motivated by a way to drain NASA funding for a quasi-military project. JIMO's math never worked, and it was the brainchild of people who don't care if the math works before they sic some government agencies on a job.
As far as Europa was concerned, the JIMO proposal was an X year delay, with X being mercifully hastened by O'Keefe's departure.

As it turns out, a few years ago was probably too early to have commited to a Europa mission design. It's taken a while for Galileo results to be digested, and even now, I think a Europa exploration architecture has to be considered very carefully. We're playing 20 questions with Europa, where each question costs a billion dollars or so. The best next mission to Europa might not be the best mission if we were only sending a total of one. We've got to consider what the next mission would be depending upon the first one, and then plan to make absolutely sure that no mission asks a yes/no question where the answer is, "Neither yes nor no. That's the wrong question."

It's clear that Juno is a good Jupiter mission and it can go ahead and take place. Waiting for the Europa situation to clarify before sending a mission to Jupiter is like waiting to figure out next year's taxes before eating breakfast. The two things are unrelated. Europa shouldn't preempt a good Jupiter mission any more than Europa should preempt a good Mercury mission.

Posted by: tedstryk Jun 10 2005, 04:55 PM

Another factor to consider is that a decent Europa Orbiter mission probably can't be done as a New Frontiers mission. Juno will allow some fundamental Jovian science to be accomplished. And it is one of the most productive missions that can be accomplished at Jupiter on such a budget.

Posted by: edstrick Jun 11 2005, 12:16 AM

Part of the problem is that *any* Europa orbiter mission is ***HARD***.
It takes a tremendous amount of Delta-V (velocity change) and only some of that can be done by gravity assist flyby's of the moons. Add to that the radiation environment that was crippling and killing Galileo as the extended missions proceeded, but on a continuous basis as you get in toward Europa, rather for only the periapsis pass part of month long orbits. You need extra radiation hardened electronics, AND massive shielding. The original Europa orbiter mission was nuked as it's projected costs passed some 1.2 billion, heading for and past 1.5 billion <or so>, when it was supposed to be an under 1 billion $ mission.

Good management and realistic objectives will help tremendously, but they won't solve the basic problem. It's a damn hard mission.

Posted by: Decepticon Jun 11 2005, 02:37 AM

Even with Galileo type flybys would make me happy. From the sounds of the space.com article Juno will not get that far out?!

Posted by: Phil Stooke Jun 11 2005, 03:21 AM

Ted, I missed your Amalthea images until just now - they are very nice. I think I recall a similar multispectral sequence of Thebe... would be interesting to see it.

Phil

Posted by: tedstryk Jun 11 2005, 03:30 AM

QUOTE (Phil Stooke @ Jun 11 2005, 03:21 AM)
Ted, I missed your Amalthea images until just now - they are very nice.  I think I recall a similar multispectral sequence of Thebe... would be interesting to see it. 

Phil
*


I am planning to work on that. I am also trying to create a "mask" for the E26 image based on color data from other orbits.

Posted by: BruceMoomaw Jun 11 2005, 09:04 PM

Juno's orbit will go from only 4500 km above Jupiter's 1-bar air pressure level (it will be even closer to the tops of the ammonia clouds) all the way out to 30 Jupiter radii from the planet. (They need to get that close to ensure really high-resolution gravity and magnetic maps of Jupiter -- it's the same orbit planned for the "INSIDE Jupiter" mission that was a Discovery finalist twice and has now been combined with two other Jovian Discovery proposals to create Juno.)

That periapsis will wander somewhat in latitude, although I haven't got specific figures yet -- but I believe it's enough to theoretically allow flybys of any mooon out to Callisto. PI Scott Bolton tells me that there are currently no plans for flybys of any of the moons (although, during our previous conversations, he had expressed some interest in the idea during the extended mission); but the description in Space.com says that Juno's camera may be used for longer-distance photos of Io and Amalthea.

It's important to remember that this mission has radically different goals from any mission to study Europa or the other moons -- its purpose is to study JUPITER, by God, and specifically its composition and the size of its rock/ice core, which are extremely important in answering questions about how the giant planets actually formed. (This is one of the most important questions for planetary scientists right now, and there are two radically different theories.) Also Jupiter's polar magnetosphere, which the NASA's Sun-Solar Systems Directorate -- separately from its Solar System Directorate -- has also declared to be an extremely important short-term goal for its own researches and worthy of a mission. To achieve all this, it needs an orbit completely different from those that would be used by a moon-studying orbiter -- and since such a mission is also simpler and cheaper, they decided, entirely logically, to fly it first.

As for the Europa mixup, John Rehling doesn't mention the biggest villain of all: Dan Goldin, aka "Captain Crazy". NASA's science advisory board recommended officially -- and entirely sensibly -- that a Pluto mission, which required no new technology at all, should be flown BEFORE the Europa Orbiter, and specifically in 2003. Dan Goldin, however, was determined to reverse their order because of his personal obsession with astrobiology at all costs -- "Nobody gives a damn about Pluto", he told his staffers. (His repeated urgings that NASA should use radically new technologies, entirely unnecessarily, to build a teeny-weeny Pluto probe --"the size of my fist", to quote one disgruntled researcher -- were, as he privately told his staffers, just a cover for the fact that he intended to kill the Pluto mission completely.)

The result, given the very real and major new technological difficulties in flying a Europa Orbiter, were that we didn't get either mission -- or rather that the Pluto mission was delayed until 2006 and finally rammed through by Congress over the dead bodies of Goldin, Sean O'Keefe and President Bush, which means both a more expensive Pluto mission and a distinctly scientifically inferior one to what we would have had had it been launched in 2003 or 2004. The case for such a mission, both scientifically and fiscally, was so strong that even the GOP Congress was finally firmly convinced of the idiocy of not flying it. (To my continuing amazement, I myself ended up playing a significant role in getting that decision made -- largely due to a SpaceDaily article I published in 2000 pointing out that either the Stardust or CONTOUR comet probe could be easily redesigned to fly a Pluto mission cheaply -- which is why I have a free ticket to its launch next January. No doubt other people had come up with the same idea; but Goldin, it later turned out, had been threatening to cut off their grants if they didn't keep their mouths shut. They had no such leverage over me, and so I ended up -- entirely accidentally -- belling the cat. But I digress.)

Anyway, as a result of Goldin's monomania, we ended up getting both a Pluto mission later and worse and more expensive than we could have had it, but also probably some unnecesary delays to Europa Orbiter -- which were then made worse by the fact that O'Keefe, due to his total lack of engineering training, fell for the cretinous JIMO scheme to fly a nuclear-powered battleship to Jupiter, even though the science community had officially stated that it didn't want it. (In this respect, as in many others, he got rolled by his unscrupulous NASA underlings; but one scientist has told me that O'Keefe's nuclear-enthusiast brother also helped talk him into it.) Now -- years later than we could have been -- we're back to Square One where Europa Orbiter is concerned.

What Ed Strick says is also true: the first version of Europa Orbiter was cancelled becuase it had a $1 billion cost cap, which simply could not be met. Now NASA's new Solar System Roadmap calls for it to be the first of the new class of "Small Flagship" Solar System mission -- costing between $700 million and $ 1.5 billion -- to be launched at 5-year intervals. Europa Orbiter is recommended for launch in 2014 (and it looks more and more as though the ESA will collaborate with us on it). The second Small Flagship is likely to be to Titan in 2019, and the third to Venus in 2024.

Posted by: MiniTES Jun 15 2005, 02:51 PM

QUOTE (BruceMoomaw @ Jun 11 2005, 09:04 PM)
Juno's orbit will go from only 4500 km above Jupiter's 1-bar air pressure level (it will be even closer to the tops of the ammonia clouds) all the way out to 30 Jupiter radii from the planet.  (They need to get that close to ensure really high-resolution gravity and magnetic maps of Jupiter -- it's the same orbit planned for the "INSIDE Jupiter" mission that was a Discovery finalist twice and has now been combined with two other Jovian Discovery proposals to create Juno.) 

That periapsis will wander somewhat in latitude, although I haven't got specific figures yet -- but I believe it's enough to theoretically allow flybys of any mooon out to Callisto.  PI Scott Bolton tells me that there are currently no plans for flybys of any of the moons (although, during our previous conversations, he had expressed some interest in the idea during the extended mission); but the description in Space.com says that Juno's camera may be used for longer-distance photos of Io and Amalthea.

It's important to remember that this mission has radically different goals from any mission to study Europa or the other moons -- its purpose is to study JUPITER, by God, and specifically its composition and the size of its rock/ice core, which are extremely important in answering questions about how the giant planets actually formed.  (This is one of the most important questions for planetary scientists right now, and there are two radically different theories.)  Also Jupiter's polar magnetosphere, which the NASA's Sun-Solar Systems Directorate -- separately from its Solar System Directorate -- has also declared to be an extremely important short-term goal for its own researches and worthy of a mission.  To achieve all this, it needs an orbit completely different from those that would be used by a moon-studying orbiter -- and since such a mission is also simpler and cheaper, they decided, entirely logically, to fly it first.

As for the Europa mixup, John Rehling doesn't mention the biggest villain of all: Dan Goldin, aka "Captain Crazy".  NASA's science advisory board recommended officially -- and entirely sensibly -- that a Pluto mission, which required no new technology at all, should be flown BEFORE the Europa Orbiter, and specifically in 2003.  Dan Goldin, however, was determined to reverse their order because of his personal obsession with astrobiology at all costs -- "Nobody gives a damn about Pluto", he told his staffers.  (His repeated urgings that NASA should use radically new technologies, entirely unnecessarily, to build a teeny-weeny Pluto probe --"the size of my fist", to quote one disgruntled researcher -- were, as he privately told his staffers, just a cover for the fact that he intended to kill the Pluto mission completely.) 

The result, given the very real and major new technological difficulties in flying a Europa Orbiter, were that we didn't get either mission -- or rather that the Pluto mission was delayed until 2006 and finally rammed through by Congress over the dead bodies of Goldin, Sean O'Keefe and President Bush, which means both a more expensive Pluto mission and a distinctly scientifically inferior one to what we would have had had it been launched in 2003 or 2004.  The case for such a mission, both scientifically and fiscally, was so strong that even the GOP Congress was finally firmly convinced of the idiocy of not flying it.  (To my continuing amazement, I myself ended up playing a significant role in getting that decision made -- largely due to a SpaceDaily article I published in 2000 pointing out that either the Stardust or CONTOUR comet probe could be easily redesigned to fly a Pluto mission cheaply -- which is why I have a free ticket to its launch next January.  No doubt other people had come up with the same idea; but Goldin, it later turned out, had been threatening to cut off their grants if they didn't keep their mouths shut.  They had no such leverage over me, and so I ended up -- entirely accidentally -- belling the cat.  But I digress.) 

Anyway, as a result of Goldin's monomania, we ended up getting both a Pluto mission later and worse and more expensive than we could have had it, but also probably some unnecesary delays to Europa Orbiter -- which were then made worse by the fact that O'Keefe, due to his total lack of engineering training, fell for the cretinous JIMO scheme to fly a nuclear-powered battleship to Jupiter, even though the science community had officially stated that it didn't want it.  (In this respect, as in many others, he got rolled by his unscrupulous NASA underlings; but one scientist has told me that O'Keefe's nuclear-enthusiast brother also helped talk him into it.)  Now -- years later than we could have been -- we're back to Square One where Europa Orbiter is concerned. 

What Ed Strick says is also true:  the first version of Europa Orbiter was cancelled becuase it had a $1 billion cost cap, which simply could not be met.  Now NASA's new Solar System Roadmap calls for it to be the first of the new class of "Small Flagship" Solar System mission -- costing between $700 million and $ 1.5 billion -- to be launched at 5-year intervals.  Europa Orbiter is recommended for launch in 2014 (and it looks more and more as though the ESA will collaborate with us on it).  The second Small Flagship is likely to be to Titan in 2019, and the third to Venus in 2024.
*


Why is it spinning? Granted, the science to be done doesn't require imaging, but you CAN do some really good science with cameras. Recall the differences in what we learned between Pioneer and Voyager, much of which was due to the fact that Voyager had a camera. How much more would it cost to build a three-axis stabilized craft? If it is spinning, are our computer processing techniques good enough to reconstruct images better than we could with Pioneer. Or can I say the magic words "scan platform".... wink.gif

Who will be in charge of building the small flagships? Are these going to be MRO-class missions, or more like Discovery missions to the outer planets? I'm assuming Juno will have some RTGs to play with? What does the instrumentation look like on the possible Europa orbiter? It needs a radar, and of course a camera.

Posted by: Phil Stooke Jun 15 2005, 03:28 PM

Spinning doesn't have to mean Pioneer 10-class imaging. For one thing we are decades on in technological development! A modern push-broom scanner could produce very high quality images from a spinning platform, and if the thing can be tilted in the plane of the rotation axis it can have quite a range of viewing angles. Giotto imaged like this, albeit with a dinky little detector (sorry, Uwe) - but it could be done very well today.

I am also one of those who long for high resolution images of Amalthea.

Phil

Posted by: Decepticon Jun 15 2005, 08:17 PM

Can Juno at least take Movie like animations of the atmosphere?

This was something I was looking forward to on the Galileo mission until the antenna flop.

Posted by: BruceMoomaw Jun 15 2005, 10:17 PM

According to the Space.com article, it will indeed take some movies of cloud patterns -- although I don't know how many there will be. (It's important to keep in mind that Juno's com rate will be much lower than Galileo's was planned to be; and images require MUCH more bits than any other type of data the craft will send.)

I've recently learned that the camera will be a slightly modified version of the descent imager for the 2009 MSL -- which means it will take 2-D images instantanteously rather than using the one-line "pushbroom" technique, and that all three colors will be imaged simultaneously rathern using a filter wheel. This means that -- if the spacecraft's spin axis is simply pointed in the right direction -- it could take very rapid-fire images during a flyby of a Jovian moon, although it could store only a limited number of them. (In any case, Bolton tells me that there are currently no plans for moon flybys -- although he expressed some interest in the idea during our earlier conversations, and I think you might see it during an extended mission after the 32-orbit primary mission is over.)

Even a pushbroom camera on a spinning spacecraft, however, could take far better images than the instrument on Pioneer 10 and 11 -- which was simply a single light-meter, equipped with a filter wheel, which could record data during each of the craft's rotations and use (I believe) a tiltable mirror to build up a 2-D image -- VERY SLOWLY, since the Pioneers didn't spin that fast. (By contrast, a 1-line CCD array on a spinning craft can build up a high-res 2-D image during one single sweep of a spinning craft, if of course the CCD line is parallel to the craft's spin axis.) It took 40 minutes for the Pioneers just to build up a 200-line image, which by itself meant that the resolution was limited. It's important to keep in mind that the purpose of the Pioneers was just to serve as scouts of the environmental dangers that would be encountered by later, more advanced Jupiter craft -- dust in the Asteroid Belt, and the intensity of Jupiter's radiation belts -- and so they wer designed to be extremely simple and cheap, since fields and particles and dust detectors don't require complex pointing and have a low bit rate that doesn't require high-speed communcations or a tape recorder. Therefore, any additional science data from the Pioneers was regarded as gravy, and only a few simple instruments capable of working under those conditions were added: the Imaging Photopolarimeter, a UV photometer and an IR radiometer. (The images returned by the IPP, in fact, would have been regarded as successful even if their resolution was no better than that of Earth-based Jovian photos; the instrument's main purposes were to map zodiacal light and study the optical properties of Jupiter's clouds at sunlight angles unavailable from Earth.)

Posted by: BruceMoomaw Jun 15 2005, 10:19 PM

"...rathern using a filter wheel" is really "...rather THAN using a filter wheel". *sigh*

Posted by: Sunspot Jun 15 2005, 10:46 PM

Oh... thats a shame, I guess we probably wont ever see spectacular images of Jupiter like those from Galileo again in our lifetimes. sad.gif

Posted by: Phil Stooke Jun 15 2005, 11:26 PM

Actually we will see some good stuff in 2007 from New Horizons.

Phil

Posted by: edstrick Jun 15 2005, 11:27 PM

Why is it spinning?
Field and Particles instruments and gravity measurements really like spinning spacecraft. You cross-calibrate magnetometer data perpendicular to the spin axis, and get "whole sky" coverage with the particles instruments you simply can't get with 3-axis controlled spacecraft. Cassini (before program de-scoping) was going to have two scan platforms: One for the imaging and remote sensing spectrometers, One (or was it two?) for scanning the charged and neutral particle spectrometers across the sky. Voyagers and the gutted Cassini had to do special maneuvers to orient particle detectors in desired look-directions. With a scan platform, Voyager still could do remote sensing. Cassini is so crippled by the descoping that it has to constantly trade-off between science investigations as there is no scan platfor at all, and it has to stop all remote sensing to replay data back to Earth, then not transit 2/3 or so of the time while it's taking data. We'd have far more pictures from the mission (better mapping coverage, etc) if they hadn't lost the scan platform to bad management and radical surgery mandated by bean counters.
Oh.. Gravity studies are much helped by the stable attitude and no thruster firing of spin stabilized spacecraft. Note that the "Pioneer Effect" (teeny sunward directed apparent acceleration of the Pioneers in deep space) is utterly undetectible on the Voyagers, due to trajectory peturbations by attitude control thruster firing.

Posted by: BruceMoomaw Jun 16 2005, 02:26 AM

Fear not! We WILL see excellent images of Jupiter again in our lifetime, and in fact very soon. Not only will we have Juno's photos of Jupiter -- and the photos New Horizons will take during its Jupiter gravity-assist flyby in mid-2007 (which will take it just a short distance outside Callisto's orbit, much closer than Cassini came) -- but the Europa Orbiter will spend about 2 years in Jovian orbit setting itself up to enter an orbit almost parallel to Europa's, so that it can then brake into orbit around Europa itself with the absolute minimum of fuel required (which will still be a lot). In order to set up that orbit, it will make about half a dozen very close flybys of Ganymede and two or three of Callisto (along with a dozen of Europa itself) -- and they have always intended to take full advantage of its instrument payload during that long prelude to observe those two moons and Jupiter itself, using all the orbiter's Europa instruments (except maybe its subsurface radar sounder, whose antennas may not be deployed until it's entered Europa orbit). And it WILL have a high data-return rate.

The one part of the Jovian system that we may not see well again for a disappointingly long time is Io. However, serious consideration is being given to making one of the second-priority batch of New Frontiers missions an "Io Observer", which would enter a Jovian polar orbit to minimize its radiation dose, and then make a whole series of repeated close Io flybys to observe that world. (While the radiation environment at Io's orbit is so savage that it would knock out even the radiation-hardened Europa Orbiter in a few days if we tried to put it into orbit around Io instead, the radiation dose that a Jupiter polar orbiter would get during repeated close Io flybys is tremendously smaller -- such a craft could make fully 50 Io flybys before getting the same total radiation dose that the Europa Orbiter mission will get.) There's a good chance that we'll see this launched some time in the early 2020s.

Posted by: BruceMoomaw Jun 16 2005, 02:38 AM

Footnote: the reason that the radiation dose for a Jovian polar orbiter that makes 50 Io flybys would be so much smaller than that for an actual Io Orbiter is because Jupiter's trapped radiation is concentrated not only close to the planet (except for its very closest region), but also around its equatorial plane, where the Galilean satellites orbit. This is also what allows Juno to get away with orbiting so close to Jupiter (with solar panels, yet) without getting quickly fried; during the part of each orbit when it's near Jupiter's equator, it's also very close to the planet and thus closer than the range of Jupiter's most intense radiation belt.

Posted by: edstrick Jun 16 2005, 05:43 AM

And.... It's moving perpendicular to the belts.... like the proverbial bat-out-of-hell!

Posted by: BruceMoomaw Jun 16 2005, 07:44 AM

It would be more accurate to say that they intend to repeatedly thread the hole in the "doughnut" of high-intensity radiation around Jupiter.

Posted by: Analyst Jun 16 2005, 12:34 PM

Bruce, I want your optimism when it comes to future space missions. Your are talking about proposed missions in the 2015 to 2030 timeframe as if it's just waiting and there they are. They will not, at least not all. Roadmaps get changed, very quickly, new ones emerge and disappear.

Look at the Voyager odyssey in the late 1960ies and early 1970ies (TOPS, Grand Tour and so on), look at Galileo and Cassini (Cassini could have done several asteroid flybys, but they saved some dollars in cruise mode). I'm talking only about the cornerstone missions what left the pad. Or see Alan's fight for a (small) Pluto mission.

Analyst, pessimist, realist?

Posted by: JRehling Jun 16 2005, 01:53 PM

QUOTE (Analyst @ Jun 16 2005, 05:34 AM)
Bruce, I want your optimism when it comes to future space missions. Your are talking about proposed missions in the 2015 to 2030 timeframe as if it's just waiting and there they are. They will not, at least not all. Roadmaps get changed, very quickly, new ones emerge and disappear.

Analyst, pessimist, realist?
*


Perhaps in order to please Congress, NASA issues a new, sweeping mission document, revolutionary in its statement of mission goals, that promises a Whole New Plan about every 18 months, and it's like the last New Plan never existed (although the new new one often includes many of the elements of the old new one).
Of course, with O'Keefe's (mercifully) short tenure, we also have had high turnover at the top, not to mention a change in the US Presidency, in the last few years.
Griffin may be less faddish than his predecessors, but we'll have to see about that.

Posted by: MiniTES Jun 16 2005, 05:20 PM

QUOTE (BruceMoomaw @ Jun 16 2005, 02:38 AM)
Footnote: the reason that the radiation dose for a Jovian polar orbiter that makes 50 Io flybys would be so much smaller than that for an actual Io Orbiter is because Jupiter's trapped radiation is concentrated not only close to the planet (except for its very closest region), but also around its equatorial plane, where the Galilean satellites orbit.  This is also what allows Juno to get away with orbiting so close to Jupiter (with solar panels, yet) without getting quickly fried; during the part of each orbit when it's near Jupiter's equator, it's also very close to the planet and thus closer than the range of Jupiter's most intense radiation belt.
*



Huh? SOLAR PANELS? When will they learn... no chance of RTGs at all? How the heck do you any real data rate from Jupiter with solar?

Posted by: djellison Jun 16 2005, 06:25 PM

QUOTE (MiniTES @ Jun 16 2005, 05:20 PM)
How the heck do you any real data rate from Jupiter with solar?
*


Well - it's solar arrays, or no mission at all given the mass and financial constraints.

Consider Rosetta and Stardust - both will/have gone out way beyond martian orbit relying on solar power alone smile.gif

Doug

Posted by: BruceMoomaw Jun 17 2005, 12:08 AM

Yup -- they've had solar panels planned for a Jupiter Polar Orbiter from the very start, a decade or more ago. They also intend them for the Jupiter Multiprobe Flyby mission, whenever that flies -- and one study for NASA's 2001 Outer Planets Exploration Workshop concluded that they were also entirely practical for a SATURN Multiprobe Flyby mission: http://www.lpi.usra.edu/meetings/outerplanets2001/pdf/4113.pdf

The reasons are simple:

(1) Much lower cost.

(2) No safety concerns.

(3) They're not so heavy that you can't easily make them big enough for a Jupiter mission to have a data-return rate of several hundred bps or more -- which is all Juno or those other missions require.

(4) The orbits planned for these missions involve much lower radiation exposure -- one of the major vulnerabilities of solar cells -- than a Jupiter orbiter in the equatorial plane.

Posted by: BruceMoomaw Jun 17 2005, 12:21 AM

QUOTE (Analyst @ Jun 16 2005, 12:34 PM)
Bruce, I want your optimism when it comes to future space missions. Your are talking about proposed missions in the 2015 to 2030 timeframe as if it's just waiting and there they are. They will not, at least not all. Roadmaps get changed, very quickly, new ones emerge and disappear.

Look at the Voyager odyssey in the late 1960ies and early 1970ies (TOPS, Grand Tour and so on), look at Galileo and Cassini (Cassini could have done several asteroid flybys, but they saved some dollars in cruise mode). I'm talking only about the cornerstone missions what left the pad. Or see Alan's fight for a (small) Pluto mission.

Analyst, pessimist, realist?
*



You're right -- but the plans for a Europa orbiter seem, at long long last, to be firm. Mike Griffin was absolutely explicit on the subject in his Congressional testimony; the Decadal Survey and the new Solar System Roadmap have both unambiguously declared it to be the most important non-Mars Solar System mission for the future (as the Decadal Survey did for the Pluto probe just before Congress finally ordered Bush and O'Keefe, over their dead bodies, to fly it); and see the new word from NASA to the Outer Planets Assessment Group at its meeting last week: http://www.lpi.usra.edu/opag/jun_05_meeting/OPAGjun05report.pdf

Apparently Griffin will recommend it for a start in 2007 and flight around 2014 -- just as the S.S. Roadmap recommends.

As for those other missions: the report also says, on the negative side, that the third New Frontiers mission's AO and launch will be delayed until 5 years after Juno, instead of 3 as had been planned --although they hope to speed the schedule back up again after that. You're certainly right in saying that the current schedule in the S.S. Roadmap is over-optimistic -- such plans always are. But after the remaining three top-priority NF missions are also flown (the Moon, Venus, a comet), the Io Obsever was ranked high among the second-priority NF missions by the Decadal Survey -- apparently about first or second-place among them. So, notwithstannding NASA's inevitable delays, there is still a real chance that the Io mission will get flown some time before the end of the 2020s.

Posted by: BruceMoomaw Jun 17 2005, 12:25 AM

You'll notice that I HAVE backtracked from the Io Observer having "a good chance of being flown in the early 2020s" to "a real chance of being flown before the end of the 2020s" -- having now considered the implications of the newly announced stretchout in the New Frontiers schedule. But beyond that, I refuse to retreat.

Posted by: vjkane2000 Jun 17 2005, 02:55 AM

QUOTE (BruceMoomaw @ Jun 16 2005, 05:25 PM)
You'll notice that I HAVE backtracked from the Io Observer having "a good chance of being flown in the early 2020s" to "a real chance of being flown before the end of the 2020s" -- having now considered the implications of the newly announced stretchout in the New Frontiers schedule.  But beyond that, I refuse to retreat.
*


By the end of the 2020s, I'll be 75. I'd rather not wait that long, so I'm hoping for a Discovery-class mission to be proposed and accepted. One, called Volcan, was written up several years ago.

One can imagine what such a mission might look like:

Solar powered.
Number of encounters would be limited by cumulative radiation dose. Galileo experienced ~40Krad per encounter. The solar panels will likely be the limiting factor in the number of enounters. I'm not sure how quickly they degrade. The Volcan proposal include something like 3-5 enounters. Perhaps that can be stretched a bit, and/or the radiation per orbit lessened by choosing an encounter point or orbit inclination to minimize radiation.

The instrument compliment could be pretty simple: The Deep Impact Hi-Res and medium-res camera with visible imagers and near-IR spectrometers. A radiometer would need to also use the Hi-Res optics (possibly replacing the near-IR spectrometer). If the encounters will be very close, then a magnetometer would be nice.

The mission would include as many close encounters as the radiation limit will allow (probably at least 5, maybe 10?) spaced 1 or more months apart to allow time series studies of changes. After that limit is reached, perijove would be raised to a safe distance to allow continued observations from a distance (which is why I'd like to see something with the optical capabilities of the Deep Impact Hi-Res on the craft). Long distance time studies would continue as long as funding would allow. During this phase, observations of Jupiter or encounters with Ganymede or Callisto (radiation at Europa is too high) could be possible, but add to mission complexity and cost.

Posted by: BruceMoomaw Jun 17 2005, 07:17 AM

It's a possibility -- but I suspect you're talking about something that would still hit the NH cost band (which may be why Volcan was rejected). One other Io Discovery mission was proposed: William Smythe's "Firebird" -- a solar-powered craft which would make just a single flyby of Io, but would take thousands of photos at extremely high speed during that one flyby, plus a comparable number of near-IR mineral maps and IR thermal maps, and release two little subprobes to make very low-altitude flights through volcanic plumes carrying mass spectrometers. It would then play back its huge store of recorded data at liesure over several months after its Jupiter flyby. This, of course, would lack any ability to observe changes on Io -- as well as covering much less of its surface -- but it would also cost a lot less. It was rejected, too; but in this case we really are talking about something with a good chance of hitting the Discovery cost band if properly adjusted.

This, of course, raises another, cheaper possibility -- the fact that any craft that makes a Jupiter gravity-assist flyby en route to a more distant destination will also have a chance at one close Io flyby. New Horizons could have made one if that idiot Goldin hadn't delayed it from Nov. 2003 to Jan. 2006 for no reason -- in fact, during the 1990s, when the Pluto Express flyby was being planned for that launch window, Germany expressed interest in adding an Io volcanic-plume probe with a mass spectrometer itself.

In any case, the white paper on Io missions presented to the Decadal Survey -- which is pretty much the latest thinking on the subject -- can be found at http://www.lpi.usra.edu/opag/io.pdf .

Posted by: edstrick Jun 17 2005, 07:22 AM

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.

Posted by: BruceMoomaw Jun 17 2005, 07:22 AM

Turns out I misread that white paper -- Europa Orbiter's planned level of radiation hardness would allow an Io Observer to make not 50 Io flybys, but 100.

Posted by: vjkane2000 Jun 17 2005, 02:00 PM

Cost is, of course, a major issue for any Jupiter mission. The Io mission I described isn't much less complicated than Juno, but also not much more complicated than Messenger or Dawn. With the new spending limits on Discovery and the lack of good missions closer in, I think we'll see more Jovian missions proposed for the discovery program.

Posted by: JRehling Jun 17 2005, 04:19 PM

QUOTE (vjkane2000 @ Jun 16 2005, 07:55 PM)
The mission would include as many close encounters as the radiation limit will allow (probably at least 5, maybe 10?) spaced 1 or more months apart to allow time series studies of changes.  After that limit is reached, perijove would be raised to a safe distance to allow continued observations from a distance (which is why I'd like to see something with the optical capabilities of the Deep Impact Hi-Res on the craft).
*


A difficulty with eccentric orbit orbiters that zoom in to observe inner satellites at periapsis only is that if the mission is not very long, you observe only a limited range of lighting conditions, and with tidally-locked rotations, you observe a limited range of longitudes. This is why we've seen one side of Io much better than the other (from Galileo) and keep seeing similar longitudes of Titan -- even as late as next spring, we still won't have decent coverage of all Titan longitudes, despite many flybys.

If an orbiter could go into an eccentric polar orbit around Jupiter, it might be able to observe Io (or Europa) both coming and going (when the satellite is nearer to the Sun than Jupiter, or farther). But that's not going to be cheap in delta-v.

I'm not sure what tradeoffs are possible, but getting multiple close flybys of the same hemisphere doesn't get you a lot that a single flyby doesn't. (See Mariner 10.) Of course, the long-duration observations from farther out are all fine and good.

I'll chime in that the capability for continuous observation of Io, at least to the point of observing the several larger hotspots, from Earth had gotten pretty good, although I'm not aware of the details of any such surveys that may be ongoing.

Posted by: vjkane2000 Jun 17 2005, 05:23 PM

QUOTE (JRehling @ Jun 17 2005, 09:19 AM)
A difficulty with eccentric orbit orbiters that zoom in to observe inner satellites at periapsis only is that if the mission is not very long, you observe only a limited range of lighting conditions, and with tidally-locked rotations, you observe a limited range of longitudes. This is why we've seen one side of Io much better than the other (from Galileo) and keep seeing similar longitudes of Titan -- even as late as next spring, we still won't have decent coverage of all Titan longitudes, despite many flybys.

  If an orbiter could go into an eccentric polar orbit around Jupiter, it might be able to observe Io (or Europa) both coming and going (when the satellite is nearer to the Sun than Jupiter, or farther). But that's not going to be cheap in delta-v.

  I'm not sure what tradeoffs are possible, but getting multiple close flybys of the same hemisphere doesn't get you a lot that a single flyby doesn't. (See Mariner 10.) Of course, the long-duration observations from farther out are all fine and good.

  I'll chime in that the capability for continuous observation of Io, at least to the point of observing the several larger hotspots, from Earth had gotten pretty good, although I'm not aware of the details of any such surveys that may be ongoing.
*



The Io working group specifically said they wanted to repeat the encounter with the same geometry so that any changes between passes represent real changes and not just lighting changes.

However, if the perijove was inside Io's orbit, then the spacecraft's orbit crosses Io's orbit in two locations. It would be possible to vary the orbital timing slightly to alternative which crossing you encounter Io at. You can't get exactly opposite hemispheres, but you do increase your coverage. The downside, however, is that you are going deeper into the radiation belts and increasing the radiation dosage of each orbit. I don't know if the 40Krad Galileo dosages per orbit included going inside Io's orbit or not.

Posted by: gpurcell Jun 17 2005, 07:39 PM

QUOTE (BruceMoomaw @ Jun 17 2005, 07:17 AM)
In any case, the white paper on Io missions presented to the Decadal Survey -- which is pretty much the latest thinking on the subject -- can be found at http://www.lpi.usra.edu/opag/io.pdf .
*


Thanks for the link, Bruce. Interesting that Danztler considers the MSL 2009 launch date "FIXED."

When he is saying the Science Mission Directorate budget is being "rebalanced," what is the implication? Does this point to a reduction in the science portion of Mars exploration?

Posted by: BruceMoomaw Jun 19 2005, 10:29 PM

Damned if I know, especially with this president -- who may hold out stubbornly for continuing to have the manned program drain off money from NASA's science program like Dracula. The one upcoming change I'm virtually certain of is that Europa Orbiter will be funded in 2007. But, looking at the current science budget and the retinkerings with it that Griffin has done just in the last month, I would be inclined to suspect some money will indeed be drained out of the Mars program -- and also that the Webb Telescope will be substantially delayed both to make sure that when it does fly it will still be big enough to do a proper science job, and to make sure that there will be enough money for the Hubble repair-or-reflight and to reduce the rapidly growing new delays in the two big extrasolar-planets missions (SIM and TPF-C).

(Once again, all these problems could be radically reduced if Griffin decided to go for a Hubble unmanned reflight rather than a Shuttle repair mission -- since such a reflight could be delayed as long as necessary, and would probably cost a little less into the bargain -- but, ah, that would once again expose the manned space program as a literally total fraud, and we can't have that. Too many incumbent politicians' and bureaucrats' reputations hinge on not admitting that they made a huge mistake, which is also why the Iraq War will drag on for a couple more years before we admit that we've lost it. But I digress.)

Posted by: Bob Shaw Jun 19 2005, 10:47 PM

Bruce:

Are you talking about the Hubble II complete new vehicle idea, rather than a repair? The arithmetic is impossible to argue with (which is presumably why the DoD do it that way for their spy satellites).

It still leaves the vexed question of what to do with the original Hubble - unmanned rendezvous appears still to be a bit of a black art in the US (perhaps subcontracting the de-orbit to those guys with the Ariane mini space-tug would be a better idea, or even finding out how NPO-Energia would feel about selling a Progress de-orbit mission to NASA (bet they'd *love* to sort out NASA'a pride and joy after being 'persuaded' to dump their good ol' Mir in the ocean!)). Of course, you could always stick some gyros, comms and solar cells on a PIRS airlock module atop a Progress bus, boost the whole shooting match a couple of hundred miles higher and wait for Burt Rutan...

Bob Shaw

Posted by: BruceMoomaw Jun 19 2005, 10:58 PM

As for Van Kane's comments on the "Io Observer": I don't understand it could flyby Io at two different positions in its orbit if its periapse was lower than Io's -- the only way it could pull that trick is if it had a circular orbit IDENTICAL to Io's except for being highly inclined (a trick which Cassini, in fact, will pull with Titan later in its primary mission, but which would probably sharply increase the amount of radiation the Io Observer would be exposed to). And, indeed, the description of it in the White Paper says flatly that it would continue reexaming regions on the same hemisphere of Io close-up over and over, at intervals of a month or less, to look for detailed changes. That mission by itself, however, could do a hell of a lot scientifically.

The really interesting question is whether you could combine this with another New Frontiers mission that the Decadal Survey and Solar System Roadmap groups have expressed interest in: a "Ganymede Observer" (actually, at this point a Ganymede-Callisto Observer) which would emulate Galileo by making repeated flybys of those two moons. The question is whether you CAN combine these two mission, to thus create a "Galileo 2" which could observe the entire Jovian system except for Europa in more detail -- the problem is that to get enough radiation resistance for Io Observer you probably need a polar orbit, which in turn means that you'd have to have an awful lot of delta-V to change the orbit's apoapse to make later flybys of Ganymede and Callisto. You MIGHT be able to pul it off with some particular clever gravity-assist flybys of the various moons, but the last time I brought it up this question was still wide open.

On another subject: there are really serious mass problems with flying a Jupiter Multiple Entry Probe mission, even separately from Juno (e.g., with the probes dropped off by a flyby). Given the phenomenal difficulty of Jupiter entry, they would all need big honking heat shields (and even all the companies which manufacture the substance used in the Galileo probe's heat shield have long since stopped doing so and would have to radically retool!). And when you add that to their need for a stout pressure hull (unlike the vented Galileo probe) to get down to the 100-bar level as they wish, that's a lot of mass. Add that to the fact that their main purpose was to map water, ammonia and H2S and winds at different locations and deeper depths -- and that Juno's orbital instruments, by itself, will do a lot of that -- and I think that the Galileo probe and Juno together have removed a lot of the justification for any more near-term Jupiter entry probes.

Now, the heat shield mass needed to enter any of the other three giant planets (including Saturn) is MUCH smaller -- and in the case of Uranus and Neptune, even at the great depths you want the probes to get down to (hopefully, as much as 1000 bars to reach the water cloud), temperatures are no problem at all and you could probably make the probe vented in structure, as both the Galileo probe and the deepest robotic submersibles on Earth are (although a strong radio data signal from that depth is a problem for any entry probe). For these reasons, I suspect that we're going to see deep entry probes for at least one of the other giant planets -- maybe even all of them -- before we see another Jupiter entry probe.

Posted by: BruceMoomaw Jun 19 2005, 11:54 PM

"Are you talking about the Hubble II complete new vehicle idea, rather than a repair? The arithmetic is impossible to argue with (which is presumably why the DoD do it that way for their spy satellites)."

Oh, yes (although the DoD does have another reason adequate by itself, namely that they can't launch Shuttles into polar orbit). And the design for Hubble II is already full-ripe: see http://www.pha.jhu.edu/hop/ . The Aerospace Corporation study commissioned by NASA itself to compare the the three ways to deal with the Hubble problem ( http://www.npr.org/programs/morning/features/2004/dec/hubble/hubble.pdf ) concluded that HOP was not only as cheap as a Shuttle repair mission, but about 20% more likely to succeed (and without risking any lives) -- and, as you'll see when you look at HOP's design, it would carry, in addition to the two new instruments planned for Hubble, at least one and maybe two radically new instruments giving it greatly expanded capabilities beyond Hubble. Two days later, the National Academy of Sciences muddied the waters by stating in its own report that a Shuttle repair mission would be better -- but their reasons for doing so are incredibly vague; indeed, they only mentioned the reflight possibility at all in one short paragraph on one page! ( http://www.nap.edu/catalog/11169.html ; pg. 39). And my attempts to extract more information from the N.A.S. on why they made that statement have been totally unsuccessful.

I imagine, though, that we'll see the Shuttle repair mission instead -- after all, NASA, like any con artist finally backed into a corner, is frantically grabbing at anything they can, and the supposed "usefulness" of a Shuttle repair mission to Hubble is the only argument they have left for that miserable white elephant that still has an ability to take in otherwise knowledgeable skeptics (such as Paul Krugman).

"It still leaves the vexed question of what to do with the original Hubble - unmanned rendezvous appears still to be a bit of a black art in the US (perhaps subcontracting the de-orbit to those guys with the Ariane mini space-tug would be a better idea, or even finding out how NPO-Energia would feel about selling a Progress de-orbit mission to NASA (bet they'd *love* to sort out NASA'a pride and joy after being 'persuaded' to dump their good ol' Mir in the ocean!)). Of course, you could always stick some gyros, comms and solar cells on a PIRS airlock module atop a Progress bus, boost the whole shooting match a couple of hundred miles higher and wait for Burt Rutan..."

Once again: since they can't possibly cram a Deorbit Motor into the Shuttle cargo bay along with the other equipment they'd need for that repair mission, that will be separately built and robotically launched to Hubble in any case (for about $400 million). Orbital Services is absolutely confident that they can build that simpler mission, and succesfully dock it with Hubble. Of course, a few heretics like Jeffrey Bell are also asking why we need to spend $400 million to eliminate the miniscule chance that any piece of Hubble would hit anyone on the head in any case...

Posted by: JRehling Jun 20 2005, 01:25 AM

[quote=BruceMoomaw,Jun 19 2005, 03:58 PM]
As for Van Kane's comments on the "Io Observer": I don't understand it could flyby Io at two different positions in its orbit if its periapse was lower than Io's
[/quote]

Imagine the way Halley's Comet's orbit intersects the Earth's (assuming the two orbits were nearly coplanar). They intersect in two places. On some passes, a close encounter will happen at one intersection, on some, at the other. On many, no encounter at all. Of course, there's no design behind the natural case. Clever choice of orbital period could allow close encounters to occur at both locations, on different orbits.

[quote]
The really interesting question is whether you could combine this with another New Frontiers mission that the Decadal Survey and Solar System Roadmap groups have expressed interest in: a "Ganymede Observer" (actually, at this point a Ganymede-Callisto Observer) which would emulate Galileo by making repeated flybys of those two moons. The question is whether you CAN combine these two mission, to thus create a "Galileo 2" which could observe the entire Jovian system except for Europa in more detail
[/unquote]

If Io were only to be observed from afar, then a perijove near Ganymede would suffice save a whole lot of delta-v.

[quote]
For these reasons, I suspect that we're going to see deep entry probes for at least one of the other giant planets -- maybe even all of them -- before we see another Jupiter entry probe.

*

[/quote]

Interesting, and Saturn would probably serve much the same scientific purposes, if the two giants ended up with similar ratios of raw material.

Posted by: BruceMoomaw Jun 20 2005, 02:55 AM

(1) "Imagine the way Halley's Comet's orbit intersects the Earth's (assuming the two orbits were nearly coplanar). They intersect in two places. On some passes, a close encounter will happen at one intersection, on some, at the other. On many, no encounter at all. Of course, there's no design behind the natural case. Clever choice of orbital period could allow close encounters to occur at both locations, on different orbits."

Ah, I see -- you're assuming that most of the Observer's orbit would be OUTSIDE Io's orbit, whereas I was assuming that it would be in a polar orbit INSIDE Io's orbit (like Juno) and intercept Io only at each of its apoapses. Put it in a polar orbit mostly outside Io's orbital distance -- and put its periapse at one of Jupiter's poles, so that it can intercept Io either while going inward or coming back out -- and you can indeed have it intercept Io's orbit at two different spots. I need to talk with Spencer and Smythe as to whether this is the sort of orbit they might have in mind for the Observer. (I lack a good visual imagination when it comes to orbits -- or, indeed, anything else.)

By the way, one fact I forgot to mention: in response to Van Kane's other question, Galileo only ventured slightly inside Io's orbit during each of its Io flyby orbits.

(2) "If Io were only to be observed from afar, then a perijove near Ganymede would suffice to save a whole lot of delta-v."

True -- but any orbiter can do that (Europa Orbiter will regularly do it from as close as Europa's orbit). The central goal of Io Observer will be to take repeated close-up looks at Io -- so the problem, once again, is whether there's any practical way to combine its mission with that of the Ganymede-Callisto Observer (hereafter called, by me, the GC Observer).

(3) "Interesting, and Saturn would probably serve much the same scientific purposes, if the two giants ended up with similar ratios of raw material."

This is going back a ways; but, given the difficulty of a Jupiter entry, back in the early 1970s serious consideration was given to making Saturn, rather than Jupiter, the target of the first giant-planet entry probe. (Who knows? We might have ended up sending Galileo to Saturn instead, and then ended up bitching even more about the consequences of its high-gain antenna failure.)

Posted by: gpurcell Jun 20 2005, 03:09 PM

I've always thought that the best deorbit mission for Hubble is a $20 million check dispatched by the USPS to Lloyds of London....

Posted by: JRehling Jun 20 2005, 08:55 PM

QUOTE (BruceMoomaw @ Jun 19 2005, 07:55 PM)
Ah, I see -- you're assuming that most of the Observer's orbit would be OUTSIDE Io's orbit, whereas I was assuming that it would be in a polar orbit INSIDE Io's orbit (like Juno) and intercept Io only at each of its apoapses.  Put it in a polar orbit mostly outside Io's orbital distance -- and put its periapse at one of Jupiter's poles, so that it can intercept Io either while going inward or coming back out -- and you can indeed have it intercept Io's orbit at two different spots.  I need to talk with Spencer and Smythe as to whether this is the sort of orbit they might have in mind for the Observer.  (I lack a good visual imagination when it comes to orbits -- or, indeed, anything else.)


Delta-v could vary sharply from one of these possibilities to another, and in the absence of some mission-critical geometry need, it would, I expect, be a powerful factor. Orbiting close to Jupiter costs delta-v. Inclined orbits cost delta-v. I guess that something in a mainly-outside, coplanar orbit would win in every way but one, which is that it would probably take more radiation/pass, and thus live a shorter life. But if the point is to have a long duration of temporal coverage, a longer orbit with increased apojove would provide that, at the cost of time resolution (more flybys).

QUOTE
(2)  "If Io were only to be observed from afar, then a perijove near Ganymede would suffice to save a whole lot of delta-v."

True -- but any orbiter can do that (Europa Orbiter will regularly do it from as close as Europa's orbit).  The central goal of Io Observer will be to take repeated close-up looks at Io -- so the problem, once again, is whether there's any practical way to combine its mission with that of the Ganymede-Callisto Observer (hereafter called, by me, the GC Observer).
*


I've looked at some Cassini images of saturnian moons at typical Ganymede-to-Io distances, and the resolution is really not bad. Europa-to-Io would be better. What is the point of such a mission: to track lava flows at decameter resolutions?

Posted by: BruceMoomaw Jun 21 2005, 12:31 PM

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.)

Posted by: JRehling Jun 21 2005, 03:31 PM

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.

Posted by: vjkane2000 Jun 22 2005, 09:10 AM

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?

Posted by: BruceMoomaw Jun 22 2005, 10:52 PM

Well, keep in mind that Cassini's 45 close flybys of Titan over 4 years -- using only Titan itself to reset the shape of each orbit -- cover a really impressive variety of spots on its surface at closest approach. I see no reason why you couldn't do the same thing for a comparable number of Io flybys, especially since you would have four moons, rather than one, to modify the craft's orbit between flybys. (William Smythe's "Getting back to Io" paper does say that it's a lot easier to vary the longitudes of close approaches to Io than their latitudes; but Cassini does quite a lot of both during its Titan flybys.)

As John Rehling says, this mission (along with Europa Orbiter) would also make so many close flybys of Ganymede and Callisto that a mission devoted specifically to those two moons would very likely be superfluous (as, I think, a Jupiter Flyby with Muitple Entry Probes is also likely to be for quite a while, given the combination of the Galileo entry probe and Juno).

Posted by: BruceMoomaw Jun 29 2005, 06:02 PM

The presentations from the June OPAG meeting are now online:

http://www.lpi.usra.edu/opag/jun_05_meeting/agenda.html

Perhaps the most interesting are the two on the new design of the Europa
Orbiter. This work is now very advanced and detailed, and the science
payload has been greatly enlarged from the earlier design -- although it
still seems questionable that a small lander could be added. (They may also
be aiming for a launch as early as 2012.)

http://www.lpi.usra.edu/opag/jun_05_meeting/presentations/EGE_Mission_Study.
pdf
http://www.lpi.usra.edu/opag/jun_05_meeting/presentations/EGE_Science_Instru
ments_Trace_OPAG.pdf

However, most of the others are also of note. Note in particular the piece
about work on two possible Titan mission designs -- one of which consists
not of an aerobot, but of a small surface rover with inflatable wheels,
which might be able to drive 500 km in 3 years. (The other, oddly enough,
is simply a Titan orbiter -- no aerobot mission design is presented here,
although it's very unlikely that the concept has been rejected.)

http://www.lpi.usra.edu/opag/jun_05_meeting/presentations/opagtitan.pdf

Posted by: imran Jun 29 2005, 08:37 PM

Thanks for the links, Bruce. I am surprised too that they are not considering an aerobot ("blimp") mission for Titan. The orbiter mission concept sounds like Cassini Huygens mission part two, with global coverage and a little more capability. The rover mission would also not do justice to a dynamic place like Titan.

Posted by: BruceMoomaw Jun 29 2005, 10:28 PM

This hardly means that they're not considering a Titan aerobot -- it just means that one was not the subject of those particular two studies. I imagine that even the basic form of a Titan mission is still wide-open, and will remain so both until Cassini returns a lot more observations and until theorists have had a chance to chew over just what its data actually says about this complex and still very mysterious place.

The most encouraging thing to come out of those OPAG presentations is just how serious NASA finally seems to be -- at long last -- about flying a Europa mission.

Posted by: BruceMoomaw Jun 29 2005, 10:31 PM

And, for one recent JPL study of a Titan aerobot mission, see one of the presentations from the preceding OPAG meeting in February:

http://www.lpi.usra.edu/opag/feb_05_meeting/presentations/beauchamp_%20presentation.pdf

Posted by: JRehling Jun 30 2005, 05:20 PM

QUOTE (BruceMoomaw @ Jun 29 2005, 03:31 PM)
And, for one recent JPL study of a Titan aerobot mission, see one of the presentations from the preceding OPAG meeting in February:

http://www.lpi.usra.edu/opag/feb_05_meeting/presentations/beauchamp_%20presentation.pdf
*


It seems that the case for an aerobot is seriously helped by the fact that we have hardly a clue how drivable Titan's light-colored terrain might be, and the Huygens view makes it look like no wheeled craft would have a prayer. It would likely roll into a crevice, or land somewhere surrounded by crevices, and have its mobility quickly put to an end! It's possible that we could get useful recon from, eg, radar (Cassini's or Earthbound) and ascertain that there are smooth areas, but an aerobot easily trumps this possibility. I'd rather have a three-instrument aerobot floating over many kinds of terrain than a standout instrument package on wheels.

Ditto for Venus... Although I think a stationary lander would be sufficient for many purposes there. Big difference: we've already seen multiple landing sites on Venus, which surely represent most of the terrain of that whole world, vs. one on Titan, which surely doesn't!

Posted by: BruceMoomaw Jun 30 2005, 06:50 PM

Actually, we DO need more surface observation points on Venus. One of the highest-priority goals of landings (specified in the new Roadmap) is to look for patches of granite or andesite crust which would indicate the existence of oceans on ancient Venus -- and the best place by far to look for those is in the "tessera" patches, which have been the top-priority landing sites for any American Venus mission for years. We would also like to take a look at those puzzling areas of high radar reflectivity on Venus' high-altitude terrain -- and, on top of that, keep in mind that even the Soviet landers didn't do any mineralogy at all of their own basaltic landing sites.

The question is whether the best way to do this is by a surface rover, an aerobot, or a larger number of multiple stationary landers. Frankly, I'm inclined to go with the latter -- we have the technology for those RIGHT NOW. (We might also be advised to try to develop in-situ age-dating instruments for Venus' surface; we have already done some promising initial work on those, and God knows it would be easier than a Venus sample return -- which I expect to see Congress fund on the same day O.J. finds the real killers.)

Posted by: tedstryk Jun 30 2005, 06:58 PM

QUOTE (BruceMoomaw @ Jun 30 2005, 06:50 PM)
Actually, we DO need more surface observation points on Venus.  One of the highest-priority goals of landings (specified in the new Roadmap) is to look for patches of granite or andesite crust which would indicate the existence of oceans on ancient Venus -- and the best place by far to look for those is in the "tessera" patches, which have been the top-priority landing sites for any American Venus mission for years.  We would also like to take a look at those puzzling areas of high radar reflectivity on Venus' high-altitude terrain -- and, on top of that, keep in mind that even the Soviet landers didn't do any mineralogy at all of their own basaltic landing sites. 

The question is whether the best way to do this is by a surface rover, an aerobot, or a larger number of multiple stationary landers.  Frankly, I'm inclined to go with the latter -- we have the technology for those RIGHT NOW.  (We might also be advised to try to develop in-situ age-dating instruments for Venus' surface; we have already done some promising initial work on those, and God knows it would be easier than a Venus sample return -- which I expect to see Congress fund on the same day O.J. finds the real killers.)
*


It should also be noted that the Venera landings were far from random. Most cluster around the same region.

Posted by: JRehling Jun 30 2005, 07:15 PM

QUOTE (BruceMoomaw @ Jun 30 2005, 11:50 AM)
Actually, we DO need more surface observation points on Venus.  One of the highest-priority goals of landings (specified in the new Roadmap) is to look for patches of granite or andesite crust which would indicate the existence of oceans on ancient Venus -- and the best place by far to look for those is in the "tessera" patches, which have been the top-priority landing sites for any American Venus mission for years.  We would also like to take a look at those puzzling areas of high radar reflectivity on Venus' high-altitude terrain -- and, on top of that, keep in mind that even the Soviet landers didn't do any mineralogy at all of their own basaltic landing sites.


All good points; I meant that we know what the terrain is like on representive locations on Venus, and we could say that a rover would operate with no problem on Venera 10/Venera 14 terrain, and not much problem on Venera 9/Venera 13 terrain. Of course, we can easily radar-survey Venus to find slopes and roughnesses at arbitrary scales.

The kinds of terrain you mention are indeed different and worth checking out. And may be tough to rover on, in the case of tessera; tough to hit precisely in the case of the radar-bright heights.

I'd aim for identification of granite from above rather than trying to hit the bullseye with a tessera lander. I don't know if the high temps + CO2 allow an IR spectroscopic approach from aloft below the clouds, but a TES (instrument on Mars
Global Surveyor) -type survey would give loads of coverage if flown on a balloon or airplane that cruised over one of the big tessera areas. I'd be afraid of committing too much money to a lander (even a rover) and landing in the wrong valley, one valley over from the geologically older one. Venus is a big place, and just as current Mars lander site selection depended upon orbital surveys to do us much good, we would be well served by some light/broad recon of Venus before we pay for landers.

QUOTE (BruceMoomaw @ Jun 30 2005, 11:50 AM)
The question is whether the best way to do this is by a surface rover, an aerobot, or a larger number of multiple stationary landers.  Frankly, I'm inclined to go with the latter -- we have the technology for those RIGHT NOW.  (We might also be advised to try to develop in-situ age-dating instruments for Venus' surface; we have already done some promising initial work on those, and God knows it would be easier than a Venus sample return -- which I expect to see Congress fund on the same day O.J. finds the real killers.)
*


We don't have the technology for long-duration Venus landers right now -- well, unless nuclear-powered refrigeration is the way we keep the instruments alive. An aerobot may or may not require less technological development than a seriously long-lasting Venus stationary lander, because the ability to go aloft into the cool heights is certainly more of a no-moving-parts approach than the refrigeration method. Whichever is easier, a stationary Venus lander with seismometry is a must-have at some point. But I disagree that a lander-first surely offers the best science/cost plan. Another entry in the field is also a very small, VAMP-like probe that aces the isotopic analysis of the atmosphere.

I might say that a good candidate for the next Venus mission would be an isotopic analyzer that also tested some multispactral imaging on a surface unit boundary to see what an aerobot/airplane could do with a longer below-cloud groundtrack.

Posted by: BruceMoomaw Jul 1 2005, 01:01 AM

(1) "All good points; I meant that we know what the terrain is like on representive locations on Venus, and we could say that a rover would operate with no problem on Venera 10/Venera 14 terrain, and not much problem on Venera 9/Venera 13 terrain. Of course, we can easily radar-survey Venus to find slopes and roughnesses at arbitrary scales.

The kinds of terrain you mention are indeed different and worth checking out. And may be tough to rover on, in the case of tessera; tough to hit precisely in the case of the radar-bright heights."

Actually, the radar-bright heights are pretty big -- much of Venus between 2.6 and 6.6 km above the global mean (but not higher!) has this mysterious property, about which there are several theories. Perhaps the most plausible is that it's high-altitude "snow" -- made out of galena.

(2) "I'd aim for identification of granite from above rather than trying to hit the bullseye with a tessera lander. I don't know if the high temps + CO2 allow an IR spectroscopic approach from aloft below the clouds, but a TES (instrument on Mars Global Surveyor) -type survey would give loads of coverage if flown on a balloon or airplane that cruised over one of the big tessera areas. I'd be afraid of committing too much money to a lander (even a rover) and landing in the wrong valley, one valley over from the geologically older one. Venus is a big place, and just as current Mars lander site selection depended upon orbital surveys to do us much good, we would be well served by some light/broad recon of Venus before we pay for landers."

This returns me to the question of whether Venus' clouds and dense atmosphere actually allow us to do any mineralogy whatsoever from orbit -- a question about which there is still debate. I promised earlier to look this up for you, and will do as soon as I get a chance to stop juggling other plates. But there is a real chance that Venusian mineralogy is impossible from more than a small distance above the surface. (Very detailed SAR mapping -- and microwave or near-IR radiometry to look for volcanic hot spots -- are, on the other hand, entirely practical. A small -- quite possibly Discovery-class -- orbiter to do all that seems like a very good idea, and in fact was recommended by the DPS White Paper group advising the Solar System Decadal Survey a few years ago.)

I doubt that thermal-emission spectrometry is practical on Venus even at the surface -- there is far too much interference from its hot, extremely dense atmosphere. Indeed, even near-IR spectrometry of Venus' surface presents problems, because it's so hot that it actually glows dull red at night -- that is, its near-IR light from actual thermal emissions intermixes with that from its reflected sunlight in the daytime, scrambling their spectra up together. To sort out Venus' near-IR spectra (at longer than about 1 micron wavelength) in the daytime, you need a flashlamp to take comparative spectra with and without that additional reflected light -- but this is impossible to do beyond a short distance.

(3) "We don't have the technology for long-duration Venus landers right now -- well, unless nuclear-powered refrigeration is the way we keep the instruments alive. An aerobot may or may not require less technological development than a seriously long-lasting Venus stationary lander, because the ability to go aloft into the cool heights is certainly more of a no-moving-parts approach than the refrigeration method. Whichever is easier, a stationary Venus lander with seismometry is a must-have at some point."

A central part of the new Solar System Roadmap is a plan to develop solid-state electronics that CAN function at Venusian surface temperatures, so that we can fly a long-lived surface lander within the "Small Flagship" budget (less than $1.4 billion) around 2024. According to the Roadmap, we already have electronics that can function at up to 300 deg C -- but that's still not enough yet. However, there seem to be no automatic show-stoppers. As for nuclear-powered refrigeration, Mike Malin's 1992 proposal for a long-lived Venus seismic lander would have used 97% of its RTG's power just to keep its electronics cool!

And as for the aerobot: the trouble there is that we also have been unable to find a plastic so far suitable to make a balloon that can survive Venusian temperatures. NASA was counting on one called polybenzoxasole, which can do so -- but, according to http://www.lpi.usra.edu/meetings/lpsc2005/pdf/1223.pdf , they have apparently been unable to find a way to make leakproof seams in it. Thus the proposal in that abstract for a two-stage balloon, with the surface stage consisting -- remarkably -- of a cylindrical, thin-walled stainless steel bellows inflated with helium, which need expand only to modest volume to lift the craft off in that dense atmosphere and loft it to the 370 deg C. level -- at which point a balloon which we know CAN survive that temperature can be released from an insulated container to loft the craft all the way back up into the clouds. The trouble is that you can only use this setup for one landing (and takeoff) at one point, since it will be extremely difficult to repack that second balloon into its insulated container again.

Now, when we do develop electronics capable of surviving Venusian surface temperatures, it will be possible to develop a rover which -- instead of rolling along the surface -- can actually inflate one of those small steel "bellows" balloons to lift just a few meters off the surface and cruise along like a research submersible along Earth's ocean bottom, using radar (or sonar!) to tweak the balloon's buoyancy and keep it at a stable altitude between touchdowns, and using Venus' slow surface winds and/or propellers to drive it horizontally. (This "balloon" would actually be more like a ballast tank.) I've actually mentioned this possibility to the Roadmap group, since they seem not to have thought of it.

Anyway, when you read the White Paper to the Roadmap Group written by the Venus Exploration Analysis Group ( http://www.lpi.usra.edu/vexag/venusexplorationrmap.pdf ), it turns out that they are thinking both of a rover AND a long-lived seismic network as possibilities for the 2024 Venus mission -- and they even suggest that the choice may depend on whether earlier missions show still-active volcanoes on Venus.

(4) "But I disagree that a lander-first surely offers the best science/cost plan. Another entry in the field is also a very small, VAMP-like probe that aces the isotopic analysis of the atmosphere."

I agree -- and so did the Decadal Survey White Paper group, who called such a Discovery-class entry probe (also to detect near-surface gases) the highest priority right now for Venus exploration. (Amazing how much we still don't know about Venus' atmosphere, given the number of probes that have been dropped into it.) Indeed, this goal -- which is currently incorporated into the goals of the proposed New Frontiers short-lived Venus lander, which has already had to be downscaled due to cost problems -- could very easily be split off to such a separate mission, making it possible to turn the NF mission into 2 or 3 short-lived landers that would focus entirely on the surface.

(5) "I might say that a good candidate for the next Venus mission would be an isotopic analyzer that also tested some multispectral imaging on a surface unit boundary to see what an aerobot/airplane could do with a longer below-cloud groundtrack."

This could indeed be easily added to such a mission (provided that you had the carrier bus fly by Venus during the drop to receive the photos at high speed). In this connection, note also the "VEVA" mission -- proposed twice for Discovery, but never a finalist -- which would use a balloon to both analyze atmospheric composition and drop four small impact probes equipped with cameras to image different types of Venusian terrain over several thousand km ( http://techreports.jpl.nasa.gov/1999/99-1959.pdf -- where it's called "VAMUS"). The problem, again, is getting good near-IR data on surface composition -- the VEVA probes would have multispectral cameras to try to get such data below 1 micron -- but the JPL paper I cite has an intriguing, vague reference to a possible souped-up version that would add a one-spot near-IR spectrometer and laser altimeter to each probe. Since a broadband laser has recently been developed, it's possible that the laser could also be used to illuminate the surface to let the descending VEVA probe get complete near-IR spectra of the surface. Once again, however, it might be wiser to split up VEVA's different functions among separate missions -- with one entry probe doing the VEVA balloon's mass spectral atmospheric analysis, and several full-fledged short-lived survivable landers that also take descent photos.

Needless to say, I think Doug had better move this discussion over to the Venus thread at this point.

Posted by: BruceMoomaw Jul 1 2005, 04:24 AM

One more footnote here, which I forgot to include earlier, in response to John's comment: "I'd aim for identification of granite from above rather than trying to hit the bullseye with a tessera lander. I don't know if the high temps + CO2 allow an IR spectroscopic approach from aloft below the clouds, but a TES (instrument on Mars Global Surveyor) -type survey would give loads of coverage if flown on a balloon or airplane that cruised over one of the big tessera areas. I'd be afraid of committing too much money to a lander (even a rover) and landing in the wrong valley, one valley over from the geologically older one."

As with the high reflectivity regions -- but even more so -- it would be very hard to actually miss one of the tessera regions, which are often hundreds of km across. Also, it would be very good to be able to do some age-dating of a tessera patch (along with the main basalt plains, and maybe one of the more recent volcanic regions) in-situ with landers (although that experiment doesn't seem to have been on Larry Esposito's "SAGE" proposal for mutiple Venus landers for the last New Frontiers selection).

Once again, however, an excellent case can be made that -- before we dispatch any Venus landers at all -- we should fly another SAR mapping mission, with much higher resolution, in a low circular Venus orbit, as suggested by the DPS White Paper group a few years ago (and just repeated by the VEXAG group). As with Mars, a good deal of mapping reconnaissance is important in picking out the best possible Venusian landing sites, given the inevitable rarity of actual Venus landings.

Posted by: BruceMoomaw Jul 1 2005, 09:05 AM

One small error on my part: the GCMS analysis of Venus' atmosphere on the proposed VEVA mission would have been done not by the balloon (which would only carry the four imaging drop probes, plus some weather sensors and a magnetometer) -- it would have been done by a completely separate large probe dropping all the way to the surface. Which, I don't think, changes any of my points at all. And now I'm switching all my future comments on this subject to the new "Future Venus Probes" thread that Phil Stooke has just opened up on this site. Time for us to get back to Jupiter here...

Posted by: john_s Jul 7 2005, 09:49 PM

QUOTE (BruceMoomaw @ Jun 20 2005, 02:55 AM)
I need to talk with Spencer and Smythe as to whether this is the sort of orbit they might have in mind for the Observer.

*


I'm not sure what Bill Smythe had in mind, but I was definitely thinking of an orbit with perijove near Io and apojove out beyond Callisto somewhere, to minimize both delta-V and radiation exposure.

But right now, I'd be pretty happy if we could put a high-resolution camera on the revamped Europa orbiter and make high-frequency distant monitoring of Io (with ~1-km resolution) a priority for that mission in the months prior to Europa orbit insertion. You can do a lot with Io without close flybys, if you have the right instrumentation.

John Spencer

Posted by: BruceMoomaw Jul 8 2005, 02:07 AM

Ah. Thankee for the information, John. As for that high-resolution camera, its inclusion on Europa Orbiter now seems almost certain:
http://www.lpi.usra.edu/opag/jun_05_meeting/presentations/EGE_Science_Instruments_Trace_OPAG.pdf

The fact remains that we obviously still need lost more genuine closeup observations of Io as well.

Posted by: deglr6328 Jul 15 2005, 07:22 AM

blink.gif Wow! I had no idea Europa Orbiter was really moving ahead with such (apparent) certainty! Personal outlandishly absurdly wishfull thinking hope for an included experiment -->coherent microwave receiver to listen for askaryan pulses in Europa's ice to make the whole moon one big EeV/PeV neutrino http://arxiv.org/PS_cache/astro-ph/pdf/0411/0411510.pdf. I wonder how much data bandwidth it would cost to include such an (incredibly unlikely) instrument.

Posted by: Bob Shaw Jul 15 2005, 11:35 AM

QUOTE (deglr6328 @ Jul 15 2005, 08:22 AM)
blink.gif Wow! I had no idea Europa Orbiter was really moving ahead with such (apparent) certainty!  Personal outlandishly absurdly wishfull thinking hope for an included experiment -->coherent microwave receiver to listen for askaryan pulses in Europa's ice to make the whole moon one big EeV/PeV neutrino http://arxiv.org/PS_cache/astro-ph/pdf/0411/0411510.pdf. I wonder how much data bandwidth it would cost to include such an (incredibly unlikely) instrument.
*


The gas giants are perhaps not the friendliest environment for a super-sensitive neutrino detection experiment - but a nice, cold KBO might be a good place. Of course, it'd need a late 21st-Century Prometheus-2 power source to drive that big ol' ion engine to get there in a reasonable time scale then drop into orbit...

Posted by: Stephen Jul 21 2005, 07:41 AM

QUOTE (BruceMoomaw @ Jul 8 2005, 02:07 AM)
Ah.  Thankee for the information, John.  As for that high-resolution camera, its inclusion on Europa Orbiter now seems almost certain:
http://www.lpi.usra.edu/opag/jun_05_meeting/presentations/EGE_Science_Instruments_Trace_OPAG.pdf

The fact remains that we obviously still need lost more genuine closeup observations of Io as well.

Incidently (and otherwise OT), I notice that same June 2005 OPAG meeting had a couple of presentations on a possible Neptune orbiter about 2017.

http://www.lpi.usra.edu/opag/jun_05_meeting/presentations/OPAG_Neptune_API1.pdf

http://www.lpi.usra.edu/opag/jun_05_meeting/presentations/NEP_OPAG_Rev.pdf

(Hint to Doug: maybe it's time for a Neptune forum in the "Outer Solar System group)

Posted by: tedstryk Aug 5 2005, 03:13 PM

New JunoCam tidbit....once again, Pioneer is forgotten!

http://barsoom.msss.com/juno/index.html

Posted by: um3k Aug 6 2005, 11:12 PM

QUOTE (tedstryk @ Aug 5 2005, 11:13 AM)
New JunoCam tidbit....once again, Pioneer is forgotten!
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Red-blue doesn't count! wink.gif

Posted by: Bjorn Jonsson Nov 1 2005, 10:42 PM

QUOTE (tedstryk @ Jun 6 2005, 05:02 PM)
...I would have loved Galileo images close to Amalthea, but I am skeptical the spacecraft could have pulled it off.  I have been working on some of the images Galileo took, and it is a very interesting world, especially given the new shape-model release...

Does anyone know if a new shape model for Amalthea incorporating Galileo results has been made (and is available) somewhere? I'm of course aware of Philip Stooke's model and a few slightly modified versions of it but I have been unable to find anything really recent.

Posted by: tedstryk Nov 1 2005, 10:44 PM

QUOTE (Bjorn Jonsson @ Nov 1 2005, 10:42 PM)
Does anyone know if a new shape model for Amalthea incorporating Galileo results has been made (and is available) somewhere? I'm of course aware of Philip Stooke's model and a few slightly modified versions of it but I have been unable to find anything really recent.
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I have seen one with primary mission data, but none with the higher resolution data from the later part of the mission incorporated.

Posted by: Bjorn Jonsson Nov 1 2005, 10:47 PM

QUOTE (tedstryk @ Nov 1 2005, 10:44 PM)
I have seen one with primary mission data, but none with the higher resolution data from the later part of the mission incorporated.
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Do you know if it is available somewhere? Even something incorporating only data from the primary mission should be a significant improvement.

Posted by: tedstryk Nov 2 2005, 02:02 AM

I saw graphics made from it in Icarus a few years back. I have never seen it online, much less the numerical data behind the graphics.

Posted by: Tayfun Öner Nov 3 2005, 07:19 AM

Small satellite models, maybe created by Peter Thomas?

http://rhein-zeitung.de/on/98/09/16/topnews/jupiter.jpg

Posted by: Tayfun Öner Nov 3 2005, 07:29 AM

Larger version

http://photojournal.jpl.nasa.gov/catalog/PIA01624

Posted by: Bjorn Jonsson Nov 6 2005, 10:45 PM

Thanks - unfortunately no numerical data more recent than Stooke's model based on Voyager data seems to be available online anywhere.

Here is a rotation movie I did based on that model:

http://www.mmedia.is/bjj/misc/animations/amalthea_rotation.avi

This is the Stooke model resampled to a much bigger size using Photoshop. Some artifacts of the resampling process are visible. I may try modifying the model 'manually' by painting in some features (craters etc.) visible in the Galileo images. The texture map I used for this animation is a map of Mars (!).

Posted by: BruceMoomaw Nov 28 2005, 06:59 AM

There's a nice detailed description of the Juno mission (by far the most detailed I've seen anywhere) at http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/37654/1/05-2760.pdf .

Posted by: mars loon Dec 3 2005, 01:18 AM

QUOTE (Bjorn Jonsson @ Nov 6 2005, 10:45 PM)
Thanks - unfortunately no numerical data more recent than Stooke's model based on Voyager data seems to be available online anywhere.

Here is a rotation movie I did based on that model:

http://www.mmedia.is/bjj/misc/animations/amalthea_rotation.avi

Quote: Bruce Moomaw Nov 28 2005, 06:59 AM

There's a nice detailed description of the Juno mission (by far the most detailed I've seen anywhere) at http://trs-new.jpl.nasa.gov/dspace/bitstre...4/1/05-2760.pdf .


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Bjorn: very nice animation

Bruce: thanks for the nice Juno description

Posted by: Bricktop Dec 6 2005, 12:36 AM

QUOTE (BruceMoomaw @ Nov 28 2005, 07:59 AM)
There's a nice detailed description of the Juno mission (by far the most detailed I've seen anywhere) at http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/37654/1/05-2760.pdf .
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The file (or rather the whole site) is gone sad.gif . Or is not accesible outside the US? Does someone know where to get it else? Or could someone send it to my mail-account mymailtmp-1@yahoo.com ? (it's just a temp account to prevent spam, not wonder about the name smile.gif )

Thanks

Posted by: Sunspot Dec 6 2005, 09:22 AM

I couldn't access the file when Bruce first posted the link to it either.

Posted by: Bricktop Dec 6 2005, 10:57 AM

QUOTE (Sunspot @ Dec 6 2005, 10:22 AM)
I couldn't access the file when Bruce first posted the link to it either.
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It is indeed not accesible outside the US. Just use an US-located proxy to access it, I used the first from this list: http://www.aliveproxy.com/us-proxy-list/

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