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Unmanned Spaceflight.com _ Juno _ Juno development, launch, and cruise

Posted by: PhilHorzempa Apr 3 2006, 09:57 PM

I thought that it was time to start a new thread devoted to the JUNO Jupiter
Orbiter mission. This New Frontiers Mission #2 seems to be a "stealth" project
with little information available on the Web. In fact, the official NASA JUNO
web site is quite pitiful. It contains the minimal amount of information on what
seems to be an intriguing mission, in terms of both science and engineering.

Does the UMSF community have information on this mission that has not
been widely seen before?

Another Phil

Posted by: jamescanvin Apr 4 2006, 01:19 AM

Up to now we've been using the "http://www.unmannedspaceflight.com/index.php?showtopic=1039&st=80" thread. But I guess we're well past the 'picking' so a new thread is in order.

Bruce posted a link to a good pdf on the mission: http://trs-new.jpl.nasa.gov/dspace/bitstre...4/1/05-2760.pdf (at the time only visible in the US, but I had no problems here in Oz just now...) for a nice bit of background.

James

Posted by: Decepticon Apr 4 2006, 12:16 PM

Will this probe make any attempt to image Jupiter's moons?

Posted by: Sunspot Apr 4 2006, 01:55 PM

QUOTE (jamescanvin @ Apr 4 2006, 02:19 AM) *
Bruce posted a link to a good pdf on the mission: http://trs-new.jpl.nasa.gov/dspace/bitstre...4/1/05-2760.pdf (at the time only visible in the US, but I had no problems here in Oz just now...) for a nice bit of background.

James


Couldn't access it here, (UK)

Posted by: Analyst Apr 4 2006, 02:53 PM

Try http://trs-new.jpl.nasa.gov/dspace/handle/2014/37654.

Analyst

Posted by: Sunspot Apr 4 2006, 03:12 PM

QUOTE (Analyst @ Apr 4 2006, 03:53 PM) *
Try http://trs-new.jpl.nasa.gov/dspace/handle/2014/37654.

Analyst


Still nothing, page just times out eventually.....maybe it's a problem my end.

Posted by: lyford Apr 4 2006, 03:17 PM

I think the link got munged in the quote. Correct address is:

http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/37654/1/05-2760.pdf

Copy and paste the link if it still doesn't work.

Posted by: Sunspot Apr 4 2006, 06:05 PM

QUOTE (lyford @ Apr 4 2006, 04:17 PM) *
I think the link got munged in the quote. Correct address is:

http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/37654/1/05-2760.pdf

Copy and paste the link if it still doesn't work.


Same thing sad.gif

Posted by: Harder Apr 4 2006, 06:39 PM

Keep on trying! This pdf doc is a good read. I got it from http://trs-new.jpl.nasa.gov/dspace/ and typed 05-2760 in the search window.

Success,
Peter

Posted by: BruceMoomaw Apr 4 2006, 06:59 PM

Or just turn to that address for the overall JPL Technical Papers site and type in "juno" in the search window. (This same technique works for lots of other interesting JPL papers, too.)

I have a few crumbs more information about this mission besides those in the article, which I'll reprint here as soon as I get over this damn headache. One thing we had better purge purselves of, though, is the hope that it will do any significant studies of the Galilean moons. It's designed to study Jupiter -- period -- and its orbit and mission duration make it almost impossible for it to study anything else (except for long-range studies of Io's ionosphere and torus).

Posted by: BruceMoomaw Apr 10 2006, 03:05 AM

OK, here are those crumbs. The JPL description is pretty good, but there are a few things missing from it:

(1) The 2002 Solar System Decadal Survey noted that the five main goals for the next Jupiter mission are: (A) Determine if Jupiter has a central core to constrain models of its formation; ( B ) determine the planetary water abundance; ( C ) determine if the winds persist into Jupiter's interior or are confined to the weather layer; (D) assess the structure of Jupiter's magnetic field to learn how the internal dynamo works; and (E) measure the polar magnetosphere to understand its rotation and relation to the aurora. Juno will do a nice job on all five - and while, the Survey's original desire for at least one and preferably 2 or 3 deep entry probes (down to 100 bars) would have further improved the data on ( B ) and ( C ), the added expense was so great that a deep Jovian Multiprobe Flyby mission by itself is now ranked pretty low on the list of desired New Horizons missions -- shallow Galileo-type entry probes of the other giant planets are higher-ranked. Moreover, the data from Juno will allow us to better plan the targeting of those deep Jupiter entry probes when we finally DO fly them. (Note also that -- if they absolutely have to descope Juno -- they could toss off every single instrument except the microwave radiometer and magnetometer, and lose only goal (E) in the process.)

(2) Currently we know Jupiter's gravity-field harmonics down to level 6 -- Juno will take it down to level 12 to 14. Not only can it nail down the size of any hevy-element core -- which is crucial to decide which of the two rival theories of giant-planet formation is true -- but it can measure that core's rotation rate, and even obtain profiles of the density of the planet's middle layers sensitive enough to determine how deep its convective wind cycles really run, all the way down 1/5 of the way to the core!

(3) Our current knowledge of Jupiter's magnetic-field harmonics is level 4. Juno will take it all the way down to level 20 -- much BETTER than we can ever obtain for Earth itself, where we're forever limited to level 14 due to interference from crustal fields! Thus Juno is likely to provide radical new information not only on the generative processes of Jupiter's magnetic field (including the dynamo radius and changes with time), but of Earth's field as well.

(4) Knowledge of the total oxygen content of Jupiter's atmosphere is crucial -- and the Galileo entry proe didn't get it because of its bad-luck fall (9-1 odds against) into a hot spot where a downdraft removed the local water vapor. The probe DID find not only that the concentration of the other heavier elements -- Ar, Kr, Xe, C, N and S -- was somewhat lower than expected, but that they were very consistent in being enriched about threefold relative to the Sun, whereas much bigger element-to-element differences had been expected in that ratio. This was a shock. The logical conclusion is that the icy planetesimals that formed Jupiter were actually made of much colder ice than that which existed at the planet's current distance from the Sun (150 K) -- those other elements were imprisoned either in regular ice at only 20-30 deg K or clathrates at >38 K, so either the planet itself formed much farther from the Sun and migrated a great distance inwards, or the planetesimals that formed it themselves came from much farther out and migrated inwards before accreting to form Jupiter at something like its present distance from the Sun. (The entry probe found further confirmation of this in the nitrogen isotopic ratios, which indicates that Jupiter's nitrogen was originally delivered as molecular N rather than as ammonia -- which in turn provides an odd clash that I've mentioned elsewhere with the indications from Huygens that Titan's nitrogen DID arrive as ammonia in relatively warm ice.)

Since water ice was the carrier of all these other heavier elements, we need to know the ratio of water ice to them -- for which we must know Jupiter's current oxygen content. If the planet's oxygen is enriched to only about the same degree relative to the Sun as all the other heavier elements measured by the Galileo entry probe, then they must have been carried into the planet in very cold water ice, from the Kuiper Belt or beyond -- and Jupiter itself may have originally accreted at that distance and then spiralled a great distance inwards. But if oxygen turns out to be enriched more relative to its solar abundance than those other elements -- say, about 9 times solar abundance -- then those other elements were trapped by water ice, and carried into the forming Jupiter, in a more diluted form as clathrate ices, which could have formed somewhat closer to the Sun.

The microwave radiometer (whose viewfield is 1 degree at the equator and 4 degrees at the poles) should allow water abundance measurements down to about 100 bars -- plus better ammonia data (which is a bit fuzzier from the Galileo probe than we would like), thus nailing down both Jupiter's overall oxygen content, and further sharpen our data on its nitrogen content. It will also get more data on the temperature and cloud depth profiles in different parts of the planet, which in turn should help tell us more about just how deep the convective and wind patterns that create the belt-zone structures really run. But it can only do all this reliably because the Galileo entry probe measured the other trace components of Jupiter's atmosphere -- some of which, like PH3, have a significant effect on the planet's microwave spectrum.

(5) Juno's mission is scheduled to run 32 orbits of 11 days each -- and any extended mission will be only a month or so, because they want to make sure that they can crash it into Jupiter, and thus avoid any chance of contaminating Europa, before they lose control of it from radiation damage. In fact, they may end the mission ahead of time -- most of its science will come from its first 16 orbits, and its periapsis latitudes are designed to give it only 5% of its total radiation dosage during that period. (As the JPL paper says, 5 of its first 7 orbits are directed toward microwave radiometry, with all the rest of its orbits being devoted to precision tracking for gravity-field data.)

(6) Juno spins at 3 rpm. Its "JunoCam" -- the most dispensable of all its instruments, whose data will be processed by students at JPL -- should send back 5-10 images per orbit. Juno is focused entirely on the planet itself -- any data it does get on the moons will be pure gravy. For instance, it's very unlikely that they will be able to arrange for it to fly through Io's flux tube.

Posted by: Bricktop Apr 10 2006, 10:29 AM

QUOTE (Sunspot @ Apr 4 2006, 08:05 PM) *
Same thing sad.gif


Try a proxy server. This is how I could get this document from Germany.

Posted by: Mariner9 Apr 11 2006, 12:36 AM

Using solar power for JUNO has always intrigued me. Starting with Pioneer 10 and onward all of our outerplante probes (including the ESA Ulysses) have been nuclear powered. The stated reason is that the available sunlight gets too low much beyond the orbit of Mars or the mid-asteroid belt.

Yet here is JUNO using solar. The panels in the diagram don't look all that much bigger big to me in relation to the craft than say the Viking orbiters or MRO, yet the solar power at Jupiter must be less than 1/4 what it is at Mars.

What am I missing? Are they using amazingly compact and low powered instruments? Is a large percentage of the power being used to charge batteries much of the time, then the batteries are used for peak power usage?

Posted by: Bart Apr 11 2006, 01:09 AM

I was rooting around on the ADS server, looking for papers related to Juno, and I found this one.

http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1564.pdf

It describes an instrument for Juno, but it's not one that's mentioned in the mission overview linked above. Is it a recent addition, a pipe dream, or something in between?

Bart

Posted by: BruceMoomaw Apr 11 2006, 02:18 AM

QUOTE (Mariner9 @ Apr 11 2006, 12:36 AM) *
Using solar power for JUNO has always intrigued me. Starting with Pioneer 10 and onward all of our outerplante probes (including the ESA Ulysses) have been nuclear powered. The stated reason is that the available sunlight gets too low much beyond the orbit of Mars or the mid-asteroid belt.

Yet here is JUNO using solar. The panels in the diagram don't look all that much bigger big to me in relation to the craft than say the Viking orbiters or MRO, yet the solar power at Jupiter must be less than 1/4 what it is at Mars.

What am I missing? Are they using amazingly compact and low powered instruments? Is a large percentage of the power being used to charge batteries much of the time, then the batteries are used for peak power usage?


The panels actually ARE somewhat bigger than those for the Mars missions. Solar panels actually are feasible to power Jupiter craft, IF you stay out of the intense radiation regions (which took a lot of careful orbital planning for Juno), which will quickly fry them -- and if you're willing to accept their weight. All three of the Discovery proposals which were Juno's ancestors (two of which were orbiters, and one of which was a finalist twice) used lightweight solar arrays -- and, in fact, the suggestion was made to put FOUR such solar panels on a copy of one of those craft and use it as the flyby carrier for a Saturn entry probe! http://www.lpi.usra.edu/meetings/outerplanets2001/pdf/4113.pdf

By the way, ESA's Rosetta comet craft, which has big solar panels, has an aphelion all the way out at Jupiter's orbit -- but it will be in a state of near-hibernation during those periods.

QUOTE (Bart @ Apr 11 2006, 01:09 AM) *
I was rooting around on the ADS server, looking for papers related to Juno, and I found this one.

http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1564.pdf

It describes an instrument for Juno, but it's not one that's mentioned in the mission overview linked above. Is it a recent addition, a pipe dream, or something in between?

Bart


I'm about to look into this. Apparently it may be added to the payload, but I haven't heard anything from any other source about it. If they can squeeze it on (maybe as a replacement for the JunoCam), it could be very useful.

Posted by: helvick Apr 11 2006, 06:34 AM

QUOTE (BruceMoomaw @ Apr 11 2006, 02:18 AM) *
The panels actually ARE somewhat bigger than those for the Mars missions.

At the risk of becoming permanantly tagged as "that Solar Power nut" I'd also add that Solar cell technology has progressed enormously since Viking days. I don't have the efficiency of the Viking orbiter arrays at hand but I'd be surprised if they were any better than 15% and were probably closer to 10%.
Similar improvements have been made in the remaining power management and distribution technologies (regulation and storage) so on a similar mass budget you can now generate 3-5x as much power using solar panels as was possible 30 years ago. Even within the time frame of the Cassini mission that increase is close to 2-3x.

Posted by: edstrick Apr 11 2006, 09:29 AM

One thing's for sure... the increase in solar cell efficiency had better top out at 100% or a trace less..... or the free-energy psycho-ceramics will win!

It's sort of like Moore's law... unless you can start engineering with nuclear-matter, we're gonna bottom out with atom sized machinery components.

Posted by: edstrick Apr 11 2006, 09:43 AM

"It describes an instrument for Juno..."

It looks to me like they're trying to persuade NASA to squeeze it on the mission. It would be much the same way the X-ray fluroescence instrument was added to the Viking's biology dominated payload after formal instrument selection was done, but Mariner 9 discovered an unexpectedly complicated and active geology. The instrument ended up with some significant compromizes from being squeezed onboard, but did a fine job anyway.

I really hope we do have good data from Junocam and / or that this proposed instrument flies. I've wanted to see more and better of the polar regions "boiling porridge" (as I call it) that we saw in Pioneer 11 data and get some good info on it's motions right up to the poles (impossible from equatorial missions).

Posted by: BruceMoomaw Apr 15 2006, 01:48 AM

Slight historical correction: NASA decided to add an element analyzer to the Viking landers BEFORE Mariner 9's discoveries -- in summer 1971, when the science payload was being seriously shaken up anyway by cost and weight overruns, and scientists were complaining about the shortage of nonbiological experiments. There was a hasty competition between the XRS and Turkevich's Surveyor alpha-scatter spectrometer, which the XRS won.

Posted by: edstrick Apr 15 2006, 08:25 AM

That's not what I recall.... but given "NASA-Speak" .... I would not be at all surprised if that was after-the-fact PR spin.

But again, my memory may be wrong... or it may have been prompted in part by the observations of "featureless terrain" and "chaotic terrain" in the Mariner 69 data instead.

Posted by: BruceMoomaw Apr 15 2006, 08:54 AM

There was a very detailed "Science News" article in late spring 1971 on the overall changes in Viking's payload. At that time, the choice between the two element anal,yzers had not yet been made, but was called imminent. By early 1972, when Icarus did a whole special issue on the Viking science payload, it had been made.

(Not that this is exactly an earthshaking point -- but they definitely had an element analyzer of some type planned before Mariner 9's results. The official Viking history, "On Mars", can probably tell us more -- I have a copy.)

Posted by: edstrick Apr 15 2006, 10:10 AM

I have an original copy of that Icarus special issue, but dragging them out of bookshelves 200 feet from here after I step over several boxes of books without breaking my legs.... inhibits a quick "lemme take a look"

Posted by: AlexBlackwell Jul 18 2006, 01:53 AM

Again, I apologize for reviving a dormant thread; however, has anyone noticed this particular http://juno.wisc.edu/?

Posted by: JRehling Jul 18 2006, 02:50 PM

QUOTE (AlexBlackwell @ Jul 17 2006, 06:53 PM) *
Again, I apologize for reviving a dormant thread; however, has anyone noticed this particular http://juno.wisc.edu/?


I crave good dormant-thread awakenings.

That site is incomplete, but apparently because they're putting very careful work into each section. In fact, it was the fact that the completed sections went so far over my head that I looked for explanations in the glossary section (which is incomplete).

The whole business with the gravitational mapping of Jupiter's interior is going to expand my math education before the mission's over.

Posted by: helvick Jul 18 2006, 04:05 PM

QUOTE (JRehling @ Jul 18 2006, 03:50 PM) *
The whole business with the gravitational mapping of Jupiter's interior is going to expand my math education before the mission's over.

I was thinking the same thing - the topic of gravitional field mapping has come up here previously and it's one of those things that I'm intrigued by but I'm a bit concerned that the mathematics will be way too much for me.

Posted by: Mariner9 Jul 18 2006, 06:39 PM

I had a chance to talk to one of the engineers on the project at the JPL open house in May. It was fascinating stuff, particulalry the plan to use the radiometers to help determine if Jupiter's belt zones above and below the equator are linked to matching internal structures inside Jupiter.

It was so off the wall, I don't fully remember the specifics, and not even sure how to describe it properly. Essentially, there is a hypothosis that for each major atmospheric belt, there is a corresponding belt opposite the equator that is powered by the same internal dynamics. AKA ... if there is a belt at +33 degrees lattitude, then the belt at -33 degrees is part of the same structure. The belt at +42 degrees is connected to the belt at -42 degrees and so on. (I'm making up the numbers just for the example).

I was also able to confirm my suspicion that not every orbit will be devoted to gravity mapping. I asked the guy and he confirmed that the high gain antenna has to be pointed directly at Earth during the Periapsis pass of the orbit, and when that is being done the vehicle rotation axis will be such that the Junocam and radiometers are not pointing at Jupiter. So there are dedicated orbits for the gravity mapping, and other orbits for the radiometry.

He also said that just a single orbit would give them the data they need for the Radiometry experiment, but naturally they plan on at least 4-5 just to be sure their data is confirmed.

Juno is a fascinating mission.... but I'm not entirely sure how to explain it to the general public. Even my eyes partially glaze over when you start talking about exploration of the polar magnetosphere, and I at least have some idea what that means.

Posted by: AlexBlackwell Jul 18 2006, 09:07 PM

QUOTE (Mariner9 @ Jul 18 2006, 08:39 AM) *
Juno is a fascinating mission.... but I'm not entirely sure how to explain it to the general public. Even my eyes partially glaze over when you start talking about exploration of the polar magnetosphere, and I at least have some idea what that means.

It'll be interesting to see if a fields and particles mission like Juno can capture the public's attention, but I agree that it's a fascinating mission. I'm sure that http://www.msss.com/juno/index.html will help in the PR department, assuming it stays on the payload.

Posted by: SFJCody Jul 18 2006, 10:07 PM

QUOTE (AlexBlackwell @ Jul 18 2006, 10:07 PM) *
It'll be interesting to see if a fields and particles mission like Juno can capture the public's attention, but I agree that it's a fascinating mission. I'm sure that http://www.msss.com/juno/index.html will help in the PR department, assuming it stays on the payload.


I think it's fortunate that a mission of this type can be attempted through New Frontiers. If the Jupiter science required a Europa Orbiter level of expenditure this mission might be sitting on the back burner.

Posted by: AlexBlackwell Jul 18 2006, 10:13 PM

QUOTE (SFJCody @ Jul 18 2006, 12:07 PM) *
I think it's fortunate that a mission of this type can be attempted through New Frontiers. If the Jupiter science required a Europa Orbiter level of expenditure this mission might be sitting on the back burner.

Juno still has to be confirmed for flight (i.e., pass its CDR). I guess we'll know then whether a Jupiter orbiter (even one sans probes) can be done on a New Frontiers budget, or at least whether such a mission isn't deemed not-doable prior to launch.

I remember that Dawn, too, looked pretty nice prior to the descopes/cancellation/re-start.

Posted by: JRehling Jul 19 2006, 06:12 PM

QUOTE (Mariner9 @ Jul 18 2006, 11:39 AM) *
I had a chance to talk to one of the engineers on the project at the JPL open house in May. It was fascinating stuff, particulalry the plan to use the radiometers to help determine if Jupiter's belt zones above and below the equator are linked to matching internal structures inside Jupiter.

It was so off the wall, I don't fully remember the specifics, and not even sure how to describe it properly. Essentially, there is a hypothosis that for each major atmospheric belt, there is a corresponding belt opposite the equator that is powered by the same internal dynamics. AKA ... if there is a belt at +33 degrees lattitude, then the belt at -33 degrees is part of the same structure. The belt at +42 degrees is connected to the belt at -42 degrees and so on. (I'm making up the numbers just for the example).


If I match your description with what I have already read, I think the question is between two alternative hypotheses:

1) The belts are "surface" phenomena only, not penetrating very deeply into the atmosphere. The northern and southern hemispheres have similar patterns because they are similar structurally: two different examples of dynamics with similar parameters.

2) The belts are where deep concentric "cylinders" happen to intersect the surface. The belt at +33 is the ring where a north-south oriented internal cylinder slices into the upper clouds in the northern hemisphere; most of the cylinder is buried very deeply; the southern intersection of the cylinder and the "surface" is at -33.

I guess there's some complex integration of the gravitational data that can help settle the question. I can't picture that analysis, but there's plenty of time to read up on it before/if the data comes back.

Posted by: centsworth_II Jul 19 2006, 08:34 PM

QUOTE (AlexBlackwell @ Jul 18 2006, 05:07 PM) *
It'll be interesting to see if a fields and particles mission like Juno can capture the public's attention...


I think that what is most likely to capture the public is the prospect of getting a description of what sits beneath the thick layers of gas and clouds. Solid? What size? Sharp transition from gas to solid? Is there a liquid layer? How deep?

I hope these sorts of questions can be answered. They are the most interesting to me, and I think the public at large.

Posted by: Richard Trigaux Jul 19 2006, 08:43 PM

QUOTE (centsworth_II @ Jul 19 2006, 08:34 PM) *
I think that what is most likely to capture the public is the prospect of getting a description of what sits beneath the thick layers of gas and clouds. Solid? What size? Sharp transition from gas to solid? Is there a liquid layer? How deep?

I hope these sorts of questions can be answered. They are the most interesting to me, and I think the public at large.


How this could be answered? By radar? or by sismology? Is it possible to make sismology on Jupiter, from an orbiter, with enough sensitivity? I don't expect sound waves like on the sun, but perhaps tidal waves, produced mainly by Io. To detect them would require a very accurate position measurement of the orbiter.

Posted by: JRehling Jul 19 2006, 09:45 PM

QUOTE (Richard Trigaux @ Jul 19 2006, 01:43 PM) *
How this could be answered? By radar? or by sismology? Is it possible to make sismology on Jupiter, from an orbiter, with enough sensitivity? I don't expect sound waves like on the sun, but perhaps tidal waves, produced mainly by Io. To detect them would require a very accurate position measurement of the orbiter.


Measuring tidal bulges is sure to be a key part of the science: Amalthea and the Galileans will induce tidal bulges. When Juno passes over them, it will speed up relative to other perijoves.

What happens when two bulges coincide? Note that it will happen on opposite sides of Jupiter simultaneously. I imagine this tells us about the upper reaches of Jupiter but not the depths. This will happen often, and every perijove, Juno will slice along a meridian located somewhere with respect to those five bulge-pairs. It'll get some interesting data every time.

Posted by: Richard Trigaux Jul 20 2006, 06:02 AM

Will the effect of these bulges be detectable by analysing Juno's position?

Analysing this position alone will be a great chalenge, as, if Juno changes speed and trajectory relative to the bulges, the moons too will do this. So assessing the trajectory alone will already be very complex, especially if the only reference is the set of jovian moons. With my opinion, we need some other stable references:
-ultra stable radio uplink from Earth
-using pulsars or other stable galactic source
-measuring star position.



Once the movement known, analysing tidal effects will too be complicated. Tides are basically waves, which want to propagate at their own speed, independently of the astronomical cause. On Earth such waves can resonate into large oceans, giving a different tide regime for the atlantic ocean and the pacific ocean. On Jupiter, we can think that we shall have resonances along the equator, or more likely different spherical vibration modes. Some will be directly excited by one of the moons, some will on the countrary opose to the excitation by one of the moons.

In a first approximation, we shall have linear waves, or more accurately a spectrum of discreet vibration modes. This will already allow us to sense the depth of the atmosphere and obtain a pressure profile. (if the waves go deep enough. This is not sure, and in heliosysmology there is still a lack of modes involving the core).

In a second step, discrepancies to the linear models will allow us to search for non linear effects, such as damping, elliptic shape of the layers, movements, layers of helium or layers of hydrogen, etc.

The dream would be, like as in heliosysmology which is now able to sense the presence of spots on the opposite side, to see inner Jupiter features like large storms, solid surface features, or convection patterns. After a computer model which was made several years ago, Jupiter would contain a set of several vortexes, paralel to its rotation axis, but avoiding the solid core.


What will be ultimately possible to see will depend on the accuracy of trajectory measurement, I think. This is worth adding some weight, like a telescope (to sense stars) or a set of large antennas.

Posted by: JRehling Jul 20 2006, 02:27 PM

QUOTE (Richard Trigaux @ Jul 19 2006, 11:02 PM) *
Will the effect of these bulges be detectable by analysing Juno's position?

Analysing this position alone will be a great chalenge, as, if Juno changes speed and trajectory relative to the bulges, the moons too will do this.


I think the key will be to measure the doppler shift of a continuous Juno-to-Earth radio signal to determine Juno's velocity and compare that to the no-bulge expectations of velocity. That's how mascons were discovered on the Moon (and Ganymede). Actually, since merely detecting the bulges is not the point, I think the analysis will be to construct models of how the ten tidal bulges alter Jupiter's shape, make predictions of what Juno's velocity should be, and refine the model based on the data. The bulges will not be moving "hills of atmosphere", though -- they should have manifestations at depth as well, which makes the models more complex, but also more informative. That will help us, in a roundabout way, understand Jupiter's interior.

Using a Juno flyby to calculate the planet's moment of inertia is also/instead a way to go about this. And with that, I find the need to read up on more mathematics.

Posted by: Richard Trigaux Jul 20 2006, 03:48 PM

A doppler analysis of a permanent signal will give us only one dimention of a three dimentional problem. Maybe it would be fine to also have a pulsar or something as a second doppler source in a perpendicular direction. But this implies a large dish...

Posted by: JRehling Jul 20 2006, 07:52 PM

QUOTE (Richard Trigaux @ Jul 20 2006, 08:48 AM) *
A doppler analysis of a permanent signal will give us only one dimention of a three dimentional problem.


True, but considering velocity to be a measure of the mass in the chord between Juno and the center of Jupiter, there's for the most part only one dimension that's unknown in Jupiter's shape. To address that qualitatively, it's not that Jupiter will suddenly be shaped like a dog-bone or a torus... that would be tough to find out from gravity data! But with a slightly warped elliptical spheroid, we can assume we know the side-to-side characteristics of the trajectory and just measure how much it accelerates due to Jupiter's gravity in the downward direction. I think knowing that one dimension will serve us pretty well.

Posted by: mcaplinger Jul 20 2006, 08:26 PM

I think you guys are at least a few orders of magnitude off concerning what's possible with radio tracking of Juno. They are using conventional X-band radiometric tracking only, and all they are looking for is the first three even spherical harmonic terms to get information about the core of Jupiter. I find it extremely unlikely that the atmosphere can even be sensed by this.

See
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/37654/1/05-2760.pdf

Posted by: Richard Trigaux Jul 21 2006, 06:19 AM

JRehling, I think that sensing several bulges moving around Jupiter is actually a three dimentional problem (or at least two, if we assume a symmetry regarding the equatorial plane).



mcaplinger, in fact you reply my previous question: "is Juno position measurement accurate enough to sense high ranking harmonics and detect tidal effects?". After your reply, it is not, and by several order of magnitude.


detecting only the first three harmonics will only allow to sense the inner spherical layer structure, and even not very accurately. No hope to detect vortexes or other exotic things.

To achieve a better accuracy would require that Juno sense three pulsars with a high accuracy, or three natural masers. But I am afraid that this would involve very large antennas, much too large for a ship like Juno.


The only practical solution would be to have a kind of GPS positioning around Jupiter.

I already said several times in this forum that a GPS positioning and radio relay (with large data storage) would be one of the first things to do for seriously exploring any planet. Such small satellites would be designed to last for tens of years, for further missions.

On Jupiter, this is especially difficult, with the radiation belts. But could be a ship like Juno be left in orbit, once it exhausted its fuel, and be used as such a relay? This would just require some tens of kilos of additional mass, and be very useful for further missions.

Posted by: mcaplinger Jul 21 2006, 02:20 PM

QUOTE (Richard Trigaux @ Jul 20 2006, 11:19 PM) *
To achieve a better accuracy would require that Juno sense three pulsars with a high accuracy, or three natural masers...
The only practical solution would be to have a kind of GPS positioning around Jupiter.

I don't think either of these solutions would work to solve the problem you're describing. You can't determine your location by observing pulsars from a single point with any kind of accuracy. You may be thinking of VLBI, which is used for geodesy on the Earth, but this requires simultaneuous observations from several locations and high bandwidth communications between them.

As to GPS, one of the components of such a system is knowledge of the transmitting satellites' positions. So without a fixed location from which to track them, I think there may be a chicken-and-egg problem if you are trying to get very high positional precision (even on Earth, GPS can't do better than a half meter or so even using DGPS.)

There may be some sort of multiple-satellite, multiple-transmitter solution to this problem, but that would require a very large investment to build.

The bottom line is that I just don't think it's practical to study this problem using gravity sensing with our current level of technology. Fortunately there are other ways; see the Juno reference I mentioned earlier.

Posted by: Mariner9 Aug 1 2006, 07:06 PM

http://www.aip.org/fyi/2006/093.html

I just found an article on the Senate Appropriations commitee, dated July 17th. It has an interesting note on JUNO:

"The Committee has provided the budget request of $120,000,000 for the Juno-Jupiter Polar Orbiter mission and fully expects NASA to maintain this mission and its out-year budget profile to accommodate a 2010 launch as originally envisioned."


I know that the budgets shift back and forth until the fall, but if this is still in the final version, it looks like we might be back to a 2010 launch.

I talked to one of the JPL engineers about JUNO at the open house in May, and he said they could launch much earlier than even 2010, but it was entirely about budget cycles at this point.

Posted by: Lorne Ipsum Sep 17 2006, 09:03 PM

QUOTE (Mariner9 @ Aug 1 2006, 01:06 PM) *
...I know that the budgets shift back and forth until the fall, but if this is still in the final version, it looks like we might be back to a 2010 launch.

I talked to one of the JPL engineers about JUNO at the open house in May, and he said they could launch much earlier than even 2010, but it was entirely about budget cycles at this point.


Sorry, not a chance of this happening. Once upon a time, the program was happily lined up for a 2010 launch. After the slip, contracts were changed, and the whole program replanned from top to bottom. If Juno had *originally* been slated for a launch before 2010, and the funding had held, it would have been doable.

At this point, though, it'd be horrendously expensive to launch in any year BUT 2011. An awful lot of analysis would have to be re-done, at the very least. Meanwhile, some number of long-lead items probably wouldn't be ready in time.

Lorne

Posted by: Roly Sep 18 2006, 02:42 AM

Any further news about JunoCam pictures of the satellites? I know this is absolutely outside the mission, but there was some speculation I believe (assuming it ends up being fitted to the spacecraft) that there may be some possibility. I seem to remember that there might be a chance at Io.

Posted by: mcaplinger Sep 18 2006, 02:50 PM

QUOTE (Roly @ Sep 17 2006, 07:42 PM) *
Any further news about JunoCam pictures of the satellites?

JunoCam is a wide-field-of-view instrument, so a satellite approach would have to be pretty close to yield anything better than what we have already. And I suspect that Juno will be deliberately kept away from the satellites to keep the orbit perturbations to a minimum. But it's a long time until this mission flies, so I wouldn't count anything out yet.

And on the topic of gravity measurements, I ran across an abstract, "Gravity Inversion Considerations for Radio Doppler Data from the JUNO Jupiter Polar Orbiter" ( http://www.aas.org/publications/baas/v36n4/dps2004/158.htm ) that describes some possibilities, though I haven't seen the full paper.

Posted by: JRehling Sep 18 2006, 04:40 PM

QUOTE (mcaplinger @ Sep 18 2006, 07:50 AM) *
JunoCam is a wide-field-of-view instrument, so a satellite approach would have to be pretty close to yield anything better than what we have already. And I suspect that Juno will be deliberately kept away from the satellites to keep the orbit perturbations to a minimum.


Since Io has a time-varying phenomenon or two, occasional medium-range pictures could be informative. Earth-based observations have been proven capable of spotting the big ones, but some more frames of what we could consider to be a "movie" with many gaps (mainly gaps) on the ongoing record of post-1979 flareups on Io couldn't hurt.

The Anderson, et al, abstract on gravity science is interesting. They do mention observing the tides raised by the Galileans and Amalthea (which is much, much closer to the cloudtops, thus having a serious tidal effect despite its small size and low density). I might as well start learning the math behind the rest of the content of that abstract now.

Posted by: gndonald Sep 19 2006, 04:07 PM

I find the current 'tussle' on the forum about this missions lack of Jupiter moon photography some what ironic, Pioneer 10/11 were essentially focused almost entirely on Jupiter to the exclusion of the satellites.

The same thing almost happened to Voyager, if the BBC documentary series http://www.imdb.com/title/tt0283775/, was accurate in its description of the 'one man' fight to have the moons included as imaging targets for Voyager.

Supposedly until the Io pictures came in the mission team was entirely composed of Atmospheric and Astrophysics specialists ready to unravel the mysteries of the Jovian atmosphere...

So in that sense this mission is a return to basics, a focus on the 'main show' namely Jupiter itself rather than what orbits around it.

Posted by: Analyst Sep 19 2006, 06:15 PM

QUOTE (gndonald @ Sep 19 2006, 04:07 PM) *
The same thing almost happened to Voyager, if the BBC documentary series http://www.imdb.com/title/tt0283775/, was accurate in its description of the 'one man' fight to have the moons included as imaging targets for Voyager.

Supposedly until the Io pictures came in the mission team was entirely composed of Atmospheric and Astrophysics specialists ready to unravel the mysteries of the Jovian atmosphere...


Very early in the planning stage (about 1972/73) MJS 77 got cameras with Mariner 10 heritage. This has not been easy (budget etc.) and I guess this is the "dramatic fight" in The Planets. The moons have been a primary science target at least since then. JPL studied many trajectories and could only get close encounters with three moons at Jupiter. At Saturn, Titan has been a so high priority, Voyager 2 could be sent to it again if Voyager 1 failed.

As for Juno: Its not about images first, not even second. It's not a sexy mission imo, but we will learn at lot.

Analyst

Posted by: tedstryk Sep 19 2006, 08:14 PM

I know the images are not a priority, but there are two things I am hoping for from JunoCam. First, any serendipitous shot it can get of the four inner moons, since coverage from Galileo and Voyager is so limited and most of the moon oriented missions likely to be selected any time soon are not likely to get close to them. Secondly, a few decent Io images for temporal coverage with better resolution than we have from earth. Plus, especially if the cloud tops are in the background, these images would be great for PR.

Posted by: gndonald Sep 21 2006, 03:13 PM

QUOTE (Analyst @ Sep 20 2006, 02:15 AM) *
Very early in the planning stage (about 1972/73) MJS 77 got cameras with Mariner 10 heritage. This has not been easy (budget etc.) and I guess this is the "dramatic fight" in The Planets. The moons have been a primary science target at least since then. JPL studied many trajectories and could only get close encounters with three moons at Jupiter. At Saturn, Titan has been a so high priority, Voyager 2 could be sent to it again if Voyager 1 failed.


I've watched the relevant episode again ('Terra Firma') and it's definitely implied that the argument was not about having cameras on Voyager, but about where they were going to be pointed when Voyager reached Jupiter.

QUOTE (Analyst @ Sep 20 2006, 02:15 AM) *
As for Juno: Its not about images first, not even second. It's not a sexy mission imo, but we will learn at lot.


You're absolutely right there, this is the sort of 'basic science' mission that needs to be carried out so that we can plan properly for the next major mission without any more incidents like dropping the atmosphere probe into the wrong region as happened with the Galileo's mission.

And its been a long time in coming, this sort of mission was first proposed by the designers of Pioneer 10/11, even before the first flyby of Jupiter. In that case they planned to use an http://tinyurl.com/mcvz4 to carry out long term (2 yr) observations of Jupiter (or Saturn) during the late 70's/early 80's. In these craft as with Juno, particles and fields studies would have been the main objective while imaging would have taken the back seat, despite the replacement of the Imaging Photopolarimeter with a 'line scanning' imager which would have presumably produced better images.

Posted by: Mariner9 Sep 21 2006, 05:11 PM

I recall reading about that proposed orbiter. I vaguely remember Dr James Van Allen being one of the proponents of it.

Basically Galileo was a hybrid space vehicle in order to do both spining (which is better for the particles and fields instruments) and a stable (better for imaging) platform.

And after all the suffering involved in engineering it, a lot of those involved swore they would never try another dual-spin spacecraft again.

Cassini was supposed to be the "cheaper' vehicle... although it seems to me that at 3 billion dollars it ended up more expensive. Difficult to be sure, since Cassini was developed later and hence with inflated dollars compared to Galileo. Also, the antenna failure on Galileo introduced a lot of extra operations expenses, on a program that already was delayed several times, and redesigned a few times. I don't think I've ever seen a final tally on Galileo's costs, but I'm pretty sure it ultimately went over 2 Billion.

Posted by: Mariner9 Sep 21 2006, 05:14 PM

I think I was a little vague about the main point I was trying to make.

Basically there were two camps propsoing instrumentation for a Jupiter orbiter. One wanted a spinning design, the other a 3-axis stabalized.

Galileo was the "all in one" compromise vehicle that came out of that.

Posted by: Analyst Sep 21 2006, 06:18 PM

QUOTE (gndonald @ Sep 21 2006, 03:13 PM) *
I've watched the relevant episode again ('Terra Firma') and it's definitely implied that the argument was not about having cameras on Voyager, but about where they were going to be pointed when Voyager reached Jupiter.


I have to be more specific. The cameras initially planned for MJS 77 were a simpler design than the ones finally flown (lower resolution, more noise etc.). It was because the moons were a high priority they switched to the best ones available (Mariner 10) in about the 1972/73 timeframe. So long before launch the interest in the moons forced some design changes.

This said, I am sure there have been long discussion about where to point the scan platform during the encounters, sometimes the planet scientist won, sometime the moon nerds.

Analyst

Posted by: Roly Sep 24 2006, 12:26 PM

Given Junocam's heritage from MSL's MARDI, I wonder how will it cope with the radiation environment around Jupiter; I seem to remember something about a giant tantalum block shield for SSI, though Juno's orbit is more benign than Galileo's, and it doesn't have to last very long.

For inner moons like Io and Europa, any estimates of the sort of resolution that might be expected, given the 15km per pixel officially provided for images of Jupiter's poles?

Posted by: vjkane2000 Nov 2 2006, 03:39 PM

Juno's camera has been quoted on their website as having a 15km resolution. Does anyone know at what distance that resolution occurs? Is it over the poles or a perijove?

Posted by: Lorne Ipsum Nov 3 2006, 12:18 AM

QUOTE (vjkane2000 @ Nov 2 2006, 09:39 AM) *
Juno's camera has been quoted on their website as having a 15km resolution. Does anyone know at what distance that resolution occurs? Is it over the poles or a perijove?


Should be over the poles -- JunoCam's reason for existence (well, OK, aside from EPO value...) is for gathering polar mosaics. I don't think anybody's exactly sure (yet) whether or not JunoCam will even produce usable images at perijove, due to the radiation environment there.

Lorne

Posted by: ugordan Nov 3 2006, 08:33 AM

If the perijove is well inside Io's orbit, doesn't that mean much lower radiation fluxes? Also, flying over the poles you're basically above/below the main radiation belts, right?

Posted by: vjkane2000 Nov 3 2006, 03:50 PM

QUOTE (Lorne Ipsum @ Nov 2 2006, 04:18 PM) *
Should be over the poles -- JunoCam's reason for existence (well, OK, aside from EPO value...) is for gathering polar mosaics. I don't think anybody's exactly sure (yet) whether or not JunoCam will even produce usable images at perijove, due to the radiation environment there.

Lorne


I recall that the Galileo probe found that radiation dipped as it came very close to the planet. I don't remember if 'very close' was above or below Juno's perijove. Also 'dipped' is relative. It might still be quite high relative to what the camera can handle.

I would love to see detailed images of the clouds up close. Assuming the radiation can be tolerated, there are a couple of potential issues. First, the craft will be moving very quickly. I don't know if the spacecraft's spin will act as a partial counter or make the problem worse. Second, will the spacecraft nadir be on the lit side of the terminator. Even if it is, the illumination will still be fairly dark.

One suggestion that these problems can be overcome is that the proposed Italian IR instrument would take pictures during close approach. If it can do it, then there is hope for JunoCam.

Net out of all this, as much as I want to see a high resolution image of the those belts and zones, I'm not holding my breath.

Posted by: edstrick Nov 4 2006, 11:33 AM

The Voyagers got considerable amounts of sampled high resolution imagery at up to some 20 or 15 km resolution <similar to Amalthea> Much of it was low contrast vaguely swirley diffuse cloud patterns with little visual "pull" to grab interest. I think little of it was in color but I don't know that. Certainly, little has ever been presented to the public, other than as archived images on the Voyager disks. I've sort of wondered what could be done with it... maybe superimpose it in synchronized wide angle shots.. I suspect some was mosaics or strips of imaging to sample Jupiter at high rez but I don't remember.

Posted by: vjkane2000 Nov 4 2006, 08:49 PM

QUOTE (edstrick @ Nov 4 2006, 03:33 AM) *
The Voyagers got considerable amounts of sampled high resolution imagery at up to some 20 or 15 km resolution <similar to Amalthea> Much of it was low contrast vaguely swirley diffuse cloud patterns with little visual "pull" to grab interest. I think little of it was in color but I don't know that. Certainly, little has ever been presented to the public, other than as archived images on the Voyager disks. I've sort of wondered what could be done with it... maybe superimpose it in synchronized wide angle shots.. I suspect some was mosaics or strips of imaging to sample Jupiter at high rez but I don't remember.


The attached Cassini image suggests that images along the terminator would tend be be washed out. However, the image was processed to highlight the brighter areas.

I've just always been struck by the beauty of cloud images from Earth orbit and hope that we could get something similar from King of Storms. But probably a wish to go ungranted.

Posted by: NMRguy Nov 10 2006, 09:28 AM

As discussed above, imaging with JunoCam is a peripheral goal for the mission. But Juno will be the first Jupiter probe to be placed into a polar orbit, and we are beginning to see the advantages of this orbital inclination from Cassini (http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=703).

Does anyone know JunoCam’s pointing direction and whether it will be able to ride along with any of the other instruments? The Juno team reports that primary science measurements are taken at ± 3 hours from perijove for all science orbits. Furthermore, only two science modes (and thus pointing directions) are necessary for the entire primary mission. These include radiometry and gravity science.

Since the closest passes over Jupiter’s polar regions are included in the primary science windows, will the team allow JunoCam to image the poles during the mission, or is this something they will focus on late in the game? Can we expect similarly informative and stunning Jupiter polar images from Juno as we will get from Cassini?

Posted by: Bjorn Jonsson Nov 10 2006, 03:26 PM

An obvious problem is that Jupiter's poles never get much sunlight due to Jupiter's low axial tilt (~3°). Compare this to Saturn's ~27°. Obviously the poles are not in darkness but they are more difficult to image and you cannot image a big around around the pole in a single image (or over a period of several minutes). Vertical relief is also less pronounced on Jupiter since the atmosphere is more 'compressed' than Saturn's.

Posted by: nprev Nov 10 2006, 04:04 PM

I would imagine that IR-band imaging would be an inflexible requirement, then.

Posted by: Lorne Ipsum Dec 26 2006, 10:06 PM

QUOTE (NMRguy @ Nov 10 2006, 03:28 AM) *
Does anyone know JunoCam’s pointing direction and whether it will be able to ride along with any of the other instruments?


Last I'd heard, it'll be pointing perpendicular to the spin axis, much like most other instruments.

QUOTE
The Juno team reports that primary science measurements are taken at ± 3 hours from perijove for all science orbits.


Strictly speaking, *between* +/-3 hours from perijove.

QUOTE
Since the closest passes over Jupiter’s polar regions are included in the primary science windows, will the team allow JunoCam to image the poles during the mission, or is this something they will focus on late in the game?


My understanding is that since JunoCam is riding along for EPO (education & public outreach), it won't be particularly radiation "hard." I don't think anybody's expecting it to last past the first dozen orbits or so.

QUOTE
Can we expect similarly informative and stunning Jupiter polar images from Juno as we will get from Cassini?


Sure hope so...

Lorne

Posted by: John Flushing Jan 10 2007, 12:34 AM

I dug out an article from June of 2005.

http://space.newscientist.com/article/dn7457-new-robotic-probe-planned-for-jupiter.html.

Posted by: Thu Mar 12 2007, 11:05 AM

A new article for Juno:
Juno Gets A Little Bigger With One More Payload For Jovian Delivery - http://www.spacedaily.com/reports/Juno_Gets_A_Little_Bigger_With_One_More_Payload_For_Jovian_Delivery_999.html

I'm wondering with some questions, could anybody help me out?
- This will be the farthest solar-powered s/c ever ventured outside Mars's orbit, isn't it? I'm not sure if Rosetta crosses Jupiter's orbit or not?
- How big the solar panels will be to give adequate power output from Jupiter for the 8-proposed instruments?
- This is from the article: "This will let it "thread the needle" through Jupiter's most intense doughnut-shaped radiation belts" - what does it mean? Are there some areas in Jupiter's radiation belts where the radiation level is lower than others?

Posted by: Lorne Ipsum Mar 12 2007, 11:22 AM

QUOTE (Thu @ Mar 12 2007, 04:05 AM) *
I'm wondering with some questions, could anybody help me out?
- This will be the farthest solar-powered s/c ever ventured outside Mars's orbit, isn't it? I'm not sure if Rosetta's orbit reaches Jupiter or not?


Rosetta will go out to 5.2 AU from the Sun, which is about at Jupiter's orbit. The difference, though, is that (if I'm not mistaken) Rosetta will just spend some time there on it's way to a comet, while Juno will actually be conducting science at 5.2 AU.

QUOTE (Thu @ Mar 12 2007, 04:05 AM) *
- How big the solar panels will be to give adequate power output from Jupiter for the 8-proposed instruments?


Huge.

You might want to check http://juno.wisc.edu/index.html out (it's Juno's public outreach web site).

QUOTE (Thu @ Mar 12 2007, 04:05 AM) *
- This is from the article: "This will let it "thread the needle" through Jupiter's most intense doughnut-shaped radiation belts" - what does it mean? Are there some areas in Jupiter's radiation belts where the radiation level is lower than others?


The idea is that by being in a polar orbit, the spacecraft can skim below the radiation belts on one side of Jupiter, and above them on the other side. Well, most of them, anyway. The Juno site has a good diagram http://juno.wisc.edu/Images/using/Instruments/PMS/Polar_Magnetosphere_Global_View.jpg.

Hope this helps...

Posted by: AndyG Mar 12 2007, 11:31 AM

QUOTE (Thu @ Mar 12 2007, 11:05 AM) *
- How big the solar panels will be to give adequate power output from Jupiter for the 8-proposed instruments?

http://juno.wisc.edu/spacecraft.html suggests three panels of ~2m by 9m. Assuming 50 square metres of panels operating at ~20% efficiency and at 5.2 AU, the power available is going to be around 500W - about the same as from Galileo's 2 RTGs.

Andy

Posted by: helvick Mar 12 2007, 12:20 PM

20% efficiency is conservative, http://news.com.com/Solar+cell+breaks+efficiency+record/2100-11395_3-6141527.htmlhttp://news.com.com/Solar+cell+breaks+efficiency+record/2100-11395_3-6141527.html. The panels on the MER's were around 23% so I'd assume that the best space rated arrays are substantially better than that now.

Posted by: Thu Mar 12 2007, 12:24 PM

Thanks Lorne Ipsum, that really helps smile.gif

Posted by: djellison Mar 12 2007, 12:56 PM

There's also the issue of how much of that 3 x 9 x 2 m area is actually filled with arrays. Technically a 54m^2 area, but what's the packing density of the arrays going to be like - how much will be taken up with hinges etc... 8% is probably a fairly good guess, making it 50m^2 - and that's where the 500W comes from smile.gif

What I want to know is what the downlink will be like smile.gif

Doug

Posted by: Thu Mar 12 2007, 02:09 PM

Talking of solar power, I remembered that Deep Space 1 used the innovative solar concentrator arrays for its mission but not sure about the improvement over conventional solar panels. Anybody knows the result of the test? Has this new technology been applied to other spacecrafts?

Posted by: centsworth_II Mar 12 2007, 04:26 PM

QUOTE (djellison @ Mar 12 2007, 08:56 AM) *
What I want to know is what the downlink will be like smile.gif

The lack of photographic images will make it easy to meet the
needs of the other instruments, won't it? Also, aren't scientific
observations limited to a small part of the orbit? There should
be no trouble getting down all the data that Juno can produce.
IMHO

Posted by: vjkane2000 Mar 12 2007, 04:30 PM

QUOTE (helvick @ Mar 12 2007, 04:20 AM) *
20% efficiency is conservative, http://news.com.com/Solar+cell+breaks+efficiency+record/2100-11395_3-6141527.htmlhttp://news.com.com/Solar+cell+breaks+efficiency+record/2100-11395_3-6141527.html. The panels on the MER's were around 23% so I'd assume that the best space rated arrays are substantially better than that now.


Does anyone know what the current space rated solar panels are at? The Boeing press release is a laboratory result for Earth surface applications. Does rating panels for space result in higher or lower efficiency?

Posted by: edstrick Mar 13 2007, 08:44 AM

Bruce Moomaw has a couple articles worth checking out:

http://www.spacedaily.com/reports/Juno_Gets_A_Little_Bigger_With_One_More_Payload_For_Jovian_Delivery_999.html

Basically, the italians proposed a second meteorology cam for Juno, together with an infrared cam/spectrometer, and a Ka-band transponder to improve radio tracking.

The meteorology cam was rejected as too similar to JunoCam, but the IR instrument's provisionally accepted, as is the transponder. If the IR instrument does fly, it patches what to me has seemed a major hole in the mission's instrumentation: The ability to see and measure with good resolution cloud structures and the "hot spots" of downwelling (like the one the Galileo probe fell into) that are water and ammonia depleted relative to the deep atmospheric average. This gives the linkage between visible cloud patterns/meteorology, deeper cloud structure, and the to-be-microwave-mapped sub-cloud atmosphere distribution of water and ammonia.

GO FOR IT!

also, on lunar robotic exploration and budget/political/patronage chicanery:
http://www.space-travel.com/reports/NASA_Budget_Tucked_Away_For_Now_But_Hard_Decisions_Only_Deferred_999.html

Posted by: helvick Mar 13 2007, 10:57 AM

http://www.boeing.com/defense-space/space/bss/factsheets/spectrolab/spectrolab.htmlthat 28.3% is the current state of the art for space rated cells with 33% expected by 2009.

To put the 40.7% number in perspective http://upload.wikimedia.org/wikipedia/commons/4/4f/Nrel_best_research_pv_cell_efficiencies.pngso it appears to take around a decade to go from state of the art to sufficiently mature to become available in a space rated array.

The optical concentrator approach has a major drawback as it requires much more accurate sun pointing. I suspect that that would rule the approach out for any craft in a reasonably tight orbit of a planet but that's just a hunch.

Posted by: Analyst Mar 13 2007, 06:02 PM

QUOTE (djellison @ Mar 12 2007, 01:56 PM) *
What I want to know is what the downlink will be like smile.gif


With 500 watts total power this should not be an issue during downlink. Voyager works today with less than 300 watts and has a quite powerful telecom system. With a 2.5m high gain it should be possible to have 32 to 64 kbits/s in X-band for Juno. Like New Horizons or better. Should give us some pictures smile.gif

Analyst

Posted by: NMRguy Mar 13 2007, 10:03 PM

As far as I can tell, the Juno team has always planned to include X-band radio frequency capabilities. Does the addition of the Italian Ka-band transponder add a new dimension to the gravity science experiment, or has NASA just outsourced development of that instrument to Italy?

In more general terms, there are a multitude of radio frequencies available for gravity science. Do most space agencies choose X and Ka-bands because of their extensive communications development and because they both just pass through the atmospheric radio frequency window, or are there additional reasons? [Ka-band seems to be the shortest wavelength to still transmit through the atmosphere.]

Finally, are Doppler shifts measured concurrently for both frequency bands to achieve signal redundancy, or can we actually improve signal to noise rations with a combined analysis (or something like that)?

I’m really looking forward for this bird to get off the ground.

Posted by: edstrick Mar 14 2007, 09:35 AM

Early deep space missions (not including REALLY early pre-Mariner stuff, which I think tended to use lower frequencies) used S-band. X-band and Ka-band let you focus your spacecraft transmitted power (say 20 watts RF) onto smaller and smaller targets surrounding the Earth. The beam-spots are essentially diffraction limited and cover a vastly larger area than the Earth. You just try to have pointing accurate enough that Earth is in the near-center of the beam-spot. The result of higher frequencies is more bits of data per transmitted watt per hour.

Drawbacks include more precise antenna pointing required at the spacecraft and opacity of heavy precipitation on Earth to the shorter wavelengths.

With 2 or 3 frequencies, you can play valuable games increasing precision in ranging and doppler measurements. Space is NOT empty, it contains ionized plasma, as does Earth's ionosphere, and planetary ionospheres crossed during radio occultations. Earth also has an atmosphere, containing various vertical temperature and humdity profiles. All these have effects on the radio transmission. With one frequency, you just model them as best as you can. With more frequencies, you can start to separate out plasma effects and atmosphere effects and maybe variable column water vapor abundance effects -- directly from the data.

Plasma/ionospheres have more effect at long wavelengths... look at HF (strong) VHF (usually weak) and UHF (minimal) ionosphere bounce of radio transmissions on Earth. Gasses have different frequency dependent effects. Mariner 5 carried a radio RECEIVER for a dual frequency occultation experiment at Venus. Stanford university transmitted a dual frequency carrier wave at the spacecraft which measured the signal strength (and maybe doppler shift, I can't remember) of each signal as it went behind the planet. JPL, meantime, did a Spacecraft-to-Earth S-band occultation like Mariner 4 did at Mars. It turned out the low frequency occultation data (C band? L band?) was so strongly refracted that below certain altitudes, refracted raypaths crossed and there were "caustiics"... mirages... in the signal and it could not be uniquely interpreted. Similar experiments have not flown since on deep space missions. It would still be useful for things like Io ionosphere and trace atmosphere occultations.

Posted by: Phil Stooke Mar 15 2007, 03:35 AM

Ed, the Mariner 5 dual-frequency occultation experiment
involved one UHF and one VHF signal (can't remember their frequencies); and
the "phase" (ie. Doppler shift) of the signals was indeed measured along
with their signal strength. In fact this experiment was carried largely
because its phase-detection capability made it lots more sensitive to
electron layers in Venus' ionosphere than the S-band occultation was. (I
think I mentioned before that there was a feud over whether to carry this
experiment at all on that hastily jury-rigged planetary mission. JPL
recommended a copy of the Mariner 4 TV camera, with one visible and one UV
filter, instead; but NASA HQ overrode them. Decades later, I'm still seeing
fights over the decision in science papers.)

Posted by: edstrick Mar 15 2007, 08:31 AM

I'm an images type of guy, but with 20-20 hindsight, I think the experiments were a tossup. A Mariner 4 type camera -- IF -- it could have taken full disk and quarter-disk photos might have given them a good first clue on the atmospheeric circulation, but a Mariner 4 type, kilometers resolution, single-image-swath across the disk would have been nearly useless.

Occultation was a completely new technique that had been tested once with spectacular results but was still underdeveloped. The Stanford experiment turned out to be rather redundant, but it was a learning experience.

And it gave confidence in the overall occultation results. Combined with the Venera-4 descent data (till it was crushed at about 25 atmospheres pressure), and an (at the time debated) correction to the Venera radar altimetry point, it fixed the radius of the planet and determined the probably atmosphere surface pressure and temperature.

With 20-20 hindsight, what ***I*** would have carried on Mariner 5 was a simple but scanned infrared radiometer. Similar to that on Mariner 6/7, 9 and 10 but with an internal stepper to scan a crude raster across the planet. Mariner 2 saw, in it's very limited zig-zag pass of the IR radiometer field of view (boresighted with the microwave radiometer), depressed temperatures at the now known location of the polar high-altitude ring-cloud that surrounds the double-vortex. They would have seen that and maybe other interesting structures, though in 10-20 micrometer IR, you don't see the atmosphere windows to under the clouds.

Posted by: tedstryk Mar 15 2007, 01:48 PM

I would add that until Venus was nearly frame filling, it is questionable whether the data would have been able to tell us anything that we couldn't tell from earth (that Venus had some bright and dark clould markings in UV, but nothing about their nature).

Posted by: AlexBlackwell May 4 2007, 08:41 PM

QUOTE (AlexBlackwell @ Jul 17 2006, 03:53 PM) *
Again, I apologize for reviving a dormant thread; however, has anyone noticed this particular http://juno.wisc.edu/?

Has anyone noticed this http://juno.wisc.edu/ has been updated? It now has a Juno http://en.wikipedia.org/wiki/Favicon, too biggrin.gif

Posted by: JRehling May 6 2007, 09:19 PM

QUOTE (AlexBlackwell @ May 4 2007, 01:41 PM) *
Has anyone noticed this http://juno.wisc.edu/ has been updated? It now has a Juno http://en.wikipedia.org/wiki/Favicon, too biggrin.gif


Someone with my math skills and slightly more gumption (hint-hint) might want to calculate the minimum distance between Juno's orbit and the big five satellites. It seems like we'll get a few snaps of the satellites, and I'm curious at what resolution. Sometime between now and 2016, it would be interesting to know that.

Posted by: edstrick May 7 2007, 07:43 AM

"...Venus was nearly frame filling, it is questionable whether the data would have been able to tell us anything that we couldn't tell from earth ..."

Wrong. Earthbased data by the early 70's was poor due to seeing limitations and the need to image the atmospheric features at near UV wavelengths where seeing is worse than terrible even if it's pretty decent at near-IR/Red wavelengths. While the Mariner 4 camera was pretty limited, a well targeted series of UV images with the disk exactly filling the field of view would have provided a first real look at the cloud patterns.

But you're right after all...
My limited understanding was that any camera that might have flown on Mariner 5 would have been a minimally modified version of the Mariner 4 cam, including a 1 axis scan platform that could position the camera left-right (sort of) in azimuth as the spacecraft's trajectory took it's fixed-elevation narrow angle view across the planet. A dozen-ish frames of vague, low contrast streaky and mottled uv absorber features would have been a pretty minimal result for a major experiment. Whatever they are, the UV markings on Venus rapidly lose contrast as you zoom in on them for finer and finer details. 30% contrast at 100 km scale drops to say 3% contrast at 10 km and perhaps 0.3% contrast at 1 km scale. (I'm making up the numbers but they are the right sort of idea and probably in the ballpark estimates.)

They could see a persistent "Y" and "PSI" shaped cloud pattern aligned with the apparent equator and that it often repeated with about a 4 day period. Real cloud patterns and dynamics and meteorology was entirely beyond earthbased observation.

Mariner 10

Posted by: tedstryk May 8 2007, 01:45 PM

Based on what I have read, the Mariner-R (the design that became Mariners 3-5), with the R standing for "runt," carried a camera that was designed primarily to test conditions for future cameras. One has to remember that the Mariner-R design being used in the 1964 launch was simply due to limited rocket capability. The originally planned probes would have had much better cameras. It was more of a backup that could be flown should they have to depend on the Atlas/Agena. And it served its purpose quite well - even beyond the light leak problem, the Martian surface proved to exhibit much less contrast than expected. This discovery aided Mariners 6 and 7. And of course it made interesting scientific discoveries, such as the lack of albedo/topographic correspondence on Mars, as well as the better known spotting of craters and pretty much killing the canals. But such images of cloudtops, while they would have been more detailed than those of earth, would, as edstrick indicated, not taught us all that much for a major experiment.

Posted by: Paolo May 8 2007, 06:33 PM

QUOTE (tedstryk @ May 8 2007, 03:45 PM) *
Based on what I have read, the Mariner-R (the design that became Mariners 3-5), with the R standing for "runt,"


As far as I know, Mariner-R (for Ranger) were Mariner 1 and 2, Mariner 3-5 were originally called Mariner C, I think

Posted by: tedstryk May 8 2007, 08:27 PM

QUOTE (Paolo @ May 8 2007, 06:33 PM) *
As far as I know, Mariner-R (for Ranger) were Mariner 1 and 2, Mariner 3-5 were originally called Mariner C, I think

Yes, you are right. Mariner-C was at times called "runt" as a pejorative. I made the mistake of linking this to Mariner-R. Oops.

Posted by: edstrick May 9 2007, 08:12 AM

I have a xerox of an article from some journal like a major pub of the Geological Society of America or some such from the early 60's... maybe 1964 or 3. It's a carefully considered review of geological possibilities to look for during the exploration of Mars. It's thoughtful, well reasoned, raised essential questions regarding the possibility of finding folded mountain belts, volcanic features, erosional patterns.... etc. It totally missed the possibility of impact craters and the possibility of large areas with terrains that resulted from having minimal internal geologic activity for the majority of the planet's lifetime.

The overwhelming science results from Mariner 4 boiled down to three items.

1.) Some of the surface is REALLY old with lunar like cratering, probably impact craters. (whatever really old is).

2.) The surface pressure is confirmed by occultation to be at about 1/200'th atmosphere, as suggested by recent spectroscopy, and not the 1/10'th atmosphere most recent analyses had suggested the last couple <?> decades. Accordingly, the atmosphere must be mostly CO2 (enough to explain the spectra)

3.) There is minimal if any global magnetic field and thus no radiation belts. Thus the core is not molten or not driven to provide an active dynamo.


Pretty impressive results for such an early mission.

Posted by: JRehling May 10 2007, 08:31 PM

QUOTE (JRehling @ May 6 2007, 02:19 PM) *
Someone with my math skills and slightly more gumption (hint-hint) might want to calculate the minimum distance between Juno's orbit and the big five satellites. It seems like we'll get a few snaps of the satellites, and I'm curious at what resolution. Sometime between now and 2016, it would be interesting to know that.


I finally took the leap.

For the Galileans, Juno's closest flyby possibilities will be as it flies directly over one pole on the apojove portion of the orbit. Those distances are:

Io: 264,000 km
Europa: 355,000 km
Ganymede: 444,000 km
Callisto: 408,000 km

Amalthea will be closest, potentially, at perijove, at 105,000 km. Amalthea's distance from the polar looking view will be as little as 150,000 km.

Io and Europa's encounters will be about as far as Cassini was from Dione when THIS

http://photojournal.jpl.nasa.gov/jpeg/PIA08856.jpg

images was snapped. Of course, the Galileans are much bigger than Dione.

We should get some nice satellite images from JunoCam...

Posted by: volcanopele May 10 2007, 08:43 PM

What's the field of view of JunoCam and what is the size of an image?

Posted by: AlexBlackwell May 10 2007, 08:51 PM

QUOTE (volcanopele @ May 10 2007, 10:43 AM) *
What's the field of view of JunoCam and what is the size of an image?

I believe JunoCam FOV is 6° × 0.05°.

Posted by: volcanopele May 10 2007, 09:09 PM

hmm, a push-broom detector? Assuming each image is 1024 pixels wide, that would indicate top resolutions of:

Amalthea: 11 km/pixel
Io: 27 km/pixel
Europa: 36 km/pixel
Ganymede: 44 km/pixel
Callisto: 42 km/pixel

Posted by: djellison May 10 2007, 09:15 PM

JunoCam is a MARDI rip off isn't it? 1600 x 1200 RGB framing camera.

Doug

Posted by: AlexBlackwell May 10 2007, 09:50 PM

QUOTE (AlexBlackwell @ May 10 2007, 10:51 AM) *
I believe JunoCam FOV is 6° × 0.05°.

CORRECTION:

From Steve Matousek's paper ("The Juno NewFrontiers mission") currently in press with Acta Astronautica:

QUOTE
JunoCam is the E/PO camera. It is not a science instrument, and has no science requirements. JunoCam will not be permitted to impact S/C or science requirements. JunoCam captures three-color images of Jupiter with spatial resolution to approximately 15 km/pixel for public engagement and E/PO. It is mounted on the instrument deck with an unobstructed 18° ×3.4° FOV in the spin plane.

Posted by: vjkane May 11 2007, 01:49 AM

What would be the resolution of JunoCAM at closest approach to Jupiter (ignoring smear)? Closest approach would be ~70,000 km. I believe that the Jupiter resolution quoted above is for the polar regions when Juno is still a fair distance away.

Posted by: AlexBlackwell Sep 13 2007, 06:46 PM

Note that the http://juno.wisc.edu/index.html was recently updated.

Posted by: nprev Sep 14 2007, 12:03 AM

Little bit bummed that there isn't a radio DF experiment of some sort planned. Those three active source areas on the "surface" are still very mysterious; would like to at least set limits on their physical size.

Posted by: Del Palmer Oct 3 2007, 09:51 PM

NASA awards Atlas V contract for Juno:

http://www.nasa.gov/home/hqnews/2007/oct/HQ_C07051_Juno_Launch_Services.html

Posted by: NMRguy Oct 4 2007, 10:38 PM

QUOTE (Del Palmer @ Oct 3 2007, 11:51 PM) *
NASA awards Atlas V contract for Juno:

I was going to say something about this being "An excellent choice" since NASA and Lockheed Martin have had such brilliant success with the Atlas V in the past. New Horizons and MRO launches were nearly flawless. But apparently Atlas V had its first hick-up last June with an NRO Reconnaissance Satellite. Too much of the important information is classified, however, and the launch has been deemed a "partial success". Nonetheless, I'm still willing to give [knock on wood] the Atlas V team the benefit of the doubt.

http://www.spaceref.com/news/viewnews.html?id=1222

Posted by: mchan Oct 5 2007, 10:39 AM

QUOTE (NMRguy @ Oct 4 2007, 03:38 PM) *
Nonetheless, I'm still willing to give [knock on wood] the Atlas V team the benefit of the doubt.

http://www.spaceref.com/news/viewnews.html?id=1222

What would you rather use as a launcher?

For the injection energy to get Juno into its initial transfer trajectory to Jupiter requires a large booster. The other choices in 2011 will still be Delta-IVH (more expensive), Proton (not a US launcher for a US spacecraft and a rather more serious failure last month), and Ariane 5 (not a US launcher). None have expected mission success rates significantly higher than Atlas V. Unfortunately, with the market realities of low launch rates and high launch costs today and in the near future, the choices are rather limited. Falcon 9 looks promising as a lower cost choice, but it needs several successful flights to establish its reliability.

And that is an old article you cite that came out just after the launch with the usual tough sounding public sound bites expected at those times. Here is a more recent one with more balanced reporting:

http://spaceflightnow.com/news/n0708/16rl10valve/

Posted by: NMRguy Oct 11 2007, 01:51 PM

QUOTE (mchan @ Oct 5 2007, 12:39 PM) *
What would you rather use as a launcher?

No, I agree that the Atlas V is the best option. The trajectories achieved for NH and MRO were excellent, saving valuable fuel for future scientific efforts. I also don't think that Juno is necessarily "settling" with the Atlas V choice. I was only saddened to just find out that the rocket had its first problem--I'm still catching up on lots of old news that I missed while on two months of summer fieldwork.

Anyway, Atlas V is back on track with another successful launch.

http://www.space.com/missionlaunches/sfn-071010atlas5-countdown.html

Posted by: Geographer Nov 9 2007, 05:41 PM

QUOTE
What would you rather use as a launcher?

The Ariane 5? It's launched closer to the equator so can take advantage of more centrifugal forces than a California launch.

Posted by: djellison Nov 9 2007, 06:02 PM

And in the real world with real money and real national interests (that rightfully keep the $190m spend on the Juno LV within the US) ?

Doug

Posted by: NMRguy Nov 11 2007, 11:17 AM

The Juno team has added a couple of new videos to their site. They aren't anything too high-tech, but they give a visual description of the mission.

http://juno.wisc.edu/index_whatsnew.html

Posted by: nprev Nov 11 2007, 01:21 PM

BTW, and this is all public information, of course, the launch problem previously mentioned was with the Centaur upper stage, which cut off a few seconds too early. Problem traced to a new fuel valve design; they went back to the old one for the WGS-1 launch, which went flawlessly.

Posted by: Geographer Nov 11 2007, 04:54 PM

QUOTE
And in the real world with real money and real national interests (that rightfully keep the $190m spend on the Juno LV within the US) ?

Are you interested in science or Boeing's profits? The ESA has no problem contracting certain launches out to Russia. It's not like Boeing is going to go bankrupt if they don't get the Juno launch. It's not like you're contracting the launch to North Korea, Europe is America's ally, and they have an equally capable launch vehicle and better launch position. NASA should take advantage of it if they can.

Posted by: djellison Nov 11 2007, 05:11 PM

QUOTE (Geographer @ Nov 11 2007, 04:54 PM) *
they have an equally capable launch vehicle and better launch position.


Actually - the Ariane V is a slightly less capable launch vehicle, from a better launch position, resulting in a similar performance.

I'm not going to start ( or allow ) a political debate here - but the fact of the matter is that US tax payers pay their taxes, some of which goes to NASA, so that America can do good science and exploration. As a US tax payer, is one going to be interested in science and engineering jobs in the USA, or in France?

The Ariane V is not significantly cheaper than the Atlas V, and any difference is probably offset entirely by figuring out how much of the cost of an Atlas V launch goes straight back to the US government as income tax.

Yes - ESA and NASA colaborate on projects ( SOHO, STEREO, C-H, JWST ) - but on a trade basis...we'll build a lander, you make the orbiter - or we'll make some instruments to fly, and you can use them sometimes, or we'll launch it if you let us use it for a while..... but NASA writing a cheque to Arianespace for a launch of an American project isn't going to happen, and nor should it. This entire debate is academic as we're now down a road whereby Juno IS launching on an Atlas V- fact. However - were we to wind back history 5 years and have a significant European contribution to the project in terms of instrumentation and scientists - then perhaps the responsibility of launching the mission could become a European affair (as is happening with JWST). Writing big trans-atlantic cheques just makes no sense, for either party, and is not a sensible way to spend the respective taxpayers money.


Doug

Posted by: nprev Nov 11 2007, 05:21 PM

Doug's right...plus, of course, it is in the best interests of the US to keep its domestic launch capability afloat. There really aren't all that many launches per year globally, and US commercial interests already outsource a lot of them to Baikonur and/or Ariane, so even one or two domestic Atlas flights become critical to keep the market attractive enough for the big aerospace companies to remain in the business (esp. with the pending demise of the Delta II, which will hurt UMSF). The profit margin here is really pretty slim.

Posted by: Greg Hullender Nov 12 2007, 05:07 AM

I notice that Falcon 9 is promising to deliver essentially the same payload to LEO as an Atlas V for the same price as a Delta II launch. If SpaceX truely pulls this off, it seems to me it'll make it hard for the big aerospace companies to stay in the game at all. But it could be GREAT for UMSF. :-)

--Greg

Posted by: dvandorn Nov 12 2007, 06:37 AM

But remember, Delta IIs only look cheap in comparison with Delta IVs and Atlas Vs. We're still talking significant expense. The expense of launchers has driven a lot of commercial users to less costly -- and less reliable -- systems.

What we really need is some revolutionary new propulsion technologies that will make access to LEO a lot cheaper than can be accomplished through the sole use of chemical rockets. (And while I'm wishing, I ought to toss in a good thought for World Peace, too, I guess...? rolleyes.gif )

-the other Doug

Posted by: djellison Nov 12 2007, 08:44 AM

QUOTE (Greg Hullender @ Nov 12 2007, 05:07 AM) *
I notice that Falcon 9 is promising to deliver essentially the same payload to LEO as an Atlas V for the same price as a Delta II launch.


Falcon 9 is 9.9 to 10.4 tons to LEO

Atlas V is 10.3 to 20.5 (25 if you include the Atlas V heavy) to LEO

So really - the Falcon 9 fits inbetween the Delta II and Atlas V in terms of performance ( something of a sweet spot I would say - MRO took the cheapest Atlas V.a job that could perhaps have been done by an F9 in the future)

Now it gets exciting with the Falcon 9 heavy...27.5 ton to LEO.


Doug

Posted by: Geographer Nov 12 2007, 05:18 PM

So the only argument against big checks crossing the Atlantic is national pride? I thought we were part of the larger scientific community. If the Atlas V is the best LV for Juno, so be it. But if the Europeans provide a more suitable vehicle, ie. cheaper and more effective, then why should American taxpayers and the scientific community pay more for less?

Like I said, a single launch is not make-or-break for American rocketry. Science launches make up a small portion of total space launches anyways.

Posted by: centsworth_II Nov 12 2007, 05:32 PM

QUOTE (Geographer @ Nov 12 2007, 12:18 PM) *
So the only argument against big checks crossing the Atlantic is national pride?

If you make the rocket, why not use it? And if you stop using -- and making -- it,
you may regret it down the line, after it's too late. US business certainly has not
been adverse to exporting other jobs when it helps the bottom line!

Posted by: JRehling Nov 12 2007, 06:07 PM

QUOTE (Geographer @ Nov 12 2007, 09:18 AM) *
So the only argument against big checks crossing the Atlantic is national pride?


It, along with 99.999% of all human activity, is also a matter of individual incentive. A politician who helps conduct legislation that provides jobs where his/her constituents live is more likely to please those constituents than a politician who watches or helps the same jobs go somewhere else. Ultimately, the money for all of these projects come from taxpayers=voters. They are on average less interested in science than in avoiding unemployment, local recessions, etc.

National federal funding rarely leaves the country in substantial quantities, and it is never highly popular when it does. Likewise, state funding rarely leaves the state it arises in, ditto on other levels.

If you had a single system of government that raised revenues on both sides of the Atlantic, then these considerations would become somewhat less relevant. As it is, they are virtually laws of physics.

Posted by: djellison Nov 12 2007, 06:16 PM

QUOTE (Geographer @ Nov 12 2007, 05:18 PM) *
So the only argument against big checks crossing the Atlantic is national pride?.


No, national interests.

Pride doesn't enter into it.

I don't think we're going to get any where with this debate. At this point, I'm considering the LV issue closed and any further posts on it will be culled.

Doug

PS: Clearly Geographer can't read what I just posted. Posts culled = 1.

Posted by: Geographer Nov 13 2007, 11:10 AM

Is Jupiter the furthest target that a solar powered mission could reach? Jupiter used to require RTGs but advancing solar technology has made those unnecessary, at least for this medium cost mission. How many advances in solar technology can realistically be expected; could there eventually be a Uranus or Neptune mission with solar?

Posted by: Greg Hullender Nov 13 2007, 06:43 PM

I'll be surprised if it's ever cost-effective to use solar beyond Jupiter, now that the political opposition in the US to RTG-powered vehicles has largely disappeared. Note that there wasn't a peep about New Horizons using an RTG.

--Greg

Posted by: edstrick Nov 14 2007, 08:23 AM

I expect it *IS* cost-effective to use solar beyond Jupiter.... for very "quiet" missions. You basically need solar-sail concentrators aimed at solar panels. Not the sort of thing to easily and accurately deploy from a folded-for-launch configuration. But very deep space observatories doing things like low frequency radio work or interplanetary weather stations or other spacecraft that do not do extensive maneuvering, especially attitude changes, could relitively easily use solar power. These might be assembled/deployed in high earth orbit... L5 or whatever, and sent outbound with ion engines.

Posted by: vjkane Nov 14 2007, 02:30 PM

There have been several proposals for a Saturn atmospheric probe mission in which the carrier spacecraft is solar powered. I believe that the mission is New Frontiers class.

I once calculated the energy available at Uranus for a craft using the largest solar arrays flown on interplanetary spacecraft. It was harder to figure out than the simple geometry of light intensity loss because solar arrays can be tweaked to perform better under (if I recall correctly) different temperature ranges. (It may have been different light levels; this was awhile ago.) I even doubled the size of the arrays. No go -- just not enough light.

However -- the new stirling low cost nuclear power supplies that NASA is considering for Discovery missions probably would enable a small Uranus craft with a probe or two in terms of power. The cost would probably still fill a New Frontiers budget. I suspect that you would still need a battery to handle peak power demands.

I am admitting that I am having problems thinking of missions within a Discovery price tag that would be *enabled* by the Stirling power supply. I can think of several -- network landers on Mars or rovers on Mars -- that would be easier with such a power supply. However, my understanding is that there are fairly few missions that need just 100-200W of power (I forget the exact power offered by this generator) and that don't require expensive launchers such as anything going to Jupiter or beyond. Perhaps I'm just not clever enough.

Posted by: nprev Nov 14 2007, 03:40 PM

QUOTE (Greg Hullender @ Nov 13 2007, 10:43 AM) *
I'll be surprised if it's ever cost-effective to use solar beyond Jupiter, now that the political opposition in the US to RTG-powered vehicles has largely disappeared. Note that there wasn't a peep about New Horizons using an RTG.

--Greg


Noticed that too, and was pleasantly surprised; it's absolutely key.

I think that even if solar cell efficiency increases ridiculously (think it's around 40% right now), RTGs are still the only game in town for outer-planet missions. The recent ISS array deployment difficulty shows how much risk there is with very large arrays for UMSF (and no way to fix them, unless you get really lucky with respect to failure mode). Furthermore, all the articulation needed to maintain optimum power levels after achieving orbit around the target not only adds weight & even more mechanical complexity, but also requires a lot of power to accomplish; motor torque eats current like so many peanuts.

When you're talking very infrequent launch opportunities combined with decades of cruise time for Uranus & Neptune, I don't think we want to roll those dice...

Posted by: Jeff7 Nov 14 2007, 04:42 PM

QUOTE (Greg Hullender @ Nov 13 2007, 01:43 PM) *
I'll be surprised if it's ever cost-effective to use solar beyond Jupiter, now that the political opposition in the US to RTG-powered vehicles has largely disappeared. Note that there wasn't a peep about New Horizons using an RTG.

--Greg
New Horizons probably didn't get the media fanfare that Cassini did. Cassini was the biggest probe ever launched, going to explore big, pretty, ringed Saturn. And it had 3 RTGs. And it was making a flyby of Earth, which of course brought out the doom-n-gloom crowd. Someone at NASA/JPL would have had to screw up pretty badly to send Cassini plummeting into the ground during a routine gravitational-assist flyby.

New Horizons had one RTG, and it was on a high-speed one-way trip away from Earth. There probably were some complaints (some of the extremists probably think that saying "plutonium" is enough to cause cancer), but they just didn't get much attention on the launch of New Horizons.

Posted by: tedstryk Nov 14 2007, 04:59 PM

I don't mean to be political here, but I do wonder if some of it had to do with the fact that some of the anti-RTG folks may have realized that if the Clinton administration wouldn't stop a probe with three RTGs that would make an earth flyby, there wasn't a chance in hell the Bush administration would block a probe over one RTG with no earth flyby.

Posted by: Mariner9 Nov 14 2007, 07:07 PM

Back on the solar power for outer planets missions.

From what I understand, the ammount of power produced by solar arrays at Jupiter are practical (for some missions), but solar arrays degrade if they spend too much time in the Jovian radiation belts. Juno avoids this problem because its highly elliptical, polar orbit keeps it out of the radiation for most of the orbit.

Similarly, the furthur out your Jupiter periapsis, the less your total exposure. I think some of the orbiters being conceptualized for the Laplace mission have solar power since they have lower power requirements and stay furthur out. (I could be wrong about this, and the mission will keep evolving over the next couple years during the on going studies).

As for array deployment problems, I don't think it is a good apples to apples comparison to bring up the ISS troubles. Those arrays are huge, and involve a huge number of folds. If you look at ships like Juno, there are only a few panels to be unfolded. That being said, it's true that RPGs tend to have fewer deployment failure scenarios.

Posted by: Del Palmer Nov 14 2007, 11:21 PM

QUOTE (Mariner9 @ Nov 14 2007, 07:07 PM) *
As for array deployment problems, I don't think it is a good apples to apples comparison to bring up the ISS troubles. Those arrays are huge, and involve a huge number of folds.


Hubble's SA1 arrays were much smaller than the ISS arrays, yet the astronauts had to toss one overboard when it failed to retract...

Posted by: nprev Nov 15 2007, 01:16 AM

My whole point in bringing up the ISS array prob was to illustrate that minimizing mechanical complexity for long-duration, rare-window missions is a wise design heuristic. FWIW, I think solar power is certainly a viable option for some Jupiter & even some Saturn missions (though definitely setting hard constraints on feasible science objectives for either destination), but you very well might be talking about ISS-sized arrays or better for any place further out, which just doesn't seem prudent, practical, or affordable.

Posted by: ugordan Nov 15 2007, 12:09 PM

QUOTE (nprev @ Nov 15 2007, 02:16 AM) *
My whole point in bringing up the ISS array prob was to illustrate that minimizing mechanical complexity

That's why RTGs are very robust; no moving parts. Well, unless you're talking Stirling RTGs. I don't know how I feel about the idea of having moving parts like that on long duration missions, even if the RTGs end up more efficient than old designs.

Posted by: mchan Nov 15 2007, 12:21 PM

QUOTE (Greg Hullender @ Nov 13 2007, 10:43 AM) *
Note that there wasn't a peep about New Horizons using an RTG.


Oh, there was a peep or two from the usual hard core anti-nuke crowd. Google "space_4_peace" w/o the underscores.

Some of their demands so sadly illustrate a lack of any effort to understand what they are saying, e.g., after the Cassini SOI, they wanted Cassini to be redirected to impact the sun to avoid danger of it coming back to Earth. Some of these people would believe that NH was sending plutonium back to Pluto.

There were several anti-nuke letters in the NH RTG EIS (environmental impact statement). Which leads back to the topic of this thread since the EIS discusses alternate power options, e.g. solar, for NH.

Posted by: Greg Hullender Nov 15 2007, 07:12 PM

Since RTG's are critical to Outer-planet exploration (at least), I do think it's really on-topic to seriously discuss the things that might limit their use -- even thought that involves talking a bit about.....CUT

..... things banned at UMSF. Sorry Greg. Rules are rules. : Doug

Posted by: Juramike Oct 9 2008, 08:21 PM

http://www.space.com/scienceastronomy/081009-am-juno-jupiter.html at space.com regarding the Juno mission.

Posted by: PhilCo126 Oct 31 2008, 07:38 PM

Here's the merchandise:
http://www.bookstore.caltech.edu/jpllab/shop_product_list.asp?mscssid=V65VGR0WHGBF9P20RNJAL4DVRWHD8ED1&catalog_id=39
wink.gif

Posted by: lyford Nov 26 2008, 06:16 PM

http://www.nasa.gov/home/hqnews/2008/nov/HQ_08-309_Juno.html

QUOTE
WASHINGTON -- NASA is officially moving forward on a mission to conduct an unprecedented, in-depth study of Jupiter....
....The spacecraft is scheduled to launch aboard an Atlas rocket from Cape Canaveral, Fla., in August 2011, reaching Jupiter in 2016. The spacecraft will orbit Jupiter 32 times, skimming about 3,000 miles over the planet's cloud tops for approximately one year. The mission will be the first solar powered spacecraft designed to operate despite the great distance from the sun.

Posted by: Juramike Nov 26 2008, 06:39 PM

Is there any possibility of JunoCam (image of instruments on spacecraft http://juno.wisc.edu/Images/using/Spacecraft/Juno-Payload-System.jpg) getting images of the Galilean satellites of any decent resolution?

Or would that be a bad thing due to the solar panel requirements?

-Mike

[EDIT: Already discussed earlier in this thread (multiple times, best response http://www.unmannedspaceflight.com/index.php?s=&showtopic=2548&view=findpost&p=89942).]

Posted by: IM4 Nov 28 2008, 04:02 PM

QUOTE (Juramike @ Nov 26 2008, 06:39 PM) *
Is there any possibility of JunoCam getting images of the Galilean satellites of any decent resolution?
Or would that be a bad thing due to the solar panel requirements?
-Mike
[EDIT: Already discussed earlier in this thread (multiple times, best response http://www.unmannedspaceflight.com/index.php?s=&showtopic=2548&view=findpost&p=89942).]

Fortunately, JRehling is mistaken. In fact, Juno's orbit won't be fixed, it will rotate slowly as shown on the picture.
Baseline mission assumes 32 orbits in all. On 12-13th orbit Juno will intersect Jupiter's equatorial plane somewhere near the Callisto orbit, on 20-21th orbit close approach to Ganymede will be possible. In case of the extended mission even Europa can be explored (if only Juno can survive in the radiation belts).
I don't know whether such a "flybys" ever planned, but approaches to Galileans will be certainly much more close than those calculated by JRehling



 

Posted by: djellison Nov 28 2008, 04:09 PM

QUOTE (IM4 @ Nov 28 2008, 04:02 PM) *
On 12-13th orbit Juno will intersect Jupiter's equatorial plane somewhere near the Callisto orbit,


And will Callisto be anywhere near Juno at that time? An orbit crossing doesn't mean a close encounter.

Posted by: IM4 Nov 28 2008, 04:15 PM

QUOTE (djellison @ Nov 28 2008, 04:09 PM) *
An orbit crossing doesn't mean a close encounter.

Yes, but if we have an opportunity for encounter why not make use of it? why not to synchronize orbits?

Posted by: mcaplinger Nov 28 2008, 06:38 PM

QUOTE (IM4 @ Nov 28 2008, 08:15 AM) *
Yes, but if we have an opportunity for encounter why not make use of it? why not to synchronize orbits?

Because it's not a part of the mission goals and could potentially either take enormous amounts of delta-v or lead to unacceptable constraints on mission timing?

Also, Junocam only has a requirement to last for seven orbits.

Posted by: Hungry4info Nov 28 2008, 10:09 PM

QUOTE (mcaplinger @ Nov 28 2008, 12:38 PM) *
Also, Junocam only has a requirement to last for seven orbits.


Ouch! That's disappointing to hear. I realise though that this is a science mission, not a tourism mission... but images keep public interest alive.
Requirement to last for seven orbits... I remember hearing 90 days as the designed lifetime of the MER rovers. (of course Jupiter is a different story, radiation and such X_X)

Posted by: jekbradbury Nov 28 2008, 10:37 PM

I remember seeing a PDF of the instruments on Juno, and one page showed the power budget and how much each instrument would use during perijove and during cruise through apojove. JunoCam was listed as 0 watts for the entire cruise segment of the orbit. This makes it seem like it won't be turned on at all anywhere but closest approach.

Posted by: mcaplinger Nov 29 2008, 12:57 AM

QUOTE (jekbradbury @ Nov 28 2008, 02:37 PM) *
This makes it seem like it won't be turned on at all anywhere but closest approach.

Since the primary goal is polar imaging and the pole crossings are not typically at closest approach, this is not accurate; probably what you saw was a placeholder since we take little power and only image for tens of seconds at a time.

If someone wants to simulate the Juno orbit (public information is rather thin but see http://juno.wisc.edu/mission.html ) and see if any satellite observations are possible given that the spacecraft is spinning, I'd be happy to advocate such observations.

Posted by: vjkane Nov 29 2008, 02:29 AM

Has the team looked into the feasibility of imaging the cloud decks at perijove? Would the motion just result in a blur?

Posted by: mcaplinger Nov 29 2008, 02:50 AM

QUOTE (vjkane @ Nov 28 2008, 06:29 PM) *
Has the team looked into the feasibility of imaging the cloud decks at perijove? Would the motion just result in a blur?

Junocam already has to work with the spacecraft spin. Orbital motion is only a small fraction of that, so perijove imaging would work fine.

Posted by: vjkane Nov 29 2008, 04:46 AM

QUOTE (mcaplinger @ Nov 29 2008, 02:50 AM) *
Junocam already has to work with the spacecraft spin. Orbital motion is only a small fraction of that, so perijove imaging would work fine.

Do you know what the resolution of the cloud tops will be at perijove?

Posted by: Doc Nov 29 2008, 05:42 AM

15km/pixel

Posted by: mcaplinger Nov 29 2008, 06:09 AM

QUOTE (vjkane @ Nov 28 2008, 08:46 PM) *
Do you know what the resolution of the cloud tops will be at perijove?

I think it's around 4 km/pixel. The 15 km/pix is for the polar case when perijove is near the equator.

Posted by: Doc Nov 29 2008, 07:54 AM

Whoa, 4km/pix thats news to me; thanks for the info mcaplinger.

Posted by: Hungry4info Nov 29 2008, 05:45 PM

Is it too early to know if Juno might make an asteroid flyby or two? (i.e. Galileo style)

Posted by: Enceladus75 Nov 29 2008, 06:16 PM

QUOTE (IM4 @ Nov 28 2008, 04:15 PM) *
Yes, but if we have an opportunity for encounter why not make use of it? why not to synchronize orbits?


My understanding was that Juno's main focus was on Jupiter itself and its interior. I thought that the JunoCam was a sort of afterthought, for public outreach and schoolkids, becuase the Juno probe will be spinning and the imaging would be pretty crude, not unlike the Pioneers in the mid 1970s. How can meaningful science be achieved by trying to image the moons? ph34r.gif

Posted by: mcaplinger Nov 29 2008, 06:42 PM

QUOTE (Enceladus75 @ Nov 29 2008, 10:16 AM) *
the Juno probe will be spinning and the imaging would be pretty crude...

"Pretty crude"? I'm insulted. Despite the spacecraft spin. the Junocam images should be extremely good; comparable to or better than the best Galileo images of Jupiter. That said, we'd have to get pretty close to one of the satellites to get good images, because Junocam has a wide field of view.

As for asteroid flybys: I can't speak for the rest of the payload but for any plausible flyby distance, asteroids would be barely resolved from points by Junocam.

Posted by: vjkane Nov 29 2008, 07:38 PM

QUOTE (mcaplinger @ Nov 29 2008, 06:42 PM) *
"Pretty crude"? I'm insulted. Despite the spacecraft spin. the Junocam images should be extremely good; comparable to or better than the best Galileo images of Jupiter.

I believe that the best Galileo cloud deck images were in the 15-20km range partially because of the distance of most of Galileo's perijoves. When GLL did get in close, it tended to do pixel binning as a counter measure to radiation caused noise.

JunoCam will may provide more images of the cloud deck and at higher resolution than the Galileo mission. If it can achieve 4km/pixel at perijove, I believe that would be the highest resolution of the cloud deck ever. I just wish there was a near infrared band -- would have added a lot of science.

As for imaging satellites, the timing of Juno's orbits is selected to enable even spacing of Jovian longitudes for gravity mapping. Targeting a satellite for what would be fairly low resolution images (because JunoCam is a wide angle camera) would mess up a key goal of the Juno mission.

Posted by: Enceladus75 Nov 29 2008, 07:47 PM

"Pretty crude"? I'm insulted. Despite the spacecraft spin. the Junocam images should be extremely good; comparable to or better than the best Galileo images of Jupiter. That said, we'd have to get pretty close to one of the satellites to get good images, because Junocam has a wide field of view.

As for asteroid flybys: I can't speak for the rest of the payload but for any plausible flyby distance, asteroids would be barely resolved from points by Junocam.


I apologise and stand corrcted Mcaplinger. unsure.gif Do you work on the Juno mission yourself? I didn't realise that Junocam would have 15km resolution. That's very adequate for tracking atmospheric changes and some moon imaging, like monitoring volcanic activity on Io.

Question: How does Junocam work if Juno itself is spinning? Is it a type of scanning photometer like on Pioneers 10 and 11?

Posted by: Dominik Nov 29 2008, 10:04 PM

@mcaplinger
Wow 4 km per pixel... I wonder what resolution New Horizons had at closest approach.

Posted by: elakdawalla Nov 29 2008, 10:43 PM

Mike, given the recent experience with the New Horizons Jupiter flyby, do you think that Junocam will be able to contribute to long-term (by which I mean "the period of time that Junocam is active") monitoring of Io volcanic activity? NH showed that you don't need particularly high-res images to spot active plumes.

--Emily

Posted by: mcaplinger Nov 29 2008, 11:33 PM

QUOTE (elakdawalla @ Nov 29 2008, 02:43 PM) *
Mike, given the recent experience with the New Horizons Jupiter flyby...

Comparing Junocam to NH is apples and oranges. Note that LORRI did its imaging from something like 3 million km away and got about 15 km/pix, where Juno will be about 5000 km from the planet at closest approach, where we will get about 4 km/pixel. LORRI is about 150x higher-resolution at a given distance than Junocam, but Juno gets a lot closer to Jupiter than NH did.

As noted before, I don't know what the geometry will be like (we can't be sure until after launch, really), but Junocam is not capable of seeing the satellites with good resolution unless it's quite close to them. At a typical distance of say 500,000 km, Junocam resolution is about 400 km/pix, and Io will be about 9 pixels across.

Posted by: vjkane Nov 30 2008, 01:51 AM

My dream shot: Close up of the Great Red spot. This requires that the Red Spot be underneath the orbital track on an orbit in which the remote sensing instruments point at Jupiter. [For most orbits, the remote sensing instruments will not be pointed directly at the cloud deck, and the orbit will be dedicated to fields and particles and gravity measurements.]. Unlikely, but one can dream...

Posted by: mcaplinger Nov 30 2008, 03:00 AM

QUOTE (vjkane @ Nov 29 2008, 05:51 PM) *
This requires that the Red Spot be underneath the orbital track on an orbit in which the remote sensing instruments point at Jupiter.

The spacecraft is spinning all the time, and Junocam points at the planet once per revolution, so this is not as unlikely as you might think.

Posted by: sci44 Dec 1 2008, 09:38 PM

It is interesting to read this thread about JunoCam, since a Jupiter mission is long overdue and I think a lot of people would like to see a revisit of the Jovian system with modern imaging systems. Correct me if I am wrong, but Juno is a spin stabilised probe with no gyroscopically controlled scan platform (for weight/power constraints). In that sense, it is more like the scanning photopolarimeter on Pioneer 10/11 than Voyager/Galileo. http://history.nasa.gov/SP-349/contents.htm explains how difficult it was to convert those first extruded images of Jupiter into those famous pictures, and at distant targets it was lacking - it could http://history.nasa.gov/SP-349/p180.htm, for instance.

Even if it is a full framing camera, it must keep a wide frame of view to be able to get sufficient light from the target without motion blur. There are Cassegrain designs where the mirror is moved by an actuator during exposure - maybe that would allow sufficient stability to image Io or the other satellites at the needed magnifications (100x +) - perhaps another agency could contribute such an instrument! Juno is a daring mission, skimming the atmosphere of Jupiter - which I am sure will answer a lot of questions about Jupiter itself - but I am sure there are a lot of people out there who would like to see a replay of Galileo for the icy moons too.
I wonder to what extent the specification is conservative, at 30 orbits (and only 7 for Junocam)? Is this like Phoenix, where we are pretty sure that <-100C is going to crack the electronics, or like MER where +90 days of dust+winter might finish it off, but we are not sure? After the primary mission (in that special radiation-free orbit) I guess we will find out just how well large solar arrays can survive in the Jupiter radiation belts - if it does, it would be a shame if there is not a good imaging telescope there too..

Posted by: mcaplinger Dec 1 2008, 11:46 PM

QUOTE (sci44 @ Dec 1 2008, 01:38 PM) *
Even if it is a full framing camera, it must keep a wide frame of view to be able to get sufficient light from the target without motion blur...

The field of view has no direct relationship to "sufficient light", this is a function of f/number and exposure time. See the thread http://www.unmannedspaceflight.com/index.php?showtopic=2890 for some insight into how Junocam works.
It's required to have the wide field of view to meet the requirements on Jupiter polar imaging, and as I noted before, it has no requirements to image the satellites at all.
QUOTE
but I am sure there are a lot of people out there who would like to see a replay of Galileo for the icy moons too.

Alas, Juno is not that mission, and I don't think any money is available for enhanced imaging. The Italian IR imaging spectrometer (JIRAM) is the only other imaging system on Juno. http://adsabs.harvard.edu/abs/2007AGUFM.P51A0208A
QUOTE
I wonder to what extent the specification is conservative, at 30 orbits (and only 7 for Junocam)?

I'm not sure if anyone knows how conservative the radiation models are, but the lifetime issues are driven by radiation dose.

Posted by: sci44 Dec 2 2008, 12:12 AM

QUOTE (mcaplinger @ Dec 1 2008, 11:46 PM) *
The field of view has no direct relationship to "sufficient light", this is a function of f/number and exposure time.


Ok, I should be more accurate, and say "field of view" against "angular scan rate". Presuming a scanning platform rotating with the craft, the more magification you apply, the less time the object is in the field of view - up to the point where you cannot magnify any more - the light will not register with the CCDs. With a scan platform and telescope, you can use an extended exposure to get a picture of distant and/or dim targets. Dont get me wrong - push-broom and photopolarimeter cameras are perfect for orbital missions with reasonably close targets and the right orbital "motion" across the sensors, like MRO/Hirise->Mars - and probably for Juno->Jupiter too - but am I right to assume that major spacecraft manuevers would be needed to image a distant target? Is this complicated by the large solar sails - can Juno slow down its spin rate for such imaging?

QUOTE (mcaplinger @ Dec 1 2008, 11:46 PM) *
Alas, Juno is not that mission, and I don't think any money is available for enhanced imaging. The Italian IR imaging spectrometer (JIRAM) is the only other imaging system on Juno.
I'm not sure if anyone knows how conservative the radiation models are, but the lifetime issues are driven by radiation dose.


Yes I was just wondering if an enhanced imaging system would even be possible - and if so, if another space agency somewhere would like to take it on - otherwise its a long wait for another Jupiter mission (2030+).
As for lifetime - Galileo outlived its specification, so we can hope..

Posted by: mcaplinger Dec 2 2008, 12:39 AM

QUOTE (sci44 @ Dec 1 2008, 04:12 PM) *
I was just wondering if an enhanced imaging system would even be possible...

At this late date (launch is about 2.5 years from now), I'd say the chances of adding another payload element to Juno are effectively zero.

Note that I neglected the ultraviolet imaging spectrometer in my earlier post. I don't know what the resolutions of either JIRAM or UVS are, but there is public information available if someone wants to make the effort.

I believe imaging is only possible if the target happens to pass through the spin plane +/- half the FOV of the instrument involved. JIRAM has a 1-DOF scan mirror, I think, I don't know how UVS works, and Junocam is mostly insensitive to spin rate owing to our ingenuity in designing it smile.gif

Posted by: Juramike Dec 2 2008, 11:11 PM

While the Junocam will be really cool, one of the main missions for Juno is to try to figure out how Jupiter started and evolved. (link to mission page http://juno.wisc.edu/science.html)
This might shed light on the origin of our solar system and extend to extrasolar systems.

http://www.space.com/scienceastronomy/081125-jupiter-core.html is a recent article in space.com (I tried to link to this a few days ago, but it disappeared from the space.com archives...today it's back) about how Jupiter may have a much bigger core (14-16 Earth masses of rock!) than previously proposed. Previous predictions ranged from a core of 7 Earth masses of rock to no core at all. Juno should help nail down the absolute size of the core, and therefore, whether a rock core was required for the initial accretion.

Which came first: gas or rock?

(Solar system formation discussion that followed moved to another thread, see http://www.unmannedspaceflight.com/index.php?showtopic=5656 - moderator)

Posted by: IM4 Jan 18 2009, 04:48 PM

Did you know that Juno's pre-launch planning trajectory is available at HORIZONS? (spacecraft ID = -61)
I've created simplest Celestia addon covering time span from 2016-Aug-03 to 2017-Oct-16 (from JOI to atmospheric impact), so you can simulate Jupiter's and Galilean's views for main mission. http://rapidshare.com/files/185516308/Juno.zip.html

PS
I saw some peoples making tables of close approaches for Cassini and Saturnians - a kind of magic with SPICE kernels and routines. Could anyone reproduce that trick for Juno?

Posted by: volcanopele Jan 18 2009, 08:35 PM

hehe, you noticed that too. I've been playing with my own for a few weeks in Celestia. I'll post it when I finish my Jupiter system addon (part 2) in a week or so. For mine, I have been using XYZV files (needs the latest Celestia beta).

for those close-approach tables, you really need spice kernel files, but I believe that JPL Horizons also has this capability, but I haven't given a try. Keep in mind that Juno's camera has a very low spatial resolution, as noted above. In other words, fine for looking at Jupiter, but not very good for looking at the satellites. However, it might be interesting to see if decent science might be possible at Io, to look at it in eclipse and look the brightest hotspots. Given the low-priority of the camera though, I doubt the Juno planners would want to sacrifice time near perijove to look at Io.

Posted by: mcaplinger Jan 18 2009, 08:51 PM

QUOTE (volcanopele @ Jan 18 2009, 12:35 PM) *
Keep in mind that Juno's camera is better described as a glorified digital camera, not like the camera systems you find on Cassini, Galileo, or MRO.

I'll try not to be offended by that. smile.gif Junocam is as much a "real camera" as MARCI on MRO is.
QUOTE
Given the low-priority of the camera though, I doubt the Juno planners would want to sacrifice time near perijove to look at Io.

The imaging would presumably happen near Io closest approach, which is not especially near perijove, since Io's orbit is about 70x higher than Juno's perijove altitude. If there's a good opportunity (and even if there is one for the baseline orbit there's no reason to think the real orbit will have one) I think there's a fairly high chance that it'll be used.

Posted by: volcanopele Jan 18 2009, 09:32 PM

I apologize Mike. I edited my post to better state what I wanted to say. I, in no way, meant that Junocam wasn't a "real" camera. More accurately, I meant that Junocam wasn't the same kind of telescopic camera system like ISS, SSI, HiRISE, or CTX. The field of view of the camera and the iFOV are not sufficiently high resolution to do much geologic science.

It is good to hear that JunoCAM could be used to Io science. I love to hear that. However, as you pointed out in earlier posts, the resolution of the camera would likely make it such that observations of Io would need to be acquired within a few hours of perijove, which I would imagine would be a busy time for science on Juno, and because of JunoCAM's spatial resolution, it would be lower priority than Jupiter science during this period.

Posted by: mcaplinger Jan 18 2009, 10:29 PM

QUOTE (volcanopele @ Jan 18 2009, 01:32 PM) *
It is good to hear that JunoCAM could be used to Io science.

Keep in mind that this would rely on a serendipitous and unplannable close approach to Io sometime early in the mission before Junocam (aka JunoCam or JunoCAM) has been toasted by Jovian radiation, and that I have no idea how constrained Junocam operations will be (not sure how many bits the s/c can send down per orbit and what competition will be like for those bits). That said, if there's a good encounter it'd be disappointing to not make use of it. But I just build them, they don't let me push the shutter button, at least not very often.

Posted by: volcanopele Jan 18 2009, 11:47 PM

Well, if the camera sticks around till May 4, 2017, based on the trajectory in JPL Horizons, there is a nice encounter with Ganymede at 06:00 UTC on that day at a distance of 270,000 km when that satellite transits across Jupiter from Juno's perspective.

 

Posted by: IM4 Jan 19 2009, 07:41 PM

QUOTE (volcanopele @ Jan 18 2009, 08:35 PM) *
for those close-approach tables, you really need spice kernel files, but I believe that JPL Horizons also has this capability

Currently I am using custom "brute force"method. It has moderate accuracy but still suitable for event search. I can summarize my results as following "Top Lists", 5-10 closest approaches for every Galilean.

CODE
Name______Date___________CA_Dist (km)
Io    2017-Sep-24  17:18    141289
Io    2017-Jul-31  20:44    180270
Io    2017-Jun-07  00:10    217693
Io    2017-Apr-13  03:49    245136
Io    2017-Feb-17  07:16    279940
Io    2017-Apr-23  22:49    312179
Io    2016-Dec-24  10:44    312879
Io    2017-Jun-17  19:13    313812
Io    2017-Oct-05  11:57    321276
Io    2017-Aug-11  15:38    324122
Io    2017-Feb-28  02:33    330138
Io    2017-Aug-22  23:29    339674
Io    2017-Jan-04  06:14    341542

Europa    2017-Jul-31  14:58    110869
Europa    2017-Jul-20  18:37    224189
Europa    2017-Apr-01  21:46    230908
Europa    2017-Mar-22  01:44    266977
Europa    2016-Dec-02  04:38    348658
Europa    2016-Nov-21  08:40    355904
Europa    2017-Aug-11  09:54    382235
Europa    2016-Oct-31  02:45    453186
Europa    2017-Jul-09  21:34    453752
Europa    2017-Apr-12  16:05    455906

Ganymede    2017-Sep-24  06:52    149391
Ganymede    2017-Apr-12  16:14    168270
Ganymede    2017-May-04  09:14    216067
Ganymede    2016-Nov-20  19:02    372453
Ganymede    2016-Oct-30  02:09    400230
Ganymede    2017-Sep-02  11:54    410075

Callisto    2016-Dec-22  20:11    155386
Callisto    2016-Nov-19  14:44    232124
Callisto    2017-Jan-25  00:25    285824


Some interesting events are highlighted. Most promising encounter is one with Callisto (2016-Dec-22), close enough and just within first eight Juno's orbits. Assuming 3 degree FOV and 1024x1024 CCD, we may expect a spectacular view of that moon. Something like this:


Posted by: volcanopele Jan 19 2009, 11:59 PM

Here is a nice overview from Celestia of Juno's orbital tour plus a nice shot from the first perijove shortly after (?) JOI:




 

Posted by: mcaplinger Jan 20 2009, 12:15 AM

QUOTE (IM4 @ Jan 19 2009, 11:41 AM) *
Assuming 3 degree FOV and 1024x1024 CCD, we may expect a spectacular view of that moon.

Sorry, but since Junocam has a 70-degree FOV none of these approaches is going to be spectacular. (All this was discussed upthread.) If there happened to be one closer than, say, 50,000 km, it might be worth doing, but even that's 40 km/pixel, only a 2-3x better than HST can get.

Posted by: IM4 Jan 20 2009, 07:38 AM

QUOTE
...but since Junocam has a 70-degree FOV...

Could you provide me with detailed specification for Junocam? In this thread I found only bits of information.
Anyways, we still have JIRAM imager. According to http://jupiter-europa.cesr.fr/static_pages/presentations/coradini_jiram.pdf it has Pixel IFOV = 250 microrad, which is equivalent to spatial resolution of about 1 km/pixel for perijove passage (5000 km) - much more than Junocam has. So we still have a chance to obtain interesting images of the large moons.

Posted by: mcaplinger Jan 20 2009, 03:34 PM

QUOTE (IM4 @ Jan 19 2009, 11:38 PM) *
Could you provide me with detailed specification for Junocam?

See
http://www.unmannedspaceflight.com/index.php?s=&showtopic=2548&view=findpost&p=131840 -- 4 km at 5000 km implies an IFOV of 800 urad/pxl.

Posted by: IM4 Jan 20 2009, 06:25 PM

QUOTE (mcaplinger @ Jan 20 2009, 03:34 PM) *
4 km at 5000 km implies an IFOV of 800 urad/pxl.

Thanks.
I made another table of the best imaging opportunities: object name, date of the encounter, distance and maximum moon's image size in JIRAM and Junocam pixels. Here it is.
CODE
Name            Date            CA_Dist(km) JIRAM    Junocam
Ganymede    2017-Sep-24  06:52    149391    140,9    44
Ganymede    2017-Apr-12  16:14    168270    125,1    39,1
Callisto    2016-Dec-22  20:11    155386    123,6    38,6
Europa      2017-Jul-31  14:58    110869    113,2    35,4
Io          2017-Sep-24  17:18    141289    102,8    32,1
Ganymede    2017-May-04  09:14    216067    97,4     30,4
Callisto    2016-Nov-19  14:44    232124    82,7     25,8
Io          2017-Jul-31  20:44    180270    80,5     25,2
Callisto    2017-Jan-25  00:25    285824    67,2     21
Io          2017-Jun-07  00:10    217693    66,7     20,8
Io          2017-Apr-13  03:49    245136    59,2     18,5
Ganymede    2016-Nov-20  19:02    372453    56,5     17,7
Europa      2017-Jul-20  18:37    224189    56,0     17,5
Europa      2017-Apr-01  21:46    230908    54,4     17
Ganymede    2016-Oct-30  02:09    400230    52,6     16,4
Io          2017-Feb-17  07:16    279940    51,9     16,2
Ganymede    2017-Sep-02  11:54    410075    51,3     16
Europa      2017-Mar-22  01:44    266977    47,0     14,7

I wonder if resolution of JIRAM's images will be better or worse than that of MVIC images during NH Jupiter flyby 2 years ago?

Posted by: volcanopele Jan 20 2009, 07:05 PM

I thought JIRAM had a smaller IFOV than JunoCAM, 250 microradians versus ~800? Therefore, wouldn't the spatial resolution of JIRAM be better than JunoCAM's?

Posted by: tedstryk Jan 20 2009, 07:36 PM

Those are not km/pixel numbers, they are the moons' maximum size in pixels

Posted by: dmuller Jan 20 2009, 08:43 PM

QUOTE (volcanopele @ Jan 19 2009, 07:35 AM) *
for those close-approach tables, you really need spice kernel files, but I believe that JPL Horizons also has this capability, but I haven't given a try.


Well the Horizons webpage states the following, so get your resuts emailed to you for close approaches:

QUOTE
NOTE: Although the web-interface to HORIZONS provides nearly all capabilities of the primary telnet interface (and email interface), it does not provide the following:
Small-body PARAMETER-MATCHING population searches
(use the small-body search engine as an alternative)
Integration of USER-INPUT ORBITS
SPK BINARY FILE production
CLOSE-APPROACH TABLES



Posted by: volcanopele Jan 20 2009, 09:01 PM

QUOTE (tedstryk @ Jan 20 2009, 12:36 PM) *
Those are not km/pixel numbers, they are the moons' maximum size in pixels

Thanks for the correction there, thanks. I see it now.

Posted by: dmuller Jan 20 2009, 10:37 PM

A generic question about trajectories: does anybody in here know how to work the NAIF Spice Kernel tools/files (or whatever it's called ...) I think they would provide more accurate information for my realtime simulations than Horizons, but I just cant understand on how to work them. All I'd need is something to convert the SPK files into the good old 4 dimensions (x,z,y [wrt to solar system barycenter] and time). Feel free to send me a private message as well.

Thanks for your help in advance!

Posted by: mcaplinger Jan 21 2009, 03:17 AM

QUOTE (dmuller @ Jan 20 2009, 02:37 PM) *
does anybody in here know how to work the NAIF Spice Kernel tools/files (or whatever it's called ...) I think they would provide more accurate information for my realtime simulations than Horizons...

http://naif.jpl.nasa.gov/naif/toolkit.html but you will have to write code to use it. There's no reason that Horizons isn't just as accurate as it's probably just using the SPICE kernels internally anyway. And the orbit is going to be different than any available kernel anyway, based on the launch date and injection errors, TCMs, etc.

Posted by: dmuller Jan 21 2009, 04:15 AM

Thanks for your reply! I have the toolkit ...

QUOTE (mcaplinger @ Jan 21 2009, 02:17 PM) *
but you will have to write code to use it.
... which is the problem. I wasnt actually looking at it for Juno, but for some other missions and events (especially C/A) where Horizons is not up-to-date or as accurate as I'd like it to be. So if anybody has some ready-made SPK to (x,y,z,t) converter (the kind of one-click-and-it's-done) then I'd love a copy of it :-)

EDIT 26-Jan Thanks to a very kind soul who provided a very easy solution (easy = I can handle it!) I can now load SPICE kernels into the realtime simulations, greatly enhancing the accuracy of the trajectory of some missions. First update applied to http://www.dmuller.net/dawn. Go http://www.shatters.net/celestia/!

Posted by: tedstryk Feb 4 2009, 10:19 PM

Something else came to mind with regard to Io...would JunoCam be able to do anything equivalent to a CPROTO oversampling to slightly improve resolution?

Posted by: tedstryk Feb 5 2009, 12:52 AM

QUOTE (mccaplinger)
Since it's an area array (a pushframe with TDI, but still area) and not a line array, then no. Conceivably you could do some kind of superresoliution with multiple images, but I don't think it would help very much anyway, because these approach distances are nearly useless to get anything worth taking (i.e., better than HST.)


Mike, first of all, sorry, I accidentally hit delete instead of reply. Second, I thought it was push broom. At any rate, I could imagine it be slightly useful if it was for albedo studies of Io's polar regions (in other words, areas where Juno would have a unique angle and on Io, where things rapidly change), but it would otherwise be useless.

Posted by: climber Sep 24 2009, 10:52 AM

An article from Spaceflightnow: http://www.spaceflightnow.com/news/n0909/24juno/
I didn't realize that the launching date of MSL (Curiosity) could be affected by a late Juno launched (in her window).

Posted by: tedstryk Sep 24 2009, 12:34 PM

QUOTE
NASA Headquarters also asked the Juno project to open their launch period a few days earlier, giving the probe more time to get off the ground in early August.

"The earlier that we launch in our launch period, the sooner it frees up that one Atlas pad to start MSL preparations," Chodas said.

To accommodate the change, Juno will now follow a trajectory that arrives at Jupiter a month earlier than originally planned.


It will be interesting to see the impact this has on the trajectory. I am sure Jason will be examining it to see if it creates any Io opportunities.

Posted by: volcanopele Sep 24 2009, 05:48 PM

They haven't released a new reference trajectory, but I would imagine that even with a change in the arrival geometry, they aren't changing their science orbit very much, so it wouldn't setup opportunities that are too terribly different from what we see now.

Posted by: tedstryk Sep 24 2009, 05:51 PM

No, but I was hoping that it might (by luck) make some of the better opportunities come sooner, while JunoCam is more likely to be operational.

Posted by: Greg Hullender Sep 24 2009, 08:24 PM

Here's a question: does earlier departure really equate to earlier arrival? With both Voyager and (I thought) New Horizons, the later departure had the earlier arrival.

--Greg

Posted by: ugordan Sep 24 2009, 09:30 PM

They're not necessarily related. It depends on Jupiter injection velocity. VGR 1 and 2 had different trajectory requirements and different departure speeds. It's not impossible to time the arrival on the same date, but that wouldn't necessarily be a trajectory with lowest TCM delta-V requirements along the way.

Posted by: vjkane Sep 25 2009, 01:04 AM

QUOTE (volcanopele @ Sep 24 2009, 06:48 PM) *
They haven't released a new reference trajectory, but I would imagine that even with a change in the arrival geometry, they aren't changing their science orbit very much, so it wouldn't setup opportunities that are too terribly different from what we see now.

I think that maintaining the science orbit will be a requirement.

Posted by: mcaplinger Sep 25 2009, 03:14 AM

QUOTE (vjkane @ Sep 24 2009, 05:04 PM) *
I think that maintaining the science orbit will be a requirement.

The issue is whether the specific timing allows any providentially close approaches to the moons, but that probably won't be determinable until after launch.

Posted by: maycm Sep 25 2009, 01:25 PM

I was thinking about the extra large and sensitive solar arrays they are using - I assume the intent is to point these at the Sun, however would they get improved results by pointing them at the largest nearest emitter of indirect light, ie Jupiter itself?

Does Jupiter "collect" and radiate back in a way that would be advantategous?

Posted by: Greg Hullender Sep 25 2009, 04:32 PM

QUOTE (maycm @ Sep 25 2009, 06:25 AM) *
Does Jupiter "collect" and radiate back in a way that would be advantategous?

Think of it this way; suppose Jupiter were a perfect, flat mirror. Then it would be equally good to orient the panels towards the Sun's image in that mirror. Make it a sphere -- still perfectly reflective -- and then the image is much worse than the real Sun, since it scatters the light. Now look at the real Jupiter, which reemits lots of the light at infrared frequencies that the solar panels can't use.

I'd be surprised if Juno could get even 1% as much energy from Jupiter as from the Sun, even at closest approach.

--Greg

Posted by: tfisher Sep 26 2009, 12:11 PM

I see that the end-of-mission plans for Juno call for a crash into Jupiter for planetary protection purposes. Am I the only one who thinks that sounds kind of unnecessary? We're flying this probe into a deep space high radiation environment. Is there really any possibility that Earth bugs could survive that radiation? And the probe is being parked in a polar orbit without close satellite flybys. Is there really any possibility that it would crash into (say) Europa in any not-extremely-distant future? And if it is only the really distant future, then magnify the point about earth bugs getting thoroughly sterilized by the high radiation. I don't see the harm in flying it as long as possible to squeeze all the science we can out of it. Or is there some good science to be done on a Jupiter dive?

Posted by: djellison Sep 26 2009, 12:22 PM

QUOTE (tfisher @ Sep 26 2009, 01:11 PM) *
Is there really any possibility that Earth bugs could survive that radiation? And the probe is being parked in a polar orbit without close satellite flybys. Is there really any possibility that it would crash into (say) Europa in any not-extremely-distant future?


Yes, and yes.

It's just not a risk worth taking, Europa is too important.

Posted by: tfisher Sep 27 2009, 04:20 AM

Does anyone have a copy of the paper "Planetary Protection Trajectory Analysis for the Juno
Mission" whose abstract is at http://pdf.aiaa.org/preview/CDReadyMAST08_1856/PV2008_7368.pdf ?
I'm curious now how the probabilities really work out for impact on a moon.

Posted by: mcaplinger Sep 27 2009, 06:35 AM

QUOTE (tfisher @ Sep 26 2009, 04:11 AM) *
I don't see the harm in flying it as long as possible to squeeze all the science we can out of it.

I suspect that the mission will be extended as long as the spacecraft systems can support the final disposal of the spacecraft, much like Galileo was. But the dose rates are pretty high, so Juno likely won't last a lot longer than its primary mission anyway.

Posted by: nprev Sep 27 2009, 09:14 AM

Possibly an OT question, but how well understood is Jupiter's radiation environment by now? Is it relatively stable over time, or do solar activity and maybe Io's eruptions cause significant variations?

Posted by: Hungry4info Sep 27 2009, 01:31 PM

As I understand it, the activity on Io causes significant variability.

Posted by: elakdawalla Sep 27 2009, 01:57 PM

QUOTE (mcaplinger @ Sep 26 2009, 11:35 PM) *
I suspect that the mission will be extended as long as the spacecraft systems can support the final disposal of the spacecraft, much like Galileo was. But the dose rates are pretty high, so Juno likely won't last a lot longer than its primary mission anyway.

It was explained to me that the dose rates are actually substantially higher on the last orbits of the mission than in the earlier orbits, so Juno's not expected to be able to survive many of those later orbits. It has a polar, elliptical orbit and early in the mission the apoapsis is near the equatorial plane. That geometry makes Juno avoid most of the worst of the radiation belt, which is in a doughnut shape around the planet. But that orbit shifts over time so the apoapsis drops southward, eventually bringing the orbit down so that the northern part of it dips into that doughnut, massively increasing the dosage, and every subsequent orbit gets massively worse.

--Emily

Posted by: Jim from NSF.com Nov 20 2009, 04:45 PM

QUOTE (tedstryk @ Sep 24 2009, 07:34 AM) *
It will be interesting to see the impact this has on the trajectory. I am sure Jason will be examining it to see if it creates any Io opportunities.



I don't understand all this push for imaging Jupiter's moons. Juno doesn't not change its axis of rotation once it is in the science orbit. The axis will always be pointing towards the Earth/Sun for comm and power. Even if Juno were to encounter a moon, it wouldn't be able to do little more than like trying to take a picture from a car side window of a road side mailbox as you pass it.

Posted by: Greg Hullender Nov 20 2009, 05:22 PM

QUOTE (Jim from NSF.com @ Nov 20 2009, 08:45 AM) *
. . . like trying to take a picture from a car side window of a road side mailbox as you pass it.

I'm not sure how hard that is, but observational evidence shows that SHOOTING a mailbox from a car window as you pass by isn't that hard at all.

--Greg :-)

Posted by: vjkane Nov 20 2009, 05:35 PM

QUOTE (Greg Hullender @ Nov 20 2009, 06:22 PM) *
I'm not sure how hard that is, but observational evidence shows that SHOOTING a mailbox from a car window as you pass by isn't that hard at all.

The real problem is that the mailbox is blocks away and you have a wide angle lens that was designed to shoot the big mansion that you will be repeatedly driving right in front of.

Posted by: machi Nov 20 2009, 05:41 PM

QUOTE (Jim from NSF.com @ Nov 20 2009, 05:45 PM) *
I don't understand all this push for imaging Jupiter's moons. Juno doesn't not change its axis of rotation once it is in the science orbit. The axis will always be pointing towards the Earth/Sun for comm and power. Even if Juno were to encounter a moon, it wouldn't be able to do little more than like trying to take a picture from a car side window of a road side mailbox as you pass it.


Maybe, but with good camera you can do it. And I think, that JIRAM (imaging spectrometer for JUNO) is push-broom device, so this isn't impossible. All this is analyzed by volcanopele here http://gishbar.blogspot.com/2009/01/juno-io.html.

Posted by: mcaplinger Nov 20 2009, 05:57 PM

QUOTE (Jim from NSF.com @ Nov 20 2009, 08:45 AM) *
...like trying to take a picture from a car side window of a road side mailbox as you pass it.

I'm not following this analogy very well (don't all flybys work like that?), but Junocam can image anything within +/-35 degrees or so off the spin plane. As others have said, the issue is more that you'd have to be very close to a moon to get anything worthwhile given Junocam's low resolution.

Posted by: Ron Hobbs Dec 21 2009, 10:16 PM

NASA has just put the JUNO launch on the KSC launch schedule, http://www.nasa.gov/missions/highlights/schedule.html

August 5, 2011 wheel.gif

Posted by: dmuller Dec 21 2009, 11:19 PM

Last time I checked, the reference trajectory in the Horizons system had a launch date of 18 Aug 2011. Good to see this mission get off the ground .. 2855 days and 5.7 billion km flight distance (w.r.t. Sun) to go until planned Jupiter atmospheric entry on 16 Oct 2017

Posted by: Ron Hobbs Dec 21 2009, 11:38 PM

This probably has to do with the conflict with the MSL launch. I guess the Juno folks are going to try and get off the pad as soon as they possibly can.

Posted by: dmuller Dec 22 2009, 04:00 AM

Every day counts with regards to the Juno / MSL launch conflict ... see http://www.lpi.usra.edu/pss/jan92009/presentations/greenmslSlip.pdf slides 8 onwards. Interesting stuff.

Posted by: abbath Mar 12 2010, 09:00 AM

looking at the sheet http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/37654/1/05-2760.pdf, JUNO seems to pass closer to the north pole than the south one on every orbit. Will this difference in altitude (hence in resolution) affect the results of the mission?

IMHO the southward moving apsides will make us miss some (maybe) important small-scale features in south pole.

Posted by: djellison Mar 12 2010, 09:07 AM

Shift the orbit to be equal and you might miss some maybe important small-scale features in the North Pole. Which pole is better illuminated during the prime mission, for example?

It's all a compromise about what's possible, what's simple, what's functional and what's beneficial for science.


Posted by: Greg Hullender Mar 12 2010, 04:04 PM

Jupiter has very little axial tilt, though. I'd bet the actual reason relates to the amount of delta-V required for a smaller orbit. More delta-V means less mass for instruments, and, as Doug says, it's a compromise.

--Greg

Posted by: elakdawalla Mar 12 2010, 05:35 PM

Remember Juno's not an imaging mission; its main goals are getting at Jupiter's internal structure through gravity, magnetometer data, etc. The mission is designed to permit it to probe Jupiter's gravity and other fields at a wide variety of distances from the planet, to map things out in 3D. It's only carrying a camera at all because people like us would be pretty annoyed if a spacecraft went to Jupiter without one smile.gif

Posted by: Sunspot Mar 12 2010, 07:00 PM

I'm sure Juno's scientific results will be revelatory - but I still feel kind of sad that they are not going with a decent camera system.

Posted by: Frank Crary Mar 18 2010, 04:51 PM

QUOTE (Sunspot @ Mar 12 2010, 07:00 PM) *
I'm sure Juno's scientific results will be revelatory - but I still feel kind of sad that they are not going with a decent camera system.


It isn't a bad camera, and if you don't have a wavelength bias, Juno has an very nice imaging UV spectrometer.

Posted by: tedstryk Mar 18 2010, 07:10 PM

Very true. This should be an exciting mission both visually and scientifically.

Posted by: centsworth_II Mar 18 2010, 09:01 PM

QUOTE (Frank Crary @ Mar 18 2010, 12:51 PM) *
...if you don't have a wavelength bias, Juno has an very nice imaging UV spectrometer.
That will excite the insectoids among us. laugh.gif

Posted by: machi Mar 18 2010, 09:32 PM

Don't forget italian infrared camera/spectrometer! tongue.gif

Posted by: lyford Mar 18 2010, 11:45 PM

QUOTE (Sunspot @ Mar 12 2010, 11:00 AM) *
I'm sure Juno's scientific results will be revelatory - but I still feel kind of sad that they are not going with a decent camera system.

It's based on the http://www.msss.com/juno/index.html

Posted by: vjkane Mar 19 2010, 12:27 AM

QUOTE (lyford @ Mar 18 2010, 11:45 PM) *
It's based on the http://www.msss.com/juno/index.html

Given how close the orbiter comes to Jupiter and the size of Jupiter, the camera is well sized to the task. I just wish they had included a near-IR filter to see lower into the cloud decks.

Posted by: remcook Mar 19 2010, 08:28 AM

I will echo machi's response here: "Don't forget italian infrared camera/spectrometer" smile.gif It will look up to 5 micron, where you can see quite low.

http://www.ncbi.nlm.nih.gov/pubmed/18680411

Posted by: vjkane Mar 19 2010, 05:26 PM

Full inline quote removed - ADMIN

Quite true, but there's a big gap between red (~0.65 microns) and the 2 micron minimum on the Italian infrared camera/spectrometer. The JunoCAM's CCD almost certainly covers the near infrared (~0.8 micros), but it probably wasn't worth the cost of validating the camera with an additional filter (or the design couldn't spare the extra rows for another filter assuming that the filters are applied directly to the CCD). It would have been nice since I believe JunoCAM may have higher spatial resolution (the Italian instrument has a 10 nm resolution; can anyone compare that to JunoCAM's resolution?)

Posted by: Paolo Mar 19 2010, 06:18 PM

http://jupiter-europa.cesr.fr/static_pages/presentations/coradini_jiram.pdf includes lots of details of the Italian camera, including some simulated images

Posted by: punkboi Apr 8 2010, 06:41 AM

http://www.nasa.gov/mission_pages/juno/news/juno20100405.html

Juno Taking Shape in Denver

Assembly has begun on NASA's Juno spacecraft, which will help scientists understand the origin and evolution of Jupiter. The mission, whose principal investigator is Scott Bolton of Southwest Research Institute in San Antonio, Tex., is expected to launch in August 2011 and reach Jupiter in 2016.

The assembly, testing and launch operations phase began April 1 in a high-bay clean room at Lockheed Martin Space Systems in Denver. Engineers and technicians will spend the next few months fitting instruments and navigation equipment onto the spacecraft.

"We're excited the puzzle pieces are coming together," Bolton said. "We're one important step closer to getting to Jupiter."

Jupiter is the largest planet in our solar system. Underneath its dense cloud cover, the planet safeguards secrets to the fundamental processes and conditions that governed our solar system during its formation. As our primary example of a giant planet, Jupiter can also provide critical knowledge for understanding the planetary systems being discovered around other stars.

Juno will have nine science instruments on board to investigate the existence of a solid planetary core, map Jupiter's intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet's auroras.

"We plan to be doing a lot of testing in the next few months," said Jan Chodas, the project manager based at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We want to make sure the spacecraft is ready for the long journey to Jupiter and the harsh environment it will encounter there."

JPL manages the Juno mission for the principal investigator, Scott Bolton. Lockheed Martin Space Systems is building the spacecraft. The Italian Space Agency, Rome, is contributing an infrared spectrometer instrument and a portion of the radio science experiment.

For more information about Juno, visit http://www.nasa.gov/juno.


 

Posted by: tharrison Apr 26 2010, 04:21 AM

QUOTE (elakdawalla @ Mar 12 2010, 09:35 AM) *
It's only carrying a camera at all because people like us would be pretty annoyed if a spacecraft went to Jupiter without one smile.gif


That wouldn't necessarily stop NASA...the 2013 MAVEN mission to Mars has no camera aboard. rolleyes.gif We'll have to hope MRO keeps working!

[End thread hijack, back to your regularly scheduled Juno programming. smile.gif]

Posted by: tedstryk Apr 26 2010, 03:17 PM

QUOTE (tharrison @ Apr 26 2010, 04:21 AM) *
That wouldn't necessarily stop NASA...the 2013 MAVEN mission to Mars has no camera aboard. rolleyes.gif We'll have to hope MRO keeps working!

[End thread hijack, back to your regularly scheduled Juno programming. smile.gif]


Yes, but Mars has plenty of attendant missions with cameras, some of which will likely overlap MAVEN. Not true for Jupiter.

Posted by: punkboi Jul 13 2010, 06:38 AM

Juno Armored Up to Go to Jupiter

With guidance from JPL and the principal investigator, engineers at Lockheed Martin Space Systems designed and built a special radiation vault made of titanium for a centralized electronics hub. While other materials exist that make good radiation blockers, engineers chose titanium because lead is too soft to withstand the vibrations of launch, and some other materials were too difficult to work with.

http://www.jpl.nasa.gov/news/news.cfm?release=2010-230&cid=release_2010-230

Posted by: Explorer1 Jul 13 2010, 06:54 AM

Thanks for the link punkboi.

QUOTE
Each titanium wall measures nearly a square meter (nearly 9 square feet) in area, about 1 centimeter (a third of an inch) in thickness, and 18 kilograms (40 pounds) in mass. This titanium box -- about the size of an SUV's trunk - encloses Juno's command and data handling box [...] and about 20 other electronic assemblies. The whole vault weighs about 200 kilograms (500 pounds).

Wow, even with that much protection, the mission is suppose to last barely over a year before deorbiting? This sure puts Galileo's achievements in perspective, doesn't it (different orbit notwithstanding)?

Also, what are those big red things labelled 'remove before flight' sticking on the top of Juno, in that photo?

Posted by: Greg Hullender Jul 13 2010, 02:52 PM

I wonder when we'll start seeing regular updates on the Juno mission web site?

http://juno.wisc.edu/index_whatsnew.html

Just one year to launch, so they ought to have things to post now. I realize outreach is often a thankless job, so that's not meant to sound like a complaint. :-)

--Greg

Posted by: dmuller Jul 13 2010, 04:01 PM

QUOTE (Explorer1 @ Jul 13 2010, 04:54 PM) *
Also, what are those big red things labelled 'remove before flight' sticking on the top of Juno, in that photo?

If you ask ugordan (http://www.unmannedspaceflight.com/index.php?s=&showtopic=4453&view=findpost&p=100120), the inside of the 'remove before flight' tags http://www.unmannedspaceflight.com/index.php?s=&showtopic=4453&view=findpost&p=99931 rolleyes.gif

Posted by: volcanopele Jul 13 2010, 08:29 PM

An update eh? Well, JEDI looked good when I saw it a couple of hours ago wink.gif

Posted by: Frank Crary Jul 13 2010, 09:08 PM

QUOTE (Explorer1 @ Jul 13 2010, 06:54 AM) *
Wow, even with that much protection, the mission is suppose to last barely over a year before deorbiting? This sure puts Galileo's achievements in perspective, doesn't it (different orbit notwithstanding)?

Also, what are those big red things labelled 'remove before flight' sticking on the top of Juno, in that photo?


Galileo was on a very different orbit. It spent almost no time in the worst parts of the radiation belts. Between orbital insertion and about a year or so into extended mission, Galileo never went inside the orbit of Europa. Juno will be spending a much larger fraction of its time in the high flux parts of Jupiter's magnetosphere. The orbit is designed to avoid that, at first, but the orbit precesses over the course of a year. I think the total, unshielded dose for Juno is estimates at three or four times what they think Galileo was exposed to.

The red tag is on one of the reaction control thruster towers. They probably want the nozzles covered during shipping and handling.


Posted by: Explorer1 Jul 14 2010, 02:31 AM

QUOTE (Frank Crary @ Jul 13 2010, 01:08 PM) *
The red tag is on one of the reaction control thruster towers. They probably want the nozzles covered during shipping and handling.


Thanks for the answer. I imagine they don't want those parts bumping into anything too much.

Posted by: elakdawalla Jan 4 2011, 09:45 PM

http://photojournal.jpl.nasa.gov/catalog/PIA13746 It seems to have very minor updates to http://photojournal.jpl.nasa.gov/catalog/PIA13087 except for one thing that's kind of inexplicable. It's mirrored relative to the 2009 one. I compared the 2011 one to the 2009 one and it looks to me like it's the 2011 one that's backwards, with the Red Spot rotating in the wrong direction. But I wasn't confident enough about that to send an email to anyone -- can someone here confirm?

Posted by: ugordan Jan 4 2011, 09:49 PM

Looks like you're right. The Jupiter map is from Cassini and it's definitely mirrored left-right: http://photojournal.jpl.nasa.gov/catalog/PIA07782.

Posted by: Mr. Milton Banana Jan 6 2011, 03:56 AM

Will there be any investigation of thunderstorm activity, and if so, what kind?

Posted by: Frank Crary Jan 6 2011, 09:43 PM

QUOTE (Mr. Milton Banana @ Jan 6 2011, 03:56 AM) *
Will there be any investigation of thunderstorm activity, and if so, what kind?


If you mean cloud and storm imaging, I'm pretty sure there is going to be quite a bit of that in the visible and IR. If you mean night-side images of lightning flashes, I don't think that will be possible. During the perijove phase of the orbit, the spacecraft is over the day side. I'm fairly sure JunoCam and JIRAM can't point off nadir at all. I do think we'll get whistler data from Waves. That's caused by lighting and has been used as a measure of overall activity (as well as the source latitude.)

Posted by: DrShank Jan 27 2011, 12:13 AM

QUOTE (Frank Crary @ Jan 6 2011, 03:43 PM) *
If you mean cloud and storm imaging, I'm pretty sure there is going to be quite a bit of that in the visible and IR. If you mean night-side images of lightning flashes, I don't think that will be possible. During the perijove phase of the orbit, the spacecraft is over the day side. I'm fairly sure JunoCam and JIRAM can't point off nadir at all. I do think we'll get whistler data from Waves. That's caused by lighting and has been used as a measure of overall activity (as well as the source latitude.)


I think a key advance would be movie making of jupiter atmospheric dynamics, which Galileo could not do and HST is not funded to do. Hope they will have some long stare times! Maybe some Io plume monitoring too?

Posted by: machi Jan 27 2011, 12:23 AM

Junocam has too low resolution for some Io plume monitoring, but JIRAM can theoretically image Io with comparable resolution as NIMS imaging spectrometer. So it can detects hot spots and so on.
But Juno is spinning platform so any Io targeting can be only matter of luck, because Io monitoring isn't one of mission's or even instrument's (JIRAM) objectives.

Posted by: tedstryk Jan 27 2011, 03:28 AM

QUOTE (machi @ Jan 27 2011, 12:23 AM) *
Junocam has too low resolution for some Io plume monitoring, but JIRAM can theoretically image Io with comparable resolution as NIMS imaging spectrometer. So it can detects hot spots and so on.
But Juno is spinning platform so any Io targeting can be only matter of luck, because Io monitoring isn't one of mission's or even instrument's (JIRAM) objectives.

Other than maybe detect some gross albedo changes near the polar regions that are always highly foreshortened to earth-based telescopes, it is unlikely Junocam will do much with Io.

Posted by: ZLD Jan 27 2011, 08:28 PM

Whats the expected pariapsis of Juno? Will cloud shadows be visible at that range?

Posted by: djellison Jan 27 2011, 09:39 PM

http://en.wikipedia.org/wiki/Juno_(spacecraft)

CODE
Orbital elements
Regime    Polar
Periapsis    4300 km (2671 miles)

Posted by: nprev Jan 28 2011, 01:29 AM

Wow. I had no idea that perapsis was that low! blink.gif

Makes me think that possibly no useful imagery will be possible then; the relative velocity's going to be quite high, I assume. Are they considering adopting the Cassini 'skeet-shoot' tactic, perhaps in the XM?

Posted by: Hungry4info Jan 28 2011, 01:53 AM

It's not likely Juno will survive for a XM, and imaging science isn't a high priority as far as I know. (I get the strong impression JunoCam was installed kind of as an afterthought)

Posted by: volcanopele Jan 28 2011, 02:13 AM

Even if they plan on having an XM, the JunoCAM won't be around for it. It should die due to radiation damage around halfway through the nominal mission.

Posted by: nprev Jan 28 2011, 02:15 AM

Really! That is actually very interesting. The cam's progressive deterioration will in itself provide potentially useful engineering data.

Posted by: ZLD Jan 28 2011, 03:15 AM

Wow, that is extremely low!

For reference:
Pioneer 10: 132,086 km
Pioneer 11: 42,838 km
Voyager 1: 277,492 km
Voyager 2: 650,272 km
Ulysses: 379,123 km
Galileo: 402,327 km (rough avg)
-219,194 km (closest at arrival),
-71,398 km (closest at final pass of Amalthea),
-and of course entered the atmosphere with a final 0.9 RJ / -7140 km
Cassini: 9.7 million km
New Horizons: 2.2 million km
(Source:NSSDC, PDS)

Posted by: Explorer1 Jan 28 2011, 07:54 AM

If nothing else, the unique perspective on the inner moons (Amalthea, Metis and such) will be something to look forward to (if they're planning to look of course).

Posted by: djellison Jan 28 2011, 08:41 AM

I just had a quick look using Eyes on the Solar System (it has a baseline Juno trajectory)

CA's to Metis, Amalthea et al are on the order of 30,000 miles. Metis might be 7 pixels across. Amalthea maybe 20-30 pixels. We're talking on the order of 10km/pixel at those distances - and it would have to be a very very fortunate coincidence of geometry for them to even cross Junocams FOV.

Juno's orbit is near polar, remember - and at this time it'll be taking it's principle science data of Jupiter itself.

Posted by: machi Jan 28 2011, 11:10 AM

So close?
Then imaging spectroscopy is theoretically possible (by JIRAM). We haven't usable data from NIMS (Galileo). But these aren't objectives of the Juno mission. sad.gif

Posted by: Frank Crary Jan 28 2011, 03:23 PM

QUOTE (djellison @ Jan 28 2011, 08:41 AM) *
CA's to Metis, Amalthea et al are on the order of 30,000 miles. Metis might be 7 pixels across. Amalthea maybe 20-30 pixels. We're talking on the order of 10km/pixel at those distances - and it would have to be a very very fortunate coincidence of geometry for them to even cross Junocams FOV.

The odds are much better than that: Juno is a spinning spacecraft. Every 30 seconds, JunoCam's field of view will scan out the entire plane perpendicular to the spin axis. It could image anything in that plane. Over the course of a periapsis, that plane slides over most of the inner jovian system. Depending on the orientation of the orbit and the location of the satellites, I'd guess there is about a 50% chance to image any given satellite on a given periapsis. They just need to put in commands to image at the right time and spin phase.

That does not, however, say what the range to the satellite will be. It could be quite distant. In fact, the range to the Galilean satellites is always large on purpose. The observations of Jupiter call for a pretty well-controlled orbit. For example, each periapsis is 192 deg. of longitude from the last (to give an even sampling grid for the magnetic field/internal core measurement.) To do that without using too much fuel, the orbit was designed to avoid the Galilean satellites: Even a distant (e.g. 100,000 km) encounter would perturb the orbit and require additional corrections.

QUOTE
Juno's orbit is near polar, remember - and at this time it'll be taking it's principle science data of Jupiter itself.


That's true of the mission's science goals, but I'm not sure about JunoCam. It is on the spacecraft for public outreach and education. It isn't tied to the formal mission science requirements. It does get the best view and range of Jupiter, I think its filters reflect that, and I suspect most of the images will be of Jupiter. But if satellite images support JunoCam's outreach and education goals, I'd think they would be taken.

Posted by: Frank Crary Jan 28 2011, 03:30 PM

QUOTE (nprev @ Jan 28 2011, 01:29 AM) *
Wow. I had no idea that perapsis was that low! blink.gif

Makes me think that possibly no useful imagery will be possible then; the relative velocity's going to be quite high, I assume. Are they considering adopting the Cassini 'skeet-shoot' tactic, perhaps in the XM?


JunoCam and Juno don't do any pointing as such. The spin axis will point either at Earth or perpendicular to the orbital plane (so nadir on Jupiter is in the spin plane.) JunoCam just takes images at a commanded time and a commanded spin phase. So I don't think they can do anything like a skeet shoot. But it also means the smear from the relative velocity is less of a problem than you might think. It's designed to image from a platform spinning at 2 rpm. That's 12 deg. per second. At periapsis, the clouds are 4300 km away and the spacecraft is moving at about 50 km/s. That's about 0.7 deg. per second of smear, not much compared to the smear from spacecraft spin the instrument's built to deal with.

Posted by: djellison Jan 28 2011, 06:34 PM

I was told that the spin axis doesn't change. It's basically earth pointed throughout. Thus, it doesn't slide that axis across the system as you suggest. Yes - at some point, every moons orbit results in every moon passing through that plane at some point. However, you need a very close approach to get a worthwhile image, for those inner minor moons, it's at perihelion - so the moon will have to be on the EXACT opposite side of the spaceraft from Jupiter. And smear is a moot point - JunoCam is pushbroom.

Maybe I'm missing something regarding the orientation of the spacecraft and it's geometry - but it's only going to be at brief and fortunate times like the attached when a minor moon's going to both in the FOV, and close enough to be worth imaging. Basically - of the 360 degrees of it's orbit, those minor moons have to be in an 18 degree wide slab of it (less, actually ) to enter the JunoCam FOV, and do so fairly close to periapsis - a 1 in 20 event.

 

Posted by: vjkane Jan 28 2011, 11:50 PM

My recollection is that Doug is basically correct. Near perijove, the spacecraft will have either a nadir orientation for remote sensing (and imaging) of the atmosphere or an Earth orientation for gravity measurements so the antenna can point to Earth for tracking. Magnetic measurements presumably work equally well in either orientation. As I recall, the early orbits switch off between those orientations, and the latter orbits are only Earth orientation. In fact, as I recall, the remote sensing instruments will be turned off after the end of the nadir orientation orbits.

The difference in sun angle is small enough that the solar influx on the panels is enough to power the spacecraft with either orientation.

Anyone have better information?

Posted by: Frank Crary Feb 6 2011, 11:47 PM

QUOTE (vjkane @ Jan 29 2011, 12:50 AM) *
My recollection is that Doug is basically correct. Near perijove, the spacecraft will have either a nadir orientation for remote sensing (and imaging) of the atmosphere or an Earth orientation for gravity measurements so the antenna can point to Earth for tracking. Magnetic measurements presumably work equally well in either orientation. As I recall, the early orbits switch off between those orientations, and the latter orbits are only Earth orientation.


That's pretty much true, but maybe I can say this more clearly. On perijove for the MWR orbits, with Jupiter in the spin plane (spin axis perpendicular to orbital plane), the JunoCam or JIRAM having a chance to see a satellite are pretty small. They would have be crossing Juno's orbital plane at the time. That's also (more or less) true of the gravity orbits at the beginning of the mission. At first, the orbital plane is almost perpendicular to the Earth line (polar orbit, periapsis close to dusk local time.) But over the course of the mission, the orbital plane precesses and perijove moves towards noon. I think it moves about a degree to two per orbit, and it's at 30 or 40 closer to noon by the end of the mission. So, when Juno is 20 R_J from Jupiter, it will also be about 10 R_J behind Jupiter (as seen from Earth or the Sun.) The remote sensing fields of view would be scanning out a plane perpendicular to the Earth line and 10 R_J behind Jupiter. As Juno moves goes through periapsis, that plane would move sunward, get just a hair sunward of Jupiter itself at periapsis, and then move back again. That could greatly increase the odds of catching a satellite.

I think it's a moot point: JunoCam and JIRAM were really designed for atmospheric science, not satellite geology, so I'm not sure if this is more than a theoretical exercise. I think they could do it, but the results might be unimpressive.

QUOTE
In fact, as I recall, the remote sensing instruments will be turned off after the end of the nadir orientation orbits.


I don't think that's quite true. UVS (and WAVES, since radio astronomy might be called remote sensing) is designed to operate for the whole mission. The others are designed to accomplish all of their official goals in the first half of the mission. Because of that, they could designed to survive a lower radiation dose. But that just means no one is officially promising they will survive to the second half of the mission. They could. (For example, Galileo survived a far higher radiation does than it was designed for.) I strongly suspect the project will keep operating them for as long as they last; if they get lucky, that could be through the whole mission.

QUOTE
The difference in sun angle is small enough that the solar influx on the panels is enough to power the spacecraft with either orientation.


Towards the end of the MWR/nadir pointed perijove periods (orbit 10 or so, I think), there is a significant difference, and the power off the solar arrays is down. But that's what batteries are for. I think these perijoves were one of the things that determined the battery capacity.

Posted by: vjkane Feb 7 2011, 05:45 AM

QUOTE (Frank Crary @ Feb 6 2011, 03:47 PM) *
That's pretty much true, but maybe I can say this more clearly.

Thanks for the additional information. Are you part of the mission?

Posted by: ZLD Mar 8 2011, 02:55 AM

New update about Juno: http://solarsystem.nasa.gov/news/display.cfm?News_ID=36781

The spacecraft assembly has been completed and it is undergoing testing now.

Posted by: Paolo Mar 26 2011, 02:37 PM

There were 2 very well done articles on Juno in last week's Aviation Week
this is the only one of the two I found on their website: http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news%2Fawst%2F2011%2F03%2F21%2FAW_03_21_2011_p54-295399.xml&headline=Juno+Is+Solar+Marvel+Bound+for+Jupiter
by the way, you can read them both by searching Aviation Week on www.zinio.com

Posted by: punkboi Mar 28 2011, 06:35 PM

Juno's solar arrays are already at Cape Canaveral, undergoing tests. Juno itself should be arriving in Florida sometime next month, I believe


 

Posted by: belleraphon1 Apr 8 2011, 11:12 AM

Follow Juno's high-flying journey to Cape Canaveral Today, Friday 04/08/11

"Ever wonder what it's like to transport delicate billion-dollar space equipment across the country? It takes precision, care and a little heavy-lifting from the Air Force. NASA's Juno spacecraft will fly to Florida on a C-17 Globemaster today to start preparing for launch to Jupiter in August, and Spaceflight Now is going along for the ride."

http://spaceflightnow.com/juno/status.html

blatant political comment removed - admin

Craig

Posted by: Explorer1 Apr 8 2011, 11:03 PM

They're in motion, according to the status.

Looks like they'll make it just in time!

Posted by: punkboi Apr 9 2011, 02:14 AM

NASA's Jupiter-Bound Spacecraft Arrives in Florida

http://www.jpl.nasa.gov/news/news.cfm?release=2011-113&cid=release_2011-113

Posted by: punkboi May 5 2011, 01:38 AM

High Gain Antenna now attached to Juno

 

Posted by: Bjorn Jonsson May 17 2011, 12:26 AM

The Junocam has been delivered:

http://www.msss.com/news/index.php?id=24

And there are some interesting tidbits there, for instance

QUOTE
...is designed to take hundreds of color images of the giant planet, some at resolutions never before seen...


and

QUOTE
Junocam uses precision bandpass filters produced by Barr Associates of Westford, Massachusetts, including a red channel that sees into the near infrared to penetrate more deeply into the jovian atmosphere, and a fourth narrowband near-IR channel to map the abundance of methane


I was starting to fear that the best Voyager mosaics of the Great Red Spot (GRS) were going to remain the best (or at least among the very best) views of the GRS for the next 20-25 years or more but fortunately it now at least seems possible I was wrong.

There are lots of thing I'd love to see at significantly higher resolution than Voyager obtained (for example hi-res time lapse coverage of selected features like the GRS; cloud shadows and vertical 'relief' etc. that is visible in the highest resolution Voyager images) but I don't know if this qualifies as something that is interesting enough from a scientific point of view.

Posted by: elakdawalla May 17 2011, 05:18 AM

I'm glad they finally said this publicly:

QUOTE
Its wide-angle lens, designed and built by Rockwell-Collins Optronics of Carlsbad, California, produces sharp, low-distortion images that rival the best MSSS cameras have ever taken.

MSSS people seem just giddy about the quality of the images they're getting from this camera. And not only that: the compression algorithms they're using result in so little a reduction in image quality that probably only Bjorn and Gordan will notice the compression artifacts smile.gif I'm still not quite sure what to expect from this mission in terms of images, but I'm quite confident it'll be much more spectacular than is officially promised.

Posted by: Bjorn Jonsson Jun 29 2011, 12:04 AM

http://planetary.org/radio/ had an interview with Scott Bolton yesterday. One of the highlights: The images will be released to the web in raw form as soon as they are received. The best resolution is going to be 3 km/pixel.

If I understand correctly Juno will mainly be doing polar imaging (or the resolution is optimal there - I'm not sure). It would be interesting to know more about this and especially about possible imaging of the latitudes about 20 degrees south of the equator smile.gif.

Posted by: hendric Jun 29 2011, 04:51 PM

I sent a thank you note to the team via http://missionjuno.swri.edu/
Couldn't hurt if more did the same!
Just FYI, there is some kind of character limit in their "contact us" window, so be succinct. smile.gif

Posted by: MarcF Jul 8 2011, 03:37 PM

Juno is almost ready to fly smile.gif

http://www.sciencedaily.com/releases/2011/07/110707154500.htm

Posted by: peter59 Jul 26 2011, 06:54 PM

Amazing how low is interest in the Juno mission. I know that Juno is not Cassini, but nevertheless it is mission to Jupiter.
Here is a series of really beautiful images from KSC (including encapsulation).
http://mediaarchive.ksc.nasa.gov/search.cfm?cat=230
Launch window opens Aug. 5 (only 9 days, 20 hours from now). biggrin.gif

Posted by: punkboi Jul 26 2011, 07:04 PM

QUOTE (peter59 @ Jul 26 2011, 11:54 AM) *
Amazing how low is interest in the Juno mission.


Possibly because it's only designed to last 33 months at Jupiter...as opposed to 7 years and counting for Cassini at Saturn wink.gif

(That, and there are only so many interesting images the Junocam can take of Jupiter's poles)

Posted by: Explorer1 Jul 26 2011, 07:08 PM

The destination is still so far away, its like wondering why there's not much fuss about Rosetta or New Horizons yet.

Posted by: djellison Jul 26 2011, 07:34 PM

QUOTE (peter59 @ Jul 26 2011, 11:54 AM) *
it is mission to Jupiter.


And gets there 5 years from now. What is there to be excited about right now?

Posted by: peter59 Jul 26 2011, 07:41 PM

QUOTE (djellison @ Jul 26 2011, 07:34 PM) *
What is there to be excited about right now?

Last preparation for launch is not fascinating ?


Posted by: djellison Jul 26 2011, 07:48 PM

QUOTE (peter59 @ Jul 26 2011, 11:41 AM) *
Last preparation for launch is not fascinating ?


For the general public? Not really. For most space enthusiasts...there really isn't much to talk about.

People are not excited because it's not exciting. One defines the other

Posted by: jasedm Jul 26 2011, 08:05 PM

QUOTE (peter59 @ Jul 26 2011, 07:54 PM) *
Amazing how low is interest in the Juno mission.


People want pretty pictures.



Posted by: algorimancer Jul 26 2011, 08:12 PM

If it were planning a survey of the satellites, like Cassini and (in a better world) Galileo, I'd be plenty excited. Particles & fields and distant images of clouds on Jupiter is something I'm having trouble getting excited about. That being said, I'm perfectly happy the let the particles & fields folks have this one to themselves, as I suppose it's their turn -- and I'm sure they'll learn something interesting & valuable. The mission I'd get really excited about would be a Europa orbiter or rover.

Posted by: Toma B Jul 26 2011, 08:43 PM

QUOTE (jasedm @ Jul 26 2011, 10:05 PM) *
People want pretty pictures.

...and thats not what they will get a lot from this mission.

Posted by: ElkGroveDan Jul 26 2011, 09:14 PM

QUOTE (Toma B @ Jul 26 2011, 12:43 PM) *
...and thats not what they will get a lot from this mission.

You'll be surprised.

Posted by: helvick Jul 26 2011, 10:05 PM

I may be alone in this (on this forum, no doubt the Juno science team agree) but I'm really stoked about the non-imaging bias of Juno. I like pictures, and they do convey a sense of immediacy, but imaging is only one way of collecting data, and not a particularly useful one for many scientific objectives.

Here's hoping that there's plenty of weird data gathered that changes how we understand Gas Giants and solar system dynamics.

And there will be plenty of Junocam images in any case for those who find that boring.

Posted by: punkboi Jul 27 2011, 12:37 AM

If NASA collected names to fly on this mission a la Cassini and the Mars rovers, then I'd be excited. Of course, the microchip or CD bearing the names would probably be erased by the radiation not too long after Juno enters Jovian orbit. (I'm into space exploration for all the wrong reasons smile.gif)

Posted by: Greg Hullender Jul 27 2011, 03:17 AM

For whatever reason, the Juno team doesn't seem to have done much outreach. Their web site http://juno.wisc.edu/index_whatsnew.html hasn't been updated in three years.

--Greg

Posted by: elakdawalla Jul 27 2011, 03:22 AM

Yeah, that's something I noticed recently too. Apparently the reason that that site hasn't been taken down is "it's complicated." Anyway, the place to go for current Juno mission news and educational information is http://www.nasa.gov/mission_pages/juno/main/index.html

Posted by: djellison Jul 27 2011, 03:35 AM

There is http://missionjuno.swri.edu/

Posted by: Hungry4info Jul 27 2011, 06:16 AM

I suppose it's too early to think about potential asteroid flybys? Or has that been ruled out already?

Posted by: Explorer1 Jul 27 2011, 06:36 AM

They never mentioned any, as far as I know.
Juno will be in the main belt twice, both before and after the Earth flyby, so that doubles the chance of an encounter.

Posted by: mchan Jul 27 2011, 07:50 AM

With a tight budget, it would be tough to plan and execute an encounter. E.g., you'd have to develop instrument sequences, increase DSN allocation, temporarily increase operations staff, etc.

Juno instruments are mostly for fields and non-imaging data which are not optimum for a solid body encounter so science return is low compared to a spacecraft such as Dawn.

Posted by: machi Jul 27 2011, 10:08 AM

QUOTE (peter59 @ Jul 26 2011, 09:41 PM) *
Last preparation for launch is not fascinating ?


No, it isn't. It's horror and it's time full of fear from failure. After successful launch, then it's fascinating. smile.gif

QUOTE (helvick @ Jul 27 2011, 12:05 AM) *
I may be alone in this (on this forum, no doubt the Juno science team agree) but I'm really stoked about the non-imaging bias of Juno. I like pictures, and they do convey a sense of immediacy, but imaging is only one way of collecting data, and not a particularly useful one for many scientific objectives.


No, you are not. Juno is capable of probing Jupiter's atmosphere hundreds of bars deep (it's significantly more, than Galileo's probe could) and she can reveal fine structure of Jupiter's interior.
This is really amazing!

mchan:
I don't think they (Juno team) are planning asteroid encounter, but Juno is theoretically capable of imaging (Junocam, JIRAM), probably mapping surface of asteroid (with JIRAM) and she can find mass of asteroid (RSS). It is more, than NEAR did in Mathilde flyby (only imaging and mass measurements). Question is, if Juno can successfully track such small and fast target.
Some irregular moon of Jupiter would be another interesting target.

Posted by: scalbers Jul 27 2011, 05:35 PM

Greetings,
Might be interesting to tune into the Science Briefing (after the news conference) Wed Aug 3 at 1pm EDT. Several familiar names will be participating.
Steve
P.S. NASA TV is also airing a Science Briefing of Juno as I write this.

----- Original Message -----
Sent: Tue Jul 26 16:30:58 2011
Subject: NASA Sets Launch Coverage Events For Mission To Jupiter

July 26, 2011
MEDIA ADVISORY: M11-156
NASA SETS LAUNCH COVERAGE EVENTS FOR MISSION TO JUPITER

CAPE CANAVERAL, Fla. -- NASA's Juno spacecraft is set to launch toward Jupiter aboard a United Launch Alliance Atlas V rocket on Aug. 5. The launch window extends from 11:34 a.m. to 12:33 p.m. EDT, and the launch period extends through Aug. 26.

The spacecraft is expected to arrive at Jupiter in 2016 on a mission to investigate the gas giant's origins, structure, atmosphere and magnetosphere. Juno's color camera will provide close-up images of Jupiter, including the first detailed views of the planet's poles.

NASA will host a prelaunch news conference in the News Center at the agency's Kennedy Space Center in Florida on Wednesday, Aug. 3, at 1 p.m. EDT. Conference participants are:
-- Colleen Hartman, assistant associate administrator, Science Mission Directorate, NASA Headquarters, Washington
-- Omar Baez, NASA launch director at Kennedy -- Vernon Thorp, program manager, NASA Missions, United Launch Alliance, Denver
-- Jan Chodas, Juno project manager, Jet Propulsion Laboratory, Pasadena, Calif.
-- Tim Gasparini, Juno program manager, Lockheed Martin Space Systems, Denver
-- Clay Flinn, Atlas V launch weather officer, 45th Weather Squadron, Cape Canaveral Air Force Station, Fla.

A Juno mission science briefing will follow the prelaunch news conference. Briefing participants are:
-- Scott Bolton, Juno principal investigator, Southwest Research Institute, San Antonio
-- Toby Owen, Juno co-investigator, University of Hawaii
-- Jack Connerney, Juno Instrument lead, NASA's Goddard Space Flight Center, Greenbelt, Md.
-- Andy Ingersol, Juno co-investigator, Cal Tech, Pasadena
-- Fran Bagenai, Juno co-investigator, University of Colorado, Boulder
-- Candy Hansen, Juno co-investigator, Planetary Science Institute, Tucson

A news conference will be held at the Kennedy News Center approximately 2.5 hours after launch, and a news release will be issued as soon as Juno's condition is determined. Spokespersons will be available for interviews.

NASA Television Coverage
On Aug. 3, NASA Television's Media and Education Channels will carry the Juno prelaunch news conference live beginning at 1 p.m. On Aug. 5, NASA TV coverage of the launch will begin at 9 a.m. and conclude after spacecraft separation from the Atlas V occurs approximately 53 minutes and 49 seconds after launch. For NASA TV downlink information, schedule information and streaming video, visit: http://www.nasa.gov/ntv

Audio only of the prelaunch press conference and the launch coverage will be carried on 321-867-1220/1240/1260/7135. On launch day, mission audio of launch countdown activities, without NASA TV commentary, will be carried on 321-867-7135 starting at 7 a.m. Launch audio also be available on local amateur VHF radio frequency 146.940 MHz heard within Brevard County.

For extensive prelaunch and launch coverage online, visit: http://www.nasa.gov

A prelaunch webcast will be streamed at noon on Aug. 7. Live countdown coverage through NASA's Launch Blog begins at 9 a.m. on Aug. 5. Coverage features live updates as countdown milestones occur, as well as streaming video clips highlighting launch preparations and liftoff. For questions about countdown coverage, contact Jeanne Ryba at 321-867-7824.

To view the webcast and the blog or to learn more about the Juno mission, visit: http://www.nasa.gov/juno
The NASA News Twitter feed will be updated throughout the launch countdown at: http://www.twitter.com/nasa

Recorded Juno status reports and launch updates will be available on the Kennedy media phone line starting Monday, Aug. 1 at 321-867-2525.

NASA's Jet Propulsion Laboratory manages the Juno mission for the principal investigator, Scott Bolton. The Juno mission is part of the New Frontiers Program anaged at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems built the spacecraft. Launch management for the mission is the responsibility of NASA's Launch Services Program at the Kennedy.

Posted by: belleraphon1 Jul 28 2011, 11:11 AM

QUOTE (machi @ Jul 27 2011, 06:08 AM) *
No, you are not. Juno is capable of probing Jupiter's atmosphere hundreds of bars deep (it's significantly more, than Galileo's probe could) and she can reveal fine structure of Jupiter's interior.
This is really amazing!


helvick and machi...

Add me to the very excited list, too! The data JUNO sends back will be priceless.

And Junocam may surprise folks.

Craig


Posted by: Decepticon Jul 28 2011, 12:47 PM

Plus One! I can't wait to see this get off the ground! smile.gif

Posted by: peter59 Jul 28 2011, 04:27 PM

Juno probe mounted atop its launcher.
http://spaceflightnow.com/atlas/av029/status.html


Posted by: Lewis007 Jul 31 2011, 07:31 AM

NASA has released the press kit for the Juno launch.
http://www.jpl.nasa.gov/news/press_kits/JunoLaunch.pdf

ULA - the launch provider - has published its 'mission booklet'
http://www.ulalaunch.com/site/docs/missionbooklets/AV/av_juno_mob.pdf



Posted by: scalbers Aug 3 2011, 06:26 PM

Congrats to Bjorn whose Voyager mosaic was featured in the Juno press conference a moment ago!

Posted by: Tom Tamlyn Aug 3 2011, 08:43 PM

Does anyone know of a replay site for the press conference?

Several years ago I frequented a site, hosted, if I recall correctly, in Europe, that posted virtually every space exploration press conference. There was something un-memorable about the name, and now it's completely gone from my memory. Does this description jog anyone else's memory? (I realize I'm not giving you much to work with.)

TTT

Posted by: jamescanvin Aug 3 2011, 09:04 PM

http://www.space-multimedia.nl.eu.org/

Posted by: Tom Tamlyn Aug 3 2011, 09:49 PM

Thanks James, that's the one, and sure enough, a downloadable file for today's press conference has already been posted.

Does anyone know anything about the people who run this site? They're amazingly dedicated and hard-working.

TTT

Posted by: ugordan Aug 4 2011, 02:29 PM

QUOTE (scalbers @ Aug 3 2011, 08:26 PM) *
Congrats to Bjorn whose Voyager mosaic was featured in the Juno press conference a moment ago!

Not only that, his mosaic ended up as a Photojournal image advisory, too! Behold: http://photojournal.jpl.nasa.gov/catalog/PIA14412

Posted by: Toma B Aug 4 2011, 10:06 PM

These words said by Candy Hansen, Juno co-investigator are worth repeating and remembering:

"There are number of folks that process images as a hobby and we hope to engage that group...we will put our raw images out, and we will invite the public to process that data."

That sounds to me like a PROMISE.

that group = UMSF smile.gif

I think some of us would like to know everything there is to know, about processing JUNOCAM images by 2016.

Posted by: cIclops Aug 5 2011, 10:55 AM

Hopefully the wait won't be that long!

There's an Earth gravity assist planned for 9 October 2013 at 500kms altitude; that would be a great opportunity for a movie if the cam keeps shooting all the way in and out. Likewise a departure movie would be possible if Junocam is switched on soon after launch.

Posted by: mcaplinger Aug 5 2011, 11:48 AM

QUOTE (cIclops @ Aug 5 2011, 03:55 AM) *
Likewise a departure movie would be possible if Junocam is switched on soon after launch.

First payload checkout is around L+20 days when the Earth is a "pale blue dot" ™ as far as Junocam is concerned.

I gave Emily an infodump about how Junocam works, expected image counts, when we image, etc, so you can look for that soon, I expect.

Posted by: JGodbaz Aug 5 2011, 12:31 PM

I guess JunoCam being less of a scientific priority versus imaging systems on Dawn probably helps; the investigators don't have to worry about being pipped at the post by amateur researchers. It makes sense to use a public outreach instrument for...um... public outreach. Good news for us, anyway.

On the processing side, given that it is a pushbroom system, the processing might be a little bit more involved for those who want to work from the really low-level raw data. I might do some research into processing methods, as it seems like an interesting challenge.

Posted by: climber Aug 5 2011, 01:16 PM

QUOTE (mcaplinger @ Aug 5 2011, 01:48 PM) *
First payload checkout is around L+20 days when the Earth is a "pale blue dot" ™ as far as Junocam is concerned.

I gave Emily an infodump about how Junocam works, expected image counts, when we image, etc, so you can look for that soon, I expect.

Thank you Mike,very interesting indeed, and it's been a long time not hearing from you...

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