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Juno - Jupiter Orbiter
mcaplinger
post Nov 28 2008, 06:38 PM
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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.


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Hungry4info
post Nov 28 2008, 10:09 PM
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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)


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jekbradbury
post Nov 28 2008, 10:37 PM
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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.
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mcaplinger
post Nov 29 2008, 12:57 AM
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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.


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vjkane
post Nov 29 2008, 02:29 AM
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Has the team looked into the feasibility of imaging the cloud decks at perijove? Would the motion just result in a blur?


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mcaplinger
post Nov 29 2008, 02:50 AM
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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.


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vjkane
post Nov 29 2008, 04:46 AM
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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?


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Doc
post Nov 29 2008, 05:42 AM
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15km/pixel


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mcaplinger
post Nov 29 2008, 06:09 AM
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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.


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Doc
post Nov 29 2008, 07:54 AM
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Whoa, 4km/pix thats news to me; thanks for the info mcaplinger.


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Hungry4info
post Nov 29 2008, 05:45 PM
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Is it too early to know if Juno might make an asteroid flyby or two? (i.e. Galileo style)


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Guest_Enceladus75_*
post Nov 29 2008, 06:16 PM
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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
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mcaplinger
post Nov 29 2008, 06:42 PM
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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.


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vjkane
post Nov 29 2008, 07:38 PM
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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.


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Guest_Enceladus75_*
post Nov 29 2008, 07:47 PM
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"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?
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