Juno development, launch, and cruise, Including Earth flyby imaging Oct 9 2013 Options

[Jeff7]

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.

[tedstryk]

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.

[Mariner9]

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.

[Del Palmer]

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...

[nprev]

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.

[ugordan]

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.

[mchan]

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.

[Greg Hullender]

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

[Juramike]

article at space.com regarding the Juno mission.

[Guest_PhilCo126_*]

Here's the merchandise:
http://www.bookstore.caltech.edu/jpllab/sh...p;catalog_id=39

[lyford]

NASA Prepares for New Juno Mission to Jupiter

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.

[Juramike]

Is there any possibility of JunoCam (image of instruments on spacecraft here) 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 here).]

[IM4]

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 here).]

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

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[djellison]

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.

[IM4]

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?