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

[PhilHorzempa]

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

[Mariner9]

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?

[Guest_BruceMoomaw_*]

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/outerplan...01/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.

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.

[helvick]

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.