Juno development, launch, and cruise, Including Earth flyby imaging Oct 9 2013 |
Juno development, launch, and cruise, Including Earth flyby imaging Oct 9 2013 |
Apr 3 2006, 09:57 PM
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Member Group: Members Posts: 169 Joined: 17-March 06 Member No.: 709 |
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 |
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Dec 1 2008, 09:38 PM
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Junior Member Group: Members Posts: 63 Joined: 18-November 08 Member No.: 4490 |
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. This very interesting history on Pioneer 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 not image Io's volcanos, 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.. |
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Dec 1 2008, 11:46 PM
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Senior Member Group: Members Posts: 2517 Joined: 13-September 05 Member No.: 497 |
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. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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