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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#1
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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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Nov 10 2006, 03:26 PM
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#61
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IMG to PNG GOD Group: Moderator Posts: 2251 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
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.
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Nov 10 2006, 04:04 PM
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#62
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Merciless Robot Group: Admin Posts: 8784 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
I would imagine that IR-band imaging would be an inflexible requirement, then.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Dec 26 2006, 10:06 PM
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#63
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Newbie Group: Members Posts: 18 Joined: 17-September 06 From: USA Member No.: 1151 |
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 -------------------- Lorne Ipsum, Chief Geek
Geek Counterpoint blog & podcast |
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Guest_John Flushing_* |
Jan 10 2007, 12:34 AM
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#64
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Guests |
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Mar 12 2007, 11:05 AM
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#65
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Junior Member Group: Members Posts: 96 Joined: 20-September 06 From: Hanoi, Vietnam Member No.: 1164 |
A new article for Juno:
Juno Gets A Little Bigger With One More Payload For Jovian Delivery - http://www.spacedaily.com/reports/Juno_Get...livery_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? |
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Mar 12 2007, 11:22 AM
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#66
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Newbie Group: Members Posts: 18 Joined: 17-September 06 From: USA Member No.: 1151 |
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. - 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 this site out (it's Juno's public outreach web site). - 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 here. Hope this helps... -------------------- Lorne Ipsum, Chief Geek
Geek Counterpoint blog & podcast |
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Mar 12 2007, 11:31 AM
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#67
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Member Group: Members Posts: 593 Joined: 20-April 05 Member No.: 279 |
- How big the solar panels will be to give adequate power output from Jupiter for the 8-proposed instruments? This site 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 |
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Mar 12 2007, 12:20 PM
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#68
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Dublin Correspondent Group: Admin Posts: 1799 Joined: 28-March 05 From: Celbridge, Ireland Member No.: 220 |
20% efficiency is conservative, the state of the art is now ~41%. 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.
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Mar 12 2007, 12:24 PM
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#69
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Junior Member Group: Members Posts: 96 Joined: 20-September 06 From: Hanoi, Vietnam Member No.: 1164 |
Thanks Lorne Ipsum, that really helps
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Mar 12 2007, 12:56 PM
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#70
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Founder Group: Chairman Posts: 14433 Joined: 8-February 04 Member No.: 1 |
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
What I want to know is what the downlink will be like Doug |
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Mar 12 2007, 02:09 PM
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#71
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Junior Member Group: Members Posts: 96 Joined: 20-September 06 From: Hanoi, Vietnam Member No.: 1164 |
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?
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Mar 12 2007, 04:26 PM
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#72
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
What I want to know is what the downlink will be like 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 |
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Guest_vjkane2000_* |
Mar 12 2007, 04:30 PM
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#73
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Guests |
20% efficiency is conservative, the state of the art is now ~41%. 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? |
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Mar 13 2007, 08:44 AM
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#74
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Senior Member Group: Members Posts: 1870 Joined: 20-February 05 Member No.: 174 |
Bruce Moomaw has a couple articles worth checking out:
http://www.spacedaily.com/reports/Juno_Get...livery_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_B...ferred_999.html |
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Mar 13 2007, 10:57 AM
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#75
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Dublin Correspondent Group: Admin Posts: 1799 Joined: 28-March 05 From: Celbridge, Ireland Member No.: 220 |
This Boeing\Spectrolab marketing page indicates that 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 34% was the R&D state of the art in 2000 so 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. |
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