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Neptune Orbiter, Another proposed mission
Rob Pinnegar
post Nov 10 2005, 03:51 PM
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This seems like a good place to start off the Uranus and Neptune forum: with the next ice-giants mission.

I will admit to not knowing a whole lot about the Neptune Orbiter With Probes (NOWP), other than the fact that it's in the planning stages, and a few other details I've gathered from Wikipedia and various other Internet sources. Anyone care to get this one going with a bit more information?
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Guest_AlexBlackwell_*
post Jul 17 2006, 07:51 PM
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I apologize for reviving a dead thread; however, Frank Morring Jr., reporting from the Farnborough 2006 Air Show, has an interesting article ("Improving Solar Cell Efficiency Enables NASA's Solar-Powered Jupiter Probe") in the July 17, 2006, issue of Aviation Week & Space Technology.

While the bulk of the article relates to the Juno New Frontiers-class mission, there is an interesting passage relating to a Neptune orbiter concept:

QUOTE
While Juno will be pushing the state of the art for deep-space use of solar power, scientists have analyzed the use of sunlight to power spacecraft at planets even more distant from the Sun. NASA has studied a Neptune orbiter that would use inflatable structures to deploy the ultra-large solar arrays that would be needed there and concentrators to focus the dim sunlight on the collectors (AW&ST Dec. 13, 2004, p. 56).

[Paul] Stella [principal engineer for space power systems at JPL] is skeptical. Even without considering the inflatable structures that would be needed to hold the solar concentrators and underlying cells, there would be difficult problems to overcome with the power-generating system itself. NASA flew a solar concentrator based on Fresnel lenses on its Deep Space-1 technology testbed, which he says "worked very well." But array pointing is more critical with concentrators than with conventional planar solar arrays, and the concentrator aperture will be "about the same size" as a planar array, even if the number of cells beneath it is reduced. Ultimately, it becomes a question of whether an array large enough can be built and delivered.

"Those are pretty advanced studies," Stella says. "A solar cell at Neptune will probably generate some power, but . . . the amount of power is going to be dropped down by literally hundreds, close to a thousand, and that makes for a very big solar array. The question is, if you need 30 watts at Neptune, which is a small amount, how many thousands and tens of thousands of watts do you have to build on Earth? Our biggest communications satellites are probably on the order of 20 kw., and that's lot of solar array, very complex, and again we might need even more than that. We're getting into uncharted territory."

Engineers at JPL also are working on boosting solar-cell efficiency by increasing the number of junctions, with promising results. But there is a limit to how much sunlight can be converted to electricity.

"I would think that numbers approaching 50% are probably at least analytically feasible," says Stella. "We've done some work here. We looked at going from three junction cells to four to five to six to seven. And there's a point of diminishing returns . . . . I think we ended up probably in the order of 50%, and that doesn't mean you're going to get there."
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JRehling
post Jul 18 2006, 03:38 PM
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I would think that at some point the weight of the solar panels would be prohibitive.

I guess another concept for a Neptune orbiter would be to have solar panels spend 90%+ of a highly elliptical orbit charging batteries, with periapsis spent using that battery power to run instruments and transmit data home. In principle, there's almost no limit to how high the apoapsis is -- and such an orbit would also require less propellant. If the Neptune encounters are far apart in time, that would increase operations costs, but there'd be a lot of savings in engineering.
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Chmee
post Jul 18 2006, 03:47 PM
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QUOTE (JRehling @ Jul 18 2006, 11:38 AM) *
I would think that at some point the weight of the solar panels would be prohibitive.

I guess another concept for a Neptune orbiter would be to have solar panels spend 90%+ of a highly elliptical orbit charging batteries, with periapsis spent using that battery power to run instruments and transmit data home. In principle, there's almost no limit to how high the apoapsis is -- and such an orbit would also require less propellant. If the Neptune encounters are far apart in time, that would increase operations costs, but there'd be a lot of savings in engineering.


By why even consider a solar array when RTG's are a proven, safe, and stable power source for deep space missions? It seems such large, heavy, and complex solar arrays are solution for a problem that does not exist.
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Posts in this topic
- Rob Pinnegar   Neptune Orbiter   Nov 10 2005, 03:51 PM
- - elakdawalla   I don't know much myself about what's poss...   Nov 10 2005, 04:43 PM
|- - tedstryk   I would really like to see a Neptune orbiter with ...   Nov 10 2005, 05:26 PM
|- - Rob Pinnegar   QUOTE (tedstryk @ Nov 10 2005, 11:26 AM)Maybe...   Nov 10 2005, 05:59 PM
|- - elakdawalla   QUOTE (tedstryk @ Nov 10 2005, 10:26 AM)I wou...   Nov 10 2005, 06:20 PM
|- - JRehling   QUOTE (elakdawalla @ Nov 10 2005, 11:20 AM)Ho...   Nov 10 2005, 07:09 PM
||- - tedstryk   If an orbiter is a long way off, I think a Triton ...   Nov 10 2005, 07:13 PM
||- - ljk4-1   QUOTE (tedstryk @ Nov 10 2005, 02:13 PM)If an...   Nov 10 2005, 07:53 PM
||- - Jeff7   QUOTE (tedstryk @ Nov 10 2005, 02:13 PM)If an...   Nov 11 2005, 05:20 PM
|- - hendric   QUOTE (elakdawalla @ Nov 10 2005, 12:20 PM)Ho...   Nov 16 2005, 08:22 AM
|- - Rob Pinnegar   QUOTE (hendric @ Nov 16 2005, 02:22 AM)Accord...   Nov 16 2005, 02:02 PM
|- - tedstryk   It is no doubt battered, but so is Mimas. A possi...   Nov 16 2005, 02:28 PM
|- - Rob Pinnegar   QUOTE (tedstryk @ Nov 16 2005, 08:28 AM)A pos...   Nov 16 2005, 05:09 PM
- - RNeuhaus   The trip to planets beyond than Saturn, I think th...   Nov 10 2005, 07:38 PM
|- - tasp   QUOTE (RNeuhaus @ Nov 10 2005, 01:38 PM)The t...   Nov 10 2005, 09:49 PM
|- - RNeuhaus   QUOTE (tasp @ Nov 10 2005, 04:49 PM)Prometheu...   Nov 10 2005, 10:00 PM
|- - JRehling   QUOTE (tasp @ Nov 10 2005, 02:49 PM)Prometheu...   Nov 10 2005, 10:06 PM
|- - tasp   To revise and extend my remarks, Would a reusable...   Nov 11 2005, 12:59 AM
|- - tasp   Meanwhile, back at Neptune, Has anyone considered...   Nov 11 2005, 01:09 AM
|- - Rob Pinnegar   QUOTE (tasp @ Nov 10 2005, 07:09 PM)Has anyon...   Nov 11 2005, 01:36 AM
|- - tedstryk   QUOTE (Rob Pinnegar @ Nov 11 2005, 01:36 AM)T...   Nov 11 2005, 02:28 AM
|- - Rob Pinnegar   QUOTE (tedstryk @ Nov 10 2005, 08:28 PM)I don...   Nov 11 2005, 06:22 AM
- - Decepticon   There where some ideas for Neptune orbiter in Astr...   Nov 11 2005, 12:42 AM
- - BruceMoomaw   There has actually been quite a lot of work done b...   Nov 11 2005, 04:01 AM
- - tasp   I'll digress to Uranus orbiting briefly. Assu...   Nov 11 2005, 04:11 AM
|- - JRehling   QUOTE (tasp @ Nov 10 2005, 09:11 PM)I'll ...   Nov 11 2005, 02:23 PM
|- - tedstryk   QUOTE (JRehling @ Nov 11 2005, 02:23 PM)Unfor...   Nov 11 2005, 03:01 PM
||- - Rob Pinnegar   QUOTE (tedstryk @ Nov 11 2005, 09:01 AM)That ...   Nov 11 2005, 05:11 PM
|- - tasp   QUOTE (JRehling @ Nov 11 2005, 08:23 AM)If th...   Nov 11 2005, 03:12 PM
|- - JRehling   QUOTE (tasp @ Nov 11 2005, 08:12 AM)Can ...   Nov 11 2005, 04:45 PM
- - BruceMoomaw   I may have something to say on THAT subject in my ...   Nov 11 2005, 04:53 AM
- - BruceMoomaw   That's another reason why, given the likely de...   Nov 11 2005, 10:18 PM
- - tasp   Alex Blackwell has a post in the Uranus Orbiter th...   Nov 12 2005, 02:26 PM
|- - tedstryk   Here is an approach sequence of Proteus. All colo...   Nov 15 2005, 11:59 PM
|- - Rob Pinnegar   QUOTE (tedstryk @ Nov 15 2005, 05:59 PM)It is...   Nov 16 2005, 06:25 AM
- - tasp   And even Miranda is somewhat oblongish. Would I b...   Nov 16 2005, 06:31 PM
|- - David   QUOTE (tasp @ Nov 16 2005, 06:31 PM)And even ...   Nov 17 2005, 03:11 AM
- - tasp   I suspect the 'lumpiness' of Iapetus is a ...   Nov 17 2005, 04:46 AM
|- - Bob Shaw   QUOTE (tasp @ Nov 17 2005, 05:46 AM)I suspect...   Nov 17 2005, 08:01 PM
- - tasp   With a greater understanding or how orbital tours ...   Nov 26 2005, 02:55 PM
- - Decepticon   A simple Google search reveled this!? What P...   Nov 26 2005, 03:41 PM
- - BruceMoomaw   That's the nuclear-electric version of Neptune...   Nov 27 2005, 02:43 AM
- - Decepticon   I hate anything that Unfurls. When Galileo...   Nov 27 2005, 12:31 PM
- - BruceMoomaw   Just keep in mind that Galileo's antenna was e...   Nov 27 2005, 01:32 PM
|- - vjkane2000   QUOTE (BruceMoomaw @ Nov 27 2005, 06:32 AM)Ju...   Nov 28 2005, 03:38 AM
|- - mchan   QUOTE (BruceMoomaw @ Nov 27 2005, 05:32 AM)Ju...   Nov 29 2005, 07:51 AM
- - edstrick   In a conversation some 10? years ago, maybe at the...   Nov 28 2005, 06:06 AM
- - edstrick   Deployments have ALWAYS been one of the big missio...   Nov 29 2005, 08:44 AM
- - tasp   Just in case NASA/JPL finds themselves looking for...   Dec 5 2005, 05:23 AM
- - dvandorn   Does Triton *really* have enough of an atmosphere ...   Dec 5 2005, 07:35 AM
|- - Toma B   QUOTE (dvandorn @ Dec 5 2005, 10:35 AM)Does T...   Dec 5 2005, 08:34 AM
|- - chris   QUOTE (Toma B @ Dec 5 2005, 08:34 AM)Solution...   Dec 5 2005, 10:49 AM
||- - Toma B   QUOTE (chris @ Dec 5 2005, 01:49 PM)Which cou...   Dec 5 2005, 11:42 AM
||- - chris   QUOTE (Toma B @ Dec 5 2005, 11:42 AM)What did...   Dec 5 2005, 12:52 PM
||- - Toma B   QUOTE (chris @ Dec 5 2005, 03:52 PM)If you la...   Dec 5 2005, 01:27 PM
||- - paxdan   QUOTE (Toma B @ Dec 5 2005, 01:27 PM)Question...   Dec 5 2005, 01:47 PM
|||- - ljk4-1   Drop a probe right into one of the Triton geysers....   Dec 5 2005, 02:57 PM
||- - chris   QUOTE (Toma B @ Dec 5 2005, 01:27 PM)Question...   Dec 5 2005, 03:07 PM
||- - Toma B   QUOTE (chris @ Dec 5 2005, 06:07 PM)I wasn...   Dec 6 2005, 08:48 AM
||- - chris   QUOTE (Toma B @ Dec 6 2005, 08:48 AM)All righ...   Dec 6 2005, 10:41 AM
|- - helvick   QUOTE (Toma B @ Dec 5 2005, 09:34 AM)Mars atm...   Dec 5 2005, 12:02 PM
|- - JRehling   QUOTE (Toma B @ Dec 5 2005, 12:34 AM)Mars atm...   Dec 5 2005, 04:23 PM
- - edstrick   Note that the surface of Triton may be very rough ...   Dec 5 2005, 11:07 AM
- - tasp   Check out the last half of the Uranus orbiter thre...   Dec 5 2005, 03:05 PM
- - ermar   As a long-time lurker, sorry for spamming links, b...   Dec 10 2005, 02:23 AM
|- - Toma B   QUOTE (ermar @ Dec 10 2005, 05:23 AM)As a lon...   Dec 10 2005, 06:56 AM
- - BruceMoomaw   They definitely won't fly the nuclear-propelle...   Dec 10 2005, 06:42 AM
- - BruceMoomaw   Sure: http://www.lpi.usra.edu/opag/jun_05_meetin.....   Dec 10 2005, 08:46 AM
|- - tedstryk   QUOTE (BruceMoomaw @ Dec 10 2005, 08:46 AM)Th...   Dec 10 2005, 01:29 PM
- - AlexBlackwell   I apologize for reviving a dead thread; however, F...   Jul 17 2006, 07:51 PM
|- - Rob Pinnegar   QUOTE (AlexBlackwell @ Jul 17 2006, 01:51...   Jul 18 2006, 03:36 PM
|- - JRehling   I would think that at some point the weight of the...   Jul 18 2006, 03:38 PM
|- - Chmee   QUOTE (JRehling @ Jul 18 2006, 11:38 AM) ...   Jul 18 2006, 03:47 PM
|- - AlexBlackwell   QUOTE (Chmee @ Jul 18 2006, 05:47 AM) By ...   Jul 18 2006, 04:42 PM
- - ljk4-1   I wonder if a very large solar sail could be desig...   Jul 18 2006, 05:34 PM
- - Analyst   Before the "nuclear problem" comes the m...   Jul 20 2006, 10:54 AM
|- - antoniseb   QUOTE (Analyst @ Jul 20 2006, 04:54 AM) B...   Jul 21 2006, 11:52 PM
|- - Stephen   QUOTE (antoniseb @ Jul 21 2006, 11:52 PM)...   Jul 25 2006, 04:35 AM
|- - Greg Hullender   But surely at the distance of Neptune the force ap...   Jul 25 2006, 05:01 AM
|- - helvick   QUOTE (Greg Hullender @ Jul 25 2006, 06:0...   Jul 25 2006, 05:34 AM
- - ljk4-1   Would a Neptune orbiter be able to utilize the pla...   Jul 25 2006, 02:58 PM
|- - TritonAntares   QUOTE (ljk4-1 @ Jul 25 2006, 03:58 P...   Jul 25 2006, 11:17 PM
- - qraal   Hi All Solar concentrators are such a cool concep...   Jul 26 2006, 01:40 PM
- - mimile   There have been many good answers to the question ...   Feb 11 2007, 11:38 AM
- - Rob Pinnegar   Those are good points, but it may be worth keeping...   Feb 11 2007, 05:04 PM
- - nprev   Nereid: 27.6 deg with respect to Neptune's equ...   Feb 11 2007, 05:37 PM
|- - JRehling   It's odd that people brought the topic of Nere...   Feb 12 2007, 01:42 AM
- - nprev   Good point, JR. In fact, Nereid spins pretty fast:...   Feb 12 2007, 04:13 AM
- - tasp   OK, I am not smart enough to visualize this in my ...   Feb 12 2007, 06:24 AM
- - mchan   Possibly that the node crossings of the two orbits...   Feb 12 2007, 08:05 AM
- - tasp   Wikipedia has stats on Nereid and reports its...   Feb 12 2007, 03:14 PM
|- - JRehling   QUOTE (tasp @ Feb 12 2007, 07:14 AM) Wiki...   Feb 12 2007, 04:12 PM
- - tasp   Thanx, appreciate the clarification very much. So...   Feb 13 2007, 03:43 AM
- - Rob Pinnegar   The orbits will certainly precess -- but at that d...   Feb 14 2007, 01:57 AM
|- - TritonAntares   Hi, any ideas for an illustration, report, paper, ...   Feb 17 2007, 09:16 PM
|- - TritonAntares   Hi again, here a link to a french website dealing ...   Feb 18 2007, 02:10 PM
|- - tedstryk   It also has some of the strangest seasons, due to ...   Feb 22 2007, 02:13 PM
- - mchan   There is a graph in "The New Solar System...   Feb 17 2007, 11:42 PM
- - Rob Pinnegar   Yeah, looking at some of the references cited abov...   Mar 1 2007, 02:30 PM
- - tasp   Just throwing out some ideas here: Modify a follo...   Mar 2 2007, 05:30 AM
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