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Uranus Orbiter, The other proposed ice-giant mission
Rob Pinnegar
post Nov 11 2005, 05:13 PM
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Since the Neptune Orbiter thread has started to veer into talking about a Uranus orbiter as well, it seemed like a good idea to start a topic for Uranus.
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dvandorn
post Nov 29 2005, 02:32 PM
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The biggest problem with using steerable aerocapture / landing trajectories is that you need to have a *very* good model of the atmosphere you're using to slow down with.

It's bad enough to have only a vague idea of the temperature/pressure profile of an atmosphere you're using to do straight-line drag braking. If you're designing into your spacecraft and trajectory a need for predictable changes in direction based on lift, *any* significant variation in the atmosphere's pressure, density and temperature profile from your model will result in completely different results.

They're talking about needing a Mars orbiter for day-to-day monitoring of the upper atmosphere in order to successfully land future probes -- apparently, Mars' upper atmosphere was so much thinner and extended than predicted during Spirit's EDL that she was very nearly dashed against the surface a la Beagle II. Cassini is seeing that Titan's upper atmosphere also seems highly variable in pressure/altitude. So, in order to successfully use Titan aerobraking for a Saturn orbiter, you'd almost need to already have a working Saturn orbiter there to tell you the detail you need about Titan's atmosphere at that moment...

Like many other elegant ideas, this one tends to fall apart when you look at it in greater detail.

-the other Doug


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“The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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Posts in this topic
- Rob Pinnegar   Uranus Orbiter   Nov 11 2005, 05:13 PM
- - tasp   QUOTE (Rob Pinnegar @ Nov 11 2005, 11:13 AM)S...   Nov 11 2005, 05:46 PM
- - tasp   I admit a keen interest in Uranus. The mass ratio...   Nov 11 2005, 06:08 PM
|- - Rob Pinnegar   QUOTE (tasp @ Nov 11 2005, 12:08 PM)Would Hub...   Nov 11 2005, 07:15 PM
|- - AlexBlackwell   QUOTE (Rob Pinnegar @ Nov 11 2005, 07:15 PM)T...   Nov 11 2005, 07:59 PM
|- - tasp   QUOTE (AlexBlackwell @ Nov 11 2005, 01:59 PM)...   Nov 12 2005, 02:21 PM
|- - AlexBlackwell   QUOTE (tasp @ Nov 12 2005, 02:21 PM)I'll ...   Nov 15 2005, 06:15 PM
|- - tasp   {In re the 20 year mission life at Uranus} I real...   Nov 15 2005, 07:29 PM
- - Rob Pinnegar   Yeah, thanks Alex -- that link was a good read. Ve...   Nov 13 2005, 01:49 AM
|- - AlexBlackwell   QUOTE (Rob Pinnegar @ Nov 13 2005, 01:49 AM)Y...   Nov 15 2005, 06:01 PM
|- - hendric   QUOTE (AlexBlackwell @ Nov 15 2005, 12:01 PM)...   Nov 16 2005, 08:54 AM
|- - AlexBlackwell   QUOTE (hendric @ Nov 16 2005, 08:54 AM)For ...   Nov 16 2005, 05:56 PM
|- - tasp   QUOTE (AlexBlackwell @ Nov 16 2005, 11:56 AM)...   Nov 16 2005, 06:19 PM
|- - AlexBlackwell   QUOTE (tasp @ Nov 16 2005, 06:19 PM)I confess...   Nov 23 2005, 01:49 AM
- - tasp   Without incurring copyright snags, of course, coul...   Nov 15 2005, 06:16 PM
|- - AlexBlackwell   QUOTE (tasp @ Nov 15 2005, 06:16 PM)Without i...   Nov 15 2005, 06:34 PM
|- - tasp   QUOTE (AlexBlackwell @ Nov 15 2005, 12:34 PM)...   Nov 26 2005, 02:27 PM
- - BruceMoomaw   Orbiting Ariel would be a remarkable ending to thi...   Nov 15 2005, 07:31 PM
|- - Bob Shaw   A long time ago (the early 1970s!), I suggeste...   Nov 15 2005, 10:13 PM
- - BruceMoomaw   Well, shucks, how can anybody not jump at a bargai...   Nov 16 2005, 09:23 AM
- - BruceMoomaw   The best way to orbit -- or land on -- either Plut...   Nov 26 2005, 09:23 PM
|- - tasp   QUOTE (BruceMoomaw @ Nov 26 2005, 03:23 PM)Th...   Nov 27 2005, 01:15 AM
- - BruceMoomaw   McRonald's best paper on the subject seems to ...   Nov 27 2005, 03:17 AM
|- - tasp   QUOTE (BruceMoomaw @ Nov 26 2005, 09:17 PM)Mc...   Nov 27 2005, 03:58 AM
- - BruceMoomaw   Just keep in mind that -- because Pluto's grav...   Nov 27 2005, 10:00 AM
|- - tasp   QUOTE (BruceMoomaw @ Nov 27 2005, 04:00 AM)Ju...   Nov 28 2005, 04:45 AM
- - dvandorn   The biggest problem with using steerable aerocaptu...   Nov 29 2005, 02:32 PM
|- - tasp   QUOTE (dvandorn @ Nov 29 2005, 08:32 AM)Like ...   Nov 29 2005, 03:38 PM
- - centsworth_II   What about a small,simple atmospheric probe that w...   Nov 29 2005, 05:49 PM
- - BruceMoomaw   You don't need to grasp at straws -- Tasp...   Nov 29 2005, 09:23 PM
- - BruceMoomaw   The document for simulation tests for a Neptune or...   Nov 30 2005, 08:29 AM
|- - tasp   QUOTE (BruceMoomaw @ Nov 30 2005, 02:29 AM)Th...   Nov 30 2005, 04:36 PM
|- - vexgizmo   An excuse to post in the oh-so-obscure Uranus Orbi...   Feb 2 2006, 07:46 AM
|- - JRehling   QUOTE (tasp @ Nov 30 2005, 08:36 AM)Weird it ...   Feb 2 2006, 05:30 PM
- - PhilHorzempa   Time to re-start this thread. Thanks to Cassini, ...   Apr 9 2007, 05:07 PM
|- - JRehling   QUOTE (PhilHorzempa @ Apr 9 2007, 10:07 A...   Apr 10 2007, 03:02 PM
- - Cugel   Let's not forget that at Neptune Triton would ...   Apr 9 2007, 06:33 PM
|- - PhilHorzempa   QUOTE (Cugel @ Apr 9 2007, 02:33 PM) Let...   Apr 9 2007, 08:52 PM
- - Cugel   I stand corrected. I just wasn't following thi...   Apr 10 2007, 12:12 AM
- - Greg Hullender   Apparently the big reason to prefer Neptune to Ura...   Apr 10 2007, 12:53 AM
- - dvandorn   The other attraction of Triton is, of course, that...   Apr 10 2007, 03:22 PM
|- - JRehling   QUOTE (dvandorn @ Apr 10 2007, 08:22 AM) ...   Apr 10 2007, 05:37 PM
|- - hendric   QUOTE (JRehling @ Apr 10 2007, 12:37 PM) ...   Apr 10 2007, 09:10 PM
- - Rob Pinnegar   A couple of random thoughts in favour of Neptune o...   Apr 11 2007, 03:28 PM
|- - David   QUOTE (Rob Pinnegar @ Apr 11 2007, 03:28 ...   Apr 25 2007, 01:28 AM
- - jsheff   Don't forget that both of them have ring syste...   Apr 21 2007, 08:42 PM
- - Jyril   And don't forget Neptune's second largest ...   Apr 22 2007, 05:08 PM
- - Spirit   What about building two identical probes and launc...   Sep 22 2007, 11:45 AM
|- - infocat13   QUOTE (Spirit @ Sep 22 2007, 07:45 AM) Wh...   Sep 24 2007, 10:45 PM
|- - AscendingNode   QUOTE (infocat13 @ Sep 24 2007, 03:45 PM)...   Sep 25 2007, 12:12 AM
|- - JRehling   QUOTE (infocat13 @ Sep 24 2007, 03:45 PM)...   Sep 25 2007, 05:03 AM
- - djellison   Sounds great! You paying? Seriously - that...   Sep 22 2007, 12:12 PM
|- - JRehling   QUOTE (djellison @ Sep 22 2007, 05:12 AM)...   Sep 22 2007, 06:14 PM
|- - AscendingNode   QUOTE (JRehling @ Sep 22 2007, 11:14 AM) ...   Sep 23 2007, 05:18 AM
|- - JRehling   QUOTE (AscendingNode @ Sep 22 2007, 10:18...   Sep 23 2007, 05:56 AM
|- - ugordan   Regarding attitude-control propellant (i.e. monopr...   Sep 23 2007, 10:41 AM
|- - AscendingNode   QUOTE (JRehling @ Sep 22 2007, 10:56 PM) ...   Sep 23 2007, 02:25 PM
|- - ugordan   QUOTE (AscendingNode @ Sep 23 2007, 04:25...   Sep 23 2007, 03:00 PM
|- - JRehling   QUOTE (AscendingNode @ Sep 23 2007, 07:25...   Sep 23 2007, 09:07 PM
- - brellis   A mothership with a bunch of micro-landers would b...   Sep 22 2007, 04:37 PM
- - djellison   Whilst orbital mechanics dictate that sending Cass...   Sep 23 2007, 05:21 PM
- - tasp   I admit a burning desire for a Uranian orbiter (he...   Sep 23 2007, 05:48 PM
- - djellison   I think Neptune and Uranus orbiters are going to r...   Sep 23 2007, 06:11 PM
- - mchan   Will RTG power levels be sufficient to operate all...   Sep 23 2007, 09:09 PM
|- - tedstryk   Well, 42 years, really. That's how long till ...   Sep 24 2007, 10:11 AM
|- - ugordan   QUOTE (tedstryk @ Sep 24 2007, 12:11 PM) ...   Sep 24 2007, 11:05 AM
- - tasp   The Galileo style tour of the Uranian system is qu...   Sep 24 2007, 12:51 PM
|- - djellison   QUOTE (tasp @ Sep 24 2007, 01:51 PM) A Ur...   Sep 24 2007, 01:52 PM
||- - AscendingNode   QUOTE (djellison @ Sep 24 2007, 06:52 AM)...   Sep 24 2007, 05:34 PM
||- - djellison   QUOTE (AscendingNode @ Sep 24 2007, 06:34...   Sep 24 2007, 05:49 PM
|- - JRehling   I think one difficulty owing to the no-big-moon si...   Sep 24 2007, 03:41 PM
|- - dvandorn   QUOTE (JRehling @ Sep 24 2007, 10:41 AM) ...   Sep 24 2007, 04:32 PM
|- - AscendingNode   QUOTE (JRehling @ Sep 24 2007, 08:41 AM) ...   Sep 24 2007, 05:37 PM
|- - JRehling   Another consideration, a happy one, is that for th...   Sep 25 2007, 02:46 PM
- - djellison   The paper cited above actually discusses the plane...   Sep 24 2007, 03:46 PM
- - nprev   Infocat, I and others on the board have had variat...   Sep 25 2007, 01:00 AM
- - brellis   QUOTE requirements for planetary missions tend to ...   Sep 25 2007, 01:30 AM
|- - nprev   QUOTE (brellis @ Sep 24 2007, 06:30 PM) I...   Sep 25 2007, 03:40 AM
|- - dvandorn   QUOTE (nprev @ Sep 24 2007, 10:40 PM) ......   Sep 25 2007, 05:42 AM
|- - brellis   QUOTE (nprev @ Sep 24 2007, 08:40 PM) Can...   Sep 25 2007, 08:42 AM
- - tasp   Yeah, the Longuski paper describes a mission phase...   Sep 25 2007, 02:19 AM
- - dvandorn   Anyone have any charts handy telling us when we ha...   Sep 25 2007, 05:51 AM
- - mchan   To a first order, there can be Jupiter gravity ass...   Sep 25 2007, 07:30 AM
- - Spirit   Maybe we'll have another opportunity to flyby ...   Sep 25 2007, 04:23 PM
|- - JRehling   QUOTE (Spirit @ Sep 25 2007, 09:23 AM) Ma...   Sep 25 2007, 06:06 PM
- - algorimancer   Perhaps slightly off-topic, but there have been se...   Sep 25 2007, 07:45 PM
- - tedstryk   QUOTE (algorimancer @ Sep 25 2007, 07:45 ...   Sep 25 2007, 09:08 PM
- - algorimancer   QUOTE (tedstryk @ Sep 25 2007, 04:08 PM) ...   Sep 26 2007, 12:37 PM


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