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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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tasp
post Nov 11 2005, 06:08 PM
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I admit a keen interest in Uranus. The mass ratios of the larger satellites to Uranus are not all that different from the Galilean satellites to Jupiter. Having two systems so grossly similar , yet with such huge differences, such as the axial tilt and the strength of the magnetic field, are so intriuging.

Would Hubble (or some of the larger ground based installations) be put to good use checking for co-orbital lagrangian moons of the larger satellites? I recall Voyager doing a thorough search closer in to the planet, but could small dark co-orbitals at Titania and Oberon have been missed?

That Jupiter seems to not have them, and Saturn having a few, it makes me all the more curious for a good inspection of Uranus to see where it stands regarding Lagrangian objects.

Finding some at Uranus might bump up the level of scrutiny Cassini is giving them at Dione and Tethys.
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Rob Pinnegar
post Nov 11 2005, 07:15 PM
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QUOTE (tasp @ Nov 11 2005, 12:08 PM)
Would Hubble (or some of the larger ground based installations) be put to good use checking for co-orbital lagrangian moons of the larger satellites?  I recall Voyager doing a thorough search closer in to the planet, but could small dark co-orbitals at Titania and Oberon have been missed?

The four big Uranian moons are at about the same distance from Uranus as Tethys, Dione and Rhea are from Saturn. They also have similar masses. That being the case, you'd think that there would be at least one Lagrangian satellite somewhere in the Uranian system.

I wonder if the lack of co-orbital satellites for Ariel, Umbriel, Titania and Oberon has to do with Uranus itself, rather than the major moons? Uranus only has about 15% of Saturn's mass. Could this cause Lagrangian orbits to be less stable at Uranus?
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Guest_AlexBlackwell_*
post Nov 11 2005, 07:59 PM
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QUOTE (Rob Pinnegar @ Nov 11 2005, 07:15 PM)
The four big Uranian moons are at about the same distance from Uranus as Tethys, Dione and Rhea are from Saturn. They also have similar masses.

Interestingly, a stronger comparison exists between Uranus and Jupiter, namely that both planets have similar planet/satellite mass ratios. In fact, in 2003 Andy Heaton and Jim Longuski published a paper showing that a Galileo-style tour is, unlike at Saturn and Neptune, possible at Uranus:

Feasibility of a Galileo-Style Tour of the Uranian Satellites
Andrew F. Heaton and James M. Longuski
J. Spacecraft Rockets 40, 591-596 (2003).
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tasp
post Nov 12 2005, 02:21 PM
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QUOTE (AlexBlackwell @ Nov 11 2005, 01:59 PM)
Interestingly, a stronger comparison exists between Uranus and Jupiter, namely that both planets have similar planet/satellite mass ratios.  In fact, in 2003 Andy Heaton and Jim Longuski published a paper showing that a Galileo-style tour is, unlike at Saturn and Neptune, possible at Uranus:

Feasibility of a Galileo-Style Tour of the Uranian Satellites
Andrew F. Heaton and James M. Longuski
J. Spacecraft Rockets 40, 591-596 (2003).
First page
*



I'll be darned! How 'bout that. I was aware of the mass ratio and distance scaling between Uranus and Jupiter, but I assumed there was an inverse square {or cube} law that prevents a 'quick' style tour of the Uranian moons. I thought I was really 'pushing' things suggesting a tour of the system lasting upwards of 20 years. {btw, a 20 year mission duration at Uranus is desirable for other reasons}

The lack of a strong resonance of three (or more) members of the Uranian system doesn't hurt the mission either. The lower radiation environment at Uranus would certainly be a relief after the ordeal Galileo experienced.

Appreciate the post!
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Guest_AlexBlackwell_*
post Nov 15 2005, 06:15 PM
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QUOTE (tasp @ Nov 12 2005, 02:21 PM)
I'll be darned!  How 'bout that.  I was aware of the mass ratio and distance scaling between Uranus and Jupiter, but I assumed there was an inverse square {or cube} law that prevents a 'quick' style tour of the Uranian moons.

The most important thing for a "Galileo-like" tour is the availability of multiple satellites to utilize gravity assists, which adds flexibility to the tour design process. Cassini, on the other hand, can only use Titan and, consequently, must always return to Titan for a gravity assist to continue a given tour. This makes designing a "Cassini-like" tour very difficult, especially when multiple targets (e.g., Saturns icy satellites) are desired and the mission has severe operational constraints. Just ask the Cassini mission planners what they went though during the design process for the "T9-X" and "T18-X"-class tours.

QUOTE (tasp @ Nov 12 2005, 02:21 PM)
I thought I was really 'pushing' things suggesting a tour of the system lasting upwards of 20 years.  {btw, a 20 year mission duration at Uranus is desirable for other reasons}

I assume you're referring to monitoring Uranus' atmosphere and/or changing solar illumination?

QUOTE (tasp @ Nov 12 2005, 02:21 PM)
The lack of a strong resonance of three (or more) members of the Uranian system doesn't hurt the mission either.  The lower radiation environment at Uranus would certainly be a relief after the ordeal Galileo experienced.

Agreed.

QUOTE (tasp @ Nov 12 2005, 02:21 PM)
Appreciate the post!
*

My pleasure.

Trivia: For those who do happen to read the full paper by Heaton and Longuski, one might note that I get a brief mention in the acknowledgements section. I provided a couple of Uranus scientific references to Andy Heaton between the time he presented the paper at an AAS/AIAA conference and when he submitted the final for publication in J. Spacecraft Rockets.
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tasp
post Nov 15 2005, 07:29 PM
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{In re the 20 year mission life at Uranus}

I realize with Jupiters small axial tilt, we didn't see too many (any) seasonal effects with Galileo.

With Cassini, if we are lucky and have 7 years of probe life, we get to travel with Saturn roughly 90 degrees around the sun. We can see the rings from nearly full open to the sun to edge on. Assuming the rings look pretty much the same top and bottom (north and south?) we get to see the 'whole show' or at least be able to extrapolate it form a 7 year exploration of Saturn.

At Uranus, same thing. How does the ring look through forward scattering at edge on and full on to the sun? (I'm hoping for some phase effects, perhaps some of the Uranian ring particles are elongated and align radially to Uranus)

Additionally, if a probe arrived at Uranus with Uranian rings 45 degrees short of edge on to the sun (not that orbit for a probe would be easier to achieve in this orientation) and the probe could watch the rings go edge on then to 45 degrees further (in ~20 years), we could also get near 100% coverage in sunlight of all the surfaces of the main satellites.

A probe arrival with the rings full on to the sun, would also be desirable for other reasons.

{granted a probe with an even longer life would be great, but a factor of 2 or 3 increase from Cassini would seem technically possible}
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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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