Uranus Orbiter, The other proposed ice-giant mission |
Uranus Orbiter, The other proposed ice-giant mission |
Nov 11 2005, 05:13 PM
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#1
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Member Group: Members Posts: 509 Joined: 2-July 05 From: Calgary, Alberta Member No.: 426 |
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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Nov 11 2005, 06:08 PM
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#2
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Member Group: Members Posts: 903 Joined: 30-January 05 Member No.: 162 |
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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Nov 11 2005, 07:15 PM
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#3
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Member Group: Members Posts: 509 Joined: 2-July 05 From: Calgary, Alberta Member No.: 426 |
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_* |
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). First page |
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Nov 12 2005, 02:21 PM
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#5
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Member Group: Members Posts: 903 Joined: 30-January 05 Member No.: 162 |
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_* |
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) 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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