MESSENGER News Thread, news, updates and discussion |
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MESSENGER News Thread, news, updates and discussion |
 Dec 1 2012, 05:46 PM
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#436
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 Senior Member  Group: Members Posts: 1146 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004  |
QUOTE (Explorer1 @ Dec 1 2012, 06:21 PM)  Or maybe the 3:2 resonance does so in some way? I was thinking about this possibility too... -------------------- I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.
James Van Allen |
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Dec 1 2012, 07:22 PM
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#437
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 Senior Member Group: Moderator Posts: 6474 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Another big difference between Mercury & Mars is that the former has a very large liquid iron/nickel core in comparison to its total size; may dramatically affect its spin behavior.
-------------------- 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 2 2012, 01:53 AM
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#438
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Senior Member Group: Members Posts: 1101 Joined: 14-October 05 From: Seattle Member No.: 530 |
FYI, a lot of release images and discussion posted here:
http://messenger.jhuapl.edu/gallery/sciencePhotos/ |
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Dec 2 2012, 05:06 AM
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#439
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Senior Member Group: Members Posts: 1510 Joined: 20-April 05 Member No.: 321 |
Dynamical effects are hard to make sense of without number crunching, but in comparing Mercury and Mars, I started here:
http://articles.adsabs.harvard.edu//full/1...000293.000.html This says that for the nutation of Mars's axis, Jupiter has about triple the effect of Earth, but those sum to a tiny fraction (~1e-4) of the total precession. To switch the case to Mercury, we get several times further from Jupiter, several times closer to the Sun, and more or less swap Venus in and the Earth out. So that is to say, in the case of Mercury, the planet::Sun effects should be much smaller than that of Mars, by at least a factor of 10 to 100. Mercury's rotation is not tidally locked to the Sun, but it is clearly controlled by the Sun. Counting Venus and the Moon, three of the four closest bodies to the Sun have a lower axial inclination than any of the gas giants do (although Venus's is just less than Jupiter's) and that's not a coincidence. |
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Dec 2 2012, 09:37 AM
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#440
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Senior Member Group: Members Posts: 1146 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
I have found this on the subject: On the oscillations in Mercury's obliquity
oscillations of the spin axis have a very small amplitude, and the spin/orbit resonance really has a stabilizing effect, so much so that the solution of the n-body simulation does not differ too much from a 2-body simulation -------------------- I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.
James Van Allen |
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Feb 19 2013, 06:28 PM
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#441
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Senior Member Group: Members Posts: 1101 Joined: 14-October 05 From: Seattle Member No.: 530 |
Oblique limb view:
http://messenger.jhuapl.edu/gallery/scienc...p?image_id=1097 Relatively new view at this point, but: QUOTE This image was acquired as part of MDIS's limb imaging campaign. Once per week, MDIS captures images of Mercury's limb, with an emphasis on imaging the southern hemisphere limb. These limb images provide information about Mercury's shape and complement measurements of topography made by the Mercury Laser Altimeter (MLA) of Mercury's northern hemisphere.
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Mar 2 2013, 09:43 AM
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#442
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Senior Member Group: Members Posts: 1146 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
from this NASA release The NASA Comet ISON Observing Campaign it looks like MESSENGER will still be around to observe the comet. but I still have not seen any news on the 2nd extended mission
-------------------- I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.
James Van Allen |
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Lo-Fi Version | Time is now: 20th May 2013 - 04:21 PM |
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