Moon Images By SMART-1 |
Moon Images By SMART-1 |
Jan 20 2005, 02:45 PM
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#1
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Member Group: Members Posts: 470 Joined: 24-March 04 From: Finland Member No.: 63 |
SMART-1 is approaching its operational orbit. ESA has released some images of the Moon on this page:
http://sci.esa.int/science-e/www/object/in...fobjectid=36358 -------------------- Antti Kuosmanen
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Apr 7 2005, 09:37 PM
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#2
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Member Group: Members Posts: 753 Joined: 23-October 04 From: Greensboro, NC USA Member No.: 103 |
The other problem with really low lunar orbit might be the MASCONs - the mass concentrations which had unpredictable effects on orbits of the Lunar Orbiters and Apollo. Were those eventually mapped out well enough that we could ensure that an object in very low lunar orbit would be able to maintain a stable orbit?
-------------------- Jonathan Ward
Manning the LCC at http://www.apollolaunchcontrol.com |
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Apr 8 2005, 12:12 AM
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#3
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Senior Member Group: Moderator Posts: 2262 Joined: 9-February 04 From: Melbourne - Oz Member No.: 16 |
QUOTE (ilbasso @ Apr 8 2005, 07:37 AM) The other problem with really low lunar orbit might be the MASCONs - the mass concentrations which had unpredictable effects on orbits of the Lunar Orbiters and Apollo. Were those eventually mapped out well enough that we could ensure that an object in very low lunar orbit would be able to maintain a stable orbit? I don't know how well the MASCONs are mapped, but I don't think that really matters as they essentially make any lunar orbit unstable to some degree. I think if they were to ever lower SMART-1 to this kind of altitude it would be end of mission fairly quickly. J. -------------------- |
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Apr 8 2005, 05:29 AM
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#4
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
QUOTE (jamescanvin @ Apr 7 2005, 06:12 PM) QUOTE (ilbasso @ Apr 8 2005, 07:37 AM) The other problem with really low lunar orbit might be the MASCONs - the mass concentrations which had unpredictable effects on orbits of the Lunar Orbiters and Apollo. Were those eventually mapped out well enough that we could ensure that an object in very low lunar orbit would be able to maintain a stable orbit? I don't know how well the MASCONs are mapped, but I don't think that really matters as they essentially make any lunar orbit unstable to some degree. I think if they were to ever lower SMART-1 to this kind of altitude it would be end of mission fairly quickly. J. Low lunar orbits can be *very* unstable -- like on the matter of days to weeks. Apollo 15 was inserted into its descent orbit (60 x 9 nmi.) on the second rev after LOI, and roughly 18 hours later the perilune had descended from 50,000 feet to 37,000 feet... and dropping. The 15 crew had to perform a bail-out burn very early on PDI day to increase the perilune before the landing could proceed. Even the "mid-height" lunar orbits that the Apollo CSMs flew weren't all that stable. The Apollo 16 subsatellite was released from the standard CSM orbit (they canceled a shaping burn designed to put the subsatellite into a more stable, somewhat higher orbit), and it fell ou of orbit after only six weeks. The only lunar orbits that are stable over a long period of time are those that are propulsively maintained... *smile*... -the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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