Instrument commissioning phase, Beginning final approach to the comet |
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Instrument commissioning phase, Beginning final approach to the comet |
 Jul 16 2014, 11:40 PM
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#76
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 Merciless Robot  Group: Admin Posts: 8784 Joined: 8-December 05 From: Los Angeles Member No.: 602  |
Is it just me, or does it look like the nucleus is precessing as well as rotating?
-------------------- 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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Jul 17 2014, 01:50 AM
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#77
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 Member Group: Members Posts: 399 Joined: 28-August 07 From: San Francisco Member No.: 3511 |
So exciting, this is shaping up to be a rewarding mission...
-------------------- 'She drove until the wheels fell off...'
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Jul 17 2014, 02:27 AM
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#78
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Solar System Cartographer Group: Members Posts: 10171 Joined: 5-April 05 From: Canada Member No.: 227 |
nprev, it's hard to tell from just one jerky rotation, but that might be possible. A slow rotator lacks the ability to stabilize its rotation axis so it can precess dramatically - asteroid Toutatis is a well-known example, comet Halley is another, and Saturn's moon Hyperion may be another (rather than chaotic as often stated, but this is perhaps still uncertain).
With a reported rotation period of more than 12 hours this might be another example, but I am not sure about that. We can't be looking down the rotation axis because of the changing shape, and we are not looking at the equator because features would just track side to side. I think we are viewing within about 20 degrees of 45 degrees latitude. That might be enough to account for the changing appearance. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Jul 17 2014, 07:52 AM
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#79
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
Torque-free precession wouldn't be quite unexpected for a rigid, asymmetric body. But rotation period and precession period could well be no multiples. In this case we should note a jump in the motion (repeating the one-period loop).
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Jul 17 2014, 01:03 PM
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#80
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 Member Group: Members Posts: 796 Joined: 27-February 08 From: Heart of Europe Member No.: 4057 |
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Jul 17 2014, 01:03 PM
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#81
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 Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
and finally, an official release from ESA:
THE DUAL PERSONALITY OF COMET 67P/C-G |
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Jul 17 2014, 02:15 PM
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#82
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Junior Member Group: Members Posts: 88 Joined: 8-May 14 Member No.: 7185 |
Interesting to read the different hypotheses regarding the shape, in the official ESA release:
1) two comets melding together 2) single comet gravitationally tugged into curious shape 3) ice evaporation 4) near-catastrophic impact - We'll all be much wiser later on... |
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Jul 17 2014, 02:42 PM
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#83
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Member Group: Members Posts: 796 Joined: 27-February 08 From: Heart of Europe Member No.: 4057 |
This is slightly changed version of the published animated gif. I've only added one synthetic frame (between 338° and 0°), changed speed and contrast and gamma.
(Credit for the raw images: ESA / Rosetta / MPS for OSIRIS Team MPS / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA)
Attached thumbnail(s)
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Jul 17 2014, 03:12 PM
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#84
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
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Jul 17 2014, 05:04 PM
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#85
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
Here a heavily processed version of the tiles, enhancing small features:
 A tentative identification of some of the most distinct surface features in crops of these processed tiles:
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Jul 17 2014, 05:24 PM
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#86
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 Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
Be careful. ESA posted an image that shows you the original resolution of the data. Most of the features that you've identified are barely more than one pixel across.
Attached thumbnail(s)
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Jul 17 2014, 06:17 PM
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#87
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Member Group: Members Posts: 890 Joined: 18-November 08 Member No.: 4489 |
also that animation looks like it is FULL of jpg artifacts
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Jul 17 2014, 06:31 PM
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#88
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 Member Group: Members Posts: 238 Joined: 15-January 13 Member No.: 6842 |
What are the chances of this comet disintegrating when close to perihelion. Could these two pieces come apart?
-------------------- Curiosity rover panoramas: http://www.facebook.com/CuriosityRoverPanoramas
My Photosynth panoramas: http://photosynth.net/userprofilepage.aspx...;content=Synths |
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Jul 17 2014, 06:43 PM
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#89
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 Member Group: Members Posts: 125 Joined: 18-July 05 Member No.: 438 |
Application of a data scrubbing algorithm yields surprising results...
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Jul 17 2014, 07:55 PM
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#90
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
the German DLR space agency has a large mosaic on its website:
http://www.dlr.de/dlr/presse/en/Portaldata...3/CG_Mosaik.jpg |
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