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Phobos
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post Nov 11 2004, 11:46 PM
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http://www.esa.int/SPECIALS/Mars_Express/

These images, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, are Europe’s highest-resolution pictures so far of the Martian moon Phobos.

http://www.esa.int/SPECIALS/Mars_Express/SEM21TVJD1E_0.html
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Harkeppler
post Aug 21 2008, 09:52 AM
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Mayby grooves on phobos seem not to be due to secondary impacts from asteroid impacts on Mars; they are too defined and regularly for that. These computer simulations seems to give only the trajectory of the ejected masses but the the width of the shower. And there are too much of these grooves and they are too regularly placed. This counts for some effects connected with material resistance against stress forces per length unit.

Especially, one set of grooves seems to be more or less concentric or better: coaxial along the Mars-anti-Mars-axis and can be explaned easily with tidal effects. The "craters" along the grooves may be simply sinkholes, especially because there are no ejecta. The other set of grooves (here highlighted in red) is nearly perpendicular to the other one and can be formed earlier by the same way; a large impact may have altered phobos orientation by chance and after that tidal fractures occure in a new set. So, that older bunch of grooves is orientated around the old Mars-anti-Mars axis of Phobos. Here:

http://www.planetary.org/blog/article/00001391/

or here

http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2195.pdf

You can see the both sets, but you need another cartographic projection to see the old set as a concentric/coaxial one as well as the other.

Both groove sets are not (the old one) or not well (the new one) converging to two points but slicing phobos more like a cut potato. Here, the non-sperical shape of phobos and cartographic problems with this fact should be considered; the pseudo-convergence is an articfact of the cylindrical projection!

I would also consider that Phobos had been in an elliptic orbit first, so diffential stresses du to the tidal force change between apoareum and periareum and libration (nodding) effects due to the constant rotation period and the inconstant orbital angular velocity would have forced a result. A large impact, mayby the Stickney forming impact, would have altered the meanwhile circular orbit to an elliptic one again and it altered Phobos spin and orientation. So a second set of grooves came to existence.

You may recognize that the younger grooves, which are mostly sharper defined and smoother than the older ones (red) cross through them (and not opposite) which will give a hint which groove set was the former one.

The Stickney-impact itsself may be "buffered" by the weak material itsself, like the craters on asteroid Mathilda, and does not harm the whole structure. It is like shooting a projectile in styrofam...

It would be interesting to look for some grooves on several other moons like Amalthea; in the Saturnian system so much dust maybe hide features like that on the innermost moons.


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- Sunspot   Phobos   Nov 11 2004, 11:46 PM
- - Phil Stooke   Here's a Mars Express Phobos image from orbit ...   Nov 18 2006, 05:49 AM
- - djellison   What is it with the PDS/PSA and their total hatred...   Nov 18 2006, 07:12 AM
- - PhilCo126   Waaw thanks for sharing those!   Nov 18 2006, 09:02 AM
- - Phil Stooke   Mea culpa - I see now that the second image from t...   Nov 18 2006, 01:31 PM
|- - tedstryk   600 MB? The biggest Phobos images from that orbit ...   Nov 19 2006, 02:13 AM
- - Phil Stooke   I checked this after reading your question, Ted. ...   Nov 19 2006, 03:22 AM
- - Phil Stooke   - and another in orbit 1558, but this one is from ...   Nov 19 2006, 04:02 PM
- - Phil Stooke   I'm still exploring the Mars Express Phobos im...   Nov 19 2006, 10:37 PM
|- - ugordan   Nice image, Phil. Where do the JPEG-ish artifacts ...   Nov 20 2006, 07:54 AM
- - Phil Stooke   No, I compressed it severely to reduce the file si...   Nov 20 2006, 02:20 PM
|- - dilo   Very impressive shot, Phil... resolution should be...   Nov 20 2006, 07:45 PM
|- - dilo   sorry, wrong re-post.   Nov 20 2006, 07:52 PM
- - Phil Stooke   I will put the uncompressed image on an external w...   Nov 20 2006, 11:57 PM
|- - tedstryk   QUOTE (Phil Stooke @ Nov 20 2006, 11:57 P...   Nov 21 2006, 12:14 AM
- - Phil Stooke   Good point, Ted - actually I'll be reducing it...   Nov 21 2006, 01:33 AM
- - Phil Stooke   Here's another one... orbit 748. Phil   Nov 21 2006, 01:38 AM
- - elakdawalla   Oh, that's a nice one, Phil! Are you meth...   Nov 21 2006, 02:17 AM
- - Phil Stooke   I'm not being methodical, I'm just playing...   Nov 21 2006, 03:30 AM
- - Ian R   Good grief! Is it my imagination, or are there...   Nov 21 2006, 11:29 AM
- - edstrick   Despite impeccible logic and analysis "provin...   Nov 21 2006, 11:37 AM
- - Ian R   Good catch on the splatter pattern Ed. That certai...   Nov 21 2006, 11:45 AM
|- - tty   QUOTE (Ian R @ Nov 21 2006, 01:45 PM) Goo...   Oct 14 2007, 05:10 PM
- - Phil Stooke   Here's a link to the higher quality Phobos ima...   Nov 21 2006, 02:20 PM
- - elakdawalla   I've mirrored it here... http://s3.amazonaws.c...   Nov 21 2006, 05:48 PM
- - volcanopele   Phil, do you know the pixel scale on that particul...   Nov 21 2006, 06:36 PM
- - Phil Stooke   The PDS label says 5.9 m/pixel. and roughly 5000 ...   Nov 21 2006, 06:55 PM
|- - dilo   Thanks for the great image Phil, I hope one day yo...   Nov 21 2006, 09:03 PM
- - Phil Stooke   Here's a nice new Phobos image from Mars Expre...   Oct 14 2007, 02:18 PM
|- - Pygmee   QUOTE (Phil Stooke @ Oct 14 2007, 03:18 P...   Oct 15 2007, 08:29 PM
- - scalbers   Out of curiosity, how are things going with mappin...   Oct 14 2007, 02:29 PM
- - Phil Stooke   I should have added to my previous post - it came ...   Oct 14 2007, 05:04 PM
- - elakdawalla   Wow, Phil, that's a really cool image, thanks ...   Oct 14 2007, 06:53 PM
- - Stu   ... and add a bit of colour, just 'cos it...   Oct 14 2007, 09:04 PM
- - nprev   Great stuff, Phil & Stu!!! Now I k...   Oct 15 2007, 03:00 AM
- - Phil Stooke   I found it in the place mentioned in post 30, abov...   Oct 15 2007, 08:41 PM
- - elakdawalla   Here's the direct link to the Willner et al. a...   Oct 17 2007, 04:57 PM
- - scalbers   Shall be interesting to see what shape model resul...   Oct 19 2007, 03:43 PM
- - elakdawalla   Dr. Willner said I'd need to ask Neukum direct...   Oct 19 2007, 03:45 PM
- - Stu   Wow, that's a gorgeous picture of Phobos, than...   Oct 19 2007, 07:12 PM
|- - ugordan   That picture was around for quite a while now: htt...   Oct 19 2007, 07:23 PM
- - Phil Stooke   Here are a couple of Mars Express HRSC images of P...   Nov 11 2007, 12:13 AM
- - scalbers   That's something with three different orientat...   Nov 11 2007, 12:16 AM
- - Tayfun Öner   It is already gridded, it will be easy for Phil to...   Nov 11 2007, 08:17 AM
- - ilbasso   At first glance, I thought we were looking at it t...   Nov 11 2007, 06:48 PM
- - Decepticon   RE: Phobos   Nov 11 2007, 09:43 PM
- - peter59   The High Resolution Stereo Camera (HRSC) on Mars E...   Feb 16 2008, 05:03 PM
- - djellison   HRSC itself is great, but the super resolution bol...   Feb 16 2008, 05:19 PM
|- - algorimancer   QUOTE (djellison @ Feb 16 2008, 11:19 AM)...   Feb 16 2008, 10:57 PM
|- - ugordan   I don't think it's motion smear, more like...   Feb 16 2008, 11:13 PM
|- - algorimancer   QUOTE (ugordan @ Feb 16 2008, 05:13 PM) I...   Feb 17 2008, 02:05 PM
- - peter59   Mars Express (MEX) release #2. February 14, 2008 ...   Feb 16 2008, 06:39 PM
- - peter59   Another high (??) resolution image. Orbit 3769, P...   Feb 16 2008, 06:50 PM
|- - djellison   QUOTE (peter59 @ Feb 16 2008, 06:50 PM) A...   Feb 16 2008, 09:09 PM
- - Phil Stooke   It certainly is not motion smear, but it does look...   Feb 17 2008, 01:37 AM
|- - peter59   QUOTE (Phil Stooke @ Feb 17 2008, 02:37 A...   Feb 17 2008, 07:34 AM
|- - peter59   QUOTE (Phil Stooke @ Feb 17 2008, 02:37 A...   Feb 17 2008, 07:46 AM
- - mgrodzki   RE: Phobos   Feb 17 2008, 03:26 AM
- - djellison   the S12 image is pushbroom. PSF = Point Spread Fu...   Feb 17 2008, 02:51 PM
|- - tedstryk   Here is a quick attempt. There does seem to be mo...   Feb 17 2008, 06:08 PM
- - mgrodzki   i am wondering the nature of these phobos and deim...   Feb 17 2008, 09:00 PM
|- - tedstryk   They were, for the most part, not in official rele...   Feb 18 2008, 01:01 AM
|- - mgrodzki   QUOTE (tedstryk @ Feb 17 2008, 08:01 PM) ...   Feb 18 2008, 01:52 AM
- - GravityWaves   Mars Express to rendezvous with Martian moon http:...   Jul 16 2008, 01:02 PM
- - Phil Stooke   "As it flies by at a distance of 97 km, Mars ...   Jul 16 2008, 05:14 PM
|- - tedstryk   Yes, particularly the trailing hemisphere.   Jul 16 2008, 06:08 PM
|- - dvandorn   QUOTE (Phil Stooke @ Jul 16 2008, 12:14 P...   Jul 17 2008, 03:57 AM
- - Hungry4info   Does anyone know when those images from the 97 km ...   Jul 27 2008, 10:59 PM
- - nprev   Uh.... <Ahem!> Well, um...that's a p...   Jul 28 2008, 12:06 AM
- - elakdawalla   Agustin Chicarro (project scientist) told me they ...   Jul 28 2008, 12:14 AM
- - Stu   00.12... bye bye Monday... Maybe tomorrow...   Jul 28 2008, 11:19 PM
|- - tedstryk   He said Monday, but he didn't say which Monday   Jul 29 2008, 01:22 AM
|- - Hungry4info   QUOTE (tedstryk @ Jul 28 2008, 07:22 PM) ...   Jul 29 2008, 03:45 AM
- - nprev   Hungry, just so you know (if you don't already...   Jul 29 2008, 04:32 AM
|- - Hungry4info   QUOTE (nprev @ Jul 28 2008, 11:32 PM) Hun...   Jul 29 2008, 04:35 AM
|- - nprev   QUOTE (Hungry4info @ Jul 28 2008, 09:35 P...   Jul 29 2008, 04:37 AM
- - Stu   Just heard back from the ESA Media office... ...   Jul 29 2008, 01:02 PM
|- - 3488   unnecessary quoting removed Thanks Stu, I was be...   Jul 29 2008, 07:55 PM
- - CAP-Team   Using spice kernels (for the spacecraft, Mars and ...   Jul 29 2008, 09:53 PM
- - djellison   width of the HRSC swath is about 12 degrees - cove...   Jul 29 2008, 11:49 PM
- - bear10829   A photo of Phobos quoted to have been made during ...   Jul 30 2008, 11:57 AM
- - nprev   If I read that correctly, the headline says ...   Jul 30 2008, 12:06 PM
- - Dominik   Yes, the translation of the title is correct .   Jul 30 2008, 12:41 PM
- - lyford   So can we nickname Phobos-Grunt "SPUDnik?...   Jul 30 2008, 03:14 PM
|- - 3488   Link to DLR site of the Phobos Grunt landing site....   Jul 30 2008, 03:38 PM
- - volcanopele   Here is the link to the press release: http://www...   Jul 30 2008, 04:00 PM
|- - Hungry4info   QUOTE (volcanopele @ Jul 30 2008, 11:00 A...   Jul 30 2008, 04:08 PM
- - elakdawalla   I don't know about distortion -- Phobos looks ...   Jul 30 2008, 04:45 PM
- - elakdawalla   The opposite of a usual activity: take apart an an...   Jul 30 2008, 04:53 PM
- - ilbasso   Interesting, the relatively small number of the ti...   Jul 30 2008, 05:08 PM
- - hendric   I just had a really dumb idea, looking at that moo...   Jul 30 2008, 10:34 PM
- - jasedm   The best (for me) explanation I've heard for t...   Jul 31 2008, 12:31 PM
- - Paolo   In Astronomy & Astrophysics: New astrometric o...   Aug 21 2008, 07:42 AM
|- - SteveM   QUOTE (Paolo @ Aug 21 2008, 02:42 AM) In ...   Aug 21 2008, 09:48 PM
- - Harkeppler   Mayby grooves on phobos seem not to be due to seco...   Aug 21 2008, 09:52 AM
- - charborob   Interesting article about Phobos on the ESA websit...   Oct 16 2008, 07:23 PM
- - tanjent   In the article just quoted by charborob, there is ...   Oct 18 2008, 03:35 AM
- - peter59   I checked "forgotten" Mars Express archi...   Nov 6 2009, 02:47 PM
- - Phil Stooke   I like the last two transit images! More clos...   Nov 6 2009, 02:55 PM
- - charborob   Transit image modified to show the Martian surface...   Nov 6 2009, 04:17 PM
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