Author Topic: JFincannon's Collapsed Voids  (Read 23443 times)

JFincannon

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JFincannon's Collapsed Voids
« on: February 19, 2011, 04:09:42 pm »
This image which was on the ASU website has what I would think is a pit or cave.  Is this not a lava tube?  There are alot of deep cracks here.
M135324446LC, 2550 pixels from the left,  16296 pixels from the top.

jules

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Re: JFincannon's Collapsed Voids
« Reply #1 on: February 19, 2011, 04:32:01 pm »
That whole strip has some spectacular cracks and holes and with the sun from the left that has to be a contender. Nice find JFincannon. If a team member doesn't drop by I'll alert one to come and have a look.
M135324446LC Mare Tranquilitatis. Copernicus Crater (apologies and thanks to Irene for noticing the error!)
« Last Edit: February 22, 2011, 04:51:31 pm by jules »

IreneAnt

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Re: JFincannon's Collapsed Voids
« Reply #2 on: February 21, 2011, 01:52:09 am »
This image which was on the ASU website has what I would think is a pit or cave.  Is this not a lava tube?  There are alot of deep cracks here.
M135324446LC, 2550 pixels from the left,  16296 pixels from the top.

That whole strip has some spectacular cracks and holes and with the sun from the left that has to be a contender. Nice find JFincannon. If a team member doesn't drop by I'll alert one to come and have a look.
M135324446LC Mare Tranquilitatis.

There are definitely plenty of things that look like collapsed lava tubes in that strip. So I would say there is a good possibility that this could be one, too.  However, it isn't associated with any obvious linear features...
« Last Edit: February 21, 2011, 01:54:52 am by IreneAnt »

JFincannon

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Re: JFincannon's Collapsed Voids
« Reply #3 on: February 21, 2011, 03:23:09 pm »
Thanks for your assessment.  It seems odd to me that such an unusually shaped hole should appear in the middle of what appears normal surface terrain.  It implies some underground voids with no telltale features.

Another view: M135317661RC, 748 pixels from left and 15231 pixels from the top.

Also, I erroneously stated the image M135324446L had been mentioned before at the ASU web site, I meant the one mentioned above of the same region.
http://lroc.sese.asu.edu/news/index.php?/archives/288-Smooth-floor-in-Copernicus-crater.html
This link implies to me that there may be big voids in that floor.

IreneAnt

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Re: JFincannon's Collapsed Voids
« Reply #4 on: February 22, 2011, 02:16:03 am »
Thanks for your assessment.  It seems odd to me that such an unusually shaped hole should appear in the middle of what appears normal surface terrain.  It implies some underground voids with no telltale features.

Another view: M135317661RC, 748 pixels from left and 15231 pixels from the top.

Also, I erroneously stated the image M135324446L had been mentioned before at the ASU web site, I meant the one mentioned above of the same region.
http://lroc.sese.asu.edu/news/index.php?/archives/288-Smooth-floor-in-Copernicus-crater.html
This link implies to me that there may be big voids in that floor.

Hi JFincannon,

So sorry for the confusion. Jules said this strip was in Mare Tranquillitatis, and I didn't check the coordinates (silly me). It turns out it's not Tranquillitatis, but as you say, from the floor of Copernicus crater (in Oceanus Procellarum). 

So now, we are no longer looking at lava tubes, but rather cooling cracks. The floor of Copernicus is covered by impact melt. This is a very different process of forming and emplacing melt materials, so voids or tubes are not expected. The tops of melt sheets do, however, cool very quickly and are, therefore, prone to cracking. What we are seeing then in this area are cooling cracks.

That said, it still leaves one wondering why the hole (because it clearly is a hole!) you show here is not associated with any other linear cracking features. Very odd!

JFincannon

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Re: JFincannon's Collapsed Voids
« Reply #5 on: February 22, 2011, 04:27:18 pm »
Since it is not related to lave tube sky lights, perhaps I should move this to another topic category.

In the meantime, the attached image from the same region shows what does not look like a crater, but rather a collapse of a void and what I speculate may apply to the hole I found.  Not clear what process would form these void though.
M122346704R, 2504 pixels from the left, 44071 pixels from the top.

Any opinions?

JFincannon

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Re: JFincannon's Collapsed Voids
« Reply #6 on: February 22, 2011, 04:35:47 pm »
One other sample possible void collapse in that same region which may relate to the "hole".
M111728277R, 4058 pixels from the left, 5720 pixels from the top.

JFincannon

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Re: JFincannon's Collapsed Voids
« Reply #7 on: February 22, 2011, 04:43:33 pm »
One more "collapsed void".
M119985215L, 1816 pixels from left, 40068 pixels from top.

jules

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Re: JFincannon's Collapsed Voids
« Reply #8 on: February 22, 2011, 04:45:39 pm »
..............
M135324446LC Mare Tranquilitatis.
No idea where that came from. ??? Sorry for the confusion folks! Copernicus it is. I'll split this conversation into its own topic as it is still an interesting feature and there will no doubt be more of them.

jules

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Re: JFincannon's Collapsed Voids
« Reply #9 on: February 22, 2011, 04:55:17 pm »
If those images are craters they are certainly very "clean", well defined and somewhat unusual examples.

JFincannon

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Re: JFincannon's Collapsed Voids
« Reply #10 on: February 22, 2011, 05:01:03 pm »
Wow!  I'm honored to get my own named heading!
M102293451L has two,
Clip1: 1996 pixels from the left, 9844 pixels from the top
Clip2: 348 pixels from the left, 12523 pixels from the top.

JFincannon

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Re: JFincannon's Collapsed Voids
« Reply #11 on: February 22, 2011, 05:06:51 pm »
Just for kicks, I looked at the Lunar Orbiter images.

http://www.lpi.usra.edu/resources/lunarorbiter/frame/?5154
http://astrogeology.usgs.gov/Projects/LunarOrbiterDigitization/data/VHR/vhr_5154_h2_raw.tif.gz
Too bad the Sun is shallow, but at least we have the opposite azimuth angle. (Sun Azimuth: 91.87°, Incident Angle: 72.01°)

JFincannon

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Re: JFincannon's Collapsed Voids
« Reply #12 on: February 22, 2011, 05:16:04 pm »
From the image I found the "hole" in:
M104648293L has three clips
Clipa: 3359 pixels from the left, 14387 pixels from the top
Clipb: 2054 pixels from the left, 8539 pixels from the top
Clipc: 2890 pixels from the left, 6664 pixels from the top.

JFincannon

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Re: JFincannon's Collapsed Voids
« Reply #13 on: February 22, 2011, 05:26:14 pm »
One more
M107006443L, 2363 pixels from the left, 15022 pixels from the top.

JFincannon

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Re: JFincannon's Collapsed Voids
« Reply #14 on: February 22, 2011, 09:04:35 pm »
Three more:
M124701702R_clip1: 3542 pixels from the left, 29624 pixels from the top
M104648293R_clipa: 2715 pixels from the left, 11985 pixels from the top
M104648293R_clipb: 4470 pixels from the left, 9348 pixels from the top