Author Topic: Crater matching - Apollo 15 v LROC  (Read 12525 times)

Tom128

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Crater matching - Apollo 15 v LROC
« on: November 03, 2010, 02:43:57 am »
From Apollo 15 panoramic camera "AS15-9287 (P)"  I am unsure if it is the same crater as Geoff's boulder repellent example but there are some similarities such as a small crater hit near the rim of both craters.  If they happen to be the same crater then we have a 1971 (before) and 2009 (after) view.

 



On page 123 of PDF, "Apollo over the Moon: A view from orbit" Well worth the time to read it through.

Here is a better color version of the project than my original B&W PDF  http://history.nasa.gov/SP-362/contents.htm

« Last Edit: November 09, 2010, 03:02:51 am by Tom128 »

jules

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Re: Crater matching - Apollo 15 v LROC
« Reply #1 on: November 03, 2010, 12:56:35 pm »
I think your first picture is indeed the same as the example Tony provided. One of the images has been rotated 90 degrees.

Tom128

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Re: Crater matching - Apollo 15 v LROC
« Reply #2 on: November 04, 2010, 01:32:30 am »
Resized the Apollo 15 version and cropped both photographs at the center.  Used the negative color feature (sumo paint) of the crater centers and rotated the Apollo 15 pic near 90 degrees to match the LROC version better (I think).  Also had to flip the Apollo 15 version horizontally. I think I have both pics oriented within 10 degrees of each other in rotation. 

LROC                      Apollo 15
 

Any changes since 1971?  Looks like the boulder/debris ring around the flat surface of the crater floor has shifted in the 39 years since Apollo 15 orbited the area.
« Last Edit: November 04, 2010, 11:53:10 pm by Tom128 »

Tom128

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Re: Crater matching - Apollo 15 v LROC
« Reply #3 on: November 04, 2010, 11:45:23 pm »
Had to flip the Apollo 15 crater version horizontally to get both pics in alignment.  There is another  small crater further out that was not matching the LROC photo strip.  I think the crater centers are better aligned now, though the Apollo 15 version is still rotated about 10 degrees to the left of the LROC version.
« Last Edit: November 04, 2010, 11:55:11 pm by Tom128 »

jules

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Re: Crater matching - Apollo 15 v LROC
« Reply #4 on: November 05, 2010, 03:52:41 pm »
Well I had a go in the hope I would be able to detect some changes but I don't think there are any. It's an example of just how good the LRO photos are though.

Tom128

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Re: Crater matching - Apollo 15 v LROC
« Reply #5 on: November 05, 2010, 11:33:50 pm »
Hi Jules,

You have made an excellent enhancement of the two photographs showing the crater center in great detail and I have been looking at them very closely. Thanks for doing that  :)  I agree that the LROC version is simply a superior photograph and may account for any perceived changes/alterations.  However, there are some nagging questions when you view the two photographs side by side when annotated.

I went ahead and plotted a rough outline of each crater center starting with a mark showing the midpoint and then connecting radial lines to nearest boulder or the boulder ring itself.  This tends to highlight the circle boundary areas and give a clearer view of contour changes.  What seems striking to me is that the Apollo 15 version shows two large boulders at the bottom of the photograph, well off from the boulder ring, sitting out on the flat appearing crater surface. There are some other boulders that appear the same way as well but these two are the most pronounced. The LROC version does not show this boulder aspect. 

Notice how clear the flat looking surface is in the LROC version.  Also note the large boulders positioned well away form the boulder ring in the Apollo 15 version.  The radial line I made to the boulder furthest in clearly shows a distance differential between the photographs.  The highlighted ring shapes appear different as well but could also be simply poor resolution and albedo change that made my outline trace in some areas too far into the crater wall past the actual open area boundary. There does seem to be some anomalies with the relative distances from the center point and boulders/boulder ring between photographs. 

One intriguing mystery is; if the open crater center area in both photographs are similar in size, as they appear to be, and knowing that the furthest out of the two large boulders cannot be connected to the boulder ring without significantly altering the relative photograph proportions, why did the two boulders in the Apollo 15 version move back to the side of the boulder ring as they are no longer showing up in the LROC version?  One possibility is that the boulders rolled in from some other event or down from the crater wall.  We see a lot of boulder tracks at MZ and the boulders may have come in from the outside as well.   So, these boulders rolled down onto the flat looking surface area and stalled out. 

The answer to the mystery may be that the flat looking surface in the crater center is not really flat but sloped.
  Over time, moon quakes and other shaking events made the boulders sitting on this incline roll down to the lower level boulder ring where they sit today. 


« Last Edit: November 06, 2010, 02:51:28 am by Tom128 »

jules

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Re: Crater matching - Apollo 15 v LROC
« Reply #6 on: November 06, 2010, 05:22:07 pm »
I would really love for us to find some changes but I take a lot of convincing!! I would have drawn the 12, 2 and 6 o'clock lines in the Apollo 15 version to include the prominent "boulders." I see some linear features in these areas which match those of the LRO version. That would make the green shapes match.

However, as this is just the type of crater where I would have thought there might just be changes (many boulders / slopes etc) I'll scan the outer boulder fields just in case.

Nice work though Tom - I can see us using this system again!
« Last Edit: November 06, 2010, 05:25:22 pm by jules »

Tom128

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Re: Crater matching - Apollo 15 v LROC
« Reply #7 on: November 07, 2010, 02:40:03 am »
Hi Jules,

I found a high resolution version of the Apollo 15 crater! Click here for full image.
 


The link to the high resolution pic is below the smaller version on page 123.

http://history.nasa.gov/SP-362/ch5.2.htm
« Last Edit: November 14, 2010, 05:08:53 pm by Tom128 »

Geoff

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Re: Crater matching - Apollo 15 v LROC
« Reply #8 on: November 07, 2010, 05:16:19 pm »
Hi Tom

You're doing a great job with this crater. I'll try and help out once I've finished my image-of-the-week post.

astrostu

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Re: Crater matching - Apollo 15 v LROC
« Reply #9 on: November 07, 2010, 08:58:53 pm »
Folks - Tom asked me to chime in on this and my initial question is: How sure are you that these are the same craters?  I took a look at the LROC image and the latest Apollo image Tom posted.  To me, these don't seem to be the same crater.

First, there's an impact on the rim of the crater in the LROC image.  That doesn't mean it's not the same, for a crater could've formed in the last ~40 years, and in itself would be a good discovery.

Second, there is a boulder just outside the top of the rim on the Apollo image that doesn't seem to appear in the LROC.  While the boulder could have rolled in the last ~40 years, though I don't see a track in the LROC, it's another diagnostic.

Third, the shape looks different, and I would not expect enough erosion in just ~40 years to account for that, though it's possible the sun angle can account for some of it.

But, perhaps the one that's most important is there's a smaller crater to the upper left of the Apollo image that I do not see in the LROC image when I looked.  The sun angle should be enough to see that crater in LROC, for smaller ones elsewhere are visible, but I don't see one of that size at that distance from the crater in LROC.

If someone can show me where that smaller crater is in the LROC and that it matches for distance from the crater center in units of crater diameter/radius (need to remember to scale the crater in each image to the same size), then I'll be much more convinced.

Tom128

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Re: Crater matching - Apollo 15 v LROC
« Reply #10 on: November 07, 2010, 11:57:51 pm »
Hi Geoff, there seems to be plenty of mystery on this saga to sort out.  Been modifying this post most of the evening researching the Apollo 15 pic after reading Astrostu's comments.


How sure are you that these are the same craters?  I took a look at the LROC image and the latest Apollo image Tom posted.  To me, these don't seem to be the same crater.

Thanks for your input Astrostu.  The craters certainly look similar to me and the crater centers look quite similar aside from the boulder issue.  Both have an impact on the rim and an impact to the left that I was keying on.  I was thinking that the improved LROC resolution and photograph line of sight was playing a large role in the variations, though there are a lot of boulders and  craters with different arrangements to ponder. 

I did some looking around to see if I could come up with more information.  Took a while to find all the pieces but here is what I found.


Figure number    Frame number             Altitude, km      Sun elevation, deg     Camera tilt angle                         focal length mm   
  117                     AS15-9287                      107                   41                                   Aft                        P                   610                            3414           PF 


And here is a link to the photo strip AS15-9287  http://www.lpi.usra.edu/resources/apollo/frame/?AS15-P-9287  The posted lat and long: "Latitude / Longitude:    22.5° N / 34° E"   The issue for me is that the Apollo 15 photo strip seems to be covering quite large swath of lunar surface and the crater photograph we are looking at must be a small formation on the photo strip somewhere ::)

Once you are at the site above, go to the lunar atlas to view the photo strip locations. I believe AS159287 was taken in the location shown below between 9280 and 9290. The photo strips have a stereo pair.  Of course nothing is easy and I noticed (not shown) that the longitude is marked as East and not West at the top of the map.  Getting well over my head trying to sort this mess out.




Are we in the same playing field?  It kind of looks like we may not looking at the same crater if I am reading the LROC photo strip correctly:  "Sub spacecraft latitude 7.92  Sub spacecraft longitude 302.47"   

« Last Edit: November 12, 2010, 10:37:08 pm by Tom128 »

astrostu

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Re: Crater matching - Apollo 15 v LROC
« Reply #11 on: November 08, 2010, 01:13:55 am »
Tom, I don't see the crater on the rim of the Apollo one.  I see a boulder.  The shadows appear to me to go opposite to the shadow of the main crater, indicating a positive relief.

jules

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Re: Crater matching - Apollo 15 v LROC
« Reply #12 on: November 08, 2010, 12:05:42 pm »
Hi all,
I found and used the hi res Apollo pic in the comparison I posted above Tom:
Well I had a go in the hope I would be able to detect some changes but I don't think there are any. It's an example of just how good the LRO photos are though.

Spent some time trying to match boulders / craters in a widefield view yesterday with no luck at all and I was beginning to doubt that they were in fact the same crater. The boulder free centres do share many similarities though so I'd hate to be hasty in discarding the possibility just yet. Appreciate your comments Stu. We need more evidence!

jules

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Re: Crater matching - Apollo 15 v LROC
« Reply #13 on: November 08, 2010, 12:38:03 pm »
OK - the Apollo Image Atlas strip concentrates on the Taurus Mts - different bit of the Moon from Gamma Reiner where the LROC image is from (7.5°N 59.0°W) Different craters then!

So....the next challenge is to find the LROC version of the Apollo 15 crater!

jules

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Re: Crater matching - Apollo 15 v LROC
« Reply #14 on: November 08, 2010, 01:02:50 pm »
And that would be this one. M126704350RE

Only half the crater available but it does match up! (Image is flipped.)