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Apollo Sites from LRO
Phil Stooke
post Sep 12 2016, 08:07 PM
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Follow-up on the Apollo 12 - possible - Lunar Module Ascent Stage impact. Looking at more images of the area I have found what may be the impact site, showing up as a gouge or linear depression, possibly with a crater at the end. I attach two images, each a composite of several, to tell the story.

A is a regional map showing the Apollo 12 landing site, LM impact target and predicted impact area.
B is a close-up showing the predicted impact area and two features, the area of dark streaks described earlier, and the new feature which may be the impact site.
C is a comparison of twi LROC NAC images showing the impact feature, and a composite of the two which reduces the effects of shadowing and emphasizes albedo markings. The impact site is dark.
D is the area of dark streaks.
E-H zoom in on the impact feature to locate it unambiguously.

(These are set up as illustrations for a future book.)

Phil

Attached Image


Attached Image


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john_s
post Sep 13 2016, 02:55 AM
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Nice work! It looks quite convincing to me. I'm intrigued by your use of the images with different lighting to separate albedo and topography- is the merged image simply a linear combination of the two, or something fancier?

John
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Phil Stooke
post Sep 13 2016, 12:12 PM
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Thanks, John. The shadow-cancelling method is surprisingly easy and effective. It is just a linear addition of two images with approximately opposite lighting. Shadows and highlights cancel each other out, greatly reducing the visibility of topography and clarifying the albedo markings. I have used it with what is sometimes referred to as 'jaw-dropping' effectiveness on Lunokhod and Apollo astronaut tracks, where individual images did not reveal them clearly.

Phil


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Phil Stooke
post Sep 13 2016, 07:32 PM
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Another example of the shadow-cancelling method. This is Apollo 14, EVA 1 near the ALSEP. Two individual NAC images plus a merged version. The topography does not cancel completely because they are stretched differently, but look at how the tracks pop out!

Phil

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Phil Stooke
post Nov 2 2016, 04:46 PM
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Allow me to introduce to you.... the Apollo 14 LM Ascent Stage impact site!

Attached Image



This is almost exactly at the tracking location. Its latitude and longitude in Quickmap coordinates are 3.4202 S, 19.6368 W (340.3632 E). My hero, Ewen Whitaker, who sadly just died aged 94 a couple of weeks ago, tried to locate the impact site and suggested it was at the location of an unusual dark spot in an Apollo 16 Metric Camera image (frame 2508). He had just observed that Ranger and other artificial impacts tended to look dark from orbit, so it was a reasonable suggestion. But it was not quite in the right place. In this case he was mistaken. This spot shows features very similar to the Apollo 12 LM Ascent Stage impact, illustrated above on this page. I will be presenting this at LPSC.


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Ian R
post Nov 3 2016, 10:31 AM
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Nice discovery Phil, and sad news about Ewen Whitaker.

How is the second edition of your Lunar Atlas coming along?


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Phil Stooke
post Nov 3 2016, 12:18 PM
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Thanks. The book is coming along pretty well. It went fast during my half-year sabbatical, January to June. Now I'm back teaching it's slowed down a lot. But I hope to finish the revision of the first volume (ending at Luna 24) by December next year, and then get into a Volume 2 which is everything after Luna 24 up to the present. It is greatly improved by the use of LRO data and corrections to some errors in Vol. 1.

Phil


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