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The New York Times article What Happened to Earth’s Ancient Craters? Scientists Seek Clues on the Moon’s Pocked Surface includes a NASA photo with the caption:

Astronaut Charles M. Duke Jr., of the Apollo 16 mission, near Plum Crater on the moon in 1972.CreditJSC/NASA

I show a cropped section of the photo below, where I have annotated it with some arrows between footprints and a perceived "edge" of the crater. Since each point is a different distance from the camera, it is impossible to make simple measurements from the image without a sophisticated 3D hypothetical reconstruction, probably including a models of the camera ant the terrain.

There may however be more information about this walk both in various scientific reports of the mission, and memoirs as well, since this looks pretty scary!

Question: How close did Apollo 16 astronaut Charles M. Duke Jr. get to the edge of Plum crater? If he had tripped, was there any possibility of falling directly into the crater and not being able to get out? How deep was the crater at this point?

I believe the image is AS16-114-18423 (21 April 1972) which can be found at https://spaceflight.nasa.gov/gallery/images/apollo/apollo16/html/as16-114-18423.html

below: cropped and full size from NYTimes "Astronaut Charles M. Duke Jr., of the Apollo 16 mission, near Plum Crater on the moon in 1972.CreditJSC/NASA"

enter image description here

enter image description here

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    $\begingroup$ Looking at the depth of focus of these images, I guess they were taken with the 60 mm lens but not with the 500 mm. Somebody experienced in photogrammetry may determin the distance to the edge when knowing the focal length of the lens used. $\endgroup$ – Uwe Jan 18 at 23:53
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    $\begingroup$ @Uwe photogrammetry gets extremely hard on subjects that have no straight lines or flat surfaces like the 3D contour of the lunar surface here. Forming homographies is fairly straightforward when you have known 3D models to compare, but here I am not sure that it is possible. $\endgroup$ – uhoh Jan 18 at 23:56
  • $\begingroup$ One could get a crude estimate by finding Charlie Duke's height from NASA records, measuring his height in the photo & then measuring the near horizontal distance of the foot print to the edge of the crater & getting the distance that way. $\endgroup$ – Fred Jan 19 at 16:27
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It looks like he was about 2-3 feet away judging by his height. The chance of him tripping and falling is very small. If he did happen to though it appears the crater had about a 50% grade at the steepest. It would be possible to climb out, especially with the much lower gravity. It might be a bit difficult with the spacesuit. I think the big danger would be that you could potentially crack the visor on the way down.

Seen from the side, Plumb Crater is not as large nor as deep as might seem to be from the image in the question.

enter image description here

Source click for full size.

''Mosaic of Apollo 16 Hasselblad camera images. Reduced to 50% of original size. The original images are in the public domain because they are works of the U.S. Government (NASA). Immediate source: Apollo Lunar Surface Journal, Apollo 16 Image Library Hasselblad Magazine 109/G (B&W) AS16-109-17789 AS16-109-17790 AS16-109-17791 AS16-109-17792)

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  • $\begingroup$ Seeing from the side, the crater looks not dangerously steep. But the astronaut is standing at another point of the crater's edge compared to the image of the question. $\endgroup$ – Uwe Jan 20 at 10:29
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    $\begingroup$ To me it looks like a bit more, at least 6 feet or so. The right red arrow goes across a darker feature, which I'd assume to be a tiny crater, mostly round in reality. On the next photo, where the astronaut is standing, we see that this craterlet's diameter is about half the astronaut's height. And the distance between footprints and the edge is about twice as long. (The left arrow appears to be shorter, but it's probably misleading, the slope is just a bit steeper) $\endgroup$ – IMil Jul 12 at 1:10

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