# Tag Info

66

Oh, I can answer this one. In my structural geology class, we breezed over a few paragraphs on the tectonics of impact craters, but it was in the textbook, and, being space-related, I was intrigued. One note: while most of the papers you'll find are on our own geology, the moon isn't that different compositionally from Earth at all, so I'm assuming the ...

12

It might help to compare the crater formation to a drop impact: It seems that rock can behave like a viscous mass if you hit it fast enough.

12

It's actually a rebound effect that occurs with an impact forming a large crater. https://www.lpi.usra.edu/education/explore/shaping_the_planets/impact-cratering/ explains: Central peaks – Peaks formed in the central area of the floor of a large crater. For larger craters (typically a few tens of kilometers in diameter) the excavated crater becomes so ...

6

Overall it seems that the NYT article has garbled the details: although the initial low-angle sunlight made Surveyor Crater look too steep, the estimated angle of about 11 degrees proved manageable by sidling down the rim. From the Apollo 12 Lunar Surface Journal transcripts and commentary by the astronauts (https://www.hq.nasa.gov/alsj/a12/a12.html): ...

3

The d/D ratio of Martian craters vary from 0.1 to 0.4 with mean value of 0.23. The largest crater with diameter 33m has d/D ratio of 0.2 but smaller craters have higher d/D value. One crater has a surprisingly high d/D value: 0.5. A plot of d/D ratio vs diameter is drawn showing the variation in the values: Shallower craters have d/D values of more than 0.3 ...

1

Photos from Mars Reconnaissance Orbiter show the impact sites from Curiosity's 2 main ballast weights about 80 km from the rover, plus the impact sites of the 6 smaller weights jettisoned just before separation... I guess its fair to assume Perseverance's ballast weights would be a similar distance. https://www.nasa.gov/mission_pages/MRO/main/index.html

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It helps to do the math. Tangent 21 degrees = .384 = 38.4 % grade. This is around 5 times steeper than most anything you'll see driving around the Rocky mountains of Western USA. Very difficult to climb out of, even when not wearing a bulky space suit. Important to remember, even though moon gravity is 1/6th earth (1.62m/s$^2$), there is no "terminal ...

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