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Journal by khallow
While reading the recent story about the Chinese lunar rover examining a boulder at close range, I thought of an interesting question. How much would lunar boulders move over billions of years and what would be pushing them around? It seems like an appropriate model would be a very warped billiard table covered in a layer of thick sand with the boulders more or less loose on the top. The sand corresponds to lunar regolith which is a thick layer of meteorite-caused dust that covers the entire moon.
Slight vibrations shouldn't move them much because they would be nestled in that regolith. But enough occurrences of large forces say from nearby earthquakes or asteroid impacts could move them a great distance over those long periods , I guess it depends on whether the regolith rapidly absorbs the energy of the boulder or not.
It seems like a random walk computer model that one could run with modest resources once one can characterize how the forces would act on these boulders.
Distribution of boulders and boulder tracks might well inform us of how common and how big such disruptive forces are as well as the locations of any repetitive forces (say from a fault zone).
While I don't think it's likely, even the heat/freeze cycle of lunar day/night might move these things around.
So what do you think?
Slight vibrations shouldn't move them much because they would be nestled in that regolith. But enough occurrences of large forces say from nearby earthquakes or asteroid impacts could move them a great distance over those long periods , I guess it depends on whether the regolith rapidly absorbs the energy of the boulder or not.
It seems like a random walk computer model that one could run with modest resources once one can characterize how the forces would act on these boulders.
Distribution of boulders and boulder tracks might well inform us of how common and how big such disruptive forces are as well as the locations of any repetitive forces (say from a fault zone).
While I don't think it's likely, even the heat/freeze cycle of lunar day/night might move these things around.
So what do you think?
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
Do not use if foil seal is broken.
(Score: 0) by Anonymous Coward on Wednesday January 12 2022, @12:18PM (1 child)
no atmosphere to speak of, no tectonic activity as far as I know.
so I'd guess most boulders on the moon are either very old, from the time of active volcanoes, or they were formed during asteroid impacts.
there are those reports of ice, and ice melt/freeze cycles could affect soil enough to move rocks a bit, but any boulders on the moon are probably in stable equilibrium points and at most they'll wiggle a bit, possibly settling better into the dust.
on Earth though, like the other poster says, there are a lot of moving rocks https://www.youtube.com/watch?v=89-AFHieDpM [youtube.com] (if you pay attention, you'll note an early instance of "remote interview").
(Score: 1) by khallow on Wednesday January 12 2022, @02:46PM
The moon still gets earthquakes. But the entire moon is quiet enough and rigid enough that NASA could detect rather small meteorite impacts with the seismometers brought with the Apollo missions (apparently five were brought over). For example, the Apollo 11 seismometer measured [nasa.gov] 100-200 meteorite impacts over a three week period (including some time out of action due to lunar night).