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Tidally-induced acceleration as a potential cause of the Lunar Crustal Dichotomy
  • Joshua Knicely
Joshua Knicely
University of Alaska Fairbanks

Corresponding Author:[email protected]

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Analysis of GRAIL data revealed a lunar crustal dichotomy that can be described by a degree 1 spherical harmonic. A simple explanation of this observation is a superposition of the Moon’s self-gravity and an external and constant acceleration. I explored the possibility that the Moon experienced a much greater prograde acceleration in the past (when it was considerably closer to the Earth). I use a simple density balance approximation to determine the approximate acceleration needed to produce the observed asymmetry: ~0.009 m/s2 (or ~1/2% of the Moon’s self-gravity). In order to produce this acceleration, the Moon would need to be within ~13,000 km of the Earth. This is well within the Roche limit for completely fluid bodies (~18,350 km); for completely rigid bodies, the Roche limit is ~9,480 km. From this, it is extremely unlikely for tidally-induced acceleration to explain the observed crustal asymmetry.
02 Nov 2023Submitted to ESS Open Archive
03 Nov 2023Published in ESS Open Archive