125 Lunar Science and Exploration in the Artemis Era

Current and anticipated science return in the areas of geology, composition, and interior of the Moon from current lunar-focused studies and upcoming payloads expected to land on the Moon in the next decade.

Monday, 20 October 2025
1:30 PM - 5:30 PM
HBGCC, 214C

How’s the Weather(ing) on the Moon? Sedimentological Analysis of In Situ Lunar Regolith from Apollo 17 Double Drive Tube 73001/2 using X-Ray Computed Tomography

Paper number: 125-5
Program: Technical Sessions
Time: 2:35 PM – 2:50 PM

Authors

  • Richard Ketcham Presenting Author
    University of Texas at Austin - Jackson School of Geosciences, Austin, TX
  • Melanie Garza
    University of Texas at Austin - Jackson School of Geosciences, Austin, TX
  • Romy Hanna
    University of Texas at Austin - Jackson School of Geosciences, Austin, TX
  • Dave Edey
    University of Texas at Austin - Jackson School of Geosciences, Austin, TX

Abstract

The double drive tube core 73001/2 collected by the Apollo 17 astronauts on the Light Mantle landslide deposit presents a unique opportunity to study lunar surface processes.  As part of the Apollo Next Generation Sample Analysis (ANGSA) program, high-resolution X-ray CT data were collected for each core segment prior to dissection, preserving a record of the regolith and its arrangement.  Forensic analysis using 3D visualization indicates that the upper core 73002 was severely disrupted during collection on the Moon, when roughly 40% of the contents were lost during separation of the double drive tube, causing differential sliding that disturbed core stratigraphy.  However, scans also identified discrete peds that retained their cohesion, preserving some intact regolith.  The CT data required extensive corrections to minimize scanning artifacts and allow density to be compared along and between cores, and the consistency of the CT numbers was evaluated by comparing clasts of high-Ti basalts.  Analyses based on the modal CT number of peds in 73002 and selected volumes of interest in 73001 indicate that regolith density decreases with depth below the lunar surface at the collection locality.  This observation is contrary to expectations both for lunar regolith in general and for terrestrial landslide deposits.  We attribute this difference to the unique nature of nature of the deposit and the environment: increased intergranular spacing enabled motion of the regolith material, and low gravity and lack of atmosphere and water precluded important terrestrial mechanisms for post-slide consolidation.  Subsequent regolith gardening (e.g., minor impacts), the primary consolidation mechanism, had only relatively shallow effects that probably did not extend below 35 cm beneath the surface.  The CT data revealed clast rounding, another unexpected feature of lunar regolith given the lack of normal weathering processes.  We used AI to segment all clasts of high-Ti basalt, regolith breccia, and impact melt breccia ~4 mm and larger.  3D shape analysis shows that all lithotypes have signals of both fragmentation and rounding, with the high-Ti basalts being somewhat more angular in a given size class than the breccias, consistent with them being on average more resistant to abrasion.  The landslide event itself could have been a cause of rounding (as well as fragmentation), but a definitive interpretation will require 3D analysis of regolith from different lunar settings.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-414247

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