New Space and Tech

Photometry Of LROC NAC Resolved Rock-rich Regions On The Moon

By Keith Cowing

Status Report

astro-ph.EP

January 27, 2023

Filed under Artemis, astro-ph.EP, imaging, LROC, Lunar, Lunar Reconnaissance Orbiter, Moon

Photometry Of LROC NAC Resolved Rock-rich Regions On The Moon — Overview of boulder fields indicated by the solid circles coloured by region and reference rock free (white crosses) at North Ray crater overlain on NAC images (M129187331L and M129187331R). The radial distance from the craters is denoted by the red and orange circles that correspond to twice and thrice the crater radius respectively. The image resolution is ~0.5 m per pixel. — astro-ph.EP

The study of meter and sub-meter scale geological features, especially boulders and boulder fields, on the surface of airless bodies can provide insight into the evolution of the regolith and the contribution of various processes to its formation.

Prior studies have examined the photometric properties of the lunar regolith surrounding young craters using image ratios.

We extend this methodology to extracting surface properties, in particular the roughness characteristics, exclusive to boulder fields and the boulders that constitute them around impact craters. In this study, rock-rich regions on the Moon are investigated using photometric roughness by employing a normalised logarithmic phase ratio difference metric to measure and compare the slope of the phase curve (reflectance versus phase angle) of a rock-rich field to a rock-free field.

We compare the photometric roughness of rock-rich fields on simulated images with the photometric roughness of rock-rich fields on LROC NAC images (0.5m/pixel). Using this technique, we determine that rock-rich surfaces are not necessarily photometrically rougher than rock-free areas.

Additionally, we find the roughness of resolved rock fields to indicate the presence of diverse sub-mm scale rock roughness (microtopography) and, possibly, variable rock single scattering albedo. These latter properties are likely controlled by rock petrology and material response to weathering and erosion.

Spatial clustering of photometrically smooth and rough boulder fields in the downrange and uprange of two craters is observed, reflecting ejecta asymmetry and possibly indicating asymmetric modification of ejecta rock surfaces during the impact excavation process.

Rachael M. Marshal, Ottaviano Ruesch, Christian Woehler, Kay Wohlfarth, Sergey Velichko

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2301.09885 [astro-ph.EP] (or arXiv:2301.09885v1 [astro-ph.EP] for this version)
Journal reference: Icarus (April 2023) Volume:394
Related DOI:
https://doi.org/10.1016/j.icarus.2022.115419
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Submission history
From: Rachael Martina Marshal
[v1] Tue, 24 Jan 2023 09:44:17 UTC (5,390 KB)
https://arxiv.org/abs/2301.09885

Keith Cowing

SpaceRef co-founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.

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