Lunar Surface Strength Estimate from Orbiter II Photograph

Abstract

Lunar Orbiter II photographed a 13-meter boulder which has rolled down the inner slope of a 3-kilometer crater leaving a track 6 meters wide. A static-bearing . strength of 4 x 10(6) dynes per square centimeter at 75-centimeter depth is estimated from these data if certain assumptions are made.

Analysis of Lunar Boulder Tracks: Implications for Trafficability of Pyroclastic Deposits

“…Analysis of boulder tracks on the surface of the Moon has been used to estimate the bearing capacity of regolith since the Lunar Orbiter program began imaging the lunar surface in 1966 (Eggleston et al, ; Filice, ; Moore, ). The ultimate bearing capacity is the maximum load the ground can sustain before failure (Meyerhof, ).…”

“…In addition, NASA's Lunar Orbiter missions from 1966 to 1967 (LPI USRA, n.d.) returned photographs of the surface, which led to the discovery of boulder tracks carved by rockfalls. These boulder tracks were studied (Eggleston et al, ; Filice, ; Hovland & Mitchell, & ; Moore, ; Moore et al, ; Pike, ) to derive geomechanical properties of the lunar regolith in regions not been directly sampled by landers. Results suggested crew and rovers would be able to traverse the surface safely.…”

Global Drivers and Transport Mechanisms of Lunar Rockfalls

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Lunar rockfalls are ubiquitous mass wasting features that were first observed in Lunar Orbiter high-resolution photographs in the late 1960s (Eggleston et al, 1968;Filice, 1967;Moore, 1970). Rockfall events, which have been previously referred to as block falls or rolling boulders, involve the detachment of a boulder or rock mass from an elevated source region, which then slides, bounces, and rolls down the local topographic gradient, ultimately depositing downslope.

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Lunar orbital science

“…Surface water erosion could result in features resembling rills, but the source of this water is a problem. Water might have existed during the early formation stages of the Moon (Urey, 1967) or water could have been generated by major events such as the impact that formed the Orientale basin (Firsoff, 1968). It has been postulated that subsurface water, protected by a layer of ice formed by water vaporizing into the lunar vacuum might produce rills (Adler and Salisbury, 1969;Peale et al, 1968).…”

“…Slide tracks can be seen down the sides of many craters (Manned Spacecraft Center Report, in press) and large slump deposits are visible on the crater bottoms. As Figure 29 illustrates, tracks caused by boulders rolling down slopes are evident, and efforts have been made to use these data to estimate surface strength (Eggleston et al, 1967;Filice, 1967).…”