Lunar Reconnaissance Orbiter Camera

Bright Boulder Trail

High-albedo marks on the lunar surface left by a boulder bouncing down the northeast wall of farside highlands crater Moore F. Image width is 610 meters [NASA/GSFC/Arizona State University].

Impacts can cause both subtle and profound changes to the lunar surface. In this subarea of LROC NAC frame M110383422R, you see the trail of a small (3 meter diameter) boulder that after getting dislodged (probably by a small meteorite impact) bounced down the northeast rim of Moore F, a 25 km diameter crater located in the farside highlands. What is interesting about this scene is that as the boulder bounced down the rim, its contact with the lunar surface kicked up and sprayed fresh, high-albedo highlands material outwards, leaving a clear trail at least part of the way down the rim of Moore F.  Fresh, high-albedo materials on the lunar surface darken over time as they are exposed to the space environment.  A key question in lunar geology is how fast does this space weathering process take? Does it take hundreds of millions or just millions of years for a surface to mature and darken? Do very thin deposits mature faster than thick deposits (think ejecta vs. rays). Answering that question will have important ramifications for our geologic interpretations elsewhere on the lunar surface.  Having future human explorers of this region collect samples of these high-albedo soils would provide useful information about the timescale of the space weathering processes.

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