The Featured Image posted on 17 September 2013 highlighted wrinkle ridges formed through thrust faulting and compressional stresses at Reiner Gamma (centered at 301.202°E, 7.370°N). Today's Featured Image is a spectacular oblique viewpoint of the same region, similar to what an astronaut in orbit would observe looking 58° degrees from vertical. The swirls of bright material in the oblique image stand out from the dark mare surface, resulting from an albedo (brightness) contrast. Scientists are particularly interested in the cause of this albedo contrast; does it result from different minerals in the surface materials? One possibility is that the bright areas are less weathered than the darker areas.
The surface of the Moon is continuously bombarded by charged particles ejected from the Sun, cosmic rays, as well as hypervelocity impacts from comets and meteorites. Over time, these particles weather the lunar surface; minerals are degraded, broken up, and chemically altered. These weathering processes decrease the reflectance of the surface, darkening it over time. Thus, perhaps the bright areas are somehow protected from at least some of these processes?
Both the Apollo and Lunar Prospector missions detected weak magnetic fields associated with swirls. These magnetic fields prompted scientists to propose that the charged particles partially responsible for space weathering could be diverted from the bright swirls, allowing the swirls to remain relatively bright and unchanged over time. Alternatively, perhaps bright or unweathered material has been deposited here recently. In either case, the oblique image illustrates that the surface of Reiner Gamma has little topographic relief. The most noticeable topography results from small craters and tectonic faulting, and this topography is independent of the bright swirls and dark lanes. The relatively low topographic relief makes Reiner Gamma relatively easy to explore with a rover or future human sorties.
Read more about lunar swirls here:
Lunar Swirls at the Mare Ingenii Constellation Region of Interest
Reiner Gamma Constellation Region of Interest
The Swirls of Mare Ingenii
Visit Snapshots from Space to see what an astronaut's view of Reiner Gamma looks like!
Explore the full LROC NAC oblique image of Reiner Gamma below.
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