Featured Image - 08/19/2008
Features of the Rimae Fresnel Area
The geology of the Apollo 15 landing site is among the most spectacular in the Solar System. At the northernmost tip of Hadley Rille there is a fascinating region that will surely be a future astronaut field study area, shown in Figure 1. A prominent feature is Rimae Fresnel, named after the famous mathematician Augustin Fresnel. The Rimae Fresnel are a series of graben caused by tectonic stresses in the Imbrium basin. The Rimae Fresnel terrain looks familiar because it is another example of the Apennine Bench Formation, which is an unusual deposit of KREEP-rich volcanic materials discussed in a previous Featured Image. In the upper right, you can see a small deposit of darker, fine-grained pyroclastic materials blanketing the area. Scientists are also very interested the Rimae Fresnel region because the lavas that carved Hadley Rille (visible near the bottom of this image) may have followed preexisting structural features like the Rimae Fresnel as they flowed across the lunar surface. Future astronaut explorers of this region will want to obtain vital new information about the composition and evolution of the lunar interior by sampling both the unusual Apennine Bench Formation materials and the Rimae Fresnel pyroclastic deposit. Detailed fieldwork of Rimae Fresnel will also be required to learn more about the nature of lunar volcanism by fully investigating the possible relationship between tectonic features and the formation of Hadley Rille.
Figure 1. Apollo metric frame showing Mt. Hadley, the northernmost part of Hadley Rille, the Rimae Fresnel graben, and the approximate boundaries of the southern part of the Rimae Fresnel localized pyroclastic deposit (Apollo Image AS15-M-0415 [NASA/JSC/Arizona State University]).