Spectacular example of layering exposed in the wall of Bessel crater (21.8°N, 17.9°E). Image number M135073175R, incidence angle 13°, image is 500 meters across.

The outcrops exposed on the interior wall of Bessel crater (~16 km in diameter) are remarkable since they are most likely preserved layering of mare basalt. Today's Featured Image shows a portion of the northern wall, which contains multiple layers that probably represent discrete lava flow deposits in Mare Serenitatis. Over time, large, but relatively thin, lava flows spread across the extent of Mare Serenitatis. Lunar pits imaged by LROC also give us a good look at basalt flow layers. Boulders broken off of the mare layers tumble down the wall toward the floor of the crater. Bessel crater is named after Friedrich Bessel, the developer of Bessel functions. By measuring the thickness of layering found in Bessel and other craters, scientists can put constraints on the thickness of individual lava flows. What else can Bessel crater tell us about Mare Serenitatis?

NASA's Goddard Space Flight Center built and manages the mission for the Exploration Systems Mission Directorate at NASA Headquarters in Washington. The Lunar Reconnaissance Orbiter Camera was designed to acquire data for landing site certification and to conduct polar illumination studies and global mapping. Operated by Arizona State University, LROC consists of a pair of narrow-angle cameras (NAC) and a single wide-angle camera (WAC). The mission is expected to return over 70 terabytes of image data.