A Rain of Rock

3-D anaglyph of secondary craters west of Vavilov — A rain of rock carved these craters west of Vavilov crater. The ground here, which is elevated relative to the surrounding terrain, intersected with rock and other ejected debris excavated during the formation of Vavilov crater. The result was a tight cluster of irregular and V-shaped secondary craters about 2 to 2.5 km in diameter. NAC anaglyph M182123981_M182109685 [NASA/GSFC/Arizona State University].

Vavilov crater is a large crater roughly 100 km in diameter and is relatively young and well-preserved. The crater is located in the farside highlands near the equator (view in Quickmap). Vavilov crater is remarkable because of a distinct low-albedo ring around the crater that is thought to result from a high abundance of impact melt in its ejecta. Vavilov is one of several large craters that exhibit a similar low-albedo ring or partial rings just outside the crater rim (including Tycho, Ohm, Jackson, and King craters).

WAC normalized reflectance image of Vavilov crater showing dark halo — Normalized reflectance WAC image reveals the low-albedo ring around Vavilov crater. Vavilov crater is a large crater roughly 100 km in diameter [NASA/GSFC/Arizona State University].

Rocks and debris flung outward during Vavilov's formation impacted the ground at relatively low angles and velocities. The secondary craters shown in the 3-D anaglyph image above were formed when ejecta intersected an elevated bit of terrain. This raised massif is part of the degraded rim of an ancient, highly eroded crater that is itself about 75 km in diameter (see image below). The featured secondary craters are about 2 to 2.5 km in diameter, or about 2 to 2.5% of the primary (Vavilov) crater's diameter, and are located about 100 km from the rim of Vavilov (or 1 crater diameter). They are very typical of the sizes and morphologies of secondary craters found at these distances.