Recent Impact in Oceanus Procellarum

A small amount of impact melt pooled and froze on the floor of this Copernican impact crater, and is 90 x 70 m in size. What process creates impact melt pools? LROC NAC M111972680LE, image width is 750 m [NASA/GSFC/Arizona State University].

This unnamed crater is near the Reiner Gamma Swirl in Oceanus Procellarum. The crater’s relative youth makes it a great example to investigate how impact craters form. The cratering process occurs in three stages: contact and compression, excavation, and modification. The impact melt and boulders were created during contact and compression as the bolide transferred its kinetic energy to the target. 

The ejecta blanket of the unnamed crater. Image is a mosaic of NAC pair M111972680, image width is 3.0 km [NASA/GSFC/Arizona State University].

The ejecta blanket was deposited during the excavation stage, covering the surrounding mare surface with high reflectance, immature material. The modification stage brought about the final shape of the crater. As the forces involved in the impact subsided, the impact melt pooled at the bottom of the crater along with the boulders. The modification stage is still ongoing as gravity has since caused small landslides on the crater wall, and more boulders have probably eroded out of the crater wall.

Can you find similar craters in the full NAC frame?

Related Posts: Rubble Pile on Fresh Crater Floor

Action Shot

Melt and more melt

Published by Drew Enns on 12 August 2011