Small Pond

Unnamed crater floor at west edge of Mare Fecunditatis. LROC NAC M167919653R. Image center is 6.422°S, 43.747°E, image width is 561 meters. North is up [NASA/GSFC/Arizona State University].

Today's Featured Image highlights an unnamed small crater (~600 m in diameter) observed at western edge of Mare Fecunditatis. As seen in next WAC context image, the higher reflectance immature ejecta blanket of this crater suggests its young age relative to the adjacent craters. The crater walls are mostly covered by collapsed materials but the bottom still shows the original floor. The most remarkable feature is the central pit filled with impact melt (~100 m in diameter) with wrinkles on its surface. What are wrinkles telling us?

LROC WAC monochrome mosaic (100 m/pix) at western portion of Mare Fecunditatis. Image center is 6.67°S, 43.73°E. NAC footprint (blue box) and the location of today's Featured Image (yellow arrow) are indicated [NASA/GSFC/Arizona State University].

Probably this is a quenched surface of melt flows that coalesced from multiple directions, and each wrinkle corresponds to the contact boundary of different flow units. The mushroom shape extending from south toward the center could have been the last flow unit that squeezed through the earlier arriving melt. Post surface cracking may also contribute resulting in these complicated patterns. Impact melts exhibit large variety in their final shapes due to their complicated rheology changing with time. It must be interesting to see how different or similar they are to the volcanic surfaces of active Hawaiian volcanoes.

Explore the wrinkles on this tiny melt pond in full NAC frame for yourself!

Related posts:

Channels And FracturesFarside impact!Crater in 3D!Young Highlands CraterRippled PondMessy Crater

Published by Hiroyuki Sato on 15 May 2013