English: Polygonal fractures on a flow lobe of impact melt splashed out of Tycho crater. Image scale is 0.52 meters/pixel, incidence angle is 69.1°, sunlight is from left [NASA/GSFC/Arizona State University].

Tycho is a young and prominent rayed crater on the lunar nearside. During the impact that formed Tycho crater a large mass of impact melt was thrown out on its north side that resulted in a series of beautiful flow patterns. The melt ponded in several topographic lows, and as they cooled their upper crusts fractured, often in polygonal patterns.

Today's Featured Image shows a set of crisply preserved polygonal fractures. Small chains of pit chains are also seen in conjunction with the fractures. Are these pits nascent fractures that never fully developed? Or perhaps partially collapsed tubes that melt flowed through? If the latter, might there be open passages that astronauts could venture into and explore?