Depressions and positive relief features characteristic of the floor of Tycho were caused by a complex stew of granular material and impact melt cooling and settling to the floor. Image field of view is 370 meters. LROC NAC M119923147L [NASA/GSFC/Arizona State University].
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Impact melt creates a wide variety of features on the Moon. These include melt ponds, draped ejecta, viscous flows, linear and nonlinear depressions, and positive relief features. As impact melts mix with loose rock during crater formation, solid pieces of rock stick above the surface of the ponding melt to form little peaks (positive relief features). The depressions are possibly cooling fractures in the melt that result as the melt slowly solidifies and contracts (the opposite of how water behaves when it freezes), however they could also be part of an impact melt drainage network. We don't know for certain know the origin of all of these features, the best way to find out is to have astronauts traverse this terrain while exploring the Moon.
LROC WAC mosaic with arrow noting the location of the melt features within Tycho crater seen in the NAC image above. Image width is 150 km [NASA/GSFC/Arizona State University].
Can you find more impact melt features in the NAC frame?
Kilometer-wide context for the full-resolution Featured Image above, a wider looks at the 2.8 km-wide LROC Narrow Angle Camera observation highlighted above, LROC NAC M119923147LE, LRO orbit 2806, February 4, 2010 [NASA/GSFC/Arizona State University].
The LROC Wide Angle Camera mosaic affixed to the lunar digital elevation model available to users of Google Earth provides some scale and the illusion of perspective, seen here showing Tycho's interior, between the slumped northeastern interior rim and central peak, looking North [NASA/JAXA/SELENE/USGS/GSFC/Google/Arizona State University].
The Floor of Tycho - Constellation ROI