"Two of these things are not like the others"

The rim of a fracture inside Sarton Y. Left of the bright rim is outside the fracture and right of the rim is inside the fracture. Image field of view is 825 meters. See the full size LROC Featured Image HERE, a frame from LROC Narrow Angle Camera (NAC) observation M140697409L, LRO Orbit 5868, October 2, 2010. [NASA/GSFC/Arizona State University].

Sarah Braden
LROC News System

In the farside highlands at 51.3°N, 238.6°E, Sarton Y and Z stand out among the other craters. Take a look at this area in the LROC WMS Image Map.

Other craters in the region have filled floors, however, Sarton Y and Z are the only two craters to also have floor fractures. 

Why is this?  What makes Sarton Y and Z special? 

Full 3.3 kilometer width frame from LROC NAC M140697409L, October 2, 2010 [NASA/GSFC/Arizona State University].

Perhaps the subsequent impact of Sarton Y allowed the material in both craters to undergo a thermal evolution different from their surrounding counterparts, possibly causing the fractures as the floors cooled. Was there a difference in the surface material when Sarton Y and Z were formed? Both craters show evidence of slumping, but so do the other craters in the region. Age or the composition of the impactor may also play a role.

Sarton Y (l) superpositioned upon the slightly larger Sarton Z, in the farside northern highlands, as swept up April 26 and 27, 2011 in this approximately 44 km-wide frame from a LROC Wide Angle Camera 60 meter per pixel 604 nm mosaic, LOR Orbits 8471 - 8481. The yellow arrow designates the location of the rim of the fracture discussed above [NASA/GSFC/Arizona State University].

Explore more of the fractures in the NAC frame!

Related Posts:
Atlas
Gassendi's Fractures
Perched boulders