Copernicus Collapse

Collapse feature in the impact melt within the floor of Copernicus crater. NAC M168333206L, image width is 430 m [NASA/GSFC/Arizona State University].

A fresh collapse feature within the impact melt floor of Copernicus crater is 330 meters across (that's about 3 American football fields wide!). At one point the impact melt in this area was flat, but then the area collapsed forming the feature here (located at 10.204°N, 339.998°E). The rim of the depression is still very fresh with outcrops and boulders. An estimate of the depth is ~50 meters, based on shadows from another NAC image of the same area. There are a few possible causes for the collapse. A subsurface void may have formed as the impact melt flowed and cooled. Subsurface voids occur when melt emplaced shortly after the impact drains away deeper into the impact cavity. Perhaps a small bolide impacted the surface and instigated the collapse of the structurally weak void. Alternatively, the collapse might be due to seismic shaking from moonquakes disturbing the weak section of the melt deposit.

This collapse feature is much larger in diameter than the mare pits: the Mare Ingenii pit is ~130 m in diameter, the Marius Hills pit is ~65 m in diameter, and the Mare Tranquillitatis pit is ~100 m in diameter. Pits in mare basalt may have formed when a portion of a lava tube collapsed. The subsequent pit is a skylight that leads into the intact lava tube. Impact melt pits are common within impact melt deposits like the one here in Copernicus, however the depression in the Feature Image is larger in diameter than average impact melt pit. Perhaps in this case the subsurface void was larger, or the surface layer of impact melt was structurally weaker, resulting in a larger collapse area.

A previous Featured Image, Copernicus Seen Looking Straight Down featured a mosaic of Copernicus's floor (9.62°N, 339.92°E, 93 km in diameter), but today's Featured Image offers much higher resolution at 30 centimeters per pixel! The spacecraft altitude above the surface was only 29 km when this image was taken.

The red asterisk marks the location of the collapse pit within Copernicus. WAC context image is 120 km across [NASA/GSFC/Arizona State University].

Explore the entire NAC frame for more high resolution impact melt deposits!  

Related Images:

Copernicus Seen Looking Straight Down

Copernicus Central Peak

Natural Bridge on the Moon!

Impact Melt Pit

Published by Sarah Braden on 5 March 2013