LROC: Smooth Ejecta

Grooved surface created in an instant by an impact event. The linear pattern is radially symmetric to the parent crater; the parent crater must be very young as very few craters dot the ejecta blanket! 650 meter field of view from LROC Narrow Angle Camera (NAC) observation M171788458RE, orbit 10450, September 27, 2011; resolution 0.65 meter per pixel from 63.39 kilometers. View the full size LROC Featured Image HERE  [NASA/GSFC/Arizona State University].

Drew Enns
LROC News System

When an impact event deposits an ejecta blanket, nearby craters of all sizes are buried or modified. Larger craters may be preserved, while smaller examples are obliterated. In the case of today's Featured Image, a nearby impact covered the area and erased any craters that previously existed. Currently only small impact craters dot the landscape, but must have been emplaced after the ejecta blanket was deposited. In fact many of these small craters may be auto-secondaries; craters that formed as late stage blocks of ejecta landed on the just formed ejecta (all from the same impact event). Because these impacts are so few, and so small, the ejecta (and corresponding parent crater) must be very young.

Context perspective for the field of view in the LROC Featured Image, April 10, 2011 (white box), south east of a relatively fresh crater situated between the Leibnitz impact basin and Leibnitz S, all well within the South Polar-Aitken basin on the southern lunar farside; LROC NAC M171788458R [NASA/GSFC/Arizona State University].

LROC Wide Angle Camera (WAC) image, the arrow pointing to the location of today's Featured Image field of view, located at 39.614° S, 173.08° E; the nearby small fresh crater is the source of the ejecta blanket. LROC WAC observation M130516575C, LRO orbit 4367, June 7, 2010; morning incidence angle 74.54° over a field of view 55 km across, resolution 76.2 meter from 54 kilometers [NASA/GSFC/Arizona State University].

Copernican aged craters are defined by their fresh morphologies and bright ejecta, and the ejecta blanket's source crater has both. But even Copernican aged craters have a long formation history as they include any crater formed since Copernicus crater 800 million years ago. This unnamed crater is almost certainly younger than that!

How does the featured unnamed crater compare to known small fresh craters on the Moon? Check out the full LROC NAC frame HERE, and related posts below to find out!

Related Posts:
Absolute Time
How Young is Young?
Just Another Crater

Location of the bright, fresh crater, east of Leibnitz, southeast of Mare Ingenni on the lunar farside, LROC WAC DTM color-shaded relief [NASA/GSFC/DLR/Arizona State University].