|Top of a mound with fractured impact melt on the floor of Anaxagoras (75.46°N, 349.94°E). Image field of view 600 meters with sunlight from the south-by-southwest viewed at an incidence angle of 73.78° (nearly as high above the horizon as the Sun gets at such northerly latitudes. LROC Narrow Angle Camera (NAC) observation M122273232L, orbit 3153, March 3, 2010; resolution 0.49 meters per pixel from an altitude of 42.18 kilometers. View the larger (1100 x 1100) original LROC Featured Image HERE [NASA/GSFC/Arizona State University].
LROC News System
The irregularly fractured surface in today's Featured Image is on top of a north-western oriented slightly elongated mound on the floor of crater Anaxagoras (image center is 73.748°N, 349.522°E). Anaxagoras (diameter ~ 50 km) is located about 700 km north of Mare Imbrium. The floor of Anaxagoras has an irregularly-shaped central peak. Other portions of the floor are filled with debris and impact melts.
The cracked surface covers only the top portion of the mound. The northern flank of this mound (see figure below) is almost completely covered by boulders, and southern flank is smooth with only a few boulders (as seen in the left hand image below). Why did the cracking happen only at the top of the mound?
One possibility is that the cracked portion is a splashed remnant of impact melt. A solid crust formed where the melt was thickest, and then later, as melt drained downslope, the cracks formed as the crust collapsed.
|Context from the larger (LRO NAC M122273232L) frame showing the vicinity the Featured Image field of view (blue box). A conventional stretch is above; below, the same image stretched to enhance details in the shadowed area. Each FOV width is slightly less than 2000 meters [NASA/GSFC/Arizona State University].
|LROC WAC monochrome (604 nm) mosaic stitched from 10 sequential orbital passes March 21, 2011, showing a roughly 80 km-wide view of Anaxagoras an vicinity, situated on the rim of Goldschmidt on the east. Image center is 72.4°N, 350.0°E. The the location of the area detailed in the LROC Featured Image is indicated by the yellow arrow [NASA/GSFC/Arizona State University].
The interior of Anaxagoras crater was a Constellation program Region of Interest. With so many exciting features like this one, Anaxagoras crater is an excellent place for humans to explore!
Explore this irregularly cracked ridge and lots of other spectacular impact melt morphologies NAC frame HERE.
Craggy Peak, Impact Melts
Splash and flow
Chaotic crater floor in Tycho
Polygonal fractures on Tycho ejecta deposits
Impact melt in Anaxagoras crater
Exposed Fractured Bedrock in the Central Peak of Anaxagoras Crater
|This low-altitude (31 km) oblique view south from Japan's lunar orbiter SELENE-1 (Kaguya) is an excellent illustration of the difficulty in gauging scale in lunar photography. Anaxagoras could be a backyard brick barbeque pit in disrepair, or an astronaut's few foot steps away. Instead the crater is 50 kilometers wide and hundreds of kilometers away in this HDTV frame from 2009. View the release-size image HERE [JAXA/NHK/SELENE].