|Impact melt channel 2.5 kilometers southwest from the rolling rim of Petavius B crater; down-slope is to the south-southeast in a field of view 1020 meters across. Solar illumination incidence angle is 79.83° from east by northeast in LROC Narrow Angle Camera (NAC) observation M115937523R, orbit 2219, December 20, 2009; Featured Image center 20.350°S, 57.371°E, resolution 0.85 meters per pixel from 53.76 kilometers altitude. View the full size LROC Featured Image HERE [NASA/GSFC/Arizona State University].|
LROC News System
Impact melt, rock that is melted by the tremendous energy released during an impact cratering event, results in fascinating morphologies visible in many (LROC Narrow Angle Camera) NAC images. Most melt stays inside the crater, freezing into melt-ponds, but some is thrown out of the crater and flows down the exterior ejecta blanket until it is completely solidified by surface cooling.
Today's Featured Image explores a fantastic impact melt deposit on the southern rim slope of Petavius B, about 2.5 km away from the rim. The flat floored arc-shaped area at the bottom of this image was likely a pool of melt that drained out of the channel at the top. The shadows highlight the depth and steep banks of the channel.
|From LROC Wide Angle Camera observation M134816027CE (604 nm) showing familiar nearside landmark crater Petavius B and the immediate vicinity of its rim; LRO orbit 5001, July 26, 2010; incidence angle 65.53° with a resolution of 73.89 meters from 53.27 kilometers altitude [NASA/GSFC/Arizona State University].|
|Simulated perspective view of Petavius B with the range of elevations derived from LROC WAC (GLD100) digital terrain modeling in the box at lower right. The perspective view shows LROC WAC 100 meter global mapping overlaid upon LRO LOLA (laser altimetry-based) 128 m digital elevation model (v.2) available through the NASA LMMP ILIADS application [NASA/GSFC/LMMP/Arizona State University].|
Similar morphologies are found within terrestrial lava flows, but the terrestrial examples often have distinctive cracks as lava backs up beneath a crust forming tumuli or pressure ridges. Why do we not see similar structures on the Moon? This is a mystery, but perhaps the impact melts have lower viscosities or different cooling processes than the lava on Earth!
Open up the full NAC frame and find more fascinating impact melt features by yourself!
On the Floor of Thales
Herigonius K Impact Melt Flow
Lichtenberg B Flow
Outside of Giordano Bruno
Channelized impact melt