Close up of left middle of LROC image release below, "just-over" 250 meter-wide swatch of impact melt within crater Moore F. "Spectacular" lunar morphology is shown, and perhaps a deep contrast in age, witnessed by crater saturation seen through what appears to be a window left open on the distant past. The melt is rare because the Moon is a prime example of crater saturation. A close-up from 500 meters is difficult to tell apart from another 200 kilometers further. The Moon's history is about bombardment. The Moon's immediate surface is "gardened," or reworked, by micrometeorite bombardment every two million years. Though "ghosts" of craters can be seen in this remarkable close-up, the surface looks very fresh. LRO NAC M110383422LE. [NASA/GSFC/Arizona State University]
Jeff Plescia
LROC News System
The crater Moore F (37.4°N, 185°E ~ 23 km) exhibits a spectacular terraced rim and central uplift – a beautiful example of a complex impact structure. Surrounding the central uplift, the crater floor is covered by both frozen impact melt flows and debris. The melt formed as a result of the tremendous energy released in the impact event. As the crater equilibrated, the melt flowed to low spots and slowly cooled. What caused the spectacular curved cracks to form?
Perhaps the crater floor topography changed over time, fracturing the surface of the central melt pond deposit (right side of picture) and opening a series of parallel, arcuate tension (pull-apart) cracks. Or, perhaps as the melt cooled and solidified, the volume change opened the cracks. The LROC featured image on October 21 showed an adjacent portion of this same crater. Over time, LROC will image the whole crater allowing scientists to test these hypotheses and come to a clear understanding of how craters of this size form.
New LROC images of many craters from all over the Moon are showing that the deposition and evolution of impact melts is extremely complex, and melt ponds take many forms depending on local conditions.
Jeff Plescia
LROC News System
The crater Moore F (37.4°N, 185°E ~ 23 km) exhibits a spectacular terraced rim and central uplift – a beautiful example of a complex impact structure. Surrounding the central uplift, the crater floor is covered by both frozen impact melt flows and debris. The melt formed as a result of the tremendous energy released in the impact event. As the crater equilibrated, the melt flowed to low spots and slowly cooled. What caused the spectacular curved cracks to form?
Perhaps the crater floor topography changed over time, fracturing the surface of the central melt pond deposit (right side of picture) and opening a series of parallel, arcuate tension (pull-apart) cracks. Or, perhaps as the melt cooled and solidified, the volume change opened the cracks. The LROC featured image on October 21 showed an adjacent portion of this same crater. Over time, LROC will image the whole crater allowing scientists to test these hypotheses and come to a clear understanding of how craters of this size form.
New LROC images of many craters from all over the Moon are showing that the deposition and evolution of impact melts is extremely complex, and melt ponds take many forms depending on local conditions.
Explore the whole LROC image HERE.
Serendipity Thumbnail (full image = 1000 x 1000 pixel) from LRO NAC image M110383422L, Oct. 30, 2009. "Frozen" impact melt "flows" on the floor of Moore F, a far side highlands crater. Image width = 600 m (61 cm /pixel) [NASA/GSFC/Arizona State University]
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