Wednesday, June 15, 2011

Polygonal fractures on Tycho ejecta

Along with a new close-up of Surveyor 7

Polygonal fractures on a flow lobe of impact melt splashed out of Tycho crater about 109 million years ago. Image scale 0.52 meters/pixel, incidence angle is 69.1°, LROC Narrow Angle Camera (NAC) observation M150598504R, LRO orbit 7327, January 25, 2011. See the full-size LROC Featured Image HERE [NASA/GSFC/Arizona State University].

Hiroyuki Sato
LROC News System

Tycho is a young and prominent rayed crater on the lunar nearside. During the impact that formed Tycho crater a large mass of impact melt was thrown out on its north side that resulted in a series of beautiful flow patterns. The melt ponded in several topographic lows, and as they cooled their upper crusts fractured, often in polygonal patterns.

Today's Featured Image shows a set of crisply preserved polygonal fractures. Small chains of pit chains are also seen in conjunction with the fractures. Are these pits nascent fractures that never fully developed? Or perhaps partially collapsed tubes that melt flowed through? If the latter, might there be open passages that astronauts could venture into and explore?

LROC WAC 100m/pixel mosaic around Tycho crater over-lain by WAC color coded DTM 500m/pixel (DLR, Germany). Image center is 43.3°S latitude, 348.6°W longitude. Blue box and yellow star indicate the locations of today's full Featured Image. See the full-size LROC Wide Angle Camera/DEM mosaic HERE [NASA/GSFC/Arizona State University].

In January 1968, Surveyor VII (arrow) landed only a kilometer from the impact melt pond immediately to its northeast, caught once again by LROC's NAC, almost exactly forty-three years later. The plucky vehicle's distinctive square solar panel and profile can easily be seen in its long shadow (see full-resolution crop below) near the center of the full LROC NAC frame from which the LROC Featured Image above was snipped [NASA?GSFC/Arizona State University].

Surveyor VII - A very successful lander, the last U.S. unmanned lunar lander and last of an outstanding program is caught standing sentinel awaiting a valuable examination of the effects of nearly 575 two-week long blistering hot lunar days and an equal number of two-week long numbingly cold lunar nights [NASA/GSFC/Arizona State University].

Explore the polygonal fractures (and find Surveyor 7) north of Tycho by viewing the full NAC image!

The topographic color was produced as a by-product of stereo analysis of the WAC global dataset. Producing the global Digital Elevation Model (DEM) is a big job being led by LROC team members at the German Aerospace Center (DLR; English version) in Berlin.

Related posts:
Look at that flow!
Fractured Impact Melt
Fragmented Impact Melt
Natural Bridge on the Moon!
The Floor of Tycho - Constellation ROI
Surveyor 7: our fragile lunar LDEF
LOLA's Tycho and the Apollo era

No comments: