Lunar Reconnaissance Orbiter Camera

Traversing the Shackleton de Gerlache Ridge

Oblique view of Shackleton de Gerlache Ridge M1348682369
Amazing oblique view of the rim of Shackleton crater (on the left) and the Shackleton - de Gerlache ridge that runs from middle left to upper right. The south pole is near the small, sharp, bright crater on the rim of Shackleton (left side of the image about 25% up from the bottom). This spectacular area is under consideration for the Artemis III crewed landing scheduled for later in this decade. Ridgeline is about 14 kilometers long, NAC M1348682369LR [NASA/GSFC/Arizona State University].

 

The south pole of the Moon is a unique place where the Sun barely ever creeps above the horizon. For this reason, floors of craters such as 20 kilometers wide Shackleton crater have been locked in perpetual shadow for billions of years and are framed by peaks where the Sun and Earth set for only brief periods each month. Crewed landing missions could therefore enjoy the best of both worlds, utilizing volatiles such as water ice stored in the extremely cold permanently shadowed regions (PSRs) while maintaining easy access to solar energy and Earth communications. Therefore, an ancient ridge between the craters Shackleton and de Gerlache [“duh Gerlush”] has been identified as a potential landing area for future crewed and robotic landings by NASA, such as Artemis III and Intuitive Machines-2 Nova C lander.

Going back to time-proven traditions of the Apollo missions, geomorphic maps at a very large scale are needed to effectively guide and inform landing site selection, traverse planning, and in-situ landscape interpretation by rovers and astronauts. We assembled a geomorphic map covering a candidate landing site on the Shackleton-de Gerlache-ridge and the adjacent rim of Shackleton crater. The map was derived from one meter per pixel NAC image mosaics and five meters per pixel digital elevation models (DEM) from Lunar Orbiter Laser Altimeter (LOLA) ranging measurements.

Small area of geomorphic map
Small portion of the newly published geomorphic map of the Shackleton de Gerlache ridge region of the Moon.

At our mapping scale (1:8000), almost all visible morphology and texture are either a direct result of small impacts or an indirect result of larger impacts. Small impact craters range from muted to fresh, with or without surrounding ejecta affecting the landscape (solid black and yellow circles within the map). The texture resulted from mass wasting processes on the sloped walls of old craters within the upper regolith (blue-green and brown units). These textures have been referred to as “elephant hide” terrain, a common occurrence on the Moon that has the potential to inform on ground stability and thus hazard avoidance.

High resolution view of rim of Shackleton crater
The intersection of Shackleton - de Gerlache ridge and the rim of Shackleton crater is an area of high scientific interest (portion of NAC mosaic, 750 m wide, 89.684°S, 196.739°E). The white arrows point to larger (~8 m wide ) blocks that litter the surface and would be primary targets for geologic exploration. These blocks were likely ejected by the Shackleton impact event and might, thus, be pieces of lunar crust that could reveal the regional lithology, the age of Shackleton, and possibly also the age of the South Pole-Aitken basin. The yellow circle marks a relatively flat area that offers a direct line of sight onto the Shackleton crater floor. From this point, utilizing light reflected from the inner wall, a landed asset could conduct observations of the Shackleton PSR [NASA/GSFC/Arizona State University].

Link to publication: https://www.sciencedirect.com/science/article/pii/S0019103522000835

Link to full-scale map poster: https://ars.els-cdn.com/content/image/1-s2.0-S0019103522000835-mmc2.pdf

 

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