Artist’s view of two Artemis astronauts at work on the lunar surface.
Image credit: NASA

The “rebooting of the Moon” by human explorers is pegged for NASA’s Artemis III mission with the crew footing their way around the lunar south pole. The lunar south pole is located on the rim of Shackleton crater, a 13 mile (21 kilometer) diameter feature.

Moreover, the Moon’s south pole is surrounded by summits with high illumination that can provide access to solar power in a region that also contains permanently shadowed regions (PSRs). These sun-shy areas may harbor volatile elements that can be processed for crew consumables, radiation shielding, and propellant.

Image credit: NASA GSFC Arizona State University

A new study has identified areas of particular interest within the Artemis III candidate landing sites, where multiple samples of boulders and rock exposures can be collected by astronauts during a future mission.

Connecting ridge

An international team has analyzed imagery snapped by NASA’s powerful Lunar Reconnaissance Orbiter camera system. These images allow identification of features such as boulders and rocky craters and terrain around the south polar region including the “Connecting Ridge,” one of the Artemis III candidate landing sites.

Location of the south pole and Shackleton crater. White stars show the location of the south pole, site 001 (222.69°E, 89.45°S) and site 004 (204.27°E, 89.78°S). Pink square shows the location of the Artemis III candidate landing site, “Connecting Ridge”. Also shown as (a)–(c) is the lunar south pole and the points of interest of sites 001 and 004 in relation to Shackleton crater.
Image credit: ESA/Boazman, et al.

 

In geological terms, recently-formed craters that have boulders surrounding the crater are being eyed for sampling to better understand the geology of the area. The Artemis III candidate landing sites have a goodly number of boulders and rock exposures that can be investigated by astronauts during the future mission.

The new research paper – “The Distribution and Accessibility of Geologic Targets near the Lunar South Pole and Candidate Artemis Landing Sites” – has been published in the The Planetary Science Journal. Sarah Boazman, based at the European Space Agency’s ESTEC in The Netherlands, is lead author of the work.

 

Boulders, craters, rock exposures

According to the paper, boulders can be identified as bright, high contrast features with a shadow observed behind these features. Craters were identified as bowl-shaped depressions often seen as a dark circle as light cannot always reach the crater floor and rock exposures were identified as bright high contrast features often larger than boulders but casting little to no shadow.

Image credit: ESA/Boazman, et al.

“Transformative lunar science will be driven by the accessibility, recovery, and return to Earth of geological specimens,” the research paper explains. “Isolated boulders, rock exposures, and rocky craters at the lunar south pole all provide opportunities for geologic characterization and sampling of the lunar crust.”

What has been found is that boulder abundance decreases with increasing distance from the rim of Shackleton crater. “From that correlation, we infer that most of the boulders and rock exposures near Shackleton were deposited as ejecta by the Shackleton impact, and by later the reworking of that material during smaller impact events,” Boazman and colleagues explain in the paper.

Boulders were observed across the mapping area, the paper notes, with the highest densities concentrated along the rim of Shackleton crater and the Connecting Ridge between Shackleton and Henson craters.

Shown here is a rendering of 13 candidate landing regions for NASA’s Artemis III mission. Each region is approximately 9.3 by 9.3 miles (15 by 15 kilometers). A landing site is a location within those regions with an approximate 328-foot (100-meter) radius.
Image credit: NASA

Reachable areas

“Overall, there is a greater number of boulders, rock exposures, and rocky craters near the rim of Shackleton crater and the frequency of each of these features decreases with distance from Shackleton crater rim,” the paper points out. “As a result, there is greater opportunity to collect crystalline material along the Shackleton rim or the “Connecting Ridge” during a future mission to this region, as compared with more distant locations in the Shackleton ejecta deposit.”

Additionally, the researchers highlight areas that are accessible and show the distribution of features within these reachable areas.

Artistic depiction of Artemis astronauts at the lunar south pole carrying out early work to establish an Artemis Base Camp.
Image credit: NASA

“Investigations of the lunar south polar region should continue to assess the accessibility of features of interest, including isolated boulders, rock exposures, rocky craters, and PSRs, in preparation for upcoming missions to the area. Such investigations will provide crucial context for any future endeavors set to explore the south pole of the Moon,” the research paper concludes.

To access “The Distribution and Accessibility of Geologic Targets near the Lunar South Pole and Candidate Artemis Landing Sites” go to:

https://iopscience.iop.org/article/10.3847/PSJ/aca590/pdf

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