Leonard David's INSIDE OUTER SPACE

Illumination map of the south polar region of the Moon. Areas in black receive no sunlight, and areas in warmer colors are illuminated a greater fraction of the time.
Image credit: Base image mosaic from NASA, Arizona State University, and Applied Coherent Technology Corp.

New research casts a spotlight onto those dark, sunlight shy cold traps on the Moon – spots where water could be lurking as a valuable, exploitable resource.

Volatiles like water may exist in the shadows at the bottom of craters near the poles of the Moon.

However, the Moon has been on the receiving end of intense bombardment by high-velocity meteorites, and the subsequent bombardment by the rocks meteorite impacts kick up, a new research paper explains. “Crater-forming bombardment controls both the production and destruction of craters where volatiles may be safe.”

Informally tagged as Malapert massif, this feature is thought to be a remnant of the Moon’s south pole – Aitken basin rim, which formed more than 4 billion years ago. This peak (lower left) was picked as one of the Artemis III candidate landing regions for an expeditionary crew.
Image credit: NASA/Goddard Space Flight Center/Arizona State University

The research offers a model of how long volatile-harboring cold traps last on the Moon. That modeling suggests that small cold traps are extremely ephemeral, while large cold traps could last for geologic time.

The work — “The Age and Evolution of Lunar Micro Cold Traps at the Scale of Surface Exploration” – is authored by Emily Costello and Paul Lucey at the Department of Earth and Planetary Science, University of Hawai’i at Manoa in Honolulu, HI.

Lunar south pole – future Moon base location?
Credit: NASA

Production and destruction

“From our model, we can reason that 100 meter [nearly 330 feet] cold traps which formed 1 billion years ago may still be present today and may have captured the last 1 billion years of lunar volatile history,” the paper explains.

Those lunar micro cold traps that are less than 1 meter are extremely transient and last only thousands of years.

“Our model thus constrains the production and destruction timescales of cold traps,” the paper observes, “and can be used to develop expectations concerning the discoverability and history of lunar volatiles at exploration scales relevant to landers, rovers, and humans.”

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

Testable exploration

Given the future “re-booting” of the Moon and the projected zones for NASA Artemis expeditions to explore, cold traps can represent candidates for investigating both the origins and distributions of volatiles, while older — greater than 100 meter to 1 kilometer craters — may have been cold traps for geologic timescales, the paper notes.

The punch line: Larger cold traps persevere against the threat of obliteration longer than smaller cold traps.

If volatiles are discovered within sub-meter micro cold traps, Costello and Lucey add, the volatiles must have arrived over less than thousands of years timescales.

NASA’s Volatiles Investigating Polar Exploration Rover (VIPER) is to investigate the Nobile Region of Moon’s South Pole. Slated for liftoff late this year but may slip into 2025.
Image credit: NASA

The research team notes that the central conclusions of their work “hold and are both relevant to and testable by the landers, robots, and humans, who will explore the South Polar regions of the Moon.”

The research paper — “The Age and Evolution of Lunar Micro Cold Traps at the Scale of Surface Exploration” – published in AGU’s Geophysical Researcher Letters can be found at:

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GL105369