Leonard David's INSIDE OUTER SPACE

Image credit: NASA

Those deep dives by astronauts into the permanently shaded regions at the Moon’s south pole means working in areas that are among the coldest places in our solar system.

The super-cold regions on the Moon represent a novel operational environment for spacesuits. What’s more, the thermal interactions between the lunar surface and a comparatively warm spacesuit in a permanently shadowed crater may be a problem.

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

New research suggests that the temperature change of the regolith due to the presence of a warm spacesuit is large enough to influence the entrapment of volatiles present within sunlight-shy craters. There is substantial scientific curiosity about the nature of volatiles that are cold trapped in permanently shaded regions, also known as PSRs in lunar lingo.

Protect science objectives

“The absolute temperature increase can be large enough to release volatiles from their entrapment, which in turn may necessitate a spacesuit design that radiates less heat to protect science objectives,” explains life support specialist Claas Olthoff at Airbus Defense and Space in Germany. He was also a NASA Postdoctoral Fellow embedded in the Advanced Portable Life Support System Development project located at the NASA Johnson Space Center in Houston, Texas.

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

Olthoff is lead author of “Dynamic thermal interactions between spacesuits and lunar regolith in permanently shaded regions on the moon,” appearing in the journal, Acta Astronautica.

Thermal impact

Suited astronauts moving about on the Moon’s landscape will witness a changing environment from sunlight to shadow – within a few bootsteps.

“Extremely cold environmental temperatures create additional requirements in several areas of spacesuit and spacecraft design,” the paper explains. “For example, materials for the spacesuit soft goods must be selected that do not become stiff or brittle. If temperatures within the spacesuit cross the established thermal comfort or touch temperature limits, heaters may be required at strategic points within the pressure garment or the life support system.”

Astronauts explore lunar south pole crater. A water ice-rich resource ready for processing awaits?
Credit: NASA

Furthermore, as for the thermal impact of a warm object on the cold lunar regolith, small changes in surface temperature can cause volatile substances — like frozen water — to be released into the vacuum of space before they can be captured by a sample collection device, the research paper points out.

Thermal interaction

The research paper includes thermal analysis results from simulations using Virtual Spacesuit (V-SUIT), a MATLAB-based, dynamic thermal simulation tool that includes the Thermal Moon Simulator (TherMoS).

V-SUIT was created at the Technical University of Munich and consists of two major building blocks: A thermal simulation of the lunar environment and a simulation of the spacesuit itself and the human inside.

Spacesuit geometric model in V-SUIT.
Image courtesy of Claas Olthoff

From their results, it was concluded that there is significant thermal interaction between the spacesuit and the lunar surface. “The temperature change of the regolith due to the presence of the spacesuit is large enough to cause a noticeable change in effective sink temperature. However, the temperature change is not large enough to drive any design decisions on the spacesuit,” the research team concludes.

Further research

Olthoff and colleagues note there’s need for further research and experimentation to find out which lunar volatiles are most susceptible in specific surface compositions and at which temperatures.

By better appreciation of the thermal environment in these regions, that knowledge can inform the design process, the researchers observe, not only for spacesuits and rovers, but also help gauge the blueprinting of future moonwalking activities at the lunar south pole.

For more information on this research, go to – “Dynamic thermal interactions between spacesuits and lunar regolith in permanently shaded regions on the moon” at:

https://www.sciencedirect.com/science/article/abs/pii/S0094576522006737?via%3Dihub