Leonard David's INSIDE OUTER SPACE

Image credit: ESA

New research is being called the first detailed examination of sintering “real” lunar regolith. Used in the work were precious Moon samples returned to Earth by Apollo 11, Apollo 15 and Apollo 16 moonwalkers.

There is growing interest in establishing a permanently crewed base on the Moon. Lunar regolith sintering has gained significant attention as a technique for constructing on-the-spot radiation- and meteoroid-resistant habitats, roads or landing pads and other infrastructure or tools.

Apollo 16 photo shows on-site gathering of lunar specimens.
Credit: NASA

“Sintering” allows the transformation of loose powdered material into a consolidated mass using heat and/or pressure. The technique fuses particles together without melting the material to the point of liquefaction.

The term “regolith” refers to the topside layer on the Moon that covers solid rock on the lunar surface which is loose, heterogeneous, superficial deposits.

Apollo pellets

The work involved sintering of eight 0.5 g pellets from four Apollo regolith samples: 10084, 15601, 60501, and 67461. Each Apollo pellet sample was selected to examine the compositional differences between mare and highland material on the Moon, as well as the differences due to sample maturity.

Apollo 15’s Dave Scott and Lunar Rover at a Hadley Rille location.
Image credit: NASA

This research was supported by the European Space Agency (ESA) internal research funding. Findings from the work have been published in the journal Materials Today Advances.

Leader of the work is Bethany Lomax of ESA’s European Space Research and Technology Center (ESTEC) in Noordwijk, the Netherlands.

Comparison of samples

“The crux of it for me – regolith can be sintered. But different lunar regoliths behave differently when we try to process them,” explains James Carpenter, head of the Lunar Science Office within ESTEC, and a co-author of the paper, “Sintering lunar regolith pellets: a comparison of four samples from Apollo 11, 15, and 16.”

“In general if we want to work with regolith for construction or ISRU [In-situ Research Utilization] then the specifics of the materials we find at a site matter,” Carpenter explains. “And whatever we think we are learning from simulants needs to be tested against real materials.”

Inside look at one idea the European Space Agency is exploring to fabricate a lunar habitat.
Image credit: ESA/ Foster + Partners

Simulants are synthesized from terrestrial materials, concocted to mimic the chemical, mechanical or engineering properties of materials available on the Moon.

“While many high-quality simulant materials exist, lunar regolith has properties unique to space weathering processes in the lunar environment, which are challenging to mimic on Earth,” states Lomax and colleagues.

Sintering behavior

“Lunar regolith sintering is proposed as a technique to produce consolidated objects on the lunar surface from locally sourced materials,” said Carpenter. “Understanding the sintering behavior of real lunar regolith is necessary to optimize this process, however, due to the precious nature of samples it is rare for material to be allocated for such destructive studies.”

According to Carpenter, results of the new work show that real lunar regolith sinters at temperatures comparable to lunar regolith simulants sintered under the same conditions.

“This work represents the first detailed examination of sintering real lunar regolith,” Carpenter said.

To access this pioneering work – “Sintering lunar regolith pellets: a comparison of four samples from Apollo 11, 15, and 16” – go to:

https://www.sciencedirect.com/science/article/pii/S2590049825000657

ICON’s Project Olympus is a space-based construction system under active development to support the future exploration of the Moon with NASA and for commercial lunar construction projects. The Olympus construction system is being designed and engineered to construct landing pads, roadways, non-pressurized structures, 
and pressurized habitats.
Image credit: ICON