Norwegian Geotechnical Institute uses CT scans to study lunar soils

Between 1967 and 1972, NASA embarked on a remarkable series of space missions to the moon, transporting back nearly 400 kilograms of precious lunar soil samples. Today, NGI, the Norwegian Geotechnical Institute, is utilizing advanced CT-scanning technology to analyze 10,000 lunar particles obtained from the Apollo expeditions. This groundbreaking research aims to shed light on the behavior of lunar soils and their response to engineering structures when humans eventually establish a presence on the lunar surface.

NASA’s upcoming Artemis missions are set to return astronauts to the moon after a hiatus of 50 years, presenting an unprecedented opportunity for humans to live and work on our celestial neighbor for extended periods. However, the construction of a habitable lunar base poses numerous challenges. Understanding the forces the lunar ground can withstand is crucial in designing and constructing such a base. Additionally, comprehending how materials, including individual grains of lunar soil, behave under the unique lunar conditions is of utmost importance.

A field of study known as selenotechnics, analogous to geotechnics on Earth, focuses on investigating the behavior of lunar soils, or regolith. By delving into the fundamental properties of lunar soils—such as strength and grain shape—researchers at NGI are working to establish a comprehensive and up-to-date knowledge base. This vital knowledge will greatly contribute to the preparation of future space missions and assist those involved in building infrastructure or delivering equipment, including robotic rovers.

Dylan Mikesell, a senior geophysicist and principal investigator at NGI, emphasizes the significance of understanding lunar material properties for obtaining realistic and accurate information about ground conditions on the moon. The ongoing efforts to create an updated knowledge base at NGI hold immense value for the advancement of space exploration and the successful realization of lunar missions.

Moon dust and extreme temperatures

When Neil Armstrong took humanity’s inaugural lunar steps on July 21, 1969, he embarked upon a realm shrouded in mystery. The lunar landscape that greeted him and the Apollo 11 mission was adorned with regolith—a peculiar lunar soil blend composed of dust, fragments, and larger particles. This regolith layer could reach depths of up to 10 meters, masking the moon’s surface.

The moon’s stark contrast from Earth became evident as Armstrong stepped onto its soil. Devoid of an atmosphere and experiencing significantly lower gravity, the lunar environment presented a unique set of challenges. Moreover, the minuscule presence of water on the moon existed solely as ice, frozen amidst the soil particles.

Unlike our planet, where wind and water erosion gradually smooth geological materials, the moon lacked such forces in motion. Consequently, lunar soil grains retained razor-sharp edges, posing a potential hazard to equipment like space suits. Additionally, the lunar climate exhibited extreme temperature fluctuations, ranging from a bone-chilling minus 130°C to scorching highs exceeding 120°C. The moon’s surface was subject to solar radiation surpassing 200 times the levels experienced on Earth, with atmospheric particles descending upon the landscape unhindered by a protective magnetic field absent on the moon.

Another intriguing lunar dissimilarity lies in how static electricity facilitates the cohesion of two soil grains. On Earth, water plays a pivotal role in particle binding, while the moon’s unique conditions rely on static charges to foster soil clumping.

These disparities between lunar and terrestrial grounds underscore the remarkable distinctions encountered by astronauts and highlight the importance of understanding the lunar environment for future missions and the development of lunar infrastructure.

Mimicking conditions on the moon

While venturing to the moon as lunar geotechnical engineers remains beyond our reach, NGI leverages advanced testing methods for Earth’s ground conditions. These methods serve as a foundation for analyzing the lunar terrain, according to Luke Griffiths, a senior researcher at NGI.

Through CT scanning, the 10,000 particles obtained from the Apollo missions are meticulously examined, and the resulting data is transmitted to NGI. Skilled experts extract lunar particles from the CT scans, constructing a comprehensive catalog of three-dimensional grains. These grain data sets enable the calibration of computer simulation models with NGI’s laboratory tests conducted on Earth. However, replicating the moon’s unique conditions, including reduced gravity, presents a challenge when determining and testing material properties.

By meticulously pushing laboratory instruments to their limits, NGI endeavors to replicate conditions found five meters beneath the moon’s surface. However, simulating the moon’s actual surface becomes unfeasible, halting the instruments in their tracks. Consequently, the knowledge gap regarding surface conditions must be bridged through computer simulations until experiments can be conducted on the moon itself, as explained by Alex X. Jerves, a postdoctoral researcher at NGI.

The vast distance of 384,400 kilometers between Earth and the moon renders it impractical to transport all essential resources, such as water and energy, from our planet. Hence, understanding the resources present on the moon and devising effective utilization strategies becomes crucial, a concept known as In Situ Resource Utilization (ISRU). This encompasses harnessing the sun as an energy source on the moon, comprehending the lunar landscape, and identifying the metals and minerals within the regolith, mountains, and rocks. Enhancing our knowledge in these areas becomes pivotal to maximize the moon’s resources.

Norwegian expertise aims to play a significant role in addressing these challenges. The European Space Agency’s strategy for 2030 emphasizes the importance of European knowledge communities and industries in developing vital ISRU technology. NGI, on behalf of the Norwegian Space Agency, has conducted a comprehensive assessment of Norwegian capabilities within ISRU, encompassing research, development, and commercial sectors. The study concludes that Norway’s extensive experience in collecting, processing, and storing natural resources from the energy and mining sectors, combined with specialized contributions in various technological domains, positions the country well to contribute to the future utilization of lunar resources.

In the words of Sean Salazar, senior researcher at NGI, “Norway is ideally positioned to play a significant role in maximizing the utilization of the moon’s resources.”

Source: NGI Norwegian Geotechnical Institute

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