[P-PS08] Lunar Science and Exploration

[PPS08-P21] P-wave velocity and strain measurement of damaged basaltic rock samples under cryogenic temperatures

*daisuke asahina¹, Selahattin Akdag², Balazs Bradak³, Takahiro Funatsu⁴ (1.Geological survey of Japan/AIST, 2.Curtin University, 3.Kobe University, 4.Hazama Ando Corporation)

Keywords:cryogenic temperature, basaltic rock, p-wave velocity measurement, liquid nitrogen

The Moon has a unique environment that differs significantly from Earth, characterized by extreme temperature variations, the absence of an atmosphere, and low gravity. Ideally, physical property measurements should be conducted directly on the lunar surface. However, due to challenges related to transportation technology, cost, and securing energy for experimental equipment, such measurements are currently difficult to perform. As an alternative, simulating the lunar environment on Earth is considered. Nevertheless, previous attempts to replicate extreme temperature variations and high vacuum conditions have been limited, and few studies have conducted physical property tests under such conditions.

In this study, we investigated the mechanical properties of damaged Inada granite and basalt samples under extremely low-temperature conditions. Rock specimens were immersed in liquid nitrogen (LN2) while continuously measuring strain and P-wave velocity. To artificially create microcracks at different levels, the samples were subjected to high-temperature treatment ranging from 200°C to 800°C. The experimental results revealed that while intact rocks exhibit minimal changes in P-wave velocity under extremely low temperatures, samples with microcracks showed significant variations in both P-wave velocity and strain.