3:30 PM - 3:45 PM
[PPS08-19] Pressure Dependence of Thermal Conductivity in Lunar Regolith from Apollo17 and Its Implications for Lunar Heat Flow Estimation
Keywords:heat flow, regolith, thermal conductivity
We have organized an analysis team primarily focused on physical property measurements and obtained lunar regolith samples. The samples were collected from the Apollo 15 and 17 sites near the locations where the lunar crust heat flux had been measured. These samples, Fine Regolith (70000, 0161, and 15031), were collected in 5g amounts from each site.
To date, we have measured the thermal conductivity of the Apollo 17 regolith using a pressurized thermal conductivity measurement device (Sakatani et al., 2020) under vacuum and ambient conditions, up to a pressure of 150 kPa.
The results showed that, in an uncompressed state, the thermal conductivity was 0.004 W/m/K. Under the measured pressure range, the thermal conductivity increased approximately linearly with pressure, and the pressure dependence was about 10-5 (W/m/K/kPa). The crustal heat flow data from Langseth et al. (1976) assumed a thermal conductivity of 0.01 W/m/K for the lunar regolith. Based on the data obtained in this study, it suggests that the lunar crustal heat flow may be estimated to be approximately half of what was previously assumed, which could have significant implications for constraining the thermal history of the Moon.
references)
Langseth, M.G., Keihm, S., and Peters, K.(1976), Revised heat-flow values, Proc. Lunar Sci. Conf.(7th), 3143-3171.
Sakatani, N., Tanaka, S., & Arakawa, S. (2022). Development of a Small-Sized Line Heat Source Apparatus for the Thermal Conductivity Measurement of Extraterrestrial Soils. International Journal of Thermophysics, 43(6). https://doi.org/10.1007/s10765-022-03007-y
To date, we have measured the thermal conductivity of the Apollo 17 regolith using a pressurized thermal conductivity measurement device (Sakatani et al., 2020) under vacuum and ambient conditions, up to a pressure of 150 kPa.
The results showed that, in an uncompressed state, the thermal conductivity was 0.004 W/m/K. Under the measured pressure range, the thermal conductivity increased approximately linearly with pressure, and the pressure dependence was about 10-5 (W/m/K/kPa). The crustal heat flow data from Langseth et al. (1976) assumed a thermal conductivity of 0.01 W/m/K for the lunar regolith. Based on the data obtained in this study, it suggests that the lunar crustal heat flow may be estimated to be approximately half of what was previously assumed, which could have significant implications for constraining the thermal history of the Moon.
references)
Langseth, M.G., Keihm, S., and Peters, K.(1976), Revised heat-flow values, Proc. Lunar Sci. Conf.(7th), 3143-3171.
Sakatani, N., Tanaka, S., & Arakawa, S. (2022). Development of a Small-Sized Line Heat Source Apparatus for the Thermal Conductivity Measurement of Extraterrestrial Soils. International Journal of Thermophysics, 43(6). https://doi.org/10.1007/s10765-022-03007-y