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Abstract:
NASA's InSight mission [1] has installed the first geophysical observatory on Mars, including a seismometer, a magnetometer, sensors to track the rotation of the planet, an atmosphere science package and a heat flow probe HP3 [2]. Cosmochemical and geophysical models [e.g., 3,4] suggest that the average Martian surface heat flow is around 25mW/m2and may vary across the surface between 17 and 50mW/m2. HP3 was planned to use a small penetrator - nicknamed the “mole” – to install a string of temperature sensors up to a depth between 3m and 5m. A radiometer to measure the surface radiation temperature complemented the package. Sensors on the mole would measure the thermal conductivity as a function of depth. Depending on the final depth reached, temperature was to be measured daily for a period of months up to one Martian year. Unfortunately, the mole failed to penetrate to the required depth because of unexpected soil properties. Instead, it was used as a penetrometer and thermal probe to measure the thermal and mechanical properties of the top 40cm of the Martian soil. Inversion of the seismic recordings of Marsquakes allowed an estimate of the variation of the near surface temperature with depth and of the heat flow [5,6]. These estimates are consistent with the estimates from the earlier models [3,4].
[1] Banerdt et al. 2020 doi:10.1038/s41561-020-0544-y
[2] Spohn et al. (2022) doi: 10.1007/s11214-022-00941-z
[3] Plesa et al. (2016) doi:10.1002/2016JE005126
[4] Smreakr et al (2019) doi.org/10.1007/s11214-018-0563-9
[5] Khan et al. (2021) doi:10.1126/science.abf2966
[6] Drilleau et al. (2022) doi:10.1029/2021JE007067
