154-2 High Temperature Thermal Conductivity of Antarctic CM, CK and CV Chondrites and How They Relate to Other Carbonaceous Chondrites

Session: Asteroid Observations, Return Missions, and Meteoritics: Interweaving Perspectives and Data (Posters)

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Thermal properties are one of the inputs to determine the survivability of a meteor through Earth’s atmosphere. Thermal conductivity is a mathematical input used to calculate ablation rates because of the non-uniform temperature of the various materials. Ablation is used to determine mass loss and energy deposition into the atmosphere from meteor breakup, as a result thermal conductivity is indirectly used. High temperature thermal conductivity is used to determine the time to reach melt phase during atmospheric entry.

Thermal conductivity of ALH 83100 (CM1/2), EET 92002 (CK5), and BUC 10933 (CV_red3) are made and compared to previously measured carbonaceous chondrites. Measured over the range of 300K to 800K. Conductivity is measured using the comparative cut-bar method. Surface temperatures simulations are performed with the Icarus material response solver code and a one-dimensional grid that represent the stagnation point on the surface of a meteoroid. Surface is treated with an aerothermal boundary condition using the typical assumption of radiative equilibrium.

ALH 83100 thermal conductivity profile goes from 3.0 ±0.2 W/m-K at 300K to 1.4 ±0.2 W/m-K at 800K. Profile is between the values of common mineral components, but more like olivine until 700K where it flips and operates like pyroxene. EET 92002 and BUC 10933 start lower than pyroxene at comparable temperatures, with EET 92002 at 0.66 ±0.28 W/m-K and BUC 10933 at 0.99 ±0.10 W/m-K at 300K. Thermal conductivity profile for these meteorites stays flat as temperature increases to 800 K. Flat nature causes the meteorites to have a thermal conductivity similar to that of pyroxene at highest temperatures. All three meteorites do have evaporites from terrestrial weathering. Some evaporite minerals have high thermal conductivity above 4 W/m-K, which could result in raising the conductivity at lower temperatures. Above 600K the evaporites in meteorites start to be destroyed. Evaporite effect is only seen on ALH 83100.

Simulations model time it takes for the surface of meteors to reach melt phase conditions during atmospheric entry. Measurement of high temperature thermal conductivity has major changes on the time it would take to reach these conditions. Terrestrial analogs take ~0.002 seconds, while measured data shows slowest of 0.0018 seconds for CR and fastest of 0.0012 seconds for CK meteorites. This would suggest higher ablation rates.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10404

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