In situ thermal conductivity measurements of Titan's lower atmosphere |
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Authors: | B Hathi AJ Ball PM Daniell A Hagermann RD Lorenz MC Towner |
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Institution: | a PSSRI, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom b Polish Academy of Sciences, Ul. Bartycka 18 A, Warzawa 00716, Poland c Phyworks Ltd, Bristol, BS34 8HP, United Kingdom d Research Institute for Industry, School of Engineering Sciences, The University of Southampton, Southampton, SO17 1BJ, United Kingdom e Space Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA |
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Abstract: | Thermal conductivity measurements, presented in this paper (Fig. 3), were made during the descent of the Huygens probe through the atmosphere of Titan below the altitude of 30 km. The measurements are broadly consistent with reference values derived from the composition, pressure and temperature profiles of the atmosphere; except in narrow altitude regions around 19 km and 11 km, where the measured thermal conductivity is lower than the reference by 1% and 2%, respectively. Only single data point exists at each of the two altitudes mentioned above; if true however, the result supports the case for existence for molecules heavier than nitrogen in these regions (such as: ethane, other primordial noble gases, carbon dioxide, and other hydrocarbon derivatives). The increasing thermal conductivity observed below 7 km altitude could be due to some liquid deposition during the descent; either due to condensation and/or due to passing through layers of fog/cloud containing liquid nitrogen-methane. Thermal conductivity measurements do not allow conclusions to be drawn about how such liquid may have entered the sensor, but an estimate of the cumulative liquid content encountered in the last 7 km is 0.6% by volume of the Titan's atmosphere sampled during descent. |
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Keywords: | Atmospheres composition Abundances composition Titan Instrumentation |
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