Thermal and mechanical properties of the near-surface layers of comet 67P/Churyumov-Gerasimenko
Kührt, E.; Knollenberg, J.; Pelivan, I.; Grott, M.; Spohn, T.; Kaufmann, E.; Kargl, G.; Hagermann, A.; Ball, A. J.; Banaszkiewicz, M.; Grygorczuk, J.; Benkhoff, J.; Marczewski, W.; Seiferlin, K.; Hüttig, C.; Schrödter, R.; Kömle, N.; Kossacki, K. J.
Germany, Netherlands, Poland, United Kingdom, Austria, Switzerland
Abstract
Thermal and mechanical material properties determine comet evolution and even solar system formation because comets are considered remnant volatile-rich planetesimals. Using data from the Multipurpose Sensors for Surface and Sub-Surface Science (MUPUS) instrument package gathered at the Philae landing site Abydos on comet 67P/Churyumov-Gerasimenko, we found the diurnal temperature to vary between 90 and 130 K. The surface emissivity was 0.97, and the local thermal inertia was 85 ± 35 J m-2 K-1s-1/2. The MUPUS thermal probe did not fully penetrate the near-surface layers, suggesting a local resistance of the ground to penetration of >4 megapascals, equivalent to >2 megapascal uniaxial compressive strength. A sintered near-surface microporous dust-ice layer with a porosity of 30 to 65% is consistent with the data.