Thermal and mechanical properties of the near-surface layers of comet 67P/Churyumov-Gerasimenko

• DOI: 10.1126/science.aab0464
• Publication Date: 2015-07-30T19:03:21Z
• Authors: T. Spohn; J. Knollenberg; A. J. Ball; M. Banaszkiewicz; J. Benkhoff; M. Grott; J. Grygorczuk; C. Hüttig; A. Hagermann; G. Kargl; E. Kaufmann; N. Kömle; E. Kührt; K. J. Kossacki; W. Marczewski; I. Pelivan; R. Schrödter; K. Seiferlin
• Keywords: Institut für Planetenforschung; Kometen; 67P Churyumov-Gerasimenko; comets 67P/Churuympv Gerasimenko; temperature; 530; Philae; 01 natural sciences; MUPUS; 13. Climate action; Rosetta; 0103 physical sciences; surface

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 −1 s -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.