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The findings of Deep Impact on the structure and composition of Tempel-1 are compared with our experimental results on large (20 cm diameter and up to 10 cm high) samples of gas-laden amorphous ice which does not contain dust. The mechanical ~tensile strength inferred for Tempel-1: up to 12 kPa is close to our experimental findings of 2–4 kPa. This means that Tempel-1 is as fluffy as our very fluffy, talcum like, ice sample. The thermal inertia: 30<I<100 W?K?1?m?2?s1/2 is close to our value of 80. The density of 350±250 kg?m?3, is close to our value of 250–300 kg?m?3, taking into account an ice/silicate ratio of 1 in the comet, while we study pure ice. Surface morphological features, such as non-circular depressions and chaotic terrain, were observed in our experiments. The only small increase in the gas/water vapor ratio pre- and post-impact, suggest that in the area excavated by the impactor, the 135 K front did not penetrate deeper than a few meters. Altogether, the agreement between the findings of Deep Impact and our experimental results point to a loose agglomerate of ice grains (with a silicate-organic core), which was formed by a very gentle aggregation of the ice grains, without compaction. 相似文献
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Fulchignoni M. Ferri F. Angrilli F. Bar-Nun A. Barucci M.A. Bianchini G. Borucki W. Coradini M. Coustenis A. Falkner P. Flamini E. Grard R. Hamelin M. Harri A.M. Leppelmeier G.W. Lopez-Moreno J.J. McDonnell J.A.M. McKay C.P. Neubauer F.H. Pedersen A. Picardi G. Pirronello V. Rodrigo R. Schwingenschuh K. Seiff A. Svedhem H. Vanzani V. Zarnecki J. 《Space Science Reviews》2002,104(1-4):395-431
The Huygens Atmospheric Structure Instrument (HASI) is a multi-sensor package which has been designed to measure the physical
quantities characterising the atmosphere of Titan during the Huygens probe descent on Titan and at the surface. HASI sensors
are devoted to the study of Titan's atmospheric structure and electric properties, and to provide information on its surface,
whether solid or liquid.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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A Bar-Nun D Prialnik D Laufer E Kochavi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1987,7(5):45-47
The trapping of various gases by water ice at low temperatures (20-80K) and their release from the ice upon warming, was studied experimentally. The results of these experiments, together with a computation of the thermal evolution of a cometary nucleus, can explain the gas and dust jets which were observed to emanate from the nucleus of P/Halley. The experimental results are important also to the gas content of Titan. 相似文献
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V Dimitrov A Bar-Nun 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,19(7):1103-1112
The photochemistry of hydrocarbons in Titan's atmosphere is modeled by a comprehensive kinetic scheme, containing 732 elementary reactions and 147 species up to C60. Four groups of the hydrocarbons are considered: Polyacetylenes (PA), Polyvinyles (PV), Vinylacetylenes (VA) and Allenes (Polyenes). 相似文献
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