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The Strength of Cometary Surface Material: Relevance of Deep Impact Results for Philae Landing on a Comet

  • J. Biele
  • S. Ulamec
  • L. Richter
  • E. Kührt
  • J. Knollenberg
  • D. Möhlmann
  • the Philae Team
Part of the Eso Astrophysics Symposia book series (ESO)

abstract

We discuss the Deep Impact estimates of strength of the surface material of comet Tempel 1. It appears doubtful that the tensile strength is as low as originally published. The method applied neglects the weakening by the shock wave, the acceleration by gas and the ongoing discussion whether gravity or strength craters are consistent with the observations. The various definitions of strength (tensile, shear, compressive, dynamic strength) and its size-dependency are discussed. Even for extremely low cohesion, a lower limit of ≈ 1 kPa for the quasi-static compressive strength at dm-scales is derived; far more likely is a compressive strength of the order of ≈ 10 kPa for very soft comet surfaces. The Rosetta lander, Philae, will touchdown on comet Churyumov-Gerasimenko in November 2014. A soft comet surface with a compressive strength ⩾ 4 kPa indeed facilitates landing and leads to a penetration of the order of only 20 cm according to our model calculations.

Keywords

Compressive Strength Landing Gear Cometary Nucleus Deep Impact Cometary Material 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • J. Biele
    • 1
  • S. Ulamec
    • 2
  • L. Richter
    • 1
  • E. Kührt
    • 2
  • J. Knollenberg
    • 2
  • D. Möhlmann
    • 2
  • the Philae Team
    1. 1.DLRInstitute for Space Simulation CologneGermany
    2. 2.DLRInstitute for Planetary ResearchBerlinGermany

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