Comparison between the findings of Deep Impact and our experimental results on large samples of gas-laden amorphous ice

A. Bar-Nun, I. Pat-El, D. Laufer

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

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. The mechanical ∼tensile strength inferred for Tempel-1: ∼65 Pa is 30 to 60 times smaller than our experimental findings of 2-4 kPa. This means that Tempel-1 is even fluffier than our very fluffy, talcum like, ice sample. The thermal inertia: I < 100  W K-1 m-2 s1 / 2 is very close to our value of 80. The density of 620 + 470 / - 330  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, chaotic terrain and smooth surfaces, 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.

Original languageEnglish
Pages (from-to)321-325
Number of pages5
JournalIcarus
Volume187
Issue number1
DOIs
StatePublished - Mar 2007
Externally publishedYes

Bibliographical note

Funding Information:
This research was supported by the Israel Ministry of Science, through the Israel Space Agency and by the US–Israel Binational foundation (BSF). We thank Kevin Housen and Michael A'Hearn for helpful comments.

Keywords

  • Comets
  • composition
  • dynamics

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