Experimental studies of ice grain ejection by massive gas flow from ice and implications to Comets, Triton and Mars

Diana Laufer, Akiva Bar-Nun, Igal Pat-El, Ronen Jacovi

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

This is an experimental study of ice grain ejection when trapped gases are released from water ice. When ice is formed by adherence of water molecules at low temperatures, it forms an amorphous structure with many pores, where gas molecules can reside. When further ice layers are formed, the gases are trapped in the ice. Upon its warming-up, the ice structure changes, releasing fractions of the trapped gas. If they do not encounter obstacles, they are released quiescently by dynamic percolation. In a non-dense ice a huge flux of ice grains emanates from the ice, propelled by gas jets and covering its entire surface. When the overlying ice is denser, due to back-migration of water vapor during its sublimation, gas trying to escape from below cannot penetrate the dense ice and breaks it, producing non-circular craters and a chaotic terrain, as observed experimentally and in close encounters with Comets Wild 2, Tempel 1 and Hartley 2. These experimental findings explain several observations of Solar System bodies: ice grain ejection from Comets Temple 1 and Hartley 2. Also explained are the dark jets observed on Triton, where their ejection speed suggests a deep source. On Mars, dark streaks are observed in the southern pole in spring, most likely by plumes carrying dark dust, carried by winds and falling on the surface. As found by us experimentally, only frozen CO 2 covered by water ice or mixed with it will work to form jets, whereas pure frozen CO 2 will sublimate quiescently.

Original languageEnglish
Pages (from-to)73-80
Number of pages8
JournalIcarus
Volume222
Issue number1
DOIs
StatePublished - Jan 2013
Externally publishedYes

Bibliographical note

Funding Information:
This research was supported by Ministry of Science and Technology Grant 3-8349 . Special thanks to Zipi Rosen for computer assistance and to David Shtivelman for the new high-resolution electronics of the mass filter and for computer assistance.

Keywords

  • Comets
  • Comets, Nucleus
  • Mars, Polar caps
  • Triton

Fingerprint

Dive into the research topics of 'Experimental studies of ice grain ejection by massive gas flow from ice and implications to Comets, Triton and Mars'. Together they form a unique fingerprint.

Cite this