Liquid water reservoir reported under Mars polar cap

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Discussion Overview

The discussion centers around the analysis of radar profiles suggesting the presence of a liquid water reservoir beneath the Mars polar cap. Participants explore the implications of this finding, including the nature of the materials that could reflect radar signals and the conditions necessary for liquid water to exist on Mars.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that the identified region is about 20-km wide and suggest that the results are consistent with water or water-laden sediments.
  • There is a question regarding whether materials like concrete, lumber, and clay would reflect as "water-laden" materials in radar analysis.
  • One participant expresses uncertainty about what specifically would reflect radar at the wavelengths used, suggesting that "water-laden sediments" implies a significant amount of water rather than just hydrated minerals.
  • A reference is made to Kathryn Sturman, who speculated that the findings might indicate more of an aquifer-like structure, contrasting with previous SHARAD data that did not show water.
  • Additional media coverage is mentioned, indicating broader interest in the topic.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of radar data and the nature of the materials involved, indicating that multiple competing perspectives remain without consensus.

Contextual Notes

The discussion includes assumptions about radar reflection properties and the conditions under which liquid water could exist on Mars, which are not fully resolved.

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The analysis is based on 29 radar profiles collected between May 2012 and December 2015. The identified region is about 20-km wide. The report acknowledges the results are consistent with with water or water-laden sediments. A brief discussion on the BBC (with no citations) asserted that temperatures are such that there must be substantial dissolved material to depress the freezing point that much.

Abstract
 
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Would concrete reflect as a "water-laden" material? Same question for lumber and clay?
 
stefan r said:
Would concrete reflect as a "water-laden" material? Same question for lumber and clay?
I do not know the details of what would reflect radar of the wavelengths they used, but to me "water-laden sediments" carries a connotation of much more water than hydrated minerals. I heard Kathryn Sturman (geophysicist with the University of Texas) on http://www.cbc.ca/player/play/1285450307799 (starting at 11:49) say it might be more like an aquifer.

Sturman mentioned (and the Physics World summary) notes that the SHARAD data of the same region (which was higher frequency radar and would have penetrated as deep) failed to show water.
 

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