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火星の新衝突クレーターから生じた中緯度の地上の氷の分布
Shane Byrne1, Colin M Dundas, Megan R Kennedy
1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA. shane@lpl.arizona.edu
Science (New York, N.Y.)
|September 26, 2009
まとめ
新しい衝突クレーターは,火星の中緯度における地下水の氷を明らかにしています. この発見は,火星は以前にモデル化されたよりも多くの氷を保持し,深い氷の埋蔵の可能性を示唆しています.
科学分野:
- 惑星科学は惑星科学である.
- 地質学 地質学 地質学
- 天体生物学 アストロバイオロジー
背景:
- 地下水の氷は,火星の気候の歴史を理解し,潜在的な人類の探査のための重要な資源です.
- 以前の研究では,主に極域や浅瀬で,水氷の存在が示されていた.
研究 の 目的:
- 火星の中緯度における地下水の氷の存在とアクセシビリティを調査する.
- 衝突クレーターによって発掘された水氷の積層の深さと分布を決定する.
主な方法:
- 火星軌道探査機からの高解像度画像の分析により,新たな衝突クレーターが発見される.
- 発掘された材料の組成を決定するために,光譜分析 (近赤外線) を行う.
- サブリメーション率と氷の純度を評価するための熱モデリング.
- 氷床の深さを気候モデルと比較した結果.
主要な成果:
- 5つの中緯度の場所にある新しい衝突クレーターは,水氷と一致する明るい,スペクトル的に独特な物質を暴露しました.
- 何ヶ月にもわたって露出した氷の色が消えるのが観察され,亜高層化が確認された.
- 熱モデリングは,ミリメートルスケールの昇華を示し,土壌の孔内の氷ではなく,きれいな,比較的純粋な氷を示唆しました.
- 導出された氷床の深さは,大気の過去より高い水蒸気含有量を含むモデルと一致しています.
- 隕石坑は氷の中に数メートルも浸透した可能性があり,氷の垂直的な異質性が顕著であることを示している.
結論:
- 地下水の氷は,火星の中緯度で10cmの深さで存在し,衝突クレーターを通してアクセスできます.
- 観測された氷は比較的純粋で,その存在は,過去の大気中の水分含有量がより高いモデルをサポートしています.
- インパクトクレーターは,火星の地下氷を以前未試の深さまで探査するためのユニークな方法を提供し,異質性を明らかにします.
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