大気と地殻のD/H比から火星の水庫の進化
1Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor 48109, USA.
Nature
|March 30, 1995
まとめ
古代の火星は,新しい隕石のデータによると,潜在的に数百メートルの深さの広大な水庫を保持していました. これは,かつて湿った惑星であったという地質学的証拠を裏付け,大気中の水素の脱出不一致を解決する.
科学分野:
- 惑星科学は惑星科学である.
- 地質化学 地質化学
- 天体生物学 アストロバイオロジー
背景:
- 古代の火星には河川のネットワークがあり,それは30億年以上前の暖かく湿った過去を示しています.
- 地質学的証拠は,火星の地殻の数百メートルの深さにある,最近の,惑星規模の水貯蔵庫を示唆しています.
- 大気中の水素の脱出率と同位体分子は,過去と現在の地殻の水量 (0.5~6m) がはるかに小さいことを示唆している.
研究 の 目的:
- 火星の地質学的水の推定値と大気中の水素データの不一致を調和させるため.
- SNC隕石から得られた新しいデウテリウムと水素の比率測定を用いて,火星の貯水池の進化を抑制する.
主な方法:
- SNC隕石 (火星起源) の水性鉱物におけるデュテリウムと水素の比率の分析.
- 同位体組成と大気の脱出率に基づいて地殻水貯水池のサイズをモデリングする.
主要な成果:
- 新しい隕石のデータにより,現代の火星の地殻の大きな貯水池 (少なくとも数メートルの深さ) が必要とされる.
- 火星の大気中のデウテリウム濃縮は,古代の地殻の水貯蔵庫が数百メートルの深さであったことを示唆しています.
- これらの発見は,火星に古代の水が存在していたという地質学的証拠と一致しています.
結論:
- SNC隕石のデウテリウムと水素の比率は,火星の水の歴史に重要な制約を与える.
- 現在,地質学的および同位体学的証拠の両方から,古代の火星に重要な水貯蔵庫があったことが一貫して示されています.
- 火星の水の進化を理解することは,その過去の居住性を評価する鍵です.
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