メルキュアの北極近くの水氷の証拠は,MESSENGER 中性子スペクトロメーターの測定から得られた
David J Lawrence1, William C Feldman, John O Goldsten
1The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA. david.j.lawrence@jhuapl.edu
まとめ
水星の極で水氷が確認され,MESSENGER宇宙船によって検出されました. 中性子とレーダーのデータは,より薄い表面層の下に,厚く水素が豊富な層,おそらく純粋な水氷を明らかにしています.
科学分野:
- 惑星科学は惑星科学である.
- アストロジオロジー アストロジオロジー
- 宇宙地化学 宇宙地化学
背景:
- 水星の北極地域には,レーダーで明るく見える堆積物が存在し,揮発性物質の存在を示唆しています.
- 水星の極点の恒久的な影の領域は,極端な温度変動のために,水氷を保持すると仮定されています.
研究 の 目的:
- ニュートロンスペクトロメトリーデータを用いて,水星の極性堆積物の組成と構造を調査する.
- 水星の極地における水氷の兆候である水素の存在と豊富さを決定する.
主な方法:
- MESSENGER宇宙船のニュートロンスペクトロメーターによる表熱および高速ニュートロン流量測定の分析.
- ニュートロンデータの統合と水星の極地堆積物の既存のレーダー観測.
主要な成果:
- 水星の北極地域からの中性子フルースの減少は,水氷の存在と一致しています.
- 中性子データは,水素濃度が低い表面層 (10-30cm厚) の下には水素濃度が高い層 (>10cm厚) があることを示している.
- 統合されたデータは,埋もれた層がほぼ純粋な水氷であり,上層が水と同等の水素を<25%含有しているモデルに最適です.
結論:
- この発見は,水星が永久に影を浴びている極地における水氷の大量の存在を強く支持している.
- 推論された水質量 (2 × 10 ^ 16 から 10 ^ 18 グラム) は,彗星または小惑星からの揮発性物質の配送と一致しています.
- この研究は,太陽系内部の水の歴史と分布に関する重要な洞察を提供します.
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